ZSI: The Zolera Soap Infrastructure
Developer's Guide

Rich Salz,

rsalz@datapower.com
blunck@python.org

Christopher Blunck

Release 2.0.0
February 01, 2007

COPYRIGHT

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, provided that the above copyright notice(s) and this permission notice appear in all copies of the Software and that both the above copyright notice(s) and this permission notice appear in supporting documentation.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Except as contained in this notice, the name of a copyright holder shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization of the copyright holder.

Acknowledgments

We are grateful to the members of the soapbuilders mailing list (see http://groups.yahoo.com/soapbuilders), Fredrik Lundh for his soaplib package (see http://www.secretlabs.com/downloads/index.htm#soap), Cayce Ullman and Brian Matthews for their SOAP.py package (see http://sourceforge.net/projects/pywebsvcs).

We are particularly grateful to Brian Lloyd and the Zope Corporation (http://www.zope.com) for letting us incorporate his ZOPE WebServices package and documentation into ZSI.

Abstract:

ZSI, the Zolera SOAP Infrastructure, is a Python package that provides an implementation of SOAP messaging, as described in The SOAP 1.1 Specification. In particular, ZSI parses and generates SOAP messages, and converts between native Python datatypes and SOAP syntax. It can also be used to build applications using SOAP Messages with Attachments. ZSI is ``transport neutral'', and provides only a simple I/O and dispatch framework; a more complete solution is the responsibility of the application using ZSI. As usage patterns emerge, and common application frameworks are more understood, this may change.

ZSI requires Python 2.3 or later and PyXML version 0.8.3 or later.

The ZSI homepage is at http://pywebsvcs.sf.net/.

1. Introduction

ZSI, the Zolera SOAP Infrastructure, is a Python package that provides an implementation of the SOAP specification, as described in The SOAP 1.1 Specification. In particular, ZSI parses and generates SOAP messages, and converts between native Python datatypes and SOAP syntax.

ZSI requires Python 2.3 or later and PyXML version 0.8.3 or later.

The ZSI project is maintained at SourceForge, at http://pywebsvcs.sf.net. ZSI is discussed on the Python web services mailing list, visit http://lists.sourceforge.net/lists/listinfo/pywebsvcs-talkto subscribe.

For those interested in using the wsdl2py tool see the Users Guide, it contains a detailed example of how to use the code generation facilities in ZSI.

For those interested in a high-level tutorial covering ZSI and why Python was chosen, see the article http://www.xml.com/pub/a/ws/2002/06/12/soap.html, written by Rich Salz for xml.com.

SOAP-based processing typically involves several steps. The following list details the steps of a common processing model naturally supported by ZSI (other models are certainly possible):

ZSI takes data from an input stream and parses it, generating a DOM-based parse tree as part of creating a ParsedSoap object. At this point the major syntactic elements of a SOAP message -- the Header, the Body, etc. -- are available.
The application does header processing. More specifically, it does local dispatch and processing based on the elements in the SOAP Header. The SOAP actor and mustUnderstand attributes are also handled (or at least recognized) here.
ZSI next parses the Body, creating local Python objects from the data in the SOAP message. The parsing is often under the control of a list of data descriptions, known as typecodes, defined by the application because it knows what type of data it is expecting. In cases where the SOAP data is known to be completely self-describing, the parsing can be dynamic through the use of the TC.Any class.
The application now dispatches to the appropriate handler in order to do its ``real work.'' As part of its processing it may create output objects
The application creates a SoapWriter instance and outputs an initial set of namespace entries and header elements.
Any local data to be sent back to the client is serialized. As with Body parsing, the datatypes can be described through typecodes or determined dynamically (here, through introspection).
In the event of any processing exceptions, a Fault object can be raised, created, and/or serialized.

Note that ZSI is ``transport neutral'', and provides only a simple I/O and dispatch framework; a more complete solution is available through the use of included WSDL tools (wsdl2py), but otherwise this is the responsibility of the application using ZSI. As usage patterns emerge, and common application frameworks are more understood, this may change.

Within this document, tns is used as the prefix for the application's target namespace, and the term element refers to a DOM element node.)

1.1 How to Read this Document

Readers interested in using WSDL and clients to web services, and those intending on implementing web services based on existing WSDL should refer to the Users Guide. Others interested in developing the simplest SOAP applications, or spending the least amount of time on building a web services infrastructure should read chapters 2, 3, and 10 of this document. Readers who are developing complex services, and who are familiar with XML Schema and/or WSDL, should read this manual in order. This will provide them with enough information to implement the processing model described above. They can skip probably skip chapters 2 and 10.

ZSI has the capability to process WSDL definitions and XML Schema documents (described in The Web Services Description Language and XMLSchema 1.0) and generate typecodes automatically. For more information see the Users Guide.

2. Examples

This chapter contains a number of examples to show off some of ZSI's features. It is broken down into client-side and server-side examples, and explores different implementation options ZSI provides.

2.1 Server Side Examples

2.1.1 Simple example

Using the ZSI.dispatch module, it is simple to expose Python functions as web services. Each function is invoked with all the input parameters specified in the client's SOAP request. Any value returned by the function will be serialized back to the client; multiple values can be returned by returning a tuple.

The following code shows some simple services:

#!/usr/local/bin/python2.4
# SOAP Array

def hello():
    return ["Hello, world"]

def echo(*args):
    return args

def sum(*args):
    sum = 0
    for i in args: sum += i
    return [sum]

def average(*args):
    return [sum(*args) / len(args)]

from ZSI import dispatch
dispatch.AsCGI(rpc=True)

Each function defines a SOAP request, so if this script is installed as a CGI script, a SOAP message can be posted to that script's URL with any of hello, echo, or average as the request element, and the value returned by the function will be sent back. These functions expect and return SOAP-ENC:arrayType instances which are marshalled into python list instances, this script interoperates with the client.Binding. For more information see Appendix A.

The ZSI CGI dispatcher catches exceptions and sends back a SOAP fault. For example, a fault will be sent if the hello function is given any arguments, or if the average function is given a non-integer.

Here is another example but using SOAP-ENC:Struct instances which are marshalled into python dict instances, this script interoperates with the client.NamedParamBinding. For more information see Appendix B.

#!/usr/local/bin/python2.4
# SOAP Struct

def hello():
    return {"value":"Hello, world"}

def echo(**kw):
    return kw

def sum(**kw):
    sum = 0
    for i in kw.values(): sum += i
	return {"value":sum}

def average(**kw):
	d = sum(**kw)
    return d["value"] = d["value"]/len(kw)

from ZSI import dispatch
dispatch.AsCGI(rpc=True)

2.1.2 low level soap processing example

We will now show a more complete example of a robust web service implemented at the SOAP layer. It takes as input a player name and array of integers, and returns the average. It is presented in sections, following the steps detailed above. A complete working example of this service is available in Appendix C.

The first section reads in a request, and parses the SOAP header.

from ZSI import *
import sys
IN, OUT = sys.stdin, sys.stdout
try:
    ps = ParsedSoap(IN)
except ParseException, e:
    OUT.write(FaultFromZSIException(e).AsSOAP())
    sys.exit(1)
except Exception, e:
    # Faulted while processing; we assume it's in the header.
    OUT.write(FaultFromException(e, 1).AsSOAP())
    sys.exit(1)

# We are not prepared to handle any actors or mustUnderstand elements,
# so we'll arbitrarily fault back with the first one we found.
a = ps.WhatActorsArePresent()
if len(a):
    OUT.write(FaultFromActor(a[0]).AsSOAP())
    sys.exit(1)
mu = ps.WhatMustIUnderstand()
if len(mu):
    uri, localname = mu[0]
    OUT.write(FaultFromNotUnderstood(uri, localname).AsSOAP())
    sys.exit(1)

This section defines the mappings between Python objects and the SOAP data being transmitted. Recall that according to the SOAP specification, RPC input and output are modeled as a structure.

class Player:
    def __init__(self, *args):
        if not len(args): return
        self.Name = args[0]
        self.Scores = args[1:]
Player.typecode = TC.Struct(Player, [
                                TC.String('Name'),
                                TC.Array('Integer', TC.Integer(), 'Scores', undeclared=True),
                                ], 'GetAverage')
class Average:
    def __init__(self, average=None):
        self.average = average
Average.typecode = TC.Struct(Average, [
                                TC.Integer('average'),
                                ], 'GetAverageResponse')

This section parses the input, performs the application-level activity, and serializes the response.

try:
    player = ps.Parse(Player.typecode)
except EvaluateException, e:
    OUT.write(FaultFromZSIException(e).AsSOAP())
    sys.exit(1)

try:
    total = 0
    for value in player.Scores: total = total + value
    result = Average(total / len(player.Scores))
    sw = SoapWriter()
    sw.serialize(result, Average.typecode)
    sw.close()
    OUT.write(str(sw))
except Exception, e:
    OUT.write(FaultFromException(e, 0, sys.exc_info()[2]).AsSOAP())
    sys.exit(1)

In the serialize() call above, the second parameter is optional, since result is an instance of the Average class, and the Average.typecode attribute is the typecode for class instances.

2.1.3 A mod_python example

The Apache module mod_python (see http://www.modpython.org) embeds Python within the Apache server. In order to expose operations within a module via mod_python, use the dispatch.AsHandler() function. The dispatch.AsHandler() function will dispatch requests to any operation defined in the module you pass it, which allows for multiple operations to be defined in a module. The only trick is to use __import__ to load the XML encodings your service expects. This is a required workaround to avoid the pitfalls of restricted execution with respect to XML parsing.

The following is a complete example of a simple handler. The soap operations are implemented in the MyHandler module:

def hello():
    return {"value":"Hello, world"}

def echo(**kw):
    return kw

def sum(**kw):
    sum = 0
    for i in kw.values(): sum += i
	return {"value":sum}

def average(**kw):
	d = sum(**kw)
    d["value"] = d["value"]/len(kw)
	return d

Dispatching from within mod_python is achieved by passing the aforementined MyHandler module to dispatch.AsHandler(). The following code exposes the operations defined in MyHandler via SOAP:

from ZSI import dispatch
from mod_python import apache

import MyHandler
mod = __import__('encodings.utf_8', globals(), locals(), '*')
mod = __import__('encodings.utf_16_be', globals(), locals(), '*')

def handler(req):
    dispatch.AsHandler(modules=(MyHandler,), request=req)
    return apache.OK

2.2 Client Side Examples

2.2.1 Simple Example

ZSI provides two ways for a client to interactive with a server: the Binding or NamedParamBinding class and the ServiceProxy class. The first is useful when the operations to be invoked are not defined in WSDL or when only simple Python datatypes are used; the ServiceProxy class can be used to parse WSDL definitions in order to determine how to serialize and parse the SOAP messages.

During development, it is often useful to record ``packet traces'' of the SOAP messages being exchanged. Both the Binding and ServiceProxy classes provide a tracefile parameter to specify an output stream (such as a file) to capture messages. It can be particularly useful when debugging unexpected SOAP faults.

The first example provided below demonstrates how to use the NamedParamBinding class to connect to a remote service and perform an operation.

#!/usr/bin/env python
import sys,time
from ZSI.client import NamedParamBinding as NPBinding

b = NPBinding(url='http://127.0.0.1/cgi-bin/soapstruct', tracefile=sys.stdout)
print "Hello: ", b.hello()
print "Echo: ", b.echo(name="josh", year=2006, pi=3.14, time=time.gmtime())
print "Sum: ", b.sum(one=1, two=2, three=3)
print "Average: ", b.average(one=100, two=200, three=300, four=400)

2.2.2 Complex Example: pickler.py

If the operation invoked returns a ComplexType, typecode information must be provided in order to tell ZSI how to deserialize the response. Here is a sample server-side implementation (for the complete example see Appendix D):

class Person:
  def __init__(self, name=None, age=0):
    self.name = name
    self.age = age

Person.typecode = TC.Struct(Person,
			    [TC.String('name'),
			     TC.InonNegativeInteger('age')],
			    'myApp:Person')

# my web service that returns a complex structure
def getPerson(name):
  fp = open('%s.person.pickle', % name, 'r')
  return pickle.load(fp)

# my web service that accepts a complex structure
def savePerson(person):
  fp = open('%s.person.pickle' % person.name, 'w')
  pickle(person, fp)
  fp.close()

In order for ZSI to transparently deserialize the returned complex type into a Person instance, a module defining the class and its typecode can be passed into the Binding. It is also possible to explicitly tell ZSI what typecode to use by passing it as a parameter to the Binding.Receive() method.

The following fragment shows both styles:

import sys
from ZSI.client import Binding
from MyComplexTypes import Person

b = Binding(url='http://localhost/test3/pickler.py', tracefile=sys.stdout)
person = Person('christopher', 26)
rsp = b.savePerson(person)

Because the returned complex type is defined in a class present in typesmodule, transparent deserialization is possible. When sending complex types to the server, it is not necessary to list the module in typesmodule:

import sys
import MyComplexTypes
from ZSI.client import NamedParamBinding as NPBinding, Binding
from ZSI import TC

kw = {'url':'http://localhost/test3/pickler.py', 'tracefile':sys.stdout}
b = NPBinding(**kw)
rsp = b.getPerson(name='christopher')
assert type(rsp) is dict, 'expecting a dict'
assert rsp['Person']['name'] == 'christopher', 'wrong person'

b = NPBinding(typesmodule=MyComplexTypes, **kw)
rsp = b.getPerson(name='christopher')
assert isinstance(rsp['Person'], MyComplexTypes.Person), (
    'expecting instance of %s' %MyComplexTypes.Person)

b = Binding(typesmodule=MyComplexTypes, **kw)
class Name(str):
    typecode = TC.String("name")

rsp = b.getPerson(Name('christopher'))
assert isinstance(rsp['Person'], MyComplexTypes.Person), (
    'expecting instance of %s' %MyComplexTypes.Person)

3. Exceptions

exception ZSIException: Base class for all ZSI Exceptions, it is a subtype of the Python Exception class.

exception ParseException: ZSI can raise this exception while creating a ParsedSoap object. It is a subtype of the ZSIException class. The string form of a ParseException object consists of a line of human-readable text. If the backtrace is available, it will be concatenated as a second line.

The following attributes are read-only:

inheader: A boolean that indicates if the error was detected in the SOAP Header element.

str: A text string describing the error.

trace: A text string containing a backtrace to the error. This may be None if it was not possible, such as when there was a general DOM exception, or when the str text is believed to be sufficient.

exception EvaluateException: This exception is similar to ParseException, except that ZSI may raise it while converting between SOAP and local Python objects.

The following attributes are read-only:

str: A text string describing the error.

trace: A text backtrace, as described above for ParseException.

4. Utilities

ZSI defines some utility methods that general applications may want to use.

Version( ): Returns a three-element tuple containing the numbers representing the major, minor, and release identifying the ZSI version. New in version 1.1.

4.1 Low-Level Utilities

ZSI also defines some low-level utilities for its own use that start with a leading underscore and must be imported explicitly. They are documented here because they can be useful for developing new typecode classes.

These functions are mostly used in in parse methods and the ParsedSoap class. The serialization routines use the ElementProxy class to encapsulate common DOM-level operations.

Some lambda's are defined so that some DOM accessors will return an empty list rather than None. This means that rather than writing:

if elt.childNodes:
   for N in elt.childNodes:
      ...

One can write:

for N in _children(elt):
   ...

Other lambda's return SOAP-related attributes from an element, or None if not present.

_attrs( element): Returns a list of all attributes of the specified element.

_backtrace( elt, dom): This function returns a text string that traces a ``path'' from dom, a DOM root, to elt, an element within that document, in XPath syntax.

_child_elements( element): Returns a list of all children elements of the specified element.

_children( element): Returns a list of all children of the specified element.

_copyright _empty_nsuri_list

_find_arraytype( element): The value of the SOAP arrayType attribute. New in version 1.2.

_find_attr( element, name): The value of the unqualified name attribute.

_find_attrNS( element, namespaceURI, localName): The value of a name attribute in a namespace namespaceURI.

_find_attrNodeNS( element, namespaceURI, localName): Works just like _find_attrNS, but this function grabs the attribute Node to distinquish between an unspecified attribute(None) and one set to empty string("").

_find_default_namespace( element): Returns the value of the default namespace.

_find_encstyle( element): The value of the SOAP encodingStyle attribute.

_find_href( element): The value of the unqualified href attribute.

_find_type( element): The value of the XML Schema type attribute.

_find_xmlns_prefix( element, prefix): The value of the xmlns:prefix type attribute.

_find_xsi_attr( element, attribute): Find the attribute in any of the XMLSchema namespaces.

_get_element_nsuri_name( element): Returns a (namespace,name) tuple representing the element tag.

_get_idstr( obj): Substitute for id function. Python 2.3.x generates a FutureWarning for negative IDs, so we use a different prefix character to ensure uniqueness, and call abs() to avoid the warning.

_get_postvalue_from_absoluteURI( url): Returns POST value from url, and caches these values.

_resolve_prefix( element, prefix): resolve prefix to a namespaceURI. If None or empty str, return default namespace or None if not defined.

_valid_encoding( elt): Return true if the element elt has a SOAP encoding that can be handled by ZSI (currently Section 5 of the SOAP 1.1 specification or an empty encoding for XML).

5. The `ParsedSoap` module -- basic message handling

This class represents an input stream that has been parsed as a SOAP message.

class ParsedSoap( input[, **keywords])

Creates a ParsedSoap object from the provided input source. If input is not a string, then it must be an object with a read() method that supports the standard Python ``file read'' semantics.

The following keyword arguments may be used:

Keyword	Default	Description
`envelope`	`True`	expect a SOAP Envelope
`keepdom`	`False`	Do not release the DOM when this object is destroyed. To access the DOM object, use the `GetDomAndReader()` method. The reader object is necessary to properly free the DOM structure using `reader.releaseNode(dom)`. New in version 1.2.
`readerclass`	`None`	Class used to create DOM-creating XML readers; described below. New in version 1.2.
`resolver`	`None`	Value for the `resolver` attribute; see below.
`trailers`	`False`	Allow trailing data elements to appear after the `Body`.

The following attributes of a ParsedSoap are read-only:

body: The root of the SOAP Body element. Using the GetElementNSdict() method on this attribute can be useful to get a dictionary to be used with the SoapWriter class.

body_root: The element that contains the SOAP serialization root; that is, the element in the SOAP Body that ``starts off'' the data.

data_elements: A (possibly empty) list of all child elements of the Body other than the root.

header: The root of the SOAP Header element. Using the GetElementNSdict() method on this attribute can be useful to get a dictionary to be used with the SoapWriter class.

header_elements: A (possibly empty) list of all elements in the SOAP Header.

trailer_elements: Returns a (possibly empty) list of all elements following the Body. If the trailers keyword was not used when the object was constructed, this attribute will not be instantiated and retrieving it will raise an exception.

The following attribute may be modified:

resolver

If not None, this attribute can be invoked to handle absolute href's in the SOAP data. It will be invoked as follows:

resolver( uri, tc, ps, **keywords): The uri parameter is the URI to resolve. The tc parameter is the typecode that needs to resolve href; this may be needed to properly interpret the content of a MIME bodypart, for example. The ps parameter is the ParsedSoap object that is invoking the resolution (this allows a single resolver instance to handle multiple SOAP parsers).
Failure to resolve the URI should result in an exception being raised. If there is no content, return None; this is not the same as an empty string. If there is content, the data returned should be in a form understandable by the typecode.

The following methods are available:

Backtrace( elt): Returns a human-readable ``trace'' from the document root to the specified element.

FindLocalHREF( href, elt): Returns the element that has an id attribute whose value is specified by the href fragment identifier. The href must be a fragment reference -- that is, it must start with a pound sign. This method raises an EvaluateException exception if the element isn't found. It is mainly for use by the parsing methods in the TypeCode module.

GetElementNSdict( elt): Return a dictionary for all the namespace entries active at the current element. Each dictionary key will be the prefix and the value will be the namespace URI.

GetMyHeaderElements( [actorlist=None]): Returns a list of all elements in the Header that are intended for this SOAP processor. This includes all elements that either have no SOAP actor attribute, or whose value is either the special ``next actor'' value or in the actorlist list of URI's.

GetDomAndReader( ): Returns a tuple containing the dom and reader objects, (dom, reader). Unless keepdom is true, the dom and reader objects will go out of scope when the ParsedSoap instance is deleted. If keepdom is true, the reader object is needed to properly clean up the dom tree with reader.releaseNode(dom).

IsAFault( ): Returns true if the message is a SOAP fault.

Parse( how): Parses the SOAP Body according to the how parameter, and returns a Python object. If how is not a TC.TypeCode object, then it should be a Python class object that has a typecode attribute.

ResolveHREF( uri, tc[, **keywords]): This method is invoked to resolve an absolute URI. If the typecode tc has a resolver attribute, it will use it to resolve the URI specified in the uri parameter, otherwise it will use its own resolver, or raise an EvaluateException exception.
Any keyword parameters will be passed to the chosen resolver. If no content is available, it will return None. If unable to resolve the URI it will raise an EvaluateException exception. Otherwise, the resolver should return data in a form acceptable to the specified typecode, tc. (This will almost always be a file-like object holding opaque data; for XML, it may be a DOM tree.)

WhatActorsArePresent( ): Returns a list of the values of all the SOAP actor attributes found in child elements of the SOAP Header.

WhatMustIUnderstand( ): Returns a list of "(uri, localname)" tuples for all elements in the SOAP Header that have the SOAP mustUnderstand attribute set to a non-zero value.

ZSI supports multiple DOM implementations. The readerclass parameter specifies which one to use. The default is to use the DOM provided with the PyXML package developed by the Python XML SIG, provided through the PyExpat.Reader class in the xml.dom.ext.reader module.

The specified reader class must support the following methods:

fromString( string): Return a DOM object from a string.

fromStream( stream): Return a DOM object from a file-like stream.

releaseNode( dom): Free the specified DOM object.

The DOM object must support the standard Python mapping of the DOM Level 2 specification. While only a small subset of specification is used, the particular methods and attributes used by ZSI are available only by inspecting the source.

To use the cDomlette DOM provided by the 4Suite package, use the NonvalidatingReader class in the Ft.Xml.Domlette module. Due to name changes in the 1.0 version of 4Suite, a simple adapter class is required to use this DOM implementation.

from 4Suite.Xml.Domlette import NonvalidatingReaderBase

class 4SuiteAdapterReader(NonvalidatingReaderBase):

    def fromString(self, str):
        return self.parseString(str)

    def fromStream(self, stream):
        return self.parseStream(stream)

    def releaseNode(self, node):
        pass

6. The `TypeCode` classes -- data conversions

The TypeCode module defines classes used for converting data between SOAP data and local Python objects. Python numeric and string types, and sequences and dictionaries, are supported by ZSI. The TC.TypeCode class is the parent class of all datatypes understood by ZSI.

All typecodes classes have the prefix TC., to avoid name clashes.

ZSI provides fine-grain control over the names used when parsing and serializing XML into local Python objects, through the use of two attributes: the pname, the aname. The pname specifies the name expected on the XML element being parsed and the name to use for the output element when serializing. The aname is the name to use for the analogous attribute in the local Python object.

The pname is the parameter name. It specifies the incoming XML element name and the default values for the Python attribute and serialized names. All typecodes take the pname argument. This name can be specified as either a list or a string. When specified as a list, it must have two elements which are interpreted as a ``(namespace-URI, localname)'' pair. If specified this way, both the namespace and the local element name must match for the parse to succeed. For the Python attribute, and when generating output, only the ``localname'' is used. If a namespace-URI is specified then the full qualified name is used for output, and it is required for input; this requires the namespace prefix to be specified.

The aname is the attribute name. This parameter overrides any value implied by the pname. Typecodes nested in a TC.Struct or TC.ComplexType can use this parameter to specify the tag, dictionary key, or instance attribute to set.

The nsdict parameter to the SoapWriter construct can be used to specify prefix to namespace-URI mappings, these are otherwise handled automatically.

6.1 `TC.TypeCode`

The TypeCode class is the parent class of all typecodes.

class TypeCode( **keywords)

The following keyword arguments may be used:

Keyword	Default	Description
`pname`	`None`	parameter name of the object
`aname`	`None`	attribute name of the object
`minOccurs`	`1`	schema facet minimum occurances
`maxOccurs`	`1`	schema facet maximum occurances
`nillable`	`False`	schema facet is this nillable (`xsi:nil="true"`)
`typed`	`True`	Output type information (in the `xsi:type` attribute) when serializing. By special dispensation, typecodes within a `TC.Struct` object inherit this from the container.
`unique`	`0`	If true, the object is unique and will never be ``aliased'' with another object, so the `id` attribute need not be output.
`pyclass`	`None`	when parsing data, instances of this class can be created to store the data. Default behavior is reflective of specific TypeCode classes.
`attrs_aname`	`'_attrs'`	attribute name of the object where attribute values are stored. Used for serialization and parsing.

Optional elements are those which do not have to be an incoming message, or which have the XML Schema nil attribute set. When parsing the message as part of a Struct, then the Python instance attribute will not be set, or the element will not appear as a dictionary key. When being parsed as a simple type, the value None is returned. When serializing an optional element, a non-existent attribute, or a value of None is taken to mean not present, and the element is skipped.

typechecks: This is a class attribute. If true (the default) then all typecode constructors do more rigorous type-checking on their parameters.

tag: This is a class attribute. Specifies the global element declaration this typecode represents, the value is a "(namespace, name)" tuple.

type: This is a class attribute. Specifies the global type definition this typecode represents, the value is a "(namespace, name)" tuple.

attribute_typecode_dict: This is a class attribute. This is a dict of "(URI, NCName)" tuple keys, the values of each is a typecode. This is how attribute declarations other than SOAP and XMLSchema attribute declarations (eg. xsi:type, id, href, etc) are represented.

logger: This is a class attribute. logger instance for this class.

The following methods are useful for defining new typecode classes; see the section on dynamic typing for more details. In all of the following, the ps parameter is a ParsedSoap object.

checkname( elt, ps): Checks if the name and type of the element elt are correct and raises a EvaluateException if not. Returns the element's type as a "(uri, localname)" tuple if so.

checktype( elt, ps): Like checkname() except that the element name is ignored. This method is actually invoked by checkname() to do the second half of its processing, but is useful to invoke directly, such as when resolving multi-reference data.

nilled( elt, ps): If the element elt has data, this returns False. If it has no data, and the typecode is not optional, an EvaluateException is raised; if it is optional, a True is returned.

simple_value( elt, ps, mixed=False): Returns the text content of the element elt. If no value is present, or the element has non-text children, an EvaluateException is raised. If mixed is False if child elements are discovered an EvaluateException is raised, else join all text nodes and return the result.

6.2 `TC.Any` -- the basis of dynamic typing

SOAP provides a flexible set of serialization rules, ranging from completely self-describing to completely opaque, requiring an external schema. For example, the following are all possible ways of encoding an integer element i with a value of 12:

6.2.1 simple data

- requires type information

<tns:i xsi:type="SOAP-ENC:integer">12</tns:i>
<tns:i xsi:type="xsd:nonNegativeInteger">12</tns:i>
<SOAP-ENC:integer>12</SOAP-ENC:integer>
<tns:i>12</tns:i>

The first three lines are examples of typed elements. If ZSI is asked to parse any of the above examples, and a TC.Any typecode is given, it will properly create a Python integer for the first three, and raise a EvaluateException for the fourth.

6.2.2 compound data

- Struct or Array Compound data, such as a struct, may also be self-describing (namespace are omitted for clarity):

<tns:foo>
    <tns:i xsi:type="SOAP-ENC:integer">12</tns:i>
    <tns:name xsi:type="SOAP-ENC:string">Hello world</tns:name>
</tns:foo>

If this is parsed with a TC.Any typecode, either a Python dict is created or if aslist is True a list:

ps = ParsedSoap(xml, envelope=False)
print ps.Parse(TC.Any())
{   'name': u'Hello world',    'i': 12   }

print ps.Parse(TC.Any(aslist=True))
[ 12, u'Hello world' ]

Note that one preserves order, while the other preserves the element names.

6.2.3 class description

class Any( name[, **keywords])

Used for parsing incoming SOAP data (that is typed), and serializing outgoing Python data.

The following keyword arguments may be used:

Keyword	Default	Description
`aslist`	`False`	If true, then the data is (recursively) treated as a list of values. The default is a Python dictionary, which preserves parameter names but loses the ordering. New in version 1.1.

In addition, if the Python object being serialized with an Any has a typecode attribute, then the serialize method of the typecode will be invoked to do the serialization. This allows objects to override the default dynamic serialization.

Referring back to the compound XML data above, it is possible to create a new typecode capable of parsing elements of type mytype. This class would know that the i element is an integer, so that the explicit typing becomes optional, rather than required.

6.2.4 Adding new types

Most of the TypeCodes classes in TC are registered with Any, making an instance of itself available for dynamic typing. New TypeCode classes can be created and registered with Any by using RegisterType. In order to override an existing entry in the registry call RegisterType with clobber=True. The serialization entries are mappings between builtin Python types and a TypeCode instance, it is not possible to have one Python type map to multiple typecodes. The parsing entries are mappings between (namespaceURI,name) tuples, representing the xsi:type attribute, and a TypeCode instance. Thus, only one instance of a TypeCode class can represent a XML Schema type. So this mechanism is not appropriate for representing XML Schema element information.

class NEWTYPECODE(TypeCode)( ...): The new typecode should be derived from the TC.TypeCode class, and TypeCode.__init__() must be invoked in the new class's constructor.

parselist: This is a class attribute, used when parsing incoming SOAP data. It should be a sequence of "(uri, localname)" tuples to identify the datatype. If uri is None, it is taken to mean either the XML Schema namespace or the SOAP encoding namespace; this should only be used if adding support for additional primitive types. If this list is empty, then the type of the incoming SOAP data is assumed to be correct; an empty list also means that incoming typed data cannot by dynamically parsed.

errorlist: This is a class attribute, used when reporting a parsing error. It is a text string naming the datatype that was expected. If not defined, ZSI will create this attribute from the parselist attribute when it is needed.

seriallist: This is a class attribute, used when serializing Python objects dynamically. It specifies what types of object instances (or Python types) this typecode can serialize. It should be a sequence, where each element is a Python class object, a string naming the class, or a type object from Python's types module (if the new typecode is serializing a built-in Python type).

parse( elt, ps): ZSI invokes this method to parse the elt element and return its Python value. The ps parameter is the ParsedSoap object, and can be used for dereferencing href's, calling Backtrace() to report errors, etc.

serialize( sw, pyobj[, **keywords])

ZSI invokes this method to output a Python object to a SOAP stream. The sw parameter will be a SoapWriter object, and the pyobj parameter is the Python object to serialize.

The following keyword arguments may be used:

Keyword	Default	Description
`attrtext`	`None`	Text (with leading space) to output as an attribute; this is normally used by the `TC.Array` class to pass down indexing information.
`name`	`None`	Name to use for serialization; defaults to the name specified in the typecode, or a generated name.
`typed`	per-typecode	Whether or not to output type information; the default is to use the value in the typecode.

Once the new typecode class has been defined, it should be registered with ZSI's dynamic type system by invoking the following function:

RegisterType( class[, clobber=0[, **keywords]]): By default, it is an error to replace an existing type registration, and an exception will be raised. The clobber parameter may be given to allow replacement. A single instance of the class object will be created, and the keyword parameters are passed to the constructor.

If the class is not registered, then instances of the class cannot be processed as dynamic types. This may be acceptable in some environments.

6.3 `TC.SimpleType`

Parent class of all simple types.

empty_content: This is a class attribute. Value returned when tag or node is present, is not nilled, and without text content.

6.4 Strings

SOAP/XMLSchema Strings are Python strings.

class String( name[, **keywords])

The parent type of all strings.

The following keyword arguments may be used:

Keyword	Default	Description
`resolver`	`None`	A function that can resolve an absolute URI and return its content as a string, as described in the `ParsedSoap` description.
`strip`	`True`	If true, leading and trailing whitespace are stripped from the content.

class Enumeration( value_list, name[, **keywords]): Like TC.String, but the value must be a member of the choices sequence of text strings

In addition to TC.String, the basic string, several subtypes are provided that transparently handle common encodings. These classes create a temporary string object and pass that to the serialize() method. When doing RPC encoding, and checking for non-unique strings, the TC.String class must have the original Python string, as well as the new output. This is done by adding a parameter to the serialize() method:

Keyword	Default	Description
`orig`	`None`	If deriving a new typecode from the string class, and the derivation creates a temporary Python string (such as by `Base64String`), than this parameter is the original string being serialized.

class Base64String( name[, **keywords]): The value is encoded in Base-64.

class HexBinaryString( name[, **keywords]): Each byte is encoded as its printable version.

class URI( name[, **keywords]): The value is URL quoted (e.g., %20 for the space character).

It is often the case that a parameter will be typed as a string for transport purposes, but will in fact have special syntax and processing requirements. For example, a string could be used for an XPath expression, but it is more convenient for the Python value to actually be the compiled expression. Here is how to do that:

import xml.xpath.pyxpath
import xml.xpath.pyxpath.Compile as _xpath_compile

class XPathString(TC.String):
    def __init__(self, name, **kw):
        TC.String.__init__(self, name, **kw)

    def parse(self, elt, ps):
        val = TC.String.parse(self, elt, ps)
        try:
            val = _xpath_compile(val)
        except:
            raise EvaluateException("Invalid XPath expression",
                        ps.Backtrace(elt))
        return val

In particular, it is common to send XML as a string, using entity encoding to protect the ampersand and less-than characters.

class XMLString( name[, **keywords])

Parses the data as a string, but returns an XML DOM object. For serialization, takes an XML DOM (or element node), and outputs it as a string.

The following keyword arguments may be used:

Keyword	Default	Description
`readerclass`	`None`	Class used to create DOM-creating XML readers; described in the `ParsedSoap` chapter.

6.5 Integers

SOAP/XMLSchema integers are Python integers.

class Integer( [**keywords])

The parent type of all integers. This class handles any of the several types (and ranges) of SOAP integers.

The following keyword arguments may be used:

Keyword	Default	Description
`format`	`%d`	Format string for serializing. New in version 1.2.

class IEnumeration( choices[, **keywords]): Like TC.Integer, but the value must be a member of the choices sequence.

A number of sub-classes are defined to handle smaller-ranged numbers.

class Ibyte( [**keywords]): A signed eight-bit value.

class IunsignedByte( [**keywords]): An unsigned eight-bit value.

class Ishort( [**keywords]): A signed 16-bit value.

class IunsignedShort( [**keywords]): An unsigned 16-bit value.

class Iint( [**keywords]): A signed 32-bit value.

class IunsignedInt( [**keywords]): An unsigned 32-bit value.

class Ilong( [**keywords]): An signed 64-bit value.

class IunsignedLong( [**keywords]): An unsigned 64-bit value.

class IpositiveInteger( [**keywords]): A value greater than zero.

class InegativeInteger( [**keywords]): A value less than zero.

class InonPositiveInteger( [**keywords]): A value less than or equal to zero.

class InonNegativeInteger( [**keywords]): A value greater than or equal to zero.

6.6 Floating-point Numbers

SOAP/XMLSchema floating point numbers are Python floats.

class Decimal( [**keywords])

The parent type of all floating point numbers. This class handles any of the several types (and ranges) of SOAP floating point numbers.

The following keyword arguments may be used:

Keyword	Default	Description
`format`	`%f`	Format string for serializing. New in version 1.2.

class FPEnumeration( value_list, name[, **keywords]): Like TC.Decimal, but the value must be a member of the value_list sequence. Be careful of round-off errors if using this class.

Two sub-classes are defined to handle smaller-ranged numbers.

class FPfloat( name[, **keywords]): An IEEE single-precision 32-bit floating point value.

class FPdouble( name[, **keywords]): An IEEE double-precision 64-bit floating point value.

6.7 Dates and Times

SOAP dates and times are Python time tuples in UTC (GMT), as documented in the Python time module. Time is tricky, and processing anything other than a simple absolute time can be difficult. (Even then, timezones lie in wait to trip up the unwary.) A few caveats are in order:

Some date and time formats will be parsed into tuples that are not valid time values. For example, 75 minutes is a valid duration, although not a legal value for the minutes element of a time tuple.
Fractional parts of a second may be lost when parsing, and may have extra trailing zero's when serializing.
Badly-formed time tuples may result in non-sensical values being serialized; the first six values are taken directly as year, month, day, hour, minute, second in UTC.
Although the classes Duration and Gregorian are defined, they are for internal use only and should not be included in any TypeCode you define. Instead, use the classes beginning with a lower case g in your typecodes.

In addition, badly-formed values may result in non-sensical serializations.

When serializing, an integral or floating point number is taken as the number of seconds since the epoch, in UTC.

class Duration( [**keywords]): A relative time period. Negative durations have all values less than zero; this makes it easy to add a duration to a Python time tuple.

class Gregorian( [**keywords]): An absolute time period. This class should not be instantiated directly; use one of the gXXX classes instead.

class gDateTime( [**keywords]): A date and time.

class gDate( [**keywords]): A date.

class gYearMonth( [**keywords]): A year and month.

class gYear( [**keywords]): A year.

class gMonthDay( [**keywords]): A month and day.

class gDay( [**keywords]): A day.

class gTime( [**keywords]): A time.

6.8 Boolean

SOAP Booleans are Python integers.

class Boolean( [**keywords]): When marshaling zero or the word ``false'' is returned as 0 and any non-zero value or the word ``true'' is returned as 1. When serializing, the number 0 or 1 will be generated.

6.9 XML

XML is a Python DOM element node. If the value to be serialized is a Python string, then an href is generated, with the value used as the URI. This can be used, for example, when generating SOAP with attachments. Otherwise, the XML is typically put inside a wrapper element that sets the proper SOAP encoding style.

For efficiency, incoming XML is returend as a ``pointer'' into the DOM tree maintained within the ParsedSoap object. If that object is going to go out of scope, the data will be destroyed and any XML objects will become empty elements. The class instance variable copyit, if non-zero indicates that a deep copy of the XML subtree will be made and returned as the value. Note that it is generally more efficient to keep the ParsedSoap object alive until the XML data is no longerneeded.

class XML( [**keywords])

This typecode represents a portion of an XML document embedded in a SOAP message. The value is the element node.

The following keyword arguments may be used:

Keyword	Default	Description
`copyit`	TC.XML.copyit	Return a copy of the parsed data.
`comments`	`0`	Preserve comments in output.
`inline`	`0`	The XML sub-tree is single-reference, so can be output in-place.
`resolver`	`None`	A function that can resolve an absolute URI and return its content as an element node, as described in the `ParsedSoap` description.
`wrapped`	`1`	If zero, the XML is output directly, and not within a SOAP wrapper element. New in version 1.2.

When serializing, it may be necessary to specify which namespace prefixes are ``active'' in the XML. This is done by using the unsuppressedPrefixes parameter when calling the serialize() method. (This will only work when XML is the top-level item being serialized, such as when using typecodes and document-style interfaces.)

Keyword	Default	Description
`unsuppressedPrefixes`	[]	An array of strings identifying the namespace prefixes that should be output.

6.10 ComplexType

Represents the XMLSchema ComplexType . New in version 2.0.

class ComplexType( pyclass, ofwhat[, **keywords])

This class defines a compound data structure. If pyclass is None, then the data will be marshaled into a Python dictionary, and each item in the ofwhat sequence specifies a (possible) dictionary entry. Otherwise, pyclass must be a Python class object. The data is then marshaled into the object, and each item in the ofwhat sequence specifies an attribute of the instance to set.

Note that each typecode in ofwhat must have a name.

The following keyword arguments may be used:

Keyword	Default	Description
`inorder`	`False`	Items within the structure must appear in the order specified in the `ofwhat` sequence.
`inline`	`False`	The structure is single-reference, so ZSI does not have to use `href/id` encodings.
`mutable`	`False`	If an object is going to be serialized multiple times, and its state may be modified between serializations, then this keyword should be used, otherwise a single instance will be serialized, with multiple references to it. This argument implies the `inline` argument. New in version 1.2.
`type`	`None`	A "`(uri, localname)`" tuple that defines the type of the structure. If present, and if the input data has a `xsi:type` attribute, then the namespace-qualified value of that attribute must match the value specified by this parameter. By default, type-checking is not done for structures; matching child element names is usually sufficient and senders rarely provide type information.
`mixed`	`False`	using a mixed content model, allow text and element content.
`mixed_aname`	`'_text'`	if mixed is True, text content is set in this attribute (key).

If the typed keyword is used, then its value is assigned to all typecodes in the ofwhat parameter. If any of the typecodes in ofwhat are repeatable, then the inorder keyword should not be used and the hasextras parameter must be used.

For example, the following C structure:

struct foo {
    int i;
    char* text;
};

could be declared as follows:

class foo:
    def __init__(self, name):
        self.name = name
    def __str__(self):
        return str((self.name, self.i, self.text))

foo.typecode = TC.Struct(foo,
    ( TC.Integer('i'), TC.String('text') ),
    'foo')

6.11 Struct

SOAP Struct is a complex type for accessors identified by name. No element may have the same name as any other, nor may any element have a maxOccurs > 1. SOAP Structs are either Python dictionaries or instances of application-specified classes.

6.12 Arrays

SOAP arrays are Python lists; multi-dimensional arrays are lists of lists and are indistinguishable from a SOAP array of arrays. Arrays may be sparse, in which case each element in the array is a tuple of "(subscript, data)" pairs. If an array is not sparse, a specified fill element will be used for the missing values.

Currently only singly-dimensioned arrays are supported.

class Array( atype, ofwhat[, **keywords]): The atype parameter is a (URI,NCName) tuple representing the SOAP array type. The ofwhat parameter is a typecode describing the array elements.

The following keyword arguments may be used:

Keyword	Default	Description
`childnames`	`None`	Default name to use for the child elements.
`dimensions`	`1`	The number of dimensions in the array.
`fill`	`None`	The value to use when an array element is omitted.
`mutable`	`False`	If an object is going to be serialized multiple times, and its state may be modified between serializations, then this keyword should be used, otherwise a single instance will be serialized, with multiple references to it.
`nooffset`	`0`	Do not use the SOAP `offset` attribute so skip leading elements with the same value as `fill`.
`sparse`	`False`	The array is sparse.
`size`	`None`	An integer or list of integers that specifies the maximum array dimensions.
`undeclared`	`False`	The SOAP "`arrayType`" attribute need not appear.

6.13 Apache Datatype

The Apache SOAP project, urlhttp://xml.apache.org/soap/index.html, has defined a popular SOAP datatype in the http://xml.apache.org/xml-soap namespace, a Map.

The Map type is encoded as a list of item elements. Each item has a key and value child element; these children must have SOAP type information. An Apache Map is either a Python dictionary or a list of two-element tuples.

class Apache.Map( name[, **keywords]): An Apache map. Note that the class name is dotted.

The following keyword arguments may be used:

Keyword	Default	Description
`aslist`	`0`	Use a list of tuples rather than a dictionary.

7. The `SoapWriter` module -- serializing data

The SoapWriter class is used to output SOAP messages. Note that its output is encoded as UTF-8; when transporting SOAP over HTTP it is therefore important to set the charset attribute of the Content-Type header.

The SoapWriter class reserves some namespace prefixes:

Prefix	URI
`SOAP-ENV`	`http://schemas.xmlsoap.org/soap/envelope/`
`SOAP-ENC`	`http://schemas.xmlsoap.org/soap/encoding/`
`ZSI`	`http://www.zolera.com/schemas/ZSI/`
`xsd`	`http://www.w3.org/2001/XMLSchema`
`xsi`	`http://www.w3.org/2001/XMLSchema-instance`

class SoapWriter( optional**keywords)

The following keyword arguments may be used:

Keyword	Default	Description
`encodingStyle`	None	If not `None`, then use the specified value as the value for the SOAP `encodingStyle` attribute. New in version 1.2.
`envelope`	`True`	Create a SOAP Envelope New in version 1.2.
`nsdict`	`{}`	Dictionary of namespaces to declare in the SOAP `Envelope`
`header`	`True`	create a SOAP `Header` element
`outputclass`	`ElementProxy`	wrapper around DOM or other XML library.

Creating a SoapWriter object with envelope set to False results in an object that can be used for serializing objects into a string.

serialize( pyobj[, typecode=None[, root=None[, header_pyobjs=None[, **keywords]]]]): This method serializes the pyobj Python object as directed by the typecode typecode object. If typecode is omitted, then pyobj should be a Python object instance of a class that has a typecode attribute. It returns self, so that serializations can be chained together, or so that the close() method can be invoked. The root parameter may be used to explicitly indicate the root (main element) of a SOAP encoding, or indicate that the item is not the root. If specified, it should have the numeric value of zero or one. Any other keyword parameters are passed to the typecode's serialize method.

close( ): Invokes all the callbacks, if any. The close operations can only happen once, if invoked a second time it will just return. This method will be invoked automatically if the object is deleted.

__str__( ): Invokes the close method, and returns a string representation of the serialized object. Assumes that serialize has been invoked.

The following methods are primarily useful for those writing new typecodes.

AddCallback( func, arg): Used by typecodes when serializing, allows them to add output after the SOAP Body is written but before the SOAP Envelope is closed. The function func() will be called with the SoapWriter object and the specified arg argument, which may be a tuple.

Forget( obj): Forget that obj has been seen before. This is useful when repeatedly serializing a mutable object.

Known( obj): If obj has been seen before (based on its Python id), return 1. Otherwise, remember obj and return 0.

ReservedNS( prefix, uri): Returns true if the specified namespace prefix and uri collide with those used by the implementation.

writeNSDict( nsdict): Outputs nsdict as a namespace dictionary. It is assumed that an XML start-element is pending on the output stream.

8. The `Fault` module -- reporting errors

SOAP defines a fault message as the way for a recipient to indicate it was unable to process a message. The ZSI Fault class encapsulates this.

class Fault( code, string[, **keywords])

The code parameter is a text string identifying the SOAP fault code, a namespace-qualified name. The class attribute Fault.Client can be used to indicate a problem with an incoming message, Fault.Server can be used to indicate a problem occurred while processing the request, or Fault.MU can be used to indicate a problem with the SOAP mustUnderstand attribute. The string parameter is a human-readable text string describing the fault.

The following keyword arguments may be used:

Keyword	Default	Description
`actor`	`None`	A string identifying the `actor` attribute that caused the problem (usually because it is unknown).
`detail`	`None`	A sequence of elements to output in the `detail` element; it may also be a text string, in which case it is output as-is, and should therefore be XML text.
`headerdetail`	`None`	Data, treated the same as the `detail` keyword, to be output in the SOAP header. See the following paragraph.

If the fault occurred in the SOAP Header, the specification requires that the detail be sent back as an element within the SOAP Header element. Unfortunately, the SOAP specification does not describe how to encode this; ZSI defines and uses a ZSI:detail element, which is analogous to the SOAP detail element.

The following attributes are read-only:

actor: A text string holding the value of the SOAP faultactor element.

code: A text string holding the value of the SOAP faultcode element.

detail: A text string or sequence of elements containing holding the value of the SOAP detail element, when available.

headerdetail: A text string or sequence of elements containing holding the value of the ZSI header detail element, when available.

string: A text string holding the value of the SOAP faultstring element.

AsSOAP( [, **kw]): This method serializes the Fault object into a SOAP message. The message is returned as a string. Any keyword arguments are passed to the SoapWriter constructor. New in version 1.1; the old AsSoap() method is still available.

If other data is going to be sent with the fault, the following two methods can be used. Because some data might need to be output in the SOAP Header, serializing a fault is a two-step process.

DataForSOAPHeader( ): This method returns a text string that can be included as the header parameter for constructing a SoapWriter object.

serialize( sw): This method outputs the fault object onto the sw object, which is a SoapWriter instance.

Some convenience functions are available to create a Fault from common conditions.

FaultFromActor( uri[, actor]): This function could be used when an application receives a message that has a SOAP Header element directed to an actor that cannot be processed. The uri parameter identifies the actor. The actor parameter can be used to specify a URI that identifies the application, if it is not the ultimate recipient of the SOAP message.

FaultFromException( ex, inheader[, tb[, actor]]): This function creates a Fault from a general Python exception. A SOAP ``server'' fault is created. The ex parameter should be the Python exception. The inheader parameter should be true if the error was found on a SOAP Header element. The optional tb parameter may be a Python traceback object, as returned by "sys.exc_info()[2]". The actor parameter can be used to specify a URI that identifies the application, if it is not the ultimate recipient of the SOAP message.

FaultFromFaultMessage( ps): This function creates a Fault from a ParsedSoap object passed in as ps. It should only be used if the IsAFault() method returned true.

FaultFromNotUnderstood( uri, localname,[, actor]): This function could be used when an application receives a message with the SOAP mustUnderstand attribute that it does not understand. The uri and localname parameters should identify the unknown element. The actor parameter can be used to specify a URI that identifies the application, if it is not the ultimate recipient of the SOAP message.

FaultFromZSIException( ex[, actor]): This function creates a Fault object from a ZSI exception, ParseException or EvaluateException, passed in as ex. A SOAP ``client'' fault is created. The actor parameter can be used to specify a URI that identifies the application, if it is not the ultimate recipient of the SOAP message.

9. The `resolvers` module -- fetching remote data

The resolvers module provides some functions and classes that can be used as the resolver attribute for TC.String or TC.XML typecodes. They process an absolute URL, as described above, and return the content. Because the resolvers module can import a number of other large modules, it must be imported directly, as in "from ZSI import resolvers".

These first two functions pass the URI directly to the urlopen function in the urllib module. Therefore, if used directly as resolvers, a client could direct the SOAP application to fetch any file on the network or local disk. Needless to say, this could pose a security risks.

Opaque( uri, tc, ps[, **keywords]): This function returns the data contained at the specified uri as a Python string. Base-64 decoding will be done if necessary. The tc and ps parameters are ignored; the keywords are passed to the urlopen method.

XML( uri, tc, ps[, **keywords]): This function returns a list of the child element nodes of the XML document at the specified uri. The tc and ps parameters are ignored; the keywords are passed to the urlopen method.

The NetworkResolver class provides a simple-minded way to limit the URI's that will be resolved.

class NetworkResolver( [prefixes=None]): The prefixes parameter is a list of strings defining the allowed prefixes of any URI's. If asked to fetch the content for a URI that does start with one of the prefixes, it will raise an exception.
In addition to Opaque and XML methods, this class provides a Resolve method that examines the typecode to determine what type of data is desired.

If the SOAP application is given a multi-part MIME document, the MIMEResolver class can be used to process SOAP with Attachments.

The MIMEResolver class will read the entire multipart MIME document, noting any Content-ID or Content-Location headers that appear on the headers of any of the message parts, and use them to resolve any href attributes that appear in the SOAP message.

class MIMEResolver( ct, f[, **keywords])

The ct parameter is a string that contains the value of the MIME Content-Type header. The f parameter is the input stream, which should be positioned just after the message headers.

The following keyword arguments may be used:

Keyword	Default	Description
`seekable`	`0`	Whether or not the input stream is seekable; passed to the constructor for the internal `multifile` object. Changed in version 2.0: default had been 1.
`next`	`None`	A resolver object that will be asked to resolve the URI if it is not found in the MIME document. New in version 1.1.
`uribase`	`None`	The base URI to be used when resolving relative URI's; this will typically be the value of the `Content-Location` header, if present. New in version 1.1.

In addition to to the Opaque, Resolve, and XML methods as described above, the following method is available:

GetSOAPPart( ): This method returns a stream containing the SOAP message text.

The following attributes are read-only:

parts: An array of tuples, one for each MIME bodypart found. Each tuple has two elements, a mimetools.Message object which contains the headers for the bodypart, and a StringIO object containing the data.

id_dict: A dictionary whose keys are the values of any Content-ID headers, and whose value is the appropriate parts tuple.

loc_dict: A dictionary whose keys are the values of any Content-Location headers, and whose value is the appropriate parts tuple.

10. Dispatching and Invoking

New in version 1.1.

ZSI is focused on parsing and generating SOAP messages, and provides limited facilities for dispatching to the appropriate message handler. This is because ZSI works within many client and server environments, and the dispatching styles for these different environments can be very different.

Nevertheless, ZSI includes some dispatch and invocation functions. To use them, they must be explicitly imported, as shown in the example at the start of this document.

The implementation (and names) of the these classes reflects the orientation of using SOAP for remote procedure calls (RPC).

Both client and server share a class that defines the mechanism a client uses to authenticate itself.

class AUTH( ): This class defines constants used to identify how the client authenticated: none if no authentication was provided; httpbasic if HTTP basic authentication was used, or zsibasic if ZSI basic authentication (see below)) was used.

The ZSI schema (see the last chapter of this manual) defines a SOAP header element, BasicAuth, that contains a name and password. This is similar to the HTTP basic authentication header, except that it can be used independently from an HTTP transport.

10.1 Dispatching

The ZSI.dispatch module allows you to expose Python functions as a web service. The module provides the infrastructure to parse the request, dispatch to the appropriate handler, and then serialize any return value back to the client. The value returned by the function will be serialized back to the client. If an exception occurs, a SOAP fault will be sent back to the client.

10.1.1 Dispatch Behaviors

By default the callback is invoked with the pyobj representation of the body root element, and it is expected to return a self-describing request (w/typecode). Parsing is done via a typecode from typesmodule, or Any. Other keyword options are available in dispatch mechanisms (see below) that result in different behavior.

10.1.1.1 rpc

An rpc service will ignore the body root (RPC Wrapper) of the request, and parse all "parts" of message via individual typecodes. The callback function is expected to return the parts of the message in a dict or a list. The dispatch mechanism will try to serialize it as a Struct but if this is not possible it will be serialized as an Array. Parsing done via a typecode from typesmodule, or Any. Not compatible with docstyle.

10.1.1.2 docstyle

Callback is invoked with a ParsedSoap instance representing the request, and the return value is serialized with an XML typecode (DOM). The result in wrapped as an rpc-style message, with Response appended to the request wrapper. Not compatible with rpc.

10.1.2 Special Modules

These are keyword options available to all dispatch mechansism (see below).

10.1.2.1 modules

Dispatch is based solely on the name of the root element in the incoming SOAP request; the request URL is ignored. These modules will be search for a matching function. If no modules are specified, only the __main__ module will be searched.

10.1.2.2 typesmodule

Used for parsing. This module should contain class definitions with the typecode attribute set to a TypeCode instance. By default, a class definition matching the root element name will be retrieved or the Any typecode will be used. If using rpc, each child of the root element will be used to retrieve a class definition of the same name.

10.1.3 Dispatch Mechanisms

Three dispatch mechanisms are provided: one supports standard CGI scripts, one runs a dedicated server based on the BaseHTTPServer module, and the third uses the JonPY package, http://jonpy.sourceforge.net, to support FastCGI.

AsServer( [**keywords])

This creates a HTTPServer object with a request handler that only supports the ``POST'' method. Dispatch is based solely on the name of the root element in the incoming SOAP request; the request URL is ignored.

The following keyword arguments may be used:

Keyword	Default	Description
`port`	`80`	Port to listen on.
`addr`	`''`	Address to listen on.
`docstyle`	`False`	Exhibit the docstyle behavior.
`rpc`	`False`	Exhibit the rpc behavior.
`modules`	`(__main__,)`	List of modules containing functions that can be invoked.
`typesmodule`	`(__main__,)`	This module is used for parsing, it contains class definitions that specify the `typecode` attribute.
`nsdict`	`{}`	Namespace dictionary to send in the SOAP `Envelope`

AsCGI( [**keywords])

This method parses the CGI input and invokes a function that has the same name as the top-level SOAP request element.

The following keyword arguments may be used:

Keyword	Default	Description
`rpc`	`False`	Exhibit the rpc behavior.
`modules`	`(__main__,)`	List of modules containing functions that can be invoked.
`typesmodule`	`(__main__,)`	This module is used for parsing, it contains class definitions that specify the `typecode` attribute.
`nsdict`	`{}`	Namespace dictionary to send in the SOAP `Envelope`

AsHandler( request=None[, **keywords])

This method is used within a JonPY handler to do dispatch.

The following keyword arguments may be used:

Keyword	Default	Description
`request`	`None`	modpython HTTPRequest instance.
`modules`	`(__main__,)`	List of modules containing functions that can be invoked.
`docstyle`	`False`	Exhibit the docstyle behavior.
`rpc`	`False`	Exhibit the rpc behavior.
`typesmodule`	`(__main__,)`	This module is used for parsing, it contains class definitions that specify the `typecode` attribute.
`nsdict`	`{}`	Namespace dictionary to send in the SOAP `Envelope`

AsJonPy( request=None[, **keywords])

This method is used within a JonPY handler to do dispatch.

The following keyword arguments may be used:

Keyword	Default	Description
`request`	`None`	jonpy Request instance.
`modules`	`(__main__,)`	List of modules containing functions that can be invoked.
`docstyle`	`False`	Exhibit the docstyle behavior.
`rpc`	`False`	Exhibit the rpc behavior.
`typesmodule`	`(__main__,)`	This module is used for parsing, it contains class definitions that specify the `typecode` attribute.
`nsdict`	`{}`	Namespace dictionary to send in the SOAP `Envelope`

The following code shows a sample use:

import jon.fcgi
from ZSI import dispatch
import MyHandler

class Handler(cgi.Handler):
    def process(self, req):
        dispatch.AsJonPy(modules=(MyHandler,), request=req)

jon.fcgi.Server({jon.fcgi.FCGI_RESPONDER: Handler}).run()

10.1.4 Other Dispatch Stuff

GetClientBinding( ): More sophisticated scripts may want to use access the client binding object, which encapsulates all information about the client invoking the script. This function returns None or the binding information, an object of type ClientBinding, described below.

class ClientBinding( ...): This object contains information about the client. It is created internally by ZSI.

GetAuth( ): This returns a tuple containing information about the client identity. The first element will be one of the constants from the AUTH class described above. For HTTP or ZSI basic authentication, the next two elements will be the name and password provided by the client.

GetNS( ): Returns the namespace URI that the client is using, or an empty string. This can be useful for versioning.

GetRequest( ): Returns the ParsedSoap object of the incoming request.

The following attribute is read-only:

environ: A dictionary of the environment variables. This is most useful when AsCGI() is used.

10.2 The `client` module -- sending SOAP messages

ZSI includes a module to connect to a SOAP server over HTTP, send requests, and parse the response. It is built on the standard Python httplib and Cookie modules. It must be explicitly imported, as in "from ZSI.client import AUTH,Binding".

10.2.1 _Binding

class _Binding( [**keywords])

This class encapsulates a connection to a server, known as a binding. A single binding may be used for multiple RPC calls. Between calls, modifiers may be used to change the URL being posted to, etc.

Cookies are also supported; if a response comes back with a Set-Cookie header, it will be parsed and used in subsequent interactions.

The following keyword arguments may be used:

Keyword	Default	Description
`auth`	`(AUTH.none,)`	A tuple with authentication information; the first value should be one of the constants from the `AUTH` class.
`nsdict`	`{}`	Namespace dictionary to send in the SOAP `Envelope`
`soapaction`	`''`	Value for the `SOAPAction` HTTP header.
`readerclass`	`None`	Class used to create DOM-creating XML readers; see the description in the `ParsedSoap` class.
`writerclass`	`None`	ElementProxy Class used to create XML writers; see the description in the `SoapWriter` class.
`tracefile`	`None`	An object with a `write` method, where packet traces will be recorded.
`transport`	HTTPConnection/HTTPSConnection	transport class
`transdict`	{}	keyword arguments for connection initialization
`url`	n/a	URL to post to.
`wsAddressURI`	None	URI, identifies the WS-Address specification to use. By default it's not used.
`sig_handler`	None	XML Signature handler, must sign and verify.

If using SSL, the cert_file and key_file keyword parameters may also be used. For details see the documentation for the httplib module.

Once a _Binding object has been created, the following modifiers are available. All of them return the binding object, so that multiple modifiers can be chained together.

AddHeader( header, value): Output the specified header and value with the HTTP headers.

SetAuth( style, name, password): The style should be one of the constants from the AUTH class described above. The remaining parameters will vary depending on the style. Currently only basic authentication data of name and password are supported.

SetNS( uri): Set the default namespace for the request to the specified uri.

SetURL( url): Set the URL where the post is made to url.

ResetHeaders( ): Remove any headers that were added by AddHeader().

The following attribute may also be modified:

trace: If this attribute is not None, it should be an object with a write method, where packet traces will be recorded.

Once the necessary parameters have been specified (at a minimum, the URL must have been given in the constructor are through SetURL), invocations can be made.

RPC( url, opname, pyobj, replytype=None[, **keywords]): This is the highest-level invocation method. It calls Send() to send pyobj to the specified url to perform the opname operation, and calls Receive() expecting to get a reply of the specified replytype.
This method will raise a TypeError if the response does not appear to be a SOAP message, or if is valid SOAP but contains a fault.

Send( url, opname, pyboj[, **keywords])

This sends the specified pyobj to the specified url, invoking the opname method. The url can be None if it was specified in the Binding constructor or if SetURL has been called. See below for a shortcut version of this method.

The following keyword arguments may be used:

SOAP Envelope

Keyword	Default	Description
`auth_header`	`None`	String (containing presumably serialized XML) to output as an authentication header.
`nsdict`	`{}`	Namespace dictionary to send in the SOAP `Envelope`
`requesttypecode`	n/a	Typecode specifying how to serialize the data.
`soapaction`	Obtained from the `Binding`	Value for the `SOAPAction` HTTP header.

Methods are available to determine the type of response that came back:

IsSOAP( ): Returns true if the message appears to be a SOAP message. (Some servers return an HTML page under certain error conditions.)

IsAFault( ): Returns true if the message is a SOAP fault.

Having determined the type of the message (or, more likely, assuming it was good and catching an exception if not), the following methods are available to actually parse the data. They will continue to return the same value until another message is sent.

ReceiveRaw( ): Returns the unparsed message body.

ReceiveSoap( ): Returns a ParsedSOAP object containing the parsed message. Raises a TypeError if the message wasn't SOAP.

ReceiveFault( ): Returns a Fault object containing the SOAP fault message. Raises a TypeError if the message did not contain a fault.

Receive( replytype=None): Parses a SOAP message. The replytype specifies how to parse the data. If it s None, dynamic parsing will be used, usually resulting in a Python list. If replytype is a Python class, then the class's typecode attribute will be used, otherwise replytype is taken to be the typecode to use for parsing the data.

Once a reply has been parsed (or its type examined), the following read-only attributes are available. Their values will remain unchanged until another reply is parsed.

reply_code: The HTTP reply code, a number.

reply_headers: The HTTP headers, as a mimetools object.

reply_msg: A text string containing the HTTP reply text.

10.2.2 Binding

If an attribute is fetched other than one of those described in _Binding, it is taken to be the opname of a remote procedure, and a callable object is returned. This object dynamically parses its arguments, receives the reply, and parses that.

class Binding( [**keywords])

For other keyword arguments see _Binding.

Keyword	Default	Description
`typesmodule`	`None`	See explanation in Dispatching

opname( *args): Using this shortcut requires that the url attribute is set, either throught the constructor or SetURL().

10.2.3 NamedParamBinding

class NamedParamBinding( [**keywords])

For other keyword arguments see _Binding.

Keyword	Default	Description
`typesmodule`	`None`	See explanation in Dispatching

opname( **kwargs): Using this shortcut requires that the url attribute is set, either throught the constructor or SetURL().

11. Bibliography

Bibliography

1: This is the first item in the Bibliography.
2: This is the second item in the Bibliography.

A. CGI Script Array

A.1 Intro

This is an example of a simple web service CGI Script. The service returns and expects SOAP Arrays (python list). A sample soap trace is provided below. In this example the CGI script is dispatched as a rpc service.

A.1.1 rpc wrapper

The wrapper element of the request is the dispatch key to the callback function, the child elements are passes as a list or dict of values to the callback function. The callback function is expected to return a list or dict of values, the response wrapper is by default set to the request wrapper name appended Response.

A.2 CGI Script

#!/usr/local/bin/python2.4
# SOAP Array

def hello():
    return ["Hello, world"]

def echo(*args):
    return args

def sum(*args):
    sum = 0
    for i in args: sum += i
    return [sum]

def average(*args):
    return [sum(*args) / len(args)]

from ZSI import dispatch
dispatch.AsCGI(rpc=True)

A.3 client test script

#!/usr/bin/env python
# client.py
import sys
from ZSI.client import Binding
b = Binding(url='http://127.0.0.1/cgi-bin/simple', tracefile=sys.stdout)
print b.hello()
try:
    print b.hello(1)
except Exception, ex:
    print "Fault: ", ex

print b.echo("whatever", "hi", 1, 2)
print b.sum(*[2*i for i in range(5)])
print b.average(*[2*i for i in range(5)])

A.4 SOAP Trace

A.4.1 hello

$ ./client.py 
Hello:  _________________________________ Wed Oct  4 17:36:33 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<hello SOAP-ENC:arrayType="xsd:anyType[0]"></hello>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

_________________________________ Wed Oct  4 17:36:34 2006 RESPONSE:
200

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<helloResponse SOAP-ENC:arrayType="xsd:anyType[1]">
			<element id="o671b0" xsi:type="xsd:string">Hello, world</element>
		</helloResponse>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
[u'Hello, world']

A.4.2 hello fault

_________________________________ Wed Oct  4 17:36:34 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<hello SOAP-ENC:arrayType="xsd:anyType[1]">
			<element id="o1803988" xsi:type="xsd:int">1</element>
		</hello>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
_________________________________ Wed Oct  4 17:36:35 2006 RESPONSE:
500

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<SOAP-ENV:Fault>
			<faultcode>SOAP-ENV:Server</faultcode>
			<faultstring>Processing Failure</faultstring>
			<detail>
				<ZSI:FaultDetail>
<ZSI:string>exceptions:TypeError hello() takes no arguments (1 given)</ZSI:string>
<ZSI:trace>build/bdist.darwin-8.8.0-Power_Macintosh/egg/ZSI/dispatch.py:86:_Dispatch</ZSI:trace>
				</ZSI:FaultDetail>
			</detail>
		</SOAP-ENV:Fault>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Fault:  Processing Failure
exceptions:TypeError
hello() takes no arguments (1 given)
[trace: build/bdist.darwin-8.8.0-Power_Macintosh/egg/ZSI/dispatch.py:86:_Dispatch]

A.4.3 echo

_________________________________ Wed Oct  4 17:36:35 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<echo SOAP-ENC:arrayType="xsd:anyType[4]">
			<element id="o644c0" xsi:type="xsd:string">whatever</element>
			<element id="o644e0" xsi:type="xsd:string">hi</element>
			<element id="o1803988" xsi:type="xsd:int">1</element>
			<element id="o180397c" xsi:type="xsd:int">2</element>
		</echo>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
_________________________________ Wed Oct  4 17:36:36 2006 RESPONSE:
200

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<echoResponse SOAP-ENC:arrayType="xsd:anyType[4]">
			<element id="o4f4290" xsi:type="xsd:string">whatever</element>
			<element id="o4f4338" xsi:type="xsd:string">hi</element>
			<element id="o1803988" xsi:type="xsd:int">1</element>
			<element id="o180397c" xsi:type="xsd:int">2</element>
		</echoResponse>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

[u'whatever', u'hi', 1, 2]

A.4.4 sum

_________________________________ Wed Oct  4 17:36:36 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<sum SOAP-ENC:arrayType="xsd:anyType[5]">
			<element id="o1803994" xsi:type="xsd:int">0</element>
			<element id="o180397c" xsi:type="xsd:int">2</element>
			<element id="o1803964" xsi:type="xsd:int">4</element>
			<element id="o180394c" xsi:type="xsd:int">6</element>
			<element id="o1803934" xsi:type="xsd:int">8</element>
		</sum>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
_________________________________ Wed Oct  4 17:36:37 2006 RESPONSE:
200

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<sumResponse SOAP-ENC:arrayType="xsd:anyType[1]">
			<element id="o18038a4" xsi:type="xsd:int">20</element>
		</sumResponse>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
[20]

A.4.5 average

_________________________________ Wed Oct  4 17:36:37 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<average SOAP-ENC:arrayType="xsd:anyType[5]">
			<element id="o1803994" xsi:type="xsd:int">0</element>
			<element id="o180397c" xsi:type="xsd:int">2</element>
			<element id="o1803964" xsi:type="xsd:int">4</element>
			<element id="o180394c" xsi:type="xsd:int">6</element>
`			<element id="o1803934" xsi:type="xsd:int">8</element>
		</average>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
_________________________________ Wed Oct  4 17:36:38 2006 RESPONSE:
200

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<averageResponse SOAP-ENC:arrayType="xsd:anyType[1]">
			<element id="o1803964" xsi:type="xsd:int">4</element>
		</averageResponse>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
[4]

B. CGI Script Struct

B.1 Intro

This is an example of a simple web service CGI Script. The service returns and expects SOAP Structs (python dict). A sample soap trace is provided below. In this example the CGI script is dispatched as a rpc service.

B.1.1 rpc wrapper

B.2 CGI Script

#!/usr/local/bin/python2.4
# SOAP Struct

def hello():
    return {"value":"Hello, world"}

def echo(**kw):
    return kw

def sum(**kw):
    sum = 0
    for i in kw.values(): sum += i
	return {"value":sum}

def average(**kw):
	d = sum(**kw)
    return d["value"] = d["value"]/len(kw)

from ZSI import dispatch
dispatch.AsCGI(rpc=True)

B.3 client test script

#!/usr/bin/env python
import sys,time
from ZSI.client import NamedParamBinding as NPBinding

b = NPBinding(url='http://127.0.0.1/cgi-bin/soapstruct', tracefile=sys.stdout)
print "Hello: ", b.hello()
print "Echo: ", b.echo(name="josh", year=2006, pi=3.14, time=time.gmtime())
print "Sum: ", b.sum(one=1, two=2, three=3)
print "Average: ", b.average(one=100, two=200, three=300, four=400)

B.4 SOAP Trace

B.4.1 hello

C. Complete Low Level Example

C.1 Intro

This is a complete example of using the low level soap utilities in ZSI to implement a web service.

C.2 code

C.2.1 httpserver script

Minimal http server example, opens up a new process to do the SOAP processing.

#!/usr/bin/env python
# file: httpserver.py
import os
from subprocess import Popen, PIPE
from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer

class RequestHandler(BaseHTTPRequestHandler):
    def do_POST(self):
        length = int(self.headers['content-length'])
        xml_in = self.rfile.read(length)
        p = Popen(os.path.join(os.path.curdir, 'player.py'),
                  shell=True, stdin=PIPE, stdout=PIPE)

        (stdout, stderr) = p.communicate(xml_in)
        code = 200
        if stdout.find('Fault') >= 0: code = 500 
        self.send_response(code)
        self.send_header('Content-type', 'text/xml; charset="utf-8"')
        self.send_header('Content-Length', str(len(stdout)))
        self.end_headers()
        self.wfile.write(stdout)
        self.wfile.flush()

if __name__ == '__main__':
    server = HTTPServer(('localhost', 8080), RequestHandler)
    server.serve_forever()

C.2.2 typecode module

# file: typecode.py
# CHECK PYTHONPATH: Must be able to import
class Player:
    def __init__(self, *args):
        if not len(args): return
        self.Name = args[0]
        self.Scores = args[1:]
Player.typecode = TC.Struct(Player, [
                                TC.String('Name'),
                                TC.Array('Integer', TC.Integer(), 'Scores', undeclared=True),
                                ], 'GetAverage')
class Average:
    def __init__(self, average=None):
        self.average = average
Average.typecode = TC.Struct(Average, [
                                TC.Integer('average'),
                                ], 'GetAverageResponse')

C.2.3 player script

#!/usr/bin/env python
# file: player.py
from ZSI import *
import sys
IN, OUT = sys.stdin, sys.stdout
try:
    ps = ParsedSoap(IN)
except ParseException, e:
    OUT.write(FaultFromZSIException(e).AsSOAP())
    sys.exit(1)
except Exception, e:
    # Faulted while processing; we assume it's in the header.
    OUT.write(FaultFromException(e, 1).AsSOAP())
    sys.exit(1)

# We are not prepared to handle any actors or mustUnderstand elements,
# so we'll arbitrarily fault back with the first one we found.
a = ps.WhatActorsArePresent()
if len(a):
    OUT.write(FaultFromActor(a[0]).AsSOAP())
    sys.exit(1)
mu = ps.WhatMustIUnderstand()
if len(mu):
    uri, localname = mu[0]
    OUT.write(FaultFromNotUnderstood(uri, localname).AsSOAP())
    sys.exit(1)

from typecode import Player, Average
try:
    player = ps.Parse(Player.typecode)
except EvaluateException, e:
    OUT.write(FaultFromZSIException(e).AsSOAP())
    sys.exit(1)

try:
    total = 0
    for value in player.Scores: total = total + value
    result = Average(total / len(player.Scores))
    sw = SoapWriter()
    sw.serialize(result, Average.typecode)
    sw.close()
    OUT.write(str(sw))
except Exception, e:
    OUT.write(FaultFromException(e, 0, sys.exc_info()[2]).AsSOAP())
    sys.exit(1)

C.2.4 client test script

#!/usr/bin/env python2.4
#file: client.py
from ZSI import *
from ZSI.wstools.Namespaces import SCHEMA
from typecode import Player, Average

if __name__ == '__main__':
    import sys
    from ZSI.client import Binding
    b = Binding(url='http://localhost:8080', tracefile=sys.stdout)
    pyobj = b.RPC(None, None, Player("Josh",10,20,30), replytype=Average)
    print pyobj
    print pyobj.__dict__

C.3 SOAP Trace

C.3.1 GetAverage

$./client.py 
_________________________________ Thu Oct  5 14:57:39 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<GetAverage>
			<Name xsi:type="xsd:string">Josh</Name>
			<Scores>
				<element>10</element>
				<element>20</element>
				<element>30</element>
			</Scores>
		</GetAverage>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
_________________________________ Thu Oct  5 14:57:39 2006 RESPONSE:
200
OK
-------
Server: BaseHTTP/0.3 Python/2.5
Date: Thu, 05 Oct 2006 21:57:39 GMT
Content-type: text/xml; charset="utf-8"
Content-Length: 431

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<GetAverageResponse>
			<average>20</average>
		</GetAverageResponse>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

<__main__.Average instance at 0x5f9760>
{'average': 20}

C.3.2 fault

Purposely send a incorrect Nae element for the Name.

$./client.py 
_________________________________ Thu Oct  5 14:33:25 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<GetAverage>
			<Nae xsi:type="xsd:string">Josh</Nae>
			<Scores>
				<element>10</element>
				<element>20</element>
				<element>30</element>
			</Scores>
		</GetAverage>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

_________________________________ Thu Oct  5 14:33:26 2006 RESPONSE:
500
Internal Server Error

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<SOAP-ENV:Fault>
			<faultcode>SOAP-ENV:Client</faultcode>
			<faultstring>Unparseable message</faultstring>
			<detail><Eoe440>&lt;ZSI:ParseFaultDetail&gt;
&lt;ZSI:string&gt;Element "Name" missing from complexType&lt;/ZSI:string&gt;
&lt;ZSI:trace&gt;/SOAP-ENV:Envelope/SOAP-ENV:Body/GetAverage&lt;/ZSI:trace&gt;
&lt;/ZSI:ParseFaultDetail&gt;</Eoe440></detail>
		</SOAP-ENV:Fault>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>
Traceback (most recent call last):
  File "./player_client.py", line 25, in ?
    pyobj = b.RPC(None, None, Player("Josh",10,20,30), replytype=Average)
  File "/private/var/www/htdocs/guide/client.py", line 176, in RPC
    
  File "/private/var/www/htdocs/guide/client.py", line 420, in Receive
    
ZSI.FaultException: Unparseable message
<Element Node at 5f9f58: Name='Eoe440' with 0 attributes and 1 children>

D. pickler example

D.1 Intro

This is an example of a stateful mod_python web service.

D.2 code

D.2.1 typecode module

Module containing complex type typecode.

# Complex type definition
from ZSI import *
class Person:
  def __init__(self, name=None, age=0):
    self.name = name
    self.age = age

Person.typecode = TC.Struct(Person,
                            [TC.String('name'),
                             TC.InonNegativeInteger('age')],
                            pname=('urn:MyApp','Person'))

D.2.2 pickler script

Configure appache to use this script with mod_python PythonHandler.

# pickler.py
import pickle, new
from mod_python import apache
from ZSI import dispatch
import MyComplexTypes

# my web service that returns a complex structure
def getPerson(name=None):
  #fp = open('/tmp/%s.person.pickle'%Person.name, 'r')
  fp = open('/tmp/%s.person.pickle'%name, 'r')
  #return pickle.load(fp)
  p = pickle.load(fp)
  print "PERSON: ", p
  print "typecode: ", p.typecode
  return p

# my web service that accepts a complex structure
def savePerson(Person):
  print "PERSON: ", Person
  fp = open('/tmp/%s.person.pickle'%Person.name, 'w')
  pickle.dump(Person, fp)
  fp.close()
  return {}

mod = __import__('encodings.utf_8', globals(), locals(), '*')
mod = __import__('encodings.utf_16_be', globals(), locals(), '*')


handles = new.module('handles')
handles.getPerson = getPerson
handles.savePerson = savePerson
def handler(req):
    dispatch.AsHandler(modules=(handles,), request=req, typesmodule=MyComplexTypes, rpc=True)
    return apache.OK

D.2.3 client: invoke savePerson

D.2.3.1 script

import sys
from ZSI.client import Binding
from MyComplexTypes import Person

b = Binding(url='http://localhost/test3/pickler.py', tracefile=sys.stdout)
person = Person('christopher', 26)
b.savePerson(person)

D.2.3.2 SOAP Trace

_________________________________ Wed Oct 11 13:10:05 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<savePerson xmlns:ns1="urn:MyApp">
			<ns1:Person><name xsi:type="xsd:string">christopher</name>
				<age xsi:type="xsd:nonNegativeInteger">26</age>
			</ns1:Person>
		</savePerson>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

_________________________________ Wed Oct 11 13:10:05 2006 RESPONSE:
Server: Apache/2.0.53-dev (Unix) mod_ruby/1.2.4 Ruby/1.8.2(2004-12-25) 
mod_python/3.1.4 Python/2.4.1
Transfer-Encoding: chunked
Content-Type: text/xml

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<savePersonResponse></savePersonResponse>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

D.2.4 client: invoke getPerson 3 different ways

D.2.4.1 script

import sys
import MyComplexTypes
from ZSI.client import NamedParamBinding as NPBinding, Binding
from ZSI import TC

kw = {'url':'http://localhost/test3/pickler.py', 'tracefile':sys.stdout}
b = NPBinding(**kw)
rsp = b.getPerson(name='christopher')
assert type(rsp) is dict, 'expecting a dict'
assert rsp['Person']['name'] == 'christopher', 'wrong person'

b = NPBinding(typesmodule=MyComplexTypes, **kw)
rsp = b.getPerson(name='christopher')
assert isinstance(rsp['Person'], MyComplexTypes.Person), (
    'expecting instance of %s' %MyComplexTypes.Person)

b = Binding(typesmodule=MyComplexTypes, **kw)
class Name(str):
    typecode = TC.String("name")

rsp = b.getPerson(Name('christopher'))
assert isinstance(rsp['Person'], MyComplexTypes.Person), (
    'expecting instance of %s' %MyComplexTypes.Person)

D.2.4.2 SOAP Trace

All responses are exactly the same, for comparison the three requests are presented first and only the last response is included.

_________________________________ Wed Oct 11 13:19:00 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<getPerson>
			<name id="o6c2a0" xsi:type="xsd:string">christopher</name>
		</getPerson>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

** OMIT RESPONSE **

_________________________________ Wed Oct 11 13:19:00 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<getPerson>
			<name id="o6c2a0" xsi:type="xsd:string">christopher</name>
		</getPerson>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

** OMIT RESPONSE **

_________________________________ Wed Oct 11 13:19:00 2006 REQUEST:
<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<getPerson>
			<name xsi:type="xsd:string">christopher</name>
		</getPerson>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

_________________________________ Wed Oct 11 13:19:00 2006 RESPONSE:
Server: Apache/2.0.53-dev (Unix) mod_ruby/1.2.4 Ruby/1.8.2(2004-12-25) 
mod_python/3.1.4 Python/2.4.1
Transfer-Encoding: chunked
Content-Type: text/xml

<SOAP-ENV:Envelope xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" 
	xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" 
	xmlns:ZSI="http://www.zolera.com/schemas/ZSI/" 
	xmlns:xsd="http://www.w3.org/2001/XMLSchema" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<SOAP-ENV:Header></SOAP-ENV:Header>
	<SOAP-ENV:Body>
		<getPersonResponse xmlns:ns1="urn:MyApp">
			<ns1:Person>
				<name xsi:type="xsd:string">christopher</name>
				<age xsi:type="xsd:nonNegativeInteger">26</age>
			</ns1:Person>
		</getPersonResponse>
	</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

About this document ...

ZSI: The Zolera Soap Infrastructure
Developer's Guide, February 01, 2007, Release 2.0.0

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ZSI: The Zolera Soap Infrastructure Developer's Guide

Abstract:

ZSI: The Zolera Soap Infrastructure
Developer's Guide