Client side serialization of abstract types. (Was: Complex problem)

[glenn bech <gl...@webstep.no>]

I Have a WSDL

 

<definitions xmlns="http://schemas.xmlsoap.org/wsdl/"

  xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"

  xmlns:http="http://schemas.xmlsoap.org/wsdl/http/"

  xmlns:xs="http://www.w3.org/2001/XMLSchema"

  xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/"

  xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/"

  xmlns:gb="http://www.glennbech.com/abstractiontest/abstract/"

  targetNamespace="http://www.glennbech.com/abstractiontest/abstract/">

 

  <import namespace="http://www.glennbech.com/abstractiontest/abstract/"
location="abstract.xsd"/>

  <import namespace="http://www.glennbech.com/abstraction/concrete/"
location="concrete.xsd"/>

 

  <message name="CreateRequest">

    <part name="parameters" element="gb:Create"/>

  </message>

  <message name="CreateResponse">

    <part name="parameters" element="gb:CreateResponse"/>

  </message>

  <portType name="Provisioning">

    <operation name="create">

      <input message="gb:CreateRequest"/>

      <output message="gb:CreateResponse"/>

    </operation>

  </portType>

  <binding name="Provisioning" type="gb:Provisioning">

    <soap:binding style="document"
transport="http://schemas.xmlsoap.org/soap/http"/>

    <operation name="create">

      <soap:operation soapAction="gb#Create" style="document"/>

      <input>

        <soap:body use="literal"/>

      </input>

      <output>

        <soap:body use="literal"/>

      </output>

    </operation>

  </binding>

  <service name="Provisioning">

    <port name="Provisioning" binding="gb:Provisioning">

      <soap:address
location="http://localhost:8888/axis/services/Provisioning"/>

    </port>

  </service>

</definitions>'

 

Abstract.xsd

 

<xs:schema

  targetNamespace="http://www.glennbech.com/abstractiontest/abstract/"

  xmlns="http://www.glennbech.com/abstractiontest/abstract/"

  xmlns:xs="http://www.w3.org/2001/XMLSchema">

 

  <xs:complexType name="AbstractCreateItemDefinition" abstract="true"/>

  <xs:element name="CreateItemDefinition"
type="AbstractCreateItemDefinition" abstract="true"/>

  <xs:element name="CreateResponse" type="xs:int"/>

  <xs:element name="Create">

    <xs:complexType>

      <xs:sequence>

        <xs:element name="ItemType" type="xs:string"/>

        <xs:element name="ItemID" type="xs:int"/>

        <xs:element name="ItemAttributes" minOccurs="0">

          <xs:complexType>

            <xs:sequence>

              <xs:element ref="CreateItemDefinition"/>

            </xs:sequence>

          </xs:complexType>

        </xs:element>

      </xs:sequence>

    </xs:complexType>

  </xs:element>

</xs:schema>

 

Concrete.xsd

 

 

 

 

 

static {

        typeDesc.setXmlType(new
javax.xml.namespace.QName("http://www.glennbech.com/abstractiontest/abstract
/", ">>Create>ItemAttributes"));

        org.apache.axis.description.ElementDesc elemField = new
org.apache.axis.description.ElementDesc();

        elemField.setFieldName("createItemDefinition");

        elemField.setXmlName(new
javax.xml.namespace.QName("http://www.glennbech.com/abstractiontest/abstract
/", "CreateItemDefinition"));

        elemField.setXmlType(new
javax.xml.namespace.QName("http://www.glennbech.com/abstractiontest/abstract
/", "AbstractCreateItemDefinition"));

        elemField.setNillable(false);

        typeDesc.addFieldDesc(elemField);

 }

 

 

 

 

Glenn Richard Bech
Seniorkonsulent
Mob: 99356459 Tel: 40003325
Lysaker torg 2,  1366 Lysaker

 <http://www.webstep.no/> http://www.webstep.no  
Bergen - Oslo - Stavanger

 

 

  _____  

From: Anne Thomas Manes [mailto:atmanes@gmail.com] 
Sent: 24. januar 2006 14:21
To: axis-user@ws.apache.org
Subject: Re: Complex problem

 

The use of a substitutionGroup combined with an abstract type allows you to
do what you want: change both the name and type of the element. A
subtitutionGroup allows you to change the name of an element, but the type
of a substitutionGroup element must be the same as the original element, or
it must be derived from type of the original element. Using abstract types
lets you also change the element type.

An alternative solution is to use the <choice> compositor.

If you'd like to read up a little more on substitution groups and abstract
types, see:
http://www.w3schools.com/schema/schema_complex_subst.asp
http://www.w3.org/TR/xmlschema-0/#SubsGroups
http://www.zvon.org/xxl/XMLSchemaTutorial/Output/ser_substitution_st0.html
http://www.xml.com/pub/a/2000/11/29/schemas/part1.html?page=7 (page down a
bit)
http://www.xfront.com/ElementHierarchy.html

Regards,
Anne

On 1/24/06, glenn bech <gl...@webstep.no> wrote:

Hi Anne, thank you for looking into my case, I can see from the mailing list
that you're one of the ones pulling the load around here.-)

Anyways ; I realize now that the substitutiongroup attribute belongs to
elements, and not types. Personally, I'm a bit confused about the use of
*both* in my case, the abstract schema I have to work with require me to use
an xs:extension, and put the element in a substitution group. However, it is


"company policy" and I cannot get around it.

Question; Is it "common" to both use Substitution groups and abstract types
as in my case ?

Question; Since substitution groups belong to elements only, I cannot see 
how it affects Axis at all, as to my knowledge the WSDL2Java
generator only spits our classes related to the Types I define, and
I find noe trace in the classe's typedesc's of the substitution groups.

Am I Missing something? 


________________________________________
From: Anne Thomas Manes [mailto:atmanes@gmail.com]
Sent: 23. januar 2006 14:20
To: axis-user@ws.apache.org
Subject: Re: Complex problem

The substitutionGroup attribute is only valid as part of an element
definition, not as part of a complexType definition.

This:
<xs:complexType name="CreateComputerParameters" 
substitutionGroup="gb:CreateItemDefinition">
<xs:complexContent>
  <xs:extension base="gb:AbstractCreateItemDefinition">
  <xs:sequence>
  <xs:element name="cpu_speed" type="xs:int"/> 
  <xs:element name="mb_ram" type="xs:int"/>
  </xs:sequence>
  </xs:extension>
</xs:complexContent>
</xs:complexType>

Should be this:
<xs:element name="CreateComputerParameters" 
substitutionGroup="gb:CreateItemDefinition"
type="tns:CreateComputerParameters"/>
<xs:complexType name="CreateComputeParameters">
<xs:complexContent>
  <xs:extension base="gb:AbstractCreateItemDefinition"> 
  <xs:sequence>
  <xs:element name="cpu_speed" type="xs:int"/>
  <xs:element name="mb_ram" type="xs:int"/>
  </xs:sequence>
  </xs:extension> 
</xs:complexContent>
</xs:complexType>

Anne

On 1/23/06, glenn bech <gl...@webstep.no> wrote:
Hi All,

This is a rather lengthy post, I hope someone will take the time to read it 
through, as I've been struggling with the problem for a while. It describes
a complex, "real life", "business" scenario. This one is for you experts out


there! Novices, please skip this post .) 

Here is a summary; When creating an application with messages involving
abstract schema types and substitution groups, Axis as a client serializes
messages wrong, ignoring the concrete implementations in the serialization 
process using the generated base class for serialization".

I've currently been assigned to create a so called "provisioning" interface
to a company's internal database.

In practice, this means making the existing database modifiable through a 
well defined web services interface. I've been trying out axis, but have
some major issues.

The company impose a "standard" for data provisioning, that manifests itself
as an abstract XML Schema, and an abstract WSDL file. 

The WSDL file define very generic "Update", "Save" , "Delete" and "Create"
messages. It does not specify "what" to "Update", "Save", "Delete" etc. That


is deferred to implementations like mine. I've created an identical setup,
since I cannot reveal the identity of my customer.

First of all, there is a very generic XSD file that I cannot modify, It's
part of company policy.

It defines a complex type, "AbstractCreateItemDefinition". This is the base
message type for all messages that "create" items in the system.

The idea is to "extend" this Abstract type with create messages for real 
items, i.e CreateComputerDefinition, CreateVacumCleanerDefinition.

Please also notice the ref="CreateItemDefinition", this is the "magic" that
lets us put in any element that "extends" AbstractCreateDefinition here. 

<xs:schema
targetNamespace="http://www.glennbech.com/abstractiontest/abstract/"
xmlns=" http://www.glennbech.com/abstractiontest/abstract/"
xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:complexType name="AbstractCreateItemDefinition" abstract="true"/> 
<xs:element name="CreateItemDefinition"
type="AbstractCreateItemDefinition" abstract="true"/>

<xs:element name="Create">
<xs:complexType>
<xs:sequence> 
<xs:element name="ItemType" type="xs:string"/>
<xs:element name="ItemID" type="xs:int"/>
<xs:element name="ItemAttributes" minOccurs="0"> 
<xs:complexType>
<xs:sequence>
<xs:element ref="CreateItemDefinition"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType> 
</xs:element>
</xs:schema>

<xs:element name="CreateResponse" type="xs:int"/>

The WSDL file defines the "Provisioning" port, with only one operation
"Create". 

<definitions xmlns="http://schemas.xmlsoap.org/wsdl/"
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/ "
xmlns:http="http://schemas.xmlsoap.org/wsdl/http/"
xmlns:xs="http://www.w3.org/2001/XMLSchema "
xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/"
xmlns:mime="http://schemas.xmlsoap.org/wsdl/mime/ "
xmlns:gb="http://www.glennbech.com/abstractiontest/abstract/"
targetNamespace=" http://www.glennbech.com/abstractiontest/abstract/">

<import namespace="http://www.glennbech.com/abstractiontest/abstract/"
location="abstract.xsd"/>
<import namespace="http://www.glennbech.com/abstraction/concrete/"
location="concrete.xsd"/> 

<message name="CreateRequest">
<part name="parameters" element="gb:Create"/>
</message>

<message name="CreateResponse">
<part name="parameters" element="gb:CreateResponse"/> 
</message>

<portType name="Provisioning">
<operation name="Create">
<input message="gb:CreateRequest"/>
<output message="gb:CreateResponse"/> 
</operation>
</portType>

<binding name="Provisioning" type="gb:Provisioning">
<soap:binding style="document"
transport=" http://schemas.xmlsoap.org/soap/http"/>
<operation name="Create">
<soap:operation soapAction="gb#Create" style="document"/>
<input>
<soap:body use="literal"/> 
</input>
<output>
<soap:body use="literal"/>
</output>
</operation>
</binding>

<service name="Provisioning">
<port name="Provisioning" binding="gb:Provisioning"> 
<soap:address
location="http://localhost:8888/axis/services/Provisioning "/>
</port>
</service>


There is only one XSD that I have to write, that is the one defining the 
actual Items that I want to provision (Create Update Delete and Get)

Please note that they are declared as a part of a substitution group
gb:CreateItemDefinition, matching the "ref" defined in the abstract XML 
schema listed previously,.

<xs:schema
targetNamespace=" http://www.glennbech.com/abstractiontest/concrete/"
xmlns=" <http://www.glennbech.com/abstractiontest/concrete/>
http://www.glennbech.com/abstractiontest/concrete/ "
xmlns:gb="http://www.glennbech.com/abstractiontest/abstract/"
xmlns:xs=" <http://www.w3.org/2001/XMLSchema>
http://www.w3.org/2001/XMLSchema ">

<xs:complexType name="CreateComputerParameters"
substitutionGroup="gb:CreateItemDefinition">
<xs:complexContent>
<xs:extension base="gb:AbstractCreateItemDefinition"> 
<xs:sequence>
<xs:element name="cpu_speed" type="xs:int"/>
<xs:element name="mb_ram" type="xs:int"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>

<xs:complexType
name="CreateDigitalCameraParameters"
substitutionGroup="gb:CreateItemDefinition">
<xs:complexContent>
<xs:extension base="gb:AbstractCreateItemDefinition">
<xs:sequence>
<xs:element name="megapixels" type="xs:int"/>
</xs:sequence>
</xs:extension>
</xs:complexContent> 
</xs:complexType>
</xs:schema>

I run WSDL2Java on the WSDL file

wsdl2java -S -s -W -D -a -o src\ web\abstract.wsdl

...successfully. Everything looks very nice. CreateConmputerParameters are 
generated to extend the abstract class.

Generated files are listed here.

Directory of C-.....\src\com\glennbech\www\abstractiontest\concrete

23.01.200611:21<DIR>.
23.01.200611:21<DIR>.. 
23.01.200611:21 4573 CreateComputerParameters.java
23.01.200611:21 3730 CreateDigitalCameraParameters.java
2 File(s)8303 bytes

Directory of C:\.....\src\com\glennbech\www\abstractiontest\_abstract

23.01.200611:48<DIR>.
23.01.200611:48<DIR>..
23.01.200611:21 2524 AbstractCreateItemDefinition.java
23.01.200611:42 6009 Create.java
23.01.200611:21 4315 CreateItemAttributes.java
23.01.200611:21 3973 deploy.wsdd
23.01.200611:21 492 Provisioning_BindingImpl.java
23.01.200611:2110686 Provisioning_BindingStub.java
23.01.200611:21 408 Provisioning_PortType.java
23.01.200611:21 646 Provisioning_Service.java
23.01.200611:21 5703 Provisioning_ServiceLocator.java
23.01.200611:48 901 test.xml
23.01.200611:21 682 undeploy.wsdd

So I write a test class that invokes a call the service

public static void main(String[] args) throws Exception 
{
final String nsURI =
" http://www.glennbech.com/abstractiontest/abstract/";
final String serviceName = "Provisioning";
final String endPointURI =
" http://localhost:8888/axis/services/Provisioning";
final String wsdlURI = " <http://localhost:8888/axis/abstract.wsdl>
http://localhost:8888/axis/abstract.wsdl";

ServiceFactory serviceFactory = ServiceFactory.newInstance();
Service provisioningService = serviceFactory.createService(new
URL(wsdlURI), new QName(nsURI, serviceName)); 
Provisioning_BindingStub stub = new Provisioning_BindingStub(new
URL(endPointURI), provisioningService);

final int mhz = 3600;
final int mbRam = 1024;

// This is the really interesting line

Create createComputer = new Create("itemtype@computer ", 1, new Crea
teItemAttributes(new CreateComputerParameters(mhz, mbRam)));

stub.create(createComputer);

}

I deploy the service

adminclient -l http://localhost:9999/axis/services/AdminService
src\com\glennbech\www\abstractiontest\_abstract\deploy.wsdd

Now the trouble arrives... The Axis client side does not serialize my 
request object correctly. It does not recognize that I've actually
constructed my "create" message with a CreateComputerParameters, but uses
the abstract class as a base for Serialization.

xis/services/Provisioning HTTP/1.0 
Content-Type: text/xml; charset=utf-8
Accept: application/soap+xml, application/dime, multipart/related, text/*
User-Agent: Axis/1.3
Host: localhost:8888
Cache-Control: no-cache
Pragma: no-cache
SOAPAction: "gb#Create" 
Content-Length: 543

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/ "
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance ">
<soapenv:Body>
<Create xmlns="http://www.glennbech.com/abstractiontest/abstract/">
<ItemType xmlns=""> itemtype@computer</ItemType>
<ItemID xmlns="">1</ItemID>
<ItemAttributes xmlns="">
<ns1:CreateItemDefinition
xmlns:ns1=" http://www.glennbech.com/abstractiontest/abstract/"/>
</ItemAttributes>
</Create>
</soapenv:Body>

As you can see, the "Create" element has a nested "ItemAttributes" element, 
that again nest a "CreateItemDefinition" instead of the
"CreateComputerParameters" that should have been serialized.

Is this setup too complex for Axis to handle? Is this setup just to compelx 
in general? Should I call the standards department at my customer's company
and tell them to re-define the provisioning standard so it is possible to
implement it ?

All Advice are welcome !

Best regards, 

Glenn Bech