Embed string TAG in struct element using Apache XML RPC Library

As per the xml rpc specifications the struct element containing a value with specifying any TAG is considered to be string.

Some servers are not configured to handle such XML data strcutures. Apache XML RPC Library provides a flexibilty for the client code to be handle such improvisations.

Example

Standard specification considers the below mentioned XML data strcuture to be valid

<?xml version="1.0" encoding="utf-8" ?>
<methodCall><methodName>Request.myMethod</methodName>
<params>
<param>
<value>
<struct>
<member><name>Fieldname1</name><value>ANY_STRING</value></member>
<member><name>Fieldname2</name><value>ANY_STRING</value></member>
<member><name>Fieldname3</name><value><int>INTEGER</int></value></member>
<member><name>Fieldname4</name><value><dateTime.iso8601>DATE</dateTime.iso8601></value></member>
<member><name>Fieldname5</name><value><int>INTEGER</int></value></member>
<member><name>Fieldname6</name><value>ANY_STRING</value></member>
</struct>
</value>
</param>
</params>
</methodCall>

and equal to

<?xml version="1.0" encoding="utf-8" ?>
<methodCall><methodName>Request.myMethod</methodName>
<params>
<param>
<value>
<struct>
<member><name>Fieldname1</name><value><string>ANY_STRING</string></value></member>
<member><name>Fieldname2</name><value><string>ANY_STRING</string></value></member>
<member><name>Fieldname3</name><value><int>INTEGER</int></value></member>
<member><name>Fieldname4</name><value><dateTime.iso8601>DATE</dateTime.iso8601></value></member>
<member><name>Fieldname5</name><value><int>INTEGER</int></value></member>
<member><name>Fieldname6</name><value><string>ANY_STRING</string></value></member>
</struct>
</value>
</param>
</params>
</methodCall>

But as mentioned before some servers do not interpret both codes the same and therefore changes on the client's end can save the day.

Code

In order to do this custom class has to be created by extending Serializer

    public class CustomStringSerializer extends StringSerializer 
    {
        public void write(ContentHandler pHandler, Object pObject) throws SAXException 
        {
            write((ContentHandler)pHandler, STRING_TAG, pObject.toString());
        }
    }

STRING_TAG does the job for you. Next custom class TypeFactory has to be created in order to realize this change. This custom TypeFactory utilizes the above mentioned Custom Serializer while XML data structure is generated.

    public class CustomTypeFactory extends TypeFactoryImpl 
    {

        public MyTypeFactory(XmlRpcController pController) 
        {
            super(pController);
        }             
        public TypeSerializer getSerializer(XmlRpcStreamConfig pConfig, Object pObject) throws SAXException 
        { 
            if (pObject instanceof String) 
            {
                return new CustomStringSerializer();
            }  
            else 
            {
                return super.getSerializer(pConfig, pObject);
            }
        }
    }

Last step creation of client

       HashMap data = new HashMap();
       data.put("Fieldname1", new String("ANY_STRING") );
       data.put("Fieldname2", new String("ANY_STRING") );
       data.put("Fieldname3", new Integer(INTEGER));
       data.put("Fieldname4", new Date() );
       data.put("Fieldname5", new String("ANY_STRING") );
       data.put("Fieldname6", new Integer(INTEGER) );
       Vector params = new Vector();
       params.addElement(data);

       XmlRpcClientConfigImpl config = new XmlRpcClientConfigImpl();
       config.setServerURL(new URL("http://localhost:8080/RPC2"));

       XmlRpcClient client = new XmlRpcClient();
       client.setTypeFactory(new CustomTypeFactory(client));
       client.setConfig(config);
       client.execute("Request.myMethod", params);

References

I am new to Apache's XML RPC Library, this article could not have been written without the help from below mentioned references

ws.apache.org/xmlrpc/advanced.html

Marcelo Grassi [Your query at nabble forum helped me write the above code]

FahadAizaz (last edited 2009-09-20 22:47:54 by localhost)