xmlrpc/ExampleUsingThirdPartyTypes.md

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+---
+
+### Using Third Party Types in your API
+
+Eventually, you want to use third party types in your remote calls. Unfortunately the nice annotation features we saw in [Using own concrete types in your API](ExampleUsingOwnConceteTypes) and [Using interface or abstract types in your API](ExampleUsingOwnInterfaceTypes) are not applicable here because you are neither allowed to modify the classes nor makes it sense to add an additional dependency to that type.
+The Delight XML-RPC framework offers a solution to this problem by offering conversion mappings to be declared with the API (of course you can add as many mappings as you want):
+
+```java
+@ConverterMappings( 
+      @Mapping(type=URL.class,converter=URLConverter.class) 
+)
+public interface Api
+{
+    URL getHomepageLocation();
+    void addSite( URL url );
+}
+```
+
+We have to define a standalone converter to transfer instances of type URL to a XML-RPC representation and vice versa. 
+Therefor, the converter has to implemente the interface ''ParameterConverter'' to define three methods:
+
+ - getXmlRpcRepresentationType(): states what XML-RPC type will be used as transport representation
+
+ - createFrom(): takes a XML-RPC representation and creates a corresponding instance of type ''URL''.
+
+ - toXmlRpc(): takes an instance of type ''URL'' and converts it into it's XML-RPC representation.
+
+See the complete class here:
+```java
+public class URLConverter implements ParameterConverter<URL, String>
+{
+    public Type getXmlRpcRepresentationType() { return( XmlRpc.Type.STRING ); }
+    
+    public URL createFrom( String xmlRepresentation )
+        throws TypeConversionException
+    {  ...
+    }
+
+    public String toXmlRpc( URL param )
+        throws TypeConversionException
+    {
+        return( param.toExternalForm() );
+    }
+}
+```
+
+Now, without having to modify it, the type ''URL'' can be used in XML-RPC calls.
+
+```java
+Api remote_api = XmlRpc.createClient( Api.class, "handlerId", host, port );
+
+URL homepageUrl = remote_api.getHomepageLocation();
+InputStream is = homepageUrl.openStream();
+...
+
+remote_api.addSite( new URL( "http://middle.of.nowhere" ) );
+
+...
+```
+
+See also: [Using own concrete types in your API](ExampleUsingOwnConceteTypes) how to use own types contained in Collections an Maps].
+
+Examples in source code: [here](https://git.opendfki.de/delight/delight/tree/master/example-delight-webapp)
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