xmlrpc/ExampleUsingOwnInterfaceTypes.md

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+---
+
+### Using Interface Types and Abstract Classes
+
+The API is defined the same way as in the [preceeding use case](ExampleUsingOwnConceteTypes).
+
+```java
+public interface Api
+{
+    Param returnParam();
+    
+    void passAsParameter( Param p );
+}
+
+public class Impl implements Api
+{
+    public Param returnParam() { return createParam( ... ); }
+    
+    void passAsParameter( Param p ) { doSomethingWith( p ); }
+}
+
+```
+Since Param is an interface, the runtime system cannot create instances of this type without further information.
+We use the concrete attribute of the @XmlRpc annotation to tell the Delight runtime-system what concrete type to use to create instances of type Param.
+
+In this case we use the concete class ''ParamImpl'' to create instances of type Param (note that ''ParamImpl'' has to be a Convertable and also has to implement ''Param''):
+
+```java
+@XmlRpc( type=Type.STRING, 
+         concrete=ParamImpl.class )
+public interface Param
+{
+    public String printContent() { ... }
+}
+
+public class ParamImpl implements Param, 
+                                    Convertable<String>
+{
+    public ParamImpl( String xmlRpcRepresentation ) { processXmlRpc( xmlRpcRepresentation ); }
+
+    public String toXmlRpc() { return( createXmlRpcRep() ); }
+}
+```
+
+#### Client side
+
+The client can be created and used without further actions to take. No factories to register. No configuration files to load. Just like a local call to the API.
+```java
+Api remote_api = XmlRpc.createClient( Api.class, "handlerId", host, port );
+
+Param p = remote_api.returnParam();
+System.out.println( p.printContent() );
+
+Param asParam = new ParamImpl(...);
+remote_api.passAsParameter( asParam );
+
+...
+```
+
+
+See also [Using own concrete types in your API](ExampleUsingOwnConceteTypes).
+
+Examples in source code: [here](https://git.opendfki.de/delight/delight/tree/master/example-delight-webapp)