What is Aegis?

Aegis is a databinding. That is, it is a subsystem that can map Java objects to XML documents described by XML schema, and vica-versa. Aegis is designed to give useful mappings with a minimum of programmer effort, while allowing detailed control and customization.

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You can use Aegis as a client to talk to Aegis, by using the very same Java classes and configuration files in the client environment that you use on the server. However, it's not all that practical to use Aegis as a client to talk to some a service using some other data binding, since Aegis lacks a 'wsdl2java' tool.

Every CXF service and client uses a front end: JAX-WS, Simple, etc. Each of these provides a place to configure the data binding, both in Spring and via Java code.

For example, here is a Simple front-end service using Aegis as a data binding.

Using Aegis on the client side also carries severe risks of compatibility problems. Since there is no WSDL to specify the contract, small changes in your code or in CXF can result in a situation where the client and the server are incompatible. If you want to use Aegis on the client side, you should be sure to use exactly the same version of CXF on both sides. If you cannot do that, you should consider generating JAX-WS/JAX-B code for the client using wsdl2java.

Every CXF service and client uses a front end: JAX-WS, Simple, etc. Each of these provides a place to configure the data binding, both in Spring and via Java code.

For example, here is a Simple front-end service using Aegis as a data binding.

<simple:server id="pojoservice" serviceClass="demo.hw.server.HelloWorld" 
  address="/hello_world">
  <simple:serviceBean>

  <simple:server id="pojoservice" serviceClass="demo.hw.server.HelloWorld" address="/hello_world">
  	<simple:serviceBean>
  		<bean class="demo.hw.server.HelloWorldImpl" />
  	</simple:serviceBean>
         <simple:dataBinding>
       <bean class="orgdemo.apachehw.cxf.aegis.databinding.AegisDatabindingserver.HelloWorldImpl" />
  </simple:serviceBean>
  </simple<simple:dataBinding>
    <bean class="org.apache.cxf.aegis.databinding.AegisDatabinding" />
  </simple:server>dataBinding>
 </bean>simple:server>

AegisDatabinding is the class that integrates Aegis into CXF as a databinding.

Note that AegisDatabinding beans, like all databinding beans, are not reusable. The example
above uses an anonymous nested bean for the databinding. If you make a first-class bean for
a databinding, be sure to use scope='prototype' if you are inclined to define more than one endpoint.

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How about the reverse process: deserializing? (JAXB calls this unmarshalling.) In this case, by default, Aegis is presented with an XML element and asked to produce a Java object. Recall, however, that the Aegis maintains a mapping from Java types to XML Schema Types. By default, an XML instance document offers no information as to the type of a given element. How can Aegis determine the Java type? Outside of CXF, the application would have to tell Aegis the expected type for the root element of a document. Inside CXF, however, Aegis gets the benefit of the Message and

Or, as an alternative, Aegis can add xsi:type attributes to top-level elements when writing. It will always respect them when reading.

Inside CXF, Aegis gets the benefit of the Message and Part information for the service. The WSDL service configuration for a service gives enough information to associate an XML Schema type with each part. Once the front-end has determined the part, it can call Aegis with the QName for the schema type, and Aegis can look it up in the mapping.Will it be in the mapping? Yes, because Aegis precreates mappings for the types in the service's parts. Aegis cannot dynamically create or choose a Java class based on XML schema, so the type creators cannot start from XMLthe mapping.

Will it be in the mapping? Yes, inside CXF because Aegis precreates mappings for the types in the service's parts. Aegis cannot dynamically create or choose a Java class based on XML schema, so the type creators cannot start from XML. Thus, outside CXF you are responsible for ensuring that your top-level types are mapped.

Schema Validation

As of CXF 2.3, the Aegis databinding can leverage the Schema Validation capabilities built into the Woodstox 4.x Stax parser to validate incoming requests. To enable this, you must do the following:

1. Make sure you are using the Woodstox 4.x Stax parser and not a 3.x or other parser. By default, CXF 2.3 ships with an appropriate version of Woodstox.
2. If not using the CXF bundle jar, (example, if using maven), you'll need to add the cxf-wstx-msv-validation-2.3.0.jar to the classpath
3. If not using maven or similar to obtain the cxf-wstx-msv-validation jar, you'll also need to add the msv validation jars as CXF does not ship them by default. You will need:

   Code Block
   isorelax-20030108.jar msv-core-2009.1.jar relaxngDatatype-20020414.jar xercesImpl-2.9.1.jar xml-resolver-1.2.jar xsdlib-2009.1.jar

4. If not using a default bus (such as configuring your own spring context), you'll need to add:

   Code Block
   xml xml
   <import resource="classpath:META-INF/cxf/cxf-extension-wstx-msv-validation.xml" />

   to load the validator utilities that Aegis will use.
5. Turn on schema validation like you would for JAXB by using the @SchemaValidation annotation or setting the "schema-validation-enabled" property on the endpoint to "true".

Using Java Classes That Aren't Visible to the Service Interface

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<mappings>
	   <mapping>
		      <method name="getUnannotatedStrings">
			         <return-type name="UnannotatedStringCollection" 
             componentType="java.lang.String"/>
		      </method>
        <method name="getValues">
         <parameter index="0" componentType="java.lang.String"/>
        </method>
	   </mapping>
</mappings>

Annotations

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