definitions.xml

Section 1.8 describes the definitions.xml file as holding all of the artifacts that are useful for configuring an SCA domain but that are not specific to a particular composite or component. It goes on to say that "All of these artifacts within and SCA Domain are defined in a global, SCA Domain-wide file named definitions.xml". To achieve our extensibility goals we, in Tuscany, consider the SCA Domain wide definitions.xml file to be a logical concept that is constructed at runtime from the contents of definitions.xml files provided in contributions and in Tuscany extensions.

Each definitions.xml file may contain.

Intents
Policy sets
Predefined binding specifications
Binding type descriptions
Implementation type descriptions

Complete Features

Add Intents and Policy Sets with an Extension

An extension, such as the modules/policy-security extension relies on some policy sets and intents being available in the SCA Domain. The definitions.xml is the place to define these and hence if you look in this extension module you will find the following.

<definitions xmlns="http://www.osoa.org/xmlns/sca/1.0"
 			targetNamespace="http://www.osoa.org/xmlns/sca/1.0"
 			xmlns:sca="http://www.osoa.org/xmlns/sca/1.0"
 			xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.0">

    <!-- POLICY SETS -->
    <policySet name="runAs" appliesTo="sca:implementation.java"/>
    <policySet name="allow" appliesTo="sca:implementation.java"/>
    <policySet name="rolesAllowed" appliesTo="sca:implementation.java"/>
    <policySet name="permitAll" appliesTo="sca:implementation.java"/>
    <policySet name="denyAll" appliesTo="sca:implementation.java"/>
    
	<!-- Policy Intents Defined by the SCA Runtime -->
	<intent name="authentication" 
	 		constrains="sca:binding">
		<description>
			Specifying this intent on references requires necessary authentication information
			to be sent along with outgoing messages. Specifying this intent on service requires
			incoming messages to be authenticated
		</description>
	</intent>
	
	<intent name="confidentiality" 
	 		constrains="sca:binding">
		<description>
			Specifying this intent requires message exchanged to be encrypted
		</description>
	</intent>
	
	<intent name="integrity" 
	 		constrains="sca:binding">
		<description>
			Specifying this intent requires message exchanged to be signed
		</description>
	</intent>
</definitions>

When this module is loaded at runtime the contents of this file are made generally available and hence in you composite you can use statements such at.


<component name="CalculatorServiceComponent">
    <implementation.java class="calculator.CalculatorServiceImpl"/>
    <reference name="addService" >
        <interface.java interface="calculator.AddService" />        
        <binding.ws uri="http://localhost:8080/sample-calculator-ws-secure-webapp/AddServiceComponent"
                    requires="authentication" />        
    </reference>
</component>

Where requires="authentication" refers to intent name="authentication" which is now available as an SCA Domain level definition.

TODO Features

Add Intents and Policy Sets with a Contribution

If contributionA provides a file such as:

<sca:definitions xmlns="http://www.osoa.org/xmlns/sca/1.0"
 			targetNamespace="http://tuscany.apache.org/xmlns/sca/1.0"
 			xmlns:sca="http://www.osoa.org/xmlns/sca/1.0"
 			xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.0">

<sca:intent name="specialAuthentication" 
            constrains="sca:binding.ws">
    <description>
        Communitcation thro this binding required Authentication.
    </description>
</sca:intent>	
 
</sca:definitions>

and ContributionB provides a file such as:

<sca:policySet name="specialAuthenticationPolicy"
 	       provides="tuscany:wsAuthentication"
 	       appliesTo="//sca:binding.ws">
    <tuscany:wsConfigParam>
        <parameter name="OutflowSecurity">
            <action>
                <items>UsernameToken</items>
                <user>TuscanyWsUser</user>
                <passwordCallbackClass>my.PWCBHandler</passwordCallbackClass>"
                <passwordType>PasswordText</passwordType>
            </action>
        </parameter>
    </tuscany:wsConfigParam>
</sca:policySet>

Then both the itent and the policySet should be available in the logical SCA Domain-wide definitions.xml and the policySet "specialAuthenticationPolicy" should successfully find the intent "tuscany:wsAuthentication". Composite files contributed to the domain will successfully be able to reference both the intent and the policy set.

See:

https://issues.apache.org/jira/browse/TUSCANY-2499
http://www.mail-archive.com/dev%40tuscany.apache.org/msg01077.html