Simple XML deployer

[dimitris]

I think I can start with the jbossXB mapping and a subset of the existing -service.xml and enhance this gradually? Something like:

<bean name="bla" class="org.jboss.bla.Bla">
 <constructor>
 <arg type="java.lang.String">value</arg>
 ...
 </constructor>

 <attribute name="yada">value</attribute>
 ...
 <demands> ???
 </demands>
 ...
 <supplies/>
 ...
</bean>

1) Do we need to create subclasses of the org.jboss.metadata.pluings.AbstractXXX classes? If yes what's a suitable package for them?
2) What goes in Supplies?
3) Instead of Supplies/Demands wouldn't Provides/Depends be more consistent with what we have now?
4) What are we supposed to store in the AbstractFeatureMetadata map
5) Is the AbstractValueMetadata 'Object getValue()/setValue(Object)' really needed? Wouldn't be better for derived classes to provide a typed version, e.g. 'String getValue()' for StringValueMetadata
6) Do we need an .xsd or .dtd for the parsed xml?

[adrian.brock]

I've written a simple XML deployer.
The implementation is in
org.jboss.kernel.plugins.deployment.xml.XMLKernelDeployer

It uses Alexey's new MappingObjectModel from JBossXB, very nice :-)

You can define your parser in just a few lines of code;
e.g. currently I have

 objectModelFactory = new MappingObjectModelFactory();
 objectModelFactory.mapElementToClass("deployment", AbstractKernelDeployment.class);
 objectModelFactory.mapElementToClass("beans", ArrayList.class);
 objectModelFactory.mapElementToClass("bean", AbstractBeanMetaData.class);
 objectModelFactory.mapElementToClass("constructorParams", ArrayList.class);
 objectModelFactory.mapElementToClass("dependency", AbstractDependencyValueMetaData.class);
 objectModelFactory.mapElementToField("dependentState", AbstractDependencyValueMetaData.class, "dependentState", StateConverter.instance);
 objectModelFactory.mapElementToClass("parameter", AbstractParameterMetaData.class);
 objectModelFactory.mapElementToField("dependency", AbstractParameterMetaData.class, "value", TypeConverter.STRING);
 objectModelFactory.mapElementToClass("value", StringValueMetaData.class);
 objectModelFactory.mapElementToClass("attributes", HashSet.class);
 objectModelFactory.mapElementToClass("attribute", AbstractAttributeMetaData.class);
 objectModelFactory.mapElementToField("dependency", AbstractAttributeMetaData.class, "value", TypeConverter.STRING);
 objectModelFactory.mapElementToClass("demands", HashSet.class);
 objectModelFactory.mapElementToClass("demand", AbstractDemandMetaData.class);
 objectModelFactory.mapElementToField("whenRequired", AbstractDemandMetaData.class, "whenRequired", StateConverter.instance);
 objectModelFactory.mapElementToClass("supplies", HashSet.class);
 objectModelFactory.mapElementToClass("supply", AbstractSupplyMetaData.class);
 objectModelFactory.mapElementToClass("interceptors", ArrayList.class);
 objectModelFactory.mapElementToClass("interceptor", AbstractInterceptorMetaData.class);

There are some examples used by the tests in
jboss-head/kernel/src/resources/test/org/jboss/test/kernel/xml/test

[starksm64]

What is the context for this starting point?

[adrian.brock]

The other use of the featuremetadata is to provide metadata to each context.
But I need to discuss this with Bill because he has two mechanisms for this:

1) getMetaData(...)
2) resolveAnnotation(...)

The annotation approach is obviously superior because it is type checked,
but we also need the mechanism to work in java1.4

Use cases, detyped approach:
1) ModelMBean descriptor

<attribute name="Blah">InitialValue
 <metadata domain="modelmbean" type="cache-timeout">NEVER</metadata>
</attribute>

2) Aspect context configuration

<attribute name="Blah">InitialValue
 <metadata domain="transaction" type="demarcation">Required</metadata>
 <metadata domain="authorization" type="roles">admin</metadata>
</attribute>

NOTE: The above xml is intended to express the idea, not specify how we are
actually going to do it/use it.
Remember, what we are configuring here using XML with be done programmatically
by the other deployers (sar, aop, ejb, etc.).

[adrian.brock]

I've written a simple XML deployer.
The implementation is in
org.jboss.kernel.plugins.deployment.xml.XMLKernelDeployer

It uses Alexey's new MappingObjectModel from JBossXB, very nice :-)

You can define your parser in just a few lines of code;
e.g. currently I have

 objectModelFactory = new MappingObjectModelFactory();
 objectModelFactory.mapElementToClass("deployment", AbstractKernelDeployment.class);
 objectModelFactory.mapElementToClass("beans", ArrayList.class);
 objectModelFactory.mapElementToClass("bean", AbstractBeanMetaData.class);
 objectModelFactory.mapElementToClass("constructorParams", ArrayList.class);
 objectModelFactory.mapElementToClass("dependency", AbstractDependencyValueMetaData.class);
 objectModelFactory.mapElementToField("dependentState", AbstractDependencyValueMetaData.class, "dependentState", StateConverter.instance);
 objectModelFactory.mapElementToClass("parameter", AbstractParameterMetaData.class);
 objectModelFactory.mapElementToField("dependency", AbstractParameterMetaData.class, "value", TypeConverter.STRING);
 objectModelFactory.mapElementToClass("value", StringValueMetaData.class);
 objectModelFactory.mapElementToClass("attributes", HashSet.class);
 objectModelFactory.mapElementToClass("attribute", AbstractAttributeMetaData.class);
 objectModelFactory.mapElementToField("dependency", AbstractAttributeMetaData.class, "value", TypeConverter.STRING);
 objectModelFactory.mapElementToClass("demands", HashSet.class);
 objectModelFactory.mapElementToClass("demand", AbstractDemandMetaData.class);
 objectModelFactory.mapElementToField("whenRequired", AbstractDemandMetaData.class, "whenRequired", StateConverter.instance);
 objectModelFactory.mapElementToClass("supplies", HashSet.class);
 objectModelFactory.mapElementToClass("supply", AbstractSupplyMetaData.class);
 objectModelFactory.mapElementToClass("interceptors", ArrayList.class);
 objectModelFactory.mapElementToClass("interceptor", AbstractInterceptorMetaData.class);

There are some examples used by the tests in
jboss-head/kernel/src/resources/test/org/jboss/test/kernel/xml/test

[adrian.brock]

On a related note, the interface
org.jboss.kernel.spi.deployment.KernelDeployment
is the start of the M2 deployer code.

The method KernelDeployment.getBeans()
doesn't have to have a fixed list of BeanMetaData like in the abstract implementation.

It can be "dynamically" generated from a more convenient metamodel like the
ejb metadata or web metadata or some intermediate form.