Apache Tuscany : Java SCA Runtime Component Hierarchy

+

The assmebly diagram

+ +

+

Composite1

+

+<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"
+    targetNamespace="http://sample"
+    xmlns:sample="http://sample"
+    name="Composite1">
+
+    <component name="ComponentA">
+        <implementation.java class="sample.ComponentAImpl"/>
+    </component>
+
+    <component name="ComponentB">
+        <!-- Implemented by Composite3 -->
+        <implementation.composite name="sample:Composite3"/>
+
+        <!-- Wired to ComponentA -->
+        <reference name="Reference1" target="ComponentA"/>
+
+        <property name="Property1">ABC</property>
+    </component>
+
+    <!-- ComponentB.Service1 is promoted -->
+    <service name="Service1" promote="ComponentB/Service1" />
+
+</composite>
+

+

Composite2

+

+<composite xmlns="http://www.osoa.org/xmlns/sca/1.0" targetNamespace="http://sample" xmlns:sample="http://sample"
+    name="Composite2">
+
+    <component name="ComponentC">
+        <implementation.java class="sample.ComponentAImpl" />
+
+        <!-- Wired to ComponentD.Service1 -->
+        <reference name="Reference1" target="ComponentD/Service1" />
+    </component>
+
+    <component name="ComponentD">
+        <!-- Implemented by Composite3 -->
+        <implementation.composite name="sample:Composite3" />
+
+        <!-- The property value is "XYZ" -->
+        <property name="Property1">XYZ</property>
+    </component>
+
+    <!-- ComponentD.Reference1 is promoted -->
+    <reference name="Reference1" promote="ComponentD/Reference1" />
+
+</composite>
+

+

Composite3

+

+<composite xmlns="http://www.osoa.org/xmlns/sca/1.0" targetNamespace="http://sample" xmlns:sample="http://sample"
+    xmlns:xsd="http://www.w3.org/2001/XMLSchema" name="Composite3">
+
+    <component name="ComponentE">
+        <implementation.java class="sample.ComponentEImpl" />
+        <reference name="Reference1" target="ComponentF/Service1" />
+
+        <!-- The property is from the composite Property1 -->
+        <property name="Property1" source="$Property1" />
+    </component>
+
+    <component name="ComponentF">
+        <implementation.java class="sample.ComponentFImpl" />
+    </component>
+
+    <service name="Service1" promote="ComponentE/Service1" />
+
+    <reference name="Reference1" promote="ComponentF/Reference1">
+        <binding.sca />
+    </reference>
+
+    <property name="Property1" type="xsd:string">123</property>
+
+</composite>
+

+

1) Two components are implemented by the same composite
+
+Path a: Composite1.ComponentB is implemented by Composite3
+Path b: Composite2.ComponentD is implemented by Composite3
+
+The service/reference can be promoted to different things:
+
+a: the final target for the ComponentF.Reference1 is Composite1.ComponentA
+b: the final target for the ComponentF.Reference1 is Composite1.Reference1 (pointing to an external service)
+
+The property can be set to different value following different composition path:
+
+a: Composite3.ComponentE.Property1 is overrided by Composite1.ComponentB.Property1 (say value="ABC")
+b: Composite3.ComponentE.Property1 is overrided by Composite2.ComponentD.Property1 (say value="XYZ")
+
+To represent the fully-configured components, we need to clone the model for Composite3 for Path a and b so that it can be used to hold different resolved values.

+ + +

Runtime Wires

+

Hi,

+ +

I'm trying to indentify all the paths of SCA component interactions which
+require to have runtime wires/invocation chains.

+ +

By the SCA spec, there are three cases for the wiring:

+ +

1) Component.Reference (A.ref1) -~~is wired to~~-> Component.Service (B.svc1)
+--------------------------------------------------------------------------------------------------
+1.1) If both the service and reference are defined by non-composite
+components, then the runtime wire is as simple as A.ref1-->B.svc1.

+ +

1.2) If the service is defined on a composite component, then it can be
+further resolved to the orginal atomic component service following the
+service promotion chain.

+ +

For example, A.ref1 --> B.svc1 (B is implemented by another composite and
+B.svc1 promotes C.svc1), then the runtime wire will be: A.ref1 --> C.svc1

+ +

1.3) If the reference is defined on a composite component, then it can be
+further resolved to the orginal atomic component reference following the
+reference promotion chain.

+ +

For example, A.ref1 --> B.svc1 (A is implemented by another composite and
+A.ref1 promotes C.ref1), then the runtime wire will be: C.ref1 --> B.svc1

+ +

2) Composite.Reference (Composite1.ref1) -~~promotes~~-> Component.Reference
+(B.ref1)
+-----------------------------------------------------------------------------------------------------------------
+If Composite1 is the top-level composite, and the B is a non-composite
+component, then the runtime wire will be: B.ref1 --> Composite1.ref1

+ +

If Composite1 is used to implement a component A in Composite2, then we need
+to futher check if A.ref1 is promoted or wired until we hit the end of the
+promotion chain. The final target will be either a composite reference or a
+component service that the out-most reference is wired to. For example, if
+A.ref1 is wired to D.svc1 in Composite2, then the runtime wire is B.ref1 -->
+D.svc1. If A.ref1 is promoted by Composite2.ref1, then the runtime wire is
+B.ref1 --> Composite2.ref1.

+ +

If B is a composite component, then we need to find out the final component
+reference that B.ref1 promotes. For example, it promotes D.ref1, then the
+runtime wire is D.ref1 --> C.ref1

+ +

3) Composite.Service (Composite1.svc1) -~~promotes~~-> Component.Service
+(A.svc1)
+-----------------------------------------------------------------------------------------------------------
+The source will be the outmost service on the promotion chain. For example,
+if Composite2.svc1 promotes B.svc1 and B is implemented by Composite1, then
+it is Composite2.svc1.

+ +

The target will be the innermost service on the promotion chain. For
+example, if A is implemented by Composite3 and Composite3.svc1 promotes
+C.svc1, then it is C.svc1.

+ +

Please note, due to the spec limitation, the composite service cannot
+promote a composite reference directly.

+ + +

Based on the above scenarios, it seems that we can create runtime wires
+using the following algorithm (assuming multiplicity = 1..1). The key is to
+get a final list of targets and selected bindings.

+ +

1) Runtime wire for references: For each of the references (r1) on
+non-composite components, find the outmost reference (r0) on the reference
+promotion chain. Then get the targets and selected bindings from r0. If SCA
+binding is used for a target, it can be further optimized to use the
+orginally promoted component service. The runtime wire should be created
+between the r1 and a target (either a component service with SCA binding or
+a reference binding) from r0.

+ +

2) Runtime wire for service promotions: For each of the service1 (s1) on
+non-composite components, find the outmost service (s0, can be the same as
+s1) on the service promotion chain. Create a runtime wire between the
+selected binding of s0 and the component that defines s1. (Can we assume
+that s1 is always local to s0?)

+ +

The service/reference promotions make the picture complicated. I hope my
+thought makes sense.

+ +

Thanks,
+Raymond

+

+ +

Runtime Context Interfaces

+

+public interface RuntimeContext<M> extends Lifecycle {
+    /**
+     * Create an intercetor for the model in the invocation chain. For a reference binding,
+     * the interceptor is responsible to make the outbound invocation over the binding protocol.
+     * For a service binding, the interceptor is responsible to dispatch the incoming call to
+     * the target component service that the service promotes. For a component implementation,
+     * the interceptor will be responsible for calling the implementation logic for the given
+     * component.
+     * 
+     * @param model The service that defines the binding
+     * @param operation The operation that the interceptor will handle
+     * @param isCallback A flag to tell if the operation is for the callback
+     * @return An interceptor that handles the invocation logic, null should be returned if no 
+     * interceptor is required
+     */
+    Interceptor createInterceptor(M model, Operation operation, boolean isCallback);
+    
+    /**
+     * Get the effective interface contract imposed by the binding or implementation. For
+     * example, it will be interface contract introspected from the WSDL portType used by the
+     * endpoint for a WebService binding.
+     * @param model The model object
+     * 
+     * @return The effective interface contract
+     */
+    InterfaceContract getEffectiveInterfaceContract(M model);
+}
+
+public interface ReferenceBindingContext extends RuntimeContext<Reference> {
+    /**
+     * @param wire
+     */
+    void setRuntimeWire(RuntimeWire wire);
+    /**
+     * @return
+     */
+    RuntimeWire getWire();    
+}
+
+public interface ServiceBindingContext extends RuntimeContext<Service> {
+    /**
+     * @param wire
+     */
+    void setRuntimeWire(RuntimeWire wire);
+    /**
+     * @return
+     */
+    RuntimeWire getWire();    
+}
+
+public interface ImplementationContext extends RuntimeContext<Component> {
+}
+

+