On Jan 30, 2008 6:33 PM, Raymond Feng <[EMAIL PROTECTED]> wrote: > Hi, > > As of today, we can add multiple interceptors to the invocation chain, but > we cannot control their ordering. When more policies are supported, I see > a > need to provide some simple ordering mechnisim for interceptors. > > SCA invocation may have three stages: reference, service and > implementation. > For example, a typical invocation chain for the reference side can be: > > reference: (SourceComponent) --> DataTransformation --> > Suspend/PropagateTransaction --> ReferenceBindingInvoker --> ... > service: (ServiceBindingListener) --> DataTransformation --> > PropagateTransaction > implementation: ManagedTransaction --> ImplementationInvoker --> > (TargetComponent) > > Here is my proposal: > > We introduce a phase concept which groups a collection of interceptors to > a > relative position in the invocation chain for each stage. There are a list > of system defined phases (such as reference.invoker or > implementation.invoker) and it can be extended by Tuscany extensions. > > Each phase is uniquely identied by the name. Each phase can define its > relative ordering using the 'before' and/or 'after' attributes. When an > interceptor is added to the InvocationChain, we can specify a phase name. > The Tuscany runtime will sort the phases by the partial order. SCA > invocations will be dispatched in the order of phases. There is no > ordering > between interceptors in the same phase. > > To define a phase, we use the following simple syntax in the service > provider file named as > "META-INF/services/org.apache.tuscany.sca.core.invocation.Phase". > > name=PhaseName, stage=stageName, before=PhaseName4 PhaseName5, > after=PhaseName3 > > name: The name of the phase > stage: The stage of the phase, it can be one of the values: reference, > service, or implemention > before: A list of phase names separated by spaces to denote this phase > should be placed before > after: A list of phase names separated by spaces to denote this phase > should > be placed after > > A special phase name '*' can be used for 'before' and 'after' attribute to > represent all phases. > > For example, > > name=reference.invoker, stage=reference, after=* > name=reference.databinding, stage=reference, before=reference.invoker > name=reference.transaction, stage=reference, after=reference.databinding > > I already have a prototype under development. Your opinions are welcome. > > Thanks, > Raymond > > Sounds ok to me, its very similar to Axis2 phases, but i do share Venkat's concern that it seems complex. Are there real use cases that require such fine control that we need to support imminently and if so could we hear a bit more detail of what they are?
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