I've started putting some code in the node implementation to allow remote
bindings to make use of reference targets for identifying service endpoints.
It's very simple at the moment. The node implementation uses the
startComposite event as a trigger to
1/ scan all services in the composite and register them with the domain
I've updated the domain implementation so that when there is no remote
domain there registrations are cached locally. It's the same code
implementing the local and remote domain so the proxy effectively provides a
write through cache.
2/ scan all references in the composite and compare them against the
registered service. Replace the binding uri with the uri from the registered
service if appropriate.
The "if appropriate" part is the tricky bit. At the moment the code [1] does
the following.
for (Component component: composite.getComponents()) {
for (ComponentReference reference: component.getReferences()) {
for (Binding binding: reference.getBindings()) {
if (binding.isUnresolved()) {
if (binding instanceof SCABindingImpl){
// TODO - only find uri if its in a remote node
} else {
// find the right endpoint for this
reference/binding. This relies on looking
// up every binding URI. If a response is
returned then it's set back into the
// binding uri
String uri = "";
try {
uri =
((SCADomainSPI)scaDomain).findServiceEndpoint(domainURI,
binding.getURI(),
binding.getClass().getName());
} catch(Exception ex) {
logger.log(Level.WARNING,
"Unable to find service: " +
domainURI + " " +
nodeURI + " " +
binding.getURI() + " " +
binding.getClass().getName() + " " +
uri);
}
if (uri.equals("") == false){
binding.setURI(uri);
}
}
}
}
}
}
There is a bit of slight of hand here;
It looks for all unresolved bindings (it seems that all remote bindings are
unresolved - is that right?)
It then uses the binding uri to look up a service which either finds
something or it doesn't
In the case that a binding.uri has no endpoint specified you will see
something like "MyComponent/MyService" in the binding uri and there's a good
chance that a service will have been registered under this name and hence
the correct target endpoint will be set back into the reference binding.
In the case that a binding uri is set by other means (via the uri attribute
for example) then it will already look something like "
http://myhost:8080/MyComponent/MyService";. This will not match any
registered service name and hence will not be reset. This may not match the
real service uri but then that's the users fault for setting it incorrectly.
This processing is slightly removed from the model itself but relies on the
model and related processing to work out what the binding.uri should be
initially, based on specified target(s) (haven't done anything about the
multiplicity case yet). I welcome any feedback about whether this is going
in the right direction. If people are happy about this I will likely pull
the service registration logic out of the sca binding and treat it in a
similar, more generic, way.
Simon
[1]
http://svn.apache.org/repos/asf/incubator/tuscany/java/sca/modules/node-impl/src/main/java/org/apache/tuscany/sca/node/impl/SCANodeImpl.java
