Millies, Sebastian wrote:
From: Jon Giddy [mailto:[email protected]]
Sent: Wednesday, November 16, 2011 5:44 PM
On 16/11/11 13:29, Simon Nash wrote:
Millies, Sebastian wrote:
can references in composite files somehow be made dynamic? In
particular, can I define or override
the endpoints in a web service reference at run time?
[snip]
It might be possible to use service references for this. A service
reference can be serialized/deserialized to/from XML. So you could
use runtime code to create the XML-equivalent form of the service
reference that you need, then deserialize the XML to create the
service reference.
We tried something like this, but failed to get it to work fully.
[snip]
We then tried a solution where, as each service starts up, it creates a
ServiceReference to itself, marshals that into Base64, and calls an
endpoint on the client, passing in its ServiceReference, which is
stored
in an internal directory (basically a HashMap). The client is then able
to retrieve the endpoints from its internal directory and use them.
However, a service registering with a client is a little bizarre. We
really wanted the service to register its ServiceReference with a
directory service, and for the client to retrieve the
ServiceReference(s) from the directory service. That is, replace the
internal HashMap with an external service. This would be the classic
Publish-Find-Bind model of Service Oriented Architecture.
However, we couldn't get it to work. The client can get the Base64
encoded ServiceReference, and perform the same actions as before, but
we
get a NullPointerException when attempting to use the reference.
It would be great to know if anyone else succeeds at this, as we feel
so
close to achieving dynamic binding in Tuscany,...and yet so far.
Jon.
My problem is similar but not identical. I would need to manipulate the
ServiceReference itself according to Simon's suggestion. Now, how would one
go about serializing and deserializing a ServiceReference to/from XML. I have
tried two approaches, neither of which will quite work:
private <T> ServiceReference<T> copy( ServiceReference<T> serviceRef, String
wsUri )
throws IOException
{
// first approach
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream( baos );
out.writeObject( serviceRef );
// will not yield XML, but binary data, so is not easily manipulable
String xml1 = baos.toString( "UTF-8" ) ;
Agreed. This isn't what I had in mind.
// second approach
ServiceReferenceImpl<T> sri = (ServiceReferenceImpl<T>) serviceRef;
String xml2 = sri.toXMLString();
// manipulate xml2 ...
ComponentContextHelper cch =
ComponentContextHelper.getCurrentComponentContextHelper();
Component comp = cch.fromXML( xml2 );
List<?> refs = comp.getReferences();
// ClassCastException, because we'll get back a RuntimeComponentReferenceImpl
ServiceReference<T> sr = (ServiceReference<T>) refs.get( 0 );
return sr;
}
This use of toXML() and fromXML() is the approach that I was suggesting.
I'll look into the ClassCastException to see if I can find a way round it.
I'm busy with another project at the moment, so it's likely to be a few
days before I have any news.
Simon
Sebastian
IDS Scheer Consulting GmbH
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