Hi Monosij,
See comments below.
Simon
Monosij Dutta-Roy wrote:
Simon -
Thanks for your help with the ServiceReference - it is almost there but
am getting a null-pointer error on trying to access the QueryResults.
I have attached the error file generated.
---------------------
Starting with QueryExecutor where I create the ServiceReference object as:
@Reference
protected ServiceReference<QueryResults> queryResults;
That looks right.
I pass it back through QueryOrchestrator > QueryService > QueryServlet
and I declare the reference in *_each_* object the same as above.
>
You should only use the @Reference annotation in QueryExecutor. In the
other classes you should declare it as a normal Java variable with the
type ServiceReference<QueryResults>.
And refer to it in the composite file as:
<reference name="queryResults"
target="QueryResultsComponent/QueryResults">
<interface.java interface="org.rd.qm.QueryResults"/>
</reference>
You should only be doing this in QueryExecutor.
It seems to work as now I do not get the PassByValue error anymore.
---------------------
But now I get a null-pointer error when trying to access the
QueryResults object in the ServiceReference object.
I set the ServiceReference<QueryResults> queryResults in QueryExecutor as:
first this way:
queryResults.getService().setResults(alPatients);
That looks right.
second in this way:
QueryResults quRes = new QueryResultsImpl();
quRes.setResults(alPatients);
queryResults.getBusinessInterface().cast(quRes);
That doesn't look right.
Essentially I am trying to set the ArrayList of results in QueryResults
and in QueryServlet trying to display the ArrayList.
So in QueryServlet I try to access the ArrayList as:
ArrayList alPatients = queryResults.getService().getResults();
That looks right.
This seems to be fine as I get an ArrayList
But I get a null-pointer when I try to iterate the ArrayList.
>
I'm not sure why this is happening. You should get the same contents
from doing this in QueryServlet as you would get if you did it in
QueryExecutor after the setResults() call. Can you try interating the
ArrayList in QueryExecutor after calling setResults() to see if that
works OK?
---------------------
Questions:
1. Seems the way I set I have set up the ServiceReference is working. Is
that the best way to set up the ServiceReference? If so it seems like it
would be a good idea to have ServiceReferences as
a separate contribution that is 'passed around'. And then take it a step
further by setting ServiceReferences as JAXB datatypes.
Contributions aren't passed around at runtime. The way you are doing it
(with the changes/corrections that I suggested above) is fine. I think
it's best to defer the JAXB issues until you have got the non-JAXB code
working.
2. I had to set up the ServiceReference in each obect, even in
QueryServlet. QueryServlet which calls QueryService (in same composite)
still needs to pass back QueryResults as a ServiceReference since
QueryService is defined as Remotable. I was planning on using
QueryService for housekeeping while still making it Remotable - and pass
back to QueryServlet only what is needed (so servlet framework can be
swapped out). But now it seems I have to make the QueryServlet (ie the
Servlet framework) depend on QueryResult or such. Is there a way to
avoid this? Am I thinking about this the right way? I am thinking
QueryServlet should only know and depend on QueryService in the same
composite. I guess then QueryService has to be Local?
If you make QueryService local, this means the code for QueryService
will always run in the same webapp as QueryServlet. Is that what
you want? Originally I thought you wanted to keep the back-end logic
separate from the UI framework. Is QueryService part of the back-end
logic or is it part of the UI framework?
3. This is a question for later once I get this working but I am
currently importing QueryOrchestrator in QueryService (webapp). Would
there be a way to go around this and not have QueryOrchestrator
connected at all. I am assuming I can go the ws.binding route and just
call the webservice that QueryOrchestrator will service - but I lose the
non-ws.binding connectivity. Would there be a way to just depend on
QueryResults - that is shared by everyone and is a ServiceReference - to
make it happen. I am just shooting in dark here a little. But my thought
is I should only want to depend on QueryResults and not worry about how
I get QueryResults. I guess I will need to try some approaches.
I'm not sure what the purpose of QueryOrchestrator is. As you say, getting
it working is the first priority. When you have it working, you can look
at the end-to-end design and make changes incrementally to change the
component structure as needed. With SCA, this should be easy to do.
4. This maybe related, not a big deal but strange. I am using Eclipse
Helios on Ubuntu and since I started using ServiceReference - the
objects from the third composite: domainBCA - which are Person and
PhysicalLocation have an error marker on them as 'import not found'. I
tried deleting them and recreating the imports, it still remains.
Removing ServiceReference makes those go away. However it does not
create a problem as such as Maven compiles fine - but it is happening in
both the composites: controller and servlet.
---------------------
Thanks for all your help and patience.
My guess is that your Eclipse workspace is missing a dependency on the
Tuscany library that provides the definition of the ServiceReference interface.
Simon
monosij
------------------------------------------------------------------------
HTTP ERROR 500
Problem accessing /qmAppSCA01/QueryServlet. Reason:
INTERNAL_SERVER_ERROR
Caused by:
java.lang.NullPointerException
at org.rd.qm.servlet.QueryServlet.getPatients(QueryServlet.java:74)
at org.rd.qm.servlet.QueryServlet.service(QueryServlet.java:91)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:401)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
at
org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at
org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at
org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:945)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at
org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
at
org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
------------------------------------------------------------------------
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