Big RDF graph and its revisions

[Andreas S. Rath (teddius)]

Hi OpenAnzo Group,

If there is a NamedGraph with millions of triples stored on the server
and you would like to get a certain revision of this graph then you
do a

IAnzoGraph namedGraphRevision =
anzoClient.getNamedGraphRevision(graph.getNamedGraphUri(), new
Long(422));

The problem with this call is that you get an exception on the client
if the graph is too big. There is no exception on the server ( i.e. in
the /var/anzo.log file)

<--- snip Exception start --->
org.openanzo.common.exceptions.AnzoException: ErrorCode[16:16393]
[COMBUS_ERROR] No Response from Server for request
74dc5e10-294b-4b98-82eb-322d4d1cb7d1.
at
org.openanzo.servicecontainer.backends.JMSConnectionBackend.requestResponse(JMSConnectionBackend.java:
731)
at
org.openanzo.servicecontainer.services.proxy.jms.JMSModelServiceProxy.getNamedGraphRevision(JMSModelServiceProxy.java:
197)
at
org.openanzo.servicecontainer.services.proxy.jms.JMSModelServiceProxy.getNamedGraphRevision(JMSModelServiceProxy.java:
168)
at
org.openanzo.client.AnzoClient.getNamedGraphRevision(AnzoClient.java:
863)
at ....
<--- snip Exception end --->


In the documentation available at " http://www.openanzo.org/projects/openanzo/wiki/AnzoClientDesign
" following is stated:
" getNamedGraphRevision - Return an in-memory copy of the given named
graph at the given revision. The returned graph may be modified in
memory, but these modifications have no effect on the named graph in
neither the repository nor the local replica"

Is there a way round the in-memory problem of big graphs?

Is it possible to replace a big graph with a earlier revision?

Thanks and all the best,
Andreas

[Ben Szekely]

Hi Andreas,
The problem is that the request-response over JMS mechanism is
timing out because the response does not come back within 30 seconds.
We'd have to go into the code and change this timeout to be something
longer, or infinte. However, I do agree that we should have a call on
the anzo client to revert a graph to a particular revision on the
server, but it may be a while before this makes it into the API, so
unfortunately reverting will have to be done manually on the client.

I'm in the process of putting together documentation for Open Anzo 3.1
which is now available for download. We will try to put a feature in
that allows you to set the timeout for various calls once you have moved
over to 3.1 where we are doing our development.

- Ben