On 12/12/2019 19:30, Nouwt, B. (Barry) wrote:
Hey Andy, thanks for the quick response.
Aha, I forgot it is a regular Jetty servlet container and your proposal of an
ActiinProcessor that refuses HTTP sounds as a possible solution.
"Concrete description of the pub/sub": we are currently using Apache ActiveMQ
with TCP and WebSocket connectors on (indeed) different ports, which works okay for now.
However, in my opinion, it would be way more elegant if we could expose this
functionality as a Fuseki service like /ds/subscribe.
I think this will be quite a challenge, since I am not sure if for example
client-side JMS ConnectionFactories accept paths for broker services.
"What parts of the Fuseki infrastructure would you want to access and reuse?"
Not sure, the main reason we want this is because it has a tighter integration with
Fuseki and this would be more elegant and consistent for the outside world: for
request/response you go to the /ds/query endpoint and for subscribe/publish you go to the
/ds/subscribe endpoint. We can then also use the Assemblers to define such subscribe
services for a particular dataset and maybe use Fuseki's GUI that shows the services as
well.
Curious about your thought about the above.
Sound like a plan!
It would be better (longer term) if Fuseki let an unregistered name
under a dataset just pass through to normal URL routing in the servlet
container (Fuseki uses a servlet.Filter and it currently drops through
for unrecognized datasets), then you could have a plain servlet or
webpage on /ds/subscribe.
This look possible to do - could you raise a JIRA ticket please?
Andy
Regards, Barry
Op 12 dec. 2019 18:02 schreef Andy Seaborne <[email protected]>:
Hi Barry,
The FusekiServer.Builder (main) or web/xml (Fuseki full) can includes
arbitrary servlets and servlet filters so anything can be added but the
naming requirement may currently get in the way.
Routing is by the dataset part fo the URL path. If you want
"/ds/myPubSub" and also /ds/sparql" then currently "myPubSub" will need
to be an ActionProcessor (and will get the logging and counters added.)
Could you give a concrete description of the pub/sub? Which protocol(s)
does it want to use if not HTTP? Plain TCP on differnt ports?
I don't think it is fundamental - changing it so failing to find a
registered ActionProcessor could make the dispatcher drop through to
normal servlet dispatch in Jetty (and 404 that way).
Or a ActionProcessor that refuses HTTP requests with 404 and does it's
own TCP thing.
What parts of the Fuseki infrastructure would you want to access and reuse?
Andy
On 12/12/2019 08:41, Nouwt, B. (Barry) wrote:
Hi all,
we are using Apache Jena Fuseki 3.13 and would like to add a custom
publish/subscribe service (next to the default SPARQL service). We are
wondering whether this is possible within the provided framework of
Operations/Processors/Actions, etc, since the Fuseki classes in the
org.apache.jena.fuseki.servlets package like HttpAction and ServletBase seem to
only support HTTP based services.
Thanks in advance!
Regards, Barry
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