Re: Announcing RESTwiki (fwd)

Hi Dan,

> I've recently been experimenting with SOAP interfaces for RDF query
> protocols; while it works (the Python and Perl SOAP libraries made things
> quite easy for me as a developer), I have some worries about the way SOAP
> uses HTTP (eg. all my queries get represented as HTTP POSTs, where the
> cacheable GET would make more sense). The RESTwiki seems like a good place
> to record these experiments; I hope to make time to do that in the near
> future.

I've also been experimenting with building a SOAP interface to an RDF store. In my
case this was in Java using the Jena RDF toolkit and the Apache SOAP 2-2 toolkit
running on Tomcat. Whilst it worked  in the sense that I can create, query and
navigate RDF models in the remote store I did find performance to be a problem. I
ended up using SOAP-with-attachments and transferring the bulk RDF data as a MIME
attachment in N-triple format and just using SOAPencoding for specifying the
operation required and the actual parameters (e.g. query specification). Even then
the overhead of going via SOAP was large - in typical configurations I was seeing
around 130ms latencies due to a mixture of the overheads of XML parsing of the SOAP
packet and problems with getting Apache SOAP to stop using TCP slow-start. I
believe I can get this down to more like 40ms but that compares badly with simple
HTTP GETs on a servlet with arguments URL-encoded which takes under 10ms on the
same network/machine configuration and data volumes.

This left me feeling that a simple direct HTTP usage pattern for remote RDF query
might be a useful alternative to a full SOAP interface.

I'll be very interested to hear how your experiments develop - keep us updated.

Cheers,
Dave