Markus,

As we've identified in previous messages, the XDI4J implementation uses 
singleton classes for parsing, making it unusable performance-wise in anything 
other than single user mode (using it on a server synchronizes/sequentializes 
every parse operation).

Regards,
Michael McIntosh
VP Development
Azigo

From: [email protected] [mailto:[email protected]] 
On Behalf Of Markus Sabadello
Sent: Friday, May 28, 2010 6:38 AM
To: Higgins (Trust Framework) Project developer discussions
Subject: Re: [higgins-dev] Sub-contexts

The IdAS-XDI-Mapping is documented here: 
http://wiki.eclipse.org/IdAS_XDI_Mapping

In theory, the Java XDI CP, the Attribute Service, and the C++ XDI CP should 
all implement that mapping, however
- the wiki page itself may be a bit outdated in a few details
- the Java XDI CP (higgins.idas.cp.xdi) implements an older version of the 
mapping and is therefore not ready for use. I don't really have an overview of 
what's needed to make it work

For a native XDI store, I believe XDI4j's BDB implementation has good 
performance, but I haven't tested it or compared to other options.

Markus
On Fri, May 28, 2010 at 11:19 AM, Joseph Boyle 
<[email protected]<mailto:[email protected]>> wrote:
I talked a little more about the backend question with Mike today.

For 4. the only XDI native store I know of is Markus's. It has a context 
provider higgins.idas.cp.xdi but Mike was not sure if this was finished and 
working. From the XDI folks perspective, of course using an XDI store would be 
ideal. Markus, do you think it is ready?

For 3. (or 2.) writing a context provider could be a joint effort among Azigo, 
the 3rd party DB vendor, and others like me. On the other hand, to do 
performance testing of Higgins with a new DB, there should be a benchmark or 
stress testing app, and Azigo would be best placed to specify and write the 
benchmark, which I'm guessing would not be hard.

Mike said that we would not expect performance problems for another year or so 
when bigger deployments are expected. Putting a small amount of work into 
evaluating databases now might save much more pain later. Perhaps this could 
even be presented as a distinct project - for example I heard Marc Davis asking 
if there has been performance testing. The DB vendors might be persuaded to 
help with the integration work, and then would have the next year to work on 
any performance problems themselves. Mike said that our current challenge right 
now is defining API to support adding metadata to sub-contexts, not 
performance, so having someone else do performance work would be an advantage.

I asked Mike what features we should specify as necessary or desirable in a 
graph database. He suggested we need to be able to attach arbitrary attributes 
to sub-contexts (subset of attributes from a context) but that I post to the 
list as Paul, Sergey and Vitaliy could respond.

Some of the graph databases offer features like multiple traversal that may be 
higher level than can be expressed by the Context Provider API. If we want to 
make use of any of these features, of course the sooner we know about them, the 
better. Also some of the graph databases claim to provide distributed storage 
and to try to optimize access across that distributed storage; this could also 
be very useful for large scale deployment, but needs to be tested in practice.


On May 27, 2010, at 7:17 AM, Paul Trevithick wrote:

> Thanks for the pointers Joe.
>
> On May 26, 2010, at 8:37 PM, Joseph Boyle wrote:
>
>> I continue to hear of more graph databases - just saw 
>> http://www.infinitegraph.com/ today. I also know of 
>> http://www.kobrix.com/hgdb.jsp and 
>> http://www.dekorte.com/projects/opensource/vertexdb/ .
>>
>> There's also a list at http://en.wikipedia.org/wiki/Graph_database
>>
>> On May 25, 2010, at 4:02 PM, Paul Trevithick wrote:
>>
>>> Options:
>>>     1. Get on the NG4Jena mailing list and ask for advice [We should do 
>>> this no matter what]
>>>     2. See if there are alternative open source quad stores with better 
>>> performance/scalability
>>>     3. Explore non-relational open source graph data bases (e.g. Infogrid, 
>>> Neo4j, etc.)
>>>     4. Use an XDI native store
>>
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>> [email protected]<mailto:[email protected]>
>> https://dev.eclipse.org/mailman/listinfo/higgins-dev
>
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