perfsonar development work

[Jason Zurawski <>]

Maciej;

> > I am helping to speed up our other worker (Yi) with his BDB work.  
> > The current branch should be good enough to download and install 
> > though (contains the necessary libs in the repository, has ant 
> > configuration information).  There are changes I am holding back 
> > until Yi finishes a little bit more development.  His deadline is 
> > very soon, I will push to get the changes in faster since we are 
> > holding you up (sorry about that).
>
> I am still curious what BDB improves? Well, I am quite sure it may be 
> faster than eXist, but
>
>   - were there made any performance tests and comparisons between eXist
>     and BDB? I am sure you did something like this, but I didn't see any
>     results and conclusions

We are working on simple tests (not completed yet) that compare eXist, 
BDB, and oracle XML (this is a part of another students work, but once 
we get results we will be more than happy to share).  We will be doing 
performance tests once the two instances are set up, and accepting 
registrations. 

>   - how far are both DB compatible? I thought BDB didn't support
>     XUpdate, so single LS functionality wouldn't work with BDB unless we
>     changed all database modification instructions. But for what? XQuery
>     Update extension?

BDB does not use XUpdate (one reason why I was interested in removing 
the XUpdate functionality several weeks ago) and instead uses it's own 
update API.  The XQuery/XPath statements are more or less the same, with 
some notable changes regarding the organization of BDB's collections.  
Yi did develop a seperate service engine to try and insert some 
transparency into the calls to the various databases.

>   - but does BDB support XQuery Update extension?

To my knowledge no, it uses a separate update API (there were always 
promises or supporting XQuery update once it was finalized, this goes 
back years however). 

>   - is XQuery processed the same by eXist and BDB?
Yes, they both should follow the standard.



> > > I also asked you whether it's possible to separate mLS changes from 
> > > singleLS? I saw you modified LSRegisterAction. Would it be possible 
> > > to divide the main method on some smaller and move mLS code to other 
> > > methods? I could help with it, but first I must know if the changes 
> > > are final. So, what is the time schedule for integration mLS with LS?
> >
> > This is up for debate, in the beginning I was under the impression 
> > the code bases would be separate (and it is still not too late to do 
> > that) and because I didn't make it to the last meeting I am unsure 
> > what the consensus is regarding keeping a single LS or going for a 
> > full mLS.  
>
> I think LS (sLS+mLS) should be regarding as one LS, but I'd like to 
> have code separation between multiLS and core LS. In fact multiLS 
> should be independent protocol from LS. And in fact it is.

If they are to be regarded as 'one' (i.e. would we still even want to 
deploy single LS instances?) then I don't see why the need in separating 
the code.

> > > Other my concern was on sending request and waiting for the response 
> > > in request processing action (as far as I remember it was sending a 
> > > request by LSRegisterRequest action and waiting for response).
> >
> > I was using timeouts to speed up the process of waiting for 
> > responses.  We never really get a 'hang' situation that way, but 
> > depending on latency and other network issues this could be a problem.
>
> You probably tested it in lab. In real 'bigger' network we may 
> experience strange behaviour... :)

I am sure there will be, but in my opinion all we can really do is go 
for a best effort attempt, and handle the failures as best we can. 


> > > What are berkeley DB support changes for? Are we intend to use 
> > > berkeley DB for LS or just for multi-LS? I am not sure. I thought 
> > > mLS would use just exist DB. Or these are just separate changes done 
> > > by Yi?
> >
> > We intend to install 2 mLSs here at UD and evaluate each database.  
> > Yi is currently seeing some good performance from BDB which is why we 
> > tied his project to mine in an effort to offer people choices when 
> > installing the mLS.
>
> OK, I fully agree, but my previous question are still open.
> Next thing is if BDB will follow "multiple files in the collection" 
> changes to LS?

Collections in BDB are a little different than eXist, there is no root 
'store' element; instead all md and d elements are inserted into the 
collection with the understanding that they are housed in a 'store'.  I 
am pretty sure you can't use multiple files (Yi is CCed and can better 
answer that question).

-jason