[dotNetRDF-develop] SparqlRemoteEndpoint and SPARQL endpoint behaviour

[Rob V. <rv...@do...>]

Hi Koos

Ok I have now made further changes to the SparqlRemoteEndpoint class so 
there are SetProxyCredentials() methods for setting credentials on a proxy 
server provided you've already set a proxy server.  If your credentials for 
the request and the proxy are the same you can set the 
UseCredentialsForProxy property to indicate that the same credentials are 
used.  If you think it'd be useful I'll add some more overloads which set 
the Proxy and Credentials at the same time?

With regards to SPARQL endpoints it may depend on the query and how you've 
configured your endpoint to operate plus what your backing store is.

Firstly the SPARQL engine in dotNetRDF passes all but 5 of the official 
SPARQL test suite, 3 fails are regarding unicode normalization behaviour 
and 2 are regarding very complex joins.  So it is possible that your 
queries fall into one of these categories or that SemWeb itself is less 
closely aligned to the official SPARQL specification (I've never tested 
this so don't know) and so it's answers include incorrect things that 
dotNetRDF excludes.

The other possibility is to do with endpoint configuration, for example if 
you have a SQL backed store and have set the load behaviour to be 
asynchronous the endpoint will answer queries before the data has fully 
loaded so you will get incomplete results until the endpoint has fully 
loaded the data.  Also if you haven't set the load mode it defaults to 
OnDemand which means it only loads data as it thinks it needs it so your 
queries may not be causing it to load all the relevant data or it may not 
load any data at all.

The third possibility is that if you've populated a SQL store your data may 
be incomplete depending on how you've done this.  A lot of the writing to 
the store is done in the background and while the code is designed to 
ensure it finishes writing depending on how your program was terminated you 
may not write all data to the database.

If you could send me some test cases i.e. example queries, data and 
web.config file snippets (with anything sensitive removed/obfustucated) 
then I could give you a better answer on this.

Regards,
Rob Vesse

----------------------------------------
From: "Strydom, Koos" <jst...@ha...>
Sent: 28 April 2010 11:52
To: rv...@do...
Subject: RE: [dotNetRDF-bugs] RdfXmlParser error with Root Element not 
found 






Hi Rob, 
  
Thanks for that, it helped heaps. One thing you need to 
add to that is you'll need credentials in most cases for 
a proxy server.  
  
I did came over some things where I query our old 
SemWeb sparql endpoint with a specific sparql query and 
it returned the expected results, but if I query my new 
dotnetRDF endpoint I do not get the same results. 
  
Both triple stores were populated with the same 
generated rdf and the respective parsers. 
  
Is that possible or where should I look for the 
problem. 
  
Regards, 
Koos 

----------------------------------------

From: Rob Vesse [mailto:rv...@do...] 

Sent: Wednesday, 28 April 2010 2:23 AM
To: Strydom, 
Koos
Subject: RE: [dotNetRDF-bugs] RdfXmlParser error with Root 
Element not found


Hi 
Koos

I've committed a change to the repository which instead adds 
SetCredentials(), ClearCredentials(), SetProxy() and ClearProxy() methods 
which 
let you set/unset credentials and proxy server as required.  The 
credentials and/or proxy are stored as member variables in the 
SparqlRemoteEndpoint instance.

Then I add some stuff to the impementation 
of the ExecuteQuery() method so that it just adds this information to the 
request as is necessary.  This avoids adding too many overloads to the API 
and means you don't have to specify credentials/proxy for every single 
request.

Hope that helps

Rob Vesse

----------------------------------------

From: "Strydom, Koos" 
<jst...@ha...>
Sent: 26 April 2010 
23:17
To: rv...@do..., "dotNetRDF Bug Report 
tracking and resolution" 
<dot...@li...>
Subject: RE: 
[dotNetRDF-bugs] RdfXmlParser error with Root Element not found 


Hi Rob, 
  
Thanks for the reply. I'll put a test case together and 
forward it to you. 
  
In the meantime I came across another opportunity 
:) 
  
I need remote SparqlEndpoint authentication and in some 
cases also WebProxy support. 
We do access a fair number of remote Sparql endpoints most 
of which require authentication 
and some need to be able to query endpoints from behind 
firewalls. 
  
I've started to create some overloads for the 
ExecuteQuery(), QueryInternal(), QueryWithResultSet() and  
QueryWithResultGraph()  methods to 
include NetworkCredentials and another set also including  
proxy server information and Credentials. I'm not sure if that is the best 
way to implement authentication but initial testing suggest that it should 
work 
just fine. 
  
Regards, 
Koos 
  
 

----------------------------------------

From: Rob Vesse 
[mailto:rv...@do...] 
Sent: Tuesday, 27 April 2010 
7:58 AM
To: dotNetRDF Bug Report tracking and 
resolution
Subject: Re: [dotNetRDF-bugs] RdfXmlParser error 
with Root Element not found


Hi Koos 


I will go ahead and add a similar method to SVN once I have proper internet 

again.  Flew out to states today for a conference and the hotel wi-fi can't 

cope this time of day with all the techies trying to use the wi-fi at the 
same 
time.


If you have a minimal test case example that reproduces the issue so I 
could look into why the bug happens and potentially fix it that would be 
very 
helpful.


Yes I have made a start on Sparql Update support, not sure how quickly 
that'll progress as only really done initial backend API outlines at the 
moment 
and haven't started properly on parser and execution support


Thanks,
Rob

----------------------------------------

From: "Strydom, Koos" 
<jst...@ha...>
Sent: Sunday, April 25, 2010 
5:05 AM
To: 
dot...@li...
Subject: 
[dotNetRDF-bugs] RdfXmlParser error with Root Element not found 


Hi 
Rob, 
As I mentioned to 
you before I'm actively in the process to implement your library in our 
open 
source project. 
In doing so I came 
across an issue where I could not parse an rdf document that's been 
generated 
dynamically,  
because it returned 
with the error "Root element not found" although the RDF document were 
valid. 
  
So to solve my 
problem I added a method to the RdfXmlParser class like 
follow 
  
        public void 
Load(IGraph g, XmlDocument 
document)
        
{
            
try
            
{
                
RdfXmlParserContext context = new RdfXmlParserContext(g, document, 
this._traceparsing);
                
this.Parse(context);
            
}........ 
  
This did the trick 
for me. 
  
Also I noticed that 
you've started on implementing Sparql Update in the library. That's very 
exciting. 
  
Best 
Regards, 
Koos 
Strydom 

----------------------------------------


  
  
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