perfsonar development work

[Slawomir Trzaszczka <>]

Yes, you are right. This situation shouldn't occur. In this situation
user should receive more "readable" message from service like 'incorrect
xpath query' or something like that. This error shouldn't be displayed
to user because : 
- cause of this error is not clear;
- internal errors should be caught and hidden from users (not from
admin)


Thanks.

Slawek



On Wed, 2009-07-08 at 17:25 -0400, Jason Zurawski wrote:
> All;
> 
> This is a request for the MDM LS specifically, but the issue pertains to 
> all services that pass along eventTypes and datum-messages regarding 
> system errors.
> 
> My dilemma: Trying to do what I thought was a simple query to both MDM 
> and pS instances of the hLS for a web page.  The query I sent:
> 
>        
> /nmwg:store[@type="LSStore"]/nmwg:metadata
> 
> The pS hLS responded ok, but the MDM hLS gave me this initially:
> 
>    eT:                error.common.storage.xmldb.open</nmwg:eventType>
>    datum:     XQuery by HTTP failed. Could not connect to eXist via pure 
> http,  nested exception was: class 
> org.perfsonar.service.base.storage.xmldb.exist.rest.ExistDbErrorException: 
> eXist DB responsed with HTTP error code code [202] additional message 
> was [Accepted]</nmwgr:datum>
> 
> I would have pegged this as a configuration error with the service since 
> the eventType appears to be 'system' related.  I figured out quickly 
> that every MDM LS out in the wild responded like this, so it appears to 
> be my fault.  After some poking I realized I should have sent this 
> variant instead:
> 
>        declare namespace nmwg="http://ggf.org/ns/nmwg/base/2.0/";;
>        
> /nmwg:store[@type="LSStore"]/nmwg:metadata
> 
> My thoughts:
> 
> 1) I am sure the above message comes from eXist directly, which is 
> unfortunately vauge.  Since my problem was really a syntax/formulation 
> error with the XQuery/XPath statement, I would much rather see this sort 
> of error message (cleaned up a little of course): "Hey Dummy, learn 
> XPath!".
> 
> Perhaps we need to spend some time decoding the error messages that 
> would come from supporting software (e.g. RRD, XMLDB, eXist, MySQL) into 
> more user/protocol friendly descriptions and having the services simply 
> look these up.  Standardizing across services/implementations would be a 
> bonus.
> 
> 2) Even though this wasn't a system error, would a system error be 
> returned via the message protocol?  I think we touched on this years ago 
> but where do we draw the line between what is good to tell the users and 
> what is good to tell the sysadmin via logging.
> 
> Thanks;
> 
> -jason
> 
> P.S. New *development* version of the 'tree' GUI that has a feature to 
> dump hLS contents:
> 
> http://dc211.internet2.edu/cgi-bin/pA/tree.cgi
>