perfSONAR User Q&A and Other Discussion

[Jason Zurawski <>]

Hi Shiraz;

The perfSONAR LS is a very general framework when it comes to accepting 
information registration - any sort of 'service' that you can represent 
in XML formats can be be registered using some of the schemata we have 
defined for use in the project.  We normally break information into 2 
categories:

 - Metadata e.g. information about the service such as how to contact it
 - Data e.g. capabilities of the service such as the form of data it 
controls

As an example we use the LS to register traditional perfSONAR services 
(e.g. Measurement Points, Measurement Archives) but have also added the 
ability to insert other entities that are not directly related to 
perfSONAR (e.g. GridFTP servers, Pheobus Gateways, REDDnet depots). 
This is still fledgling functionality and we do not have many more uses 
cases other than 'finding' these types of services.  Parsing over 
registered information is possible, just not fully explored.  Extending 
to some of the ideas you list below may require you to add extensions to 
the LS.

I would encourage you to look at the 'LSRegistrationDaemon' package 
(http://anonsvn.internet2.edu/svn/perfSONAR-PS/trunk/perfSONAR_PS-LSRegistrationDaemon/) 
as a first step to see the process we have taken to implement 
registration functionality.  It is written in perl and acts as a broker 
between the LS and other forms of services (usually by doing simple TCP 
connects to check availability of a target service).

The only real complexity that I can see currently with your ideas is 
that while it is very simple to get the XML information into your hLS, 
the gLS would need to know a little bit more about the data types you 
would be registering for summarization purposes.  Currently this is 
something that the perfSONAR developers would need to be aware of to 
adjust the algorithms, but we are working on ways to completely automate 
this step.

Hope this helps, thanks;

-jason

On 11/15/10 3:25 AM, shiraz memon wrote:
> Hi Folks,
>
> I am investigating LS currently and trying to find the potential
> feasibility whether it could be used to discover the Grid Services such
> as Job Management, Storage Management, Computing etc... on "a large
> scale" deployment. The aforementioned services are exposed as Web or
> WS-RF compliant services, thus metadata defined would be in XML format.
>
> Here are some of the high level factors, that I would use to asses the
> viability of LS within Grids
> 1. enable the service providers (any, but some are mentioned above) to
> specify the metadata easily, that can be pulled/pushed from/into LS
>        ** How easy it would be to extend the LS, so as to support the
> info. publishing services, which are not a part of PerfSONAR's network?
> 2. acquaintance of new services to LS
>        ** Can the LS simply allows the foreign services to publish their
> metadata
> 3. querying the stored information at hLS or gLS using standardised
> language, such as XPath or XQuery
>        ** I think this is there, but how would the LS handles the large
> amount of query results?
>        ** Does it provide the iterating capabilities, if the large set
> of xml documents are returned from an XMLDB?
> 4. to publish and retrieve the information in GLUE2 format
>        ** INFO: GLUE2 is a standard from OGF, the model encapsulates the
> Grid entities. the Glue-WG also have released the renderings in SQL, XML
> and LDAP format.
>        ** How challenging and realistic is to add support for GLUE2 model?
> 5. Is there any integration or extension available that can be endorsed
> out-of-the box?
>
> Thanks in advance,
> Shiraz