CERN Accelerating science

Post Mortem @ LSAT  25/1/2005

Present:  Robin Lauckner, Adriaan Rijllart, Jorg Wenninger,  Herve  Milcent, Andy Butterworth, Mike Lamont, Sergio Pasinelli, Stephen Page, Grzegorz Kruk, Francois Chevrier, Lionel Mestre

Use of CMW:

• Need to check that buffers are correctly sent and received. Exception handling at GW level needs to be established. [Calls are synchronous - will get acknowledgement]. Coupled with this need strategy for resend.
• Scalability has to be assured.

Post mortem server

• Subscribes
• What are the properties? How do we label data?
• How does server check it's got what it needs?
• Need markers of some kind to follow PM progress. How does PMS know PM has finished.
• Alternative pathway for GW if server goes down.

PM prototype proposal - reported by Lionel

Present : Mike Lamont, Sergio Pasinelli, Stephen Page, Grzegorz Kruk, Francois Chevrier, Lionel Mestre

The goal was to find agreement on a common strategy to handle post mortem data from the FECs to the post mortem server (PMS). Mike started by giving a global description of the post mortem system requirements. Stephen said that FECs being real time systems, the least processing to send data to the PMS, the best. Data being stored in memory buffers, the optimal solution would be to send those buffers directly in binary format, along with a description to decode that data (including issues such as byte ordering).

Sergio proposed the use of an open source library called BinX that would allow : - to send data in a binary format providing platform independence - to describe binary data in an XML format for further decoding At the moment BinX provides binding for C++ only altough other languages could be made available later.

For transport of the binary data from the FECs to the PMS, CMW could be used, the FEC acting as a client and the PMS acting as a server.

The use of CMW for transport alongside BinX for data encoding/decoding was generally agreed and a prototype should be made to validate the feasibility of the solution.

Once binary data is received by the PMS, it should be saved into files in the file system for persistence. The description of the binary post mortem data the PMS can accept should be provided to the PMS in advance in the XML language defined by BinX. It could also be sent along with the binary data and a prototype should show what is the best and the simplest solution.

Once the binary data is securely stored on the PMS, post processing can occur to convert data in whatever other format is more appropriate for analysis and further processing. XML could be a candidate for that.

BinX:	 Binary XML Description Language   http://www.edikt.org/binx/
Eldas: grid and enterprise data service for binary files http://www.edikt.org/eldas/

Future action

• CMW post mortem server using Binx to transfer data - Steve Page, Sergio Pasinelli
• Data conversion & generic browser - Lionel & Greg
• Dedicated QPS analysis & more specific analysis tools  - Adriaan