============= Meeting 23-Jan-2013 =============



Overflow / Open Issues

Skype/Titanpad vs. Google hangout

pvaSrv multiValue issues

New V3 Gateway implementation

Streaming (chunking) NTTables and other large data

pvAccess Authentication and Authorization

------------------------ Minutes ----------------------------

Present: TK, AJ, MS, RL, DH

NEW TOPIC: Skype/Titanpad vs. Google hangout

RL: Google seems to offer better integration of video, shared docs, shared slides, etc.
Problem: How do we integrate "old" Titanpad meeting notes with "new" notes on Google Drive?

Question: how long are the minutes kept on Titanpad? Should we archive the old minutes (to the V4 website)?

AI on AJ: Extract all old titanpad minutes into files (html preferably) on the sourceforge website and update the links.

Question: Should we switch to using Google hangouts instead of Skype conference calls, and when?

AI on RL by end of week 06: Find out how to create regular hangouts for the telecons

NEW TOPIC: pvaSrv multivalue issues

RL: There is a configuration of a group from a file, and it publishes the result under a name. This is just a plain file without proper syntax or macro expansion.
There should be predefined groups available as well as on-the-fly creation of groups.
RL: return type is an unnamed top level structure of NT_SCALAR and NT_SCALAR_ARRAY structures.
    No Alarm or Display information at the top level.
AJ - it would be nice to support both preconfigured groups and on the fly creation.
RL - we have an RPC service to create groups, and a local API within the IOC.

    Create group takes arguments group name, (once_only, specific lifetime or forever), monitor latency period, require atomic.
    Operations on the group by group name (get, put, monitor).
    Delete group by name.

RESOLUTION: Rename "multiValue" to "molecule" = bound collection of atoms.

ISSUE: How to persist remotely-created groups over a reboot?
    Consider using auto-save/restore for this, not convinced whether this is the right place.
    Would like to use the mechanism for saving files that save/restore has, but use a different file.

NEW TOPIC: New V3 Gateway implementation
TK: PSI has finished the implementation of a new V3 gateway, which is not based on gdd/CAS, but acts more like a switch or firewall: The raw CA message stream is fanned out to clients. Reason were problems with the CAs based Gateway: e.g. large arrays (images) have to be received completely by the Gateway before it can start sending the update out to its clients.
Implemented in C# on Windows.

Group: Encourage the authors to give a talk about it at the next EPICS Collab meeting in Diamond.

NEW TOPIC: Streaming (chunking) NTTables and other large data
RL: This problem is on application level - our definition of NTTable requires a pvAccess server to have the complete table in memory before it can start sending it out to the client.
MS: Full implementation - client asks specifying number of rows and offset, gets the matching part.
RL: Light implementation - client asks for the whole table, but gets sent parts, each being an NTTable that is flagged as "more to come", until the last one which is flagged "end".
MS: This requires a change in the pvAccess spec for RPC, which currently defines the RPC as "one request, one answer".
We will also need the ability for a client to cancel an ongoing RPC request.

AI on MS : Check which changes are necessary in the pvAccess spec to allow this.

NEW TOPIC: pvAccess Authentication and Authorization

BD: Should not be part of this year's charter.
DH: Then pvaSrv on a V3 IOC is a security hole, and not implementing authN will prevent installations to use pvaSrv.
AJ: Could pvaSrv use CA's Access Security? Probably.

RESOLUTION: pvaSrv will use a configurable user name and the pvAccess client host name, and utilize CA Access Security for its local V3 access
That will allow to restrict access to records for V4 pvAccess clients similar to controlling access for a PV Gateway.
DH: That should be good enough.

RESOLUTION: Pluggable AuthN and AuthZ will not be part of this year's charter