EPICS V4 Telecon 15-May-2013








0. Preliminaries (5 mins)

1. Telecon time change (10 mins).

  We now have a west coast attendee (me) and are likely to get more from SLAC.

  Proposals for times are (during summer time).

       a. UTC (GMT) Wednesdays 15:30 (1.5 hr later than now) [2]

       b. UTC (GMT) Thursday   15:30 [3]

       Any chance of even later in day?

2. Status of items for June release (15 mins)

  + ca provider in pvaccess

  + vxWorks compilation

  + pvaSrv dbPV and dbGroup for EPICS 3.14.

3. Review of chairs notes from meeting [4] (15 mins).

  *Please read before meeting, so I don't have to read it during the meeting.*

  Is this what others remember too?

4. First discussion of how to respond to the fact that many EV4 services are now

  being developed with web service interface. This won't be the last of this

  matter, but it struck me at Diamond, and I was asked to specifically schedule

  discussion on it. I do have a modest proposal for it though. Ralph's gonna hate it.

  (15 mins)

[1] http://epics-pvdata.sourceforge.net/home.html#usefulinfo 

[2] http://tinyurl.com/bvkr3cn

[3] http://tinyurl.com/b7gcsg5


1. Telecon time change (10 mins).

GW: Suggested on Thursdays at UTC 15:30

AJ & SV: We have a group meeting every other week at 16:30 UTC.


Resolution: Adopted new time 15:30UTC on Thursdays


2. Status of items for June release (15 mins)

MS has not started pvAccess CA provider yet, still maintains possible by June 7th.

VxWorks Compile: AJ can do this manually occasionally f necessary while waiting for the APS IT group to set up Jenkins

RL confirmed that dbGroup will not be part of the next delivery (4.3 release)

3. Review of chairs notes from meeting [4] (15 mins).

See email for text.  http://tinyurl.com/aj5fct5

BD: Will coordinate between Ulrik and Nikolay for the second image type.

AJ: Nicholas Schwarz was not keen on having 2 image types

AJ still to send out email about supported vxWorks versions to tech-talk

AJ: Adam Stephen and Peter Heesterman associated with JET offered help with the Windows port and other code, but haven’t been very vocal since the banquet.

AI on GW: to add appendix into Getting Started on building tips

GW’s note says, “the pvaSrv dbPv and dbGroup for EPICS V3.14 (Ralph), and clean compile under vxWorks 5.5 & 6.x (Andrew)”, -> dbGroup will not be developed until we’ve moved to Base 3.15

4. V4 Servers with Web Server interfaces

GW: Not actually true REST in most cases.

GW to GS: Are all your services providing REST interfaces?

BD: They use REST to access data, but also provide a REST service too.

GW: How to avoid bifurcation of protocols?

SV: Why is this a problem?

GW: Organizational problems, both technical and labor-wise, introduces bifurcation of skills. SLAC and PSI have teams doing IOCs while middle-ware services are written by someone who knows REST. Support burden on REST guy is high.

GS: Overstatement, physicists have choice of API.

VS: If site or author provides an API why is this a problem?

GW: You can provide both, but it causes more work for the service author. Maintenance team won’t understand the service internals or all the possible technologies that could be being used. Infrastructure maintenance team will ignore those other services.

SV: Is that a V4 WG problem?

GW: Yes, we’re trying to reduce complexity and duplication.

BD: We want web-based applications. Our job is to provide an environment for our tool developers and get out of their way. Web developers will use REST APIs.

GW: I originally thought EPICS should work over a web protocol (history) and combine them.

BD: We want to support both PVA and Web APIs.

SV: (agrees) Shouldn’t be any conflicts.

GS: GW wants a single API for all applications?

GW: Web services naturally should use REST, but a physicist doesn’t want to have to use many different APIs for the many different services that they have to connect to. Have been in that situation, it’s painful.

BD: I think this problem is more socialogical than technical.

GW: How do you architect a control system wth multiple protocols?

BD: RDB guys are still struggling with multiple protocols. Channel Finder. If RDB ends up in the IT department we lose. We need both kinds of skills (RDB and PVA) in the controls group.

GW: If you start using RDBs you need RDB skills in the controls group.

BD: My logbook is in an RDB, but I want a PVA API to it as well as a Web API.

BD thinks GW is in violent agreement with him...

GW: Our framework should help people create the right architecture.

BD: We can’t dictate to people.

GW: Agree. My proposal is that we create a REST interface to V4 data, using a reverse Proxy able to serve any V4 data via REST.

BD: That way around make sense; web application wanting to access archive data for example.

GW: Timo asked how to respond to the REST question for V4 services, hence GW’s bringing up this topic.

AI on GW: Send out something about this subject.

Meeting ended at 16:05.