Re: question about pvAccess monitor

["Johnson, Andrew N." <anj@aps.anl.gov>]

Hi Renato,

Monitors for pvAccess were based on the ideas originally developed for Channel Access, although there has been a little parallel evolution that has yet to be recombined.

1. A pvAccess channel name is the name of a top-level object, meaning that its value is usually going to be a structure with at least some and possibly many sub-fields. One function of the pvRequest object is to provide information about which subset of that top-level object you want to monitor. There are other uses for it, and if you are writing your own server code you can use it to pass additional information from the client at connection time. IIRC there is some documentation about it associated with the pvget command-line program.

2. The two language implementations (C++ and Java) are supposed to be able to interoperate perfectly, so if you come across parts that don’t we want to know about them. There could be some features of individual servers that are only available on one side though, for example there is no Java equivalent of the IOC database.

HTH,

- Andrew

-- 
Sent from my iPad

> On Apr 1, 2018, at 5:51 AM, renato sanhueza <renato.sanhueza@alumnos.usm.cl> wrote:
> 
> Hi EPICS community, I am trying to understand how the monitors of pvAccess work. I have a few quick questions, hopefully someone can help me :)
> 
> 1) What information does the monitor need about the monitored component to create the connection between them? I noticed in an example provided in Github that the monitor use a channelName (I assume that it is for the UDP broadcast name resolution mechanism) and a pvRequest string (which I don't understand)
> 
> 2) Can a C++/Java/Python component monitor another one regardless its implementation language?
> 
> 
> Best regards,
> Renato
> -- 
> Renato Sanhueza Ulsen
> Ing Civil Informática.