Re: Dynamic Loading and Unloading of EPICS Device Support and Record.

[Ralph Lange <Ralph.Lange@bessy.de>]

 On 09.09.2010 05:56, Marty Kraimer wrote:
> The following is not for an embeded system but does show a good use 
> for on-line add and delete.
> Guobao Shen (BNL) is developing a "gather" service. The service uses a 
> javaIOC. The javaIOC has gather records. Each gather record collects 
> data from a set of caV3 records and provides the result to the client 
> as an array.
> The javaIOC also has a createGather record. The client supplies a list 
> of channels to the createGather record. When the record processes it 
> creates and installs a new gather record. The gather record can be 
> temporary or permanent. If the record is temporary than after no 
> clients are attached to the record for some fixed period of time the 
> gather record is automatically deleted. If it is permanent it can be 
> deleted by request.
> Both on-line add and delete are required in other for this to be a 
> robust service.
Note that eight years ago JLab was developing a slightly similar thing 
for V3: their "Proxy IOC", based on the CAS server, was able to create, 
delete, and persist PVs on-the-fly.
Plain PVs only though, no record structure, no processing, no support. 
Just data mailboxes that applications could manage and use for 
inter-process communication through Channel Access.
Was never used outside JLab, as far as I know.

Ralph