Re: Epics V4 Questions - New to Epics 4

[Ralph Lange <ralph.lange@gmx.de>]

Hi Tim,

Answering a specific one of your questions:

On Tue, Dec 6, 2016 at 7:45 AM, Madden, Timothy J. <tmadden@aps.anl.gov> wrote:

General question:
 I know RPC stands for remote procedure call, but what does it mean in epics V4?
What does it do that epics V3 does not do?

Maybe it is easier to answer in terms of data structures:

"Normal" connections and subscriptions are using a single data type, which may be a structure in V4, but it is fixed during the connection lifetime, and it is the same structure on read, write and subscription operations.

RPC type connections may have different data types on write and read, and the returned structure may change with every call of the method.

Thus, the RPC type connections are well suited to middle-layer type services, where the data written (think: small list of arguments) are very different from the returned values (think: big arrays of structures that depend on the sent arguments).

Cheers,
~Ralph