no threads

[Sai-Lai Lo]

>>>>> Maximilian Ott writes:

> We would like to incorporate omniorb into our system but have one problem.
> For reasons I can explain offline, we don't want to use threads. Our
> system is entirely event driven.

> If I understand the omniorb design documents correctly, this shouldn't be
> a problem for the server side. It waits for an incoming request, processes
> it and returns a result. This maps nicely on an event model.

> The client side is different. A call to a server object blocks the current
> thread, which continous when the reply comes back. As an event model leads
> itself to an asynchronous style, we can restrict all methods to be
> "oneway". In this case the client would not need to block.

> How difficult would it be to take out the thread related stuff.

Firstly, it is possible to make omniORB non-threaded  with a few
localised changes. However, I have my reservations on the general
usefulness of single threaded ORBs. Take the following example:

      +------------+                           +-----------+
      |Process 1   |                           | Process 2 |
      | +-----+	   |       (1)                 |  +-----+  |
      | | A  -+----+---------------------------+->| B   |  |
      | |     |    |         (4)               |  |     |  |
      | +-----+ <---------------------------------+-----+  |
      |            |                           |  ^  |     |
      |            |        (3)                |  | |      |
      | +-----+-----------------------------------| |      |
      | | C   |<---+---------------------------+----+      |
      | +-----+    |	     (2)	       |	   |
      +------------+                           +-----------+
 
  Object A calls Object B. Object B then do a nested call to Object C
  before it replies to A. If A and C are in the same process, a single
  threaded ORB would be deadlocked forever because process 1 would not
  handle the incoming call to C until it receives a reply from B.
   
If your application is event-driven, making all methods oneway is probably
a very natural mapping and single-threaded ORB would be sufficent. 

Sai-Lai