Objects: Client-Server Relationship

[Former Member]

Hi,

As we are laready aware, there is a client - server relationship between the objects.

And in principle, objects can perform both roles simultaneously: They can offer

services to other objects while requesting services at the same time.

Consider an example, there are 3 objects. Object 1, object 2 and object 3.

Object 1 requests some services from object 2 and in turn object 2 request some services from object 3.

So in this case object 2 is playing the role of server and client.

My Query:

Is it possible that object 2 is requesting some services from object 1?

If so, it will create a 'deadlock' situation. How can we avoid this?

Please suggest...

Regards

s.a.k

[Former Member]

Hello,

it is possible and it does not produce a deadlock. The run-time control flow can "come back" to an object which has invoked another method. As in classical ABAP programming, all method calls are placed on the call stack. If an object 1 calls a method of object 2 and within the method of object 2 a method of object 1 is called, this is no problem.

The same can happen with the subroutines of different programs: Program A can call a subroutine of program B. Within this routine of program B, another (or even the same) subroutine of program A can be called.

Hope this helps,

David

[Former Member]

Dear David,

Firstly thanks for your reply...:)

Can you provide me the link from where I can get more information regarding this ?

Thank you once again for your assistance here..

Regards

s.a.k

[matt]

There are no "links" because it isn't an issue. Deadlocks occur when you have communicating processes running in seperate threads. In the situation you describe everything is in sequence in the same thread.

Standard ABAP Objects is single threaded.

For what reason are you concerned about this?

matt

[Former Member]

Hi Matt,

Thanks for your prompt response.

I was going through the abap objects document and this came to my mind.

I was unaware that these are single threaded. Thanks for that...:)

Regards

s.a.k

[Former Member]

Another query..

[Former Member]

Hi,

Continuing with the above scenario:

Consider an example, there are 3 objects. Object 1, object 2 and object 3. Each belonging to different classes.

Now what will be the case when Object 1 of class 1 requests some services from Object 2 of class 2 and in turn object 2 requests services from object 1(instance of class 1)?

Please provide your comments...

Regards

s.a.k

[Former Member]

Hello,

as Matt already said: ABAP is single-threaded, so also in this case there is no problem. Each procedure call is placed at the top of the call stack which is processed top-down. There is no danger of deadlocks.

Also remember that an object can call its own methods and especially can make recursive calls to the same method... all these method calls do not produce a deadlock (however, an infinite loop is possible).

Hope this solves your doubts,

David

[Former Member]

Hi David/Matt,

Thank you very much for the response..it cleared all the doubts..:)

Regards

s.a.k