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RE: Issue: Synch/Asynch Web services

From: He, Hao <Hao.He@thomson.com.au>
Date: Tue, 12 Aug 2003 09:28:05 +1000
Message-ID: <686B9E7C8AA57A45AE8DDCC5A81596AB046AE6EC@sydthqems01.int.tisa.com.au>
To: "'Cutler, Roger (RogerCutler)'" <RogerCutler@chevrontexaco.com>
Cc: www-ws-arch@w3.org
Hi, Roger,
 
Here is my understanding about Synch/Asynch Web services.  Is it over
simplified?
 
Suppose we have two agents in a well-controlled environment (super fast,
reliable network). Agent A sends a message m1 to Agent B and expects Agent B
to return a message m2, however long it may take. This scenario seems to me,
is a typical case of sync Web services. The essences of this process are:
1. that Agent A can relate m1 and m2 by sequence  (sending m1 to B is prior
to receiving m2 from B). 
2. that there can be no other messages between two related messages.
 
If we remove those two constraints, the process becomes async. Agent A can
send a number of messages to Agent B after sending m1.  When it receives m2
from Agent B, it can relate m1 and m2 together using other mechanism,
however that mechanism may be.
 
Interestingly, a process can be sync at the infrastructure level but be
async at the application level. For example, m2 can be a receipt rather than
final results an application intends to get. 
 
Hao
 
 



Received on Monday, 11 August 2003 19:26:19 GMT

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