The Choreography Problem

I had the same general reaction to Deb's scenarios that Mark did. In 
thinking about them further, here's what I came up with:

The problem with the scenarios appears to be that Deb is thinking like 
an application writer. The description is of the overall 
application--the effect or business process being modeled. This is 
natural, but it doesn't capture the i18n problem clearly.

The Choreography problem looks like this. Consider that you have created 
four Web services to perform some tasks. Let's say that service A 
receives customer orders, service B checks customer credit, service C 
ships product from the warehouse, and service D updates accounts receivable.

These services are SEPARATE. They each have their own WSDL file, QoS, 
and so forth. Choreography is really the bundling of extant services 
into a process, so the customer isn't billed until the product ships, 
for example.

The trick here is that an aspect of one of the MIDDLE services in the 
process may be client-influenced. How does the WSDL file that describes 
the choreographed transaction reflect that fact? What is the pattern of 
"context" or information that must be passed all the way from the 
initial SOAP processor to make the service in the middle (say the credit 
check) able to deal with a localization issue?

So I guess my points are:

1. We really need to fill in the various scenarios for the roughly five 
patterns in the usage scenarios document (language-neutral, 
client-inflenced, and the three servide-determined flavors). Since all 
of the more complex interactions appear to be the interplay between 
these patterns on various levels, doing this will give us a firm foundation.

2. This suggests that choreography and other more complex interactions 
can be thought of as ways of packaging a series of services as a 
service. If each of the services has a different pattern, what pattern 
does the overall service have?

More anon,

Addison

-- 
Addison P. Phillips
Director, Globalization Architecture
webMethods, Inc.

+1 408.962.5487  mailto:aphillips@webmethods.com
-------------------------------------------
Internationalization is an architecture. It is not a feature.

Chair, W3C I18N WG Web Services Task Force
http://www.w3.org/International/ws

Received on Thursday, 22 May 2003 12:52:29 UTC