Re:
> One thing we're experimenting with, especially for data
> which is represented by a complex graph of related objects,
> is to send the entire state of the graph to the client as
> an XML document. The client then interacts with the
> local representation until it needs some logic that's on
> the server. It's not yet clear to me whether this will
> work - the overhead may cancel any gain. Time will tell.
I couldn't disagree more with this approach. EJB was invented to enable thin
clients, so what's the point of sending the entire object graph to the client
and executing all the business logic there? We have to learn how to build
richly functional reusable-in-place server components. I can't fill in all the
details, but the solution must go something like this:
(1) Develop a detailed business object model of the application.
(2) Utilise your knowledge of the overall application, the business, the online
data, integrity constraints, security, etc to carve up the object graph to form
coarse-grained components. (In other words justify your status as a highly paid
consultant!) When doing this you can put objects into multiple components, and
you can distribute the total behaviour of an object between multiple
components. For example you could place the "display" behaviour of the customer
address object into client components and the "validate" behaviour into server
components.
(3) Utilise your knowledge of the processes which the application supports in
order to determine the information that must flow between the components as the
process executes. Devise additional PBV objects that carry this information
between the components as the process executes.
(4) Extract the subset of the modified object model corresponding to each
component
(5) Generate EJB code for each component
(6) Test components separately
(7) Deploy and collect your fee!
We need the modelling tools to support componentisation of an object model,
which I take to mean implementing steps 2-4 above without destroying the
original object model.
Ian McCallion
CICS Business Unit
IBM Hursley
[EMAIL PROTECTED]
Tel: ++44-1962-818065
Fax: ++44-1962-818069
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