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Article #240

Weird MIDAS/DataSnap behavior...

#240
From: mr_organic
Date: Wed, 29 Dec 2004 16:41
37 lines
2285 bytes
Hello all,

We have a legacy app that was created with C++Builder 5 and used MIDAS to 
communicate with an MTS/COM+ middle-tier component. We had to build a 
completely stateless client because our server was atually part of a 
cluster and we had to be able to fail over to any of the machines in the 
cluster.

We used a lot of code like this (assume that "dc" is the DCOMConnection 
component):

    	dc->Open();
    	cdsFoo->Close();
    	cdsFoo->Params->ParamValues["some_key"] = SomeValue;
    	cdsFoo->Open();
    	dc->Close();

This code worked just fine in BCB5. However, we have been trying to 
upgrade to BCB6 and I have discovered that this no longer works! The 
client dataset just keeps fetching the initial records over and over 
again, regardless of what you change the parameter to in successive 
queries. I remember talking to Borland about this when BCB6 first came 
out, but we have just applied the Patch #4, and the problem remains.

I have verified that if we maintain a stateful connection (i.e., always-
on) to the server, the retrieves work as expected. It's only in this 
"disconnected" model that the problem appears.

My question is: is this a bug in MIDAS/DataSnap, or is DataSnap 
*supposed* to be stateful regarding an "always-on" connection to the 
middle-tier? If it *is* a bug, is Borland planning to fix it?

Any info would be greatly appreciated.

Thanks,

mr_organic
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Newsgroups: borland.public.cppbuilder.database.multi-tier
Subject: Weird MIDAS/DataSnap behavior...
From: "mr_organic" <mr_organic@yourmamashouse.com>
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Date: 29 Dec 2004 08:41:02 -0800
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