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From "David W. Van Couvering" <David.Vancouver...@Sun.COM>
Subject Re: advice for client/server application
Date Thu, 23 Mar 2006 23:31:41 GMT
Yes, I see what you're saying, you're rewriting JDBC extended with file 

You could take the Derby source and extend it so that you can do file 
transfer functionality, but then you're stuck with your own fork of 
JDBC.  And I'm sorry to say that the Derby community would likely not 
accept your changes back (someone correct me if I'm wrong) because there 
would be non-standard extensions to JDBC, and we strive to be 
standards-compliant as a community.

Personally, I would just open two connections: one for JDBC work and one 
for file transfer.  Keep them separate.


Ryan P Bobko wrote:
> Thanks for the advice, but I'm not sure if that will help. I now realize what 
> makes me uneasy about my architecture is that I feel like I'm rewriting JDBC 
> little by little just so I can have my file-moving piece on top of it. JDBC 
> works great for my purposes, so my preference would be to remove my custom 
> protocol whenever possible. Is it feasible to extend the JDBC API? Or will 
> that just be more trouble than it's worth?
> I realize I just changed my question. Any more advice?
> ry
> On Wednesday 22 March 2006 07:23 pm, David W. Van Couvering wrote:
>>A common way client applications working with large result sets have
>>handled the "too much memory" problem that I've seen is to send the
>>results over in chunks.  Instead of sending all 120,000 records in one
>>response, just send 100 or 1,000.  The client processes those 1,000
>>records, throws them away, and get the next 1,000.
>>Would that work for you?
>>Ryan P Bobko wrote:
>>>Hi List,
>>>First of all, I can't say enough how impressed I've been with Derby.
>>>Every time I've thought this embedded wouldn't be able to do something I
>>>expect from a "full-blown" database (nested selects, correlated
>>>subqueries, stored procedures, you name it), it's suprised me. I love it.
>>>This isn't strictly a Derby question, but I'm hoping for some advice or
>>>suggestions with how to procede. I've been working on an application that
>>>is a sort of half-database, half-FTP client/server setup. The protocol
>>>I've implemented between the client and server lets the app do things
>>>like run queries, but also move files around based on those results. Or
>>>insert rows into the database based on where files have moved to. Files
>>>can be moved from the server to client and vice versa.
>>>Things have been working just fine, except that when I run queries, the
>>>server process does all the work and returns the results as a vector of
>>>string arrays. It's never sat well with me--and as you can imagine--now
>>>that the dataset is getting pretty big (120.000-4KB rows returned for
>>>some queries), I'm using too much memory.
>>>What I'd like to do is get my jdbc connection object onto the client so I
>>>don't have to "package" everything up when returning resultsets. The
>>>question is how?  My first idea was to just use derby's network server
>>>and write the file protocol separately, but I'd prefer to stick with just
>>>one socket if I can.
>>>Advice? Thanks for your time.

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