Interfacing with Database on Server

[vimana]

Hi,

Thanks for your response. It certainly cleared a number of questions.
I'm still a bit unsure of the following:
1. How does the execution handler interact with the process mentioned below?
I'm guessing I would need to execute the query using the execution handler?
If so, would I need to pass the query to the execution handler using the
sendupstream? I'm still confused on how to make use of the execution
handler. I've looked at the API and I'm still very confused on this.

2. Where do I create and initialize my connection pool?

3. Do I need to create a runnable object in my Business Logic Handler class?

At the moment I'm using my business logic handler to receive the message ->
check if the message is to write to a database (no response to send to
client), or to retrieve data from the database (response sent back to client
as xml). At this point, I was thinking of generating the sql query and
passing the query string downstream to the DB Handler. The DB Handler would
retrieve a connection from the connection pool and execute the query and the
result (if any) would be passed back to the Business Logic Handler. The
business logic handler will forward it back to the client using
write(Object) which would invoke the encoder codec. But in this process, at
which point does the execution handler get invoked? And is there a
particular method which I must call upon to invoke the execution handler
from within the DB Handler or Business Logic Handler?

Thanks!



Frederic Bregier wrote:
> 
> Hi,
> 
> I would suggest something in your pipeline like in that order :
> 
> - handlers for codec (your protocol on how to receive or answer
> information)
> - handler for execution handler (OrderedMemoryAwareThreadPoolExecutor)
> - handler for business
> 
> In your business, you could make all of your business code, including the
> request from the DB pool.
> Then you know what and when you need to answer to the client.
> 
> Another option is as you wrote:
> - handlers for codec (your protocol on how to receive or answer
> information)
> - handler for execution handler (OrderedMemoryAwareThreadPoolExecutor)
> - handler for business
> - handler for DB connection and queries
> 
> Then your business just pass the request (if any) to the Db Connection and
> Queries handler (using downstream).
> The Db Conn & Query handler if needed to answer just write the answer (in
> the form you need for instance as an Object) using upstream.
> Then the business get the upstream and decide or not to forward it to the
> client...
> 
> But my guess is that only one handler is easier but it greatly depends on
> your dev and logic...
> 
> HTH,
> Frederic
> 
> 
> vimana wrote:
>> 
>> Hi,
>> 
>> I'm having difficulty understanding how to interface with a DB (MySQL) on
>> the Server.
>> From what I've gathered, I'll need to create a connection pool (which
>> I've done using Apache DBCP), add an execution handler to my pipeline (I
>> used the OrderedMemoryAwareThreadPoolExecutor) and my business logic
>> handler checks if the request from the client is to save something to the
>> db or retrieve something from the db. I then would want the business
>> logic handler to pass this request to the execution handler which will
>> grab a connection from the connection pool and run the query. If the
>> query was to return a result to the client then the execution handler
>> would write the result back to the client. I'm not sure if this is the
>> correct way to go about it and if it is how do I pass the request from
>> the logic handler to execution handler (sendupstream?). And How does the
>> execution handler receive the message ? Do i attach a runnable object to
>> the context object associated with the channel in the business logic
>> handler, sendupstream and then in the handleupstream in Executionhandler
>> get the attachment and do a .execute((Runnble)ctx.getAttachment())? 
>> 
>> It would help a lot if I can get a high level overview of the correct way
>> to interact with the database.
>> 
>> Thanks!
>> 
> 
> 

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