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Date: Wed, 6 Dec 2006 13:40:22 -0800 (PST)
From: "Christopher James Blythe (JIRA)" <dev@geronimo.apache.org>
To: dev@geronimo.apache.org
Subject: [jira] Updated: (DAYTRADER-29) Async 1-Phase mode should be removed
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     [ http://issues.apache.org/jira/browse/DAYTRADER-29?page=all ]

Christopher James Blythe updated DAYTRADER-29:
----------------------------------------------

    Summary: Async 1-Phase mode should be removed  (was: Asyc 1-Phase mode should be removed)

> Async 1-Phase mode should be removed
> ------------------------------------
>
>                 Key: DAYTRADER-29
>                 URL: http://issues.apache.org/jira/browse/DAYTRADER-29
>             Project: DayTrader
>          Issue Type: Improvement
>          Components: EJB Tier
>    Affects Versions: 1.2, 2.0
>            Reporter: Christopher James Blythe
>
> Here are some comments that I added to DT-22...
> Since my involvement with Daytrader (and Trade), we've never been all that concerned with the Async 1-phase mode. Here is the lay of the land to my understanding...
> Sync mode
>  - Uses JMS topics and TradeTopicMDB to publish changes to the quote prices
>  - There is flag in the DDs to disable this but it doesn't seem to apply to direct mode (only EJB mode)
> Async 2-phase mode
>  - This mode uses a JMS queue and the TradeBroker to handle order processing
>  - Specifically, the buy and sell operations call a queueOrder method to place a message on the queue
>  - The queueOrder is part of an XA transaction because two resource managers (JMS and database) are involved to create the order in the databse and place a message on the queue
> - The MDB starts a new transaction when the message is read from the queue. The MDB then executes the completeOrder method which updates the order in the database inside the original MDB transaction context
> Async 1-phase mode
>  - Does the same as above, but does not involve an UserTransaction to provide XA
>  - Since the MDB is container-managed, TradeEJB is used to complete the order and create a new transaction (avoiding XA)
> My guess is that the Async 1-phase mode was added to messure the overhead associated with handling the XA transaction.
> I have never found that much value in Async 1-phase mode. If you are using two different resources as part of a logical transaction, you should always use XA to ensure proper rollback handling. Honestly, I see very little need to keep it around... However, there might be some possiblities I have not considered. As an added benefit of removing this option, we would remove a dependency between the TradeDirect and TradeBean code.
> I also like the idea of splitting up the modes by category and doing a little renaming to make them more descriptive.
> Persistence Run-time Modes (one has to be selected)
> 1) Direct (or JDBC)
> 2) Stateless Session Bean to Direct
> 3) Full EJB (Stateless Session Bean to Entity Beans)
> JMS Support Enablement (any can be selected)
> - Publish Quote Updates (Publish quote price changes to a JMS topic)
> - Process Buy/Sell Orders using XA (Asychronously process buy/sell orders by placing them on a JMS queue. An MDB is then responsible for reading a message form the queue and completing the order)
> Thoughts?

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