[jboss-dev] transactions change in AS 5.0

[Jonathan Halliday]

Well I'm all in favour of understanding, but I'm not 
actually convinced it makes much difference to the decision. 
The technical differences and limitations need to be 
understood/documented/resolved anyhow for the EAP. The 
question is, does that work occur in the AS 5.0.CR1->GA 
space or the AS 5.0.GA->EAP 5.0.GA part.

But to answer the question: each cluster node contains a 
transaction manager, which is responsible for coordinating 
any transactions started at that node. It may simultaniously 
be acting as a subservient node for transactions started 
elsewhere and flowed in by e.g. RMI/IIOP requests. The 
really hairy bit is the crash recovery, configuration of 
which depends on the clustering model e.g. if disk is 
shared, if IP addresses migrate to a standby node on 
failure, etc.  The testing guys are going to love it :-)

Other significant configuration implications are that you 
need an ORB for the JTS, so if we put it in 'default' then 
we need to move JacORB into the 'default' config too. And 
the way that transaction context is managed with remote 
clients will change: the current remote transaction 
demarcation and context flow solutions probably won't work 
with the JTS. (ClientUserTransaction and the EJB client 
stuff for JRMP).

Jonathan.

Dimitris Andreadis wrote:
> I think before making a decision we need to understand the technical 
> differences of jta/jts and the configuration implications.  I suppose I
> can go and RTFM, however do you see issues in having nodes in a cluster 
> running jts? Do you need to have somekind of coordinator node or the 
> nodes auto-arrange themselves?
> 
> Jonathan Halliday wrote:
>>
>> Hello all
>>
>> Arguably one for the AS list, but in light of potential impact on 
>> other projects I think it needs wider discussion, so hello dev list...
>>
>> I'm pleased to say that we will shortly be announcing the change of 
>> licence terms for the JTS (distributed, interoperable transactions 
>> between e.g. EJB containers) and XTS (transactions for Web Services) 
>> parts of JBossTS from GPL/Dual to LGPL.
>>
>> The current JBossAS release bundles our JTA ('local only' 
>> transactions), which is already LGPL.  The JTS and XTS options are 
>> available to the community as additional downloads that can be 
>> integrated into AS 4.x  The EAP 4.x releases include support for JTA 
>> only.  We have promised EAP 5.x will include JTS also, and probably at 
>> least some parts of XTS.
>>
>> Now that it's legally feasible to do so, does the AS dev community 
>> wish to include either JTS or XTS with the AS 5.x releases, in order 
>> to provide users with these increased capabilities?
>>
>> I see the advantages as: The AS will have more functionality out of 
>> the box and can be pulled into the EAP with fewer changes. For both 
>> cases it would otherwise be necessary to retrofit the additional 
>> transactions pieces and retest the server.
>>
>> I see the disadvantages as: Changing something as core as the 
>> transactions engine between CR and GA may raise issues that further 
>> delay the release. It adds additional complexity and footprint for 
>> something not all users need.
>>
>> Hybrid solutions are available, such as sticking with the JTA for the 
>> 'default' config and putting the JTS into the 'all' config. These 
>> further muddy the waters and complicate the testing, although I rather 
>> like it from a point of view of offering the most appropriate 
>> technical solution for users with different needs.
>>
>> There may be a degree of tension here between the AS (community) and 
>> EAP (product).  Putting the JTS into the AS reduces the productisation 
>> work at the cost of more engineering effort in the AS for example.
>>
>> I'm wearing my community developer hat today: JBossAS and JBossTS are 
>> open source projects, it's up to the core developers to discuss the 
>> engineering tradeoffs and make the call on this.  That may of course 
>> be unduly idealist: commercial realities dictate that EAP product 
>> management have at least some influence on the final decision :-)
>>
>> Does anyone have strong opinions one way or the other on this?
>>
>> Regards
>>
>> Jonathan Halliday
>> JBossTS dev team lead.
>>
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