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<P>As this topic involves a lot of discussion thought the better place will be wiki.</P>
<P>I was just thinking randomly to see how to integrate the work in JIRA-1816 with the work<BR>
in JIRA-1700(implementation.das support for tx inents/policies). Below are some suggestions I could gather,<BR>
but need lot of feedback and ideas.</P>
<H3><A name="TransactionIntentsandTransactionManagersupport-TransactionManagersupportinSCA%28JIRA1816%29"></A>TransactionManager support in SCA (JIRA-1816)</H3>
<P>---------------------------------------------------------------------------------------------------------------------------------<BR>
TransactionInfo - can have 2 subclasses - GlobalTransactionInfo (XADataSource...), LocalTransactionInfo (Connection...)<BR>
we can rename TransactionInfo to TransactionContext if it suits.</P>
<P>TransactionManager - also can have 2 similar flavours - LocalTransactionManager (what is there in the transaction.zip today)<BR>
and GlobalTransactionManager. GlobalTransactionManager can support say a class level annotation - @TransactionManagerFactory(Geronimo)<BR>
to have a way to inject an externally available TransactionManager like Geronimo, JOTM etc.<BR>
---------------------------------------------------------------------------------------------------------------------------------</P>
<H3><A name="TransactionIntentsandTransactionManagersupport-TxPolicySupportinimplementation.das%28JIRA1700%29"></A>Tx Policy Support in implementation.das (JIRA-1700)</H3>
<P>----------------------------------------------------------------------------------------------------------------------------------------------<BR>
I went through the Tx Policy Draft and trying to understand it in detail. Below trying to give examples of different scenarions<BR>
for implementation.das and attempting to analyze just some part from that. Getting lost in different places <IMG class="emoticon" src="http://cwiki.apache.org/confluence/images/icons/emoticons/smile.gif" height="20" width="20" align="absmiddle" alt="" border="0">. Need all possible comments.<BR>
I am just gathering all points below, with some discussions can prepare a design doc if that helps.</P>
<P>(RM=Resource Manager) (xads = XADataSource) (xares=XAResource)(conn=connection)(2PC - 2 Phase Commit)<BR>
----------------------------------------------------------------------------------------------------------------------------------------------<BR>
Note: <BR>
a> It is possible that the caller (say junit test case) passes XADataSource(which has Connection and XAResource) OR same can be obtained from <BR>
within SCA runtime.<BR>
b> At das.implementation level intents can be - managedTransaction.global, managedTransaction.local, noManagedTransaction, (still not clear why to support unqualified managedTransaction)<BR>
c> At present, implementation.das does not support oneWayInvocation - so need not consider transactedOneWay and immediateOneWay - is this right assumption?<BR>
d> At service level intents can be - propagatesTransaction, suspendsTransaction<BR>
----------------------------------------------------------------------------------------------------------------------------------------------<BR>
Scenarios:- </P>
<P><B>CASE1) 1 component - 1 impl - 1 connection info - multiple services - multiple operations/service</B></P>
<P>so at the time of createInvoker() for a service, the SCArutime can know both the intents (impl and interaction) and decide how to act on it.<BR>
i.e. during DASImplementationProvider.createInvoker().</P>
<P>1 impl == 1 RM (multiple Connections/XAConnections). <BR>
so multiple services in the same .composite will use the same RM</P>
<P>In DASImplementationProvider(component, impl) we have DASImplementationProvider.createInvoker(service, operation)<BR>
One DASImplementationProvider has 1 DataAccessEngineManager. Bue each createInvoker() has a new DASInvoker() with new das<BR>
and new DataAccessEngine. So each new invoker() will have a diff das instance.</P>
<P><B>example</B></P>
<P>scaDomain = SCADomain.newInstance("company.composite");<BR>
dasCompanyService = scaDomain.getService(CompanyService.class, "CompanyComponent/CompanyServiceComponent");</P>
<P>dasCustomerService = scaDomain.getService(CustomerService.class, "CompanyComponent/CustomerServiceComponent");</P>
<P>dasCompanyService.updateCompanies();//RM0 - das0<BR>
dasCustomerService.updateCustomers();//RM0 - das1<BR>
----------------------------------------------------------------------------------------------------------------------------------------------<BR>
<B>CASE2) also there can be - multiple RMs (multiple XAConnections for Tx support for atomic tx, if atomic is not needed can use java.sql.Connections)</B></P>
<P>scaDomain1 = SCADomain.newInstance("company.composite");<BR>
dasCompanyService = scaDomain.getService(CompanyService.class, "CompanyComponent/CompanyServiceComponent");</P>
<P>scaDomain2 = SCADomain.newInstance("customer.composite");<BR>
dasCustomerService = scaDomain.getService(CustomerService.class, "CustomerComponent/CustomerServiceComponent");</P>
<P>dasCompanyService.updateCompanies(); //RM1 - das1<BR>
dasCustomerService.updateCustomers(); //RM2 - das2<BR>
----------------------------------------------------------------------------------------------------------------------------------------------<BR>
<B>CASE3) case when at least one das (say das1) instance has a config with managedtx=true (i.e. das manages tx)</B><BR>
In this case the configs and intents of all other das instances are immeterial, because to support managedtx=true (for das1), all others will need <BR>
to follow the same mode.<BR>
----------------------------------------------------------------------------------------------------------------------------------------------<BR>
<B>CASE4) case when non-DBMS RMs are involved</B></P>
<P>scaDomain1 = SCADomain.newInstance("company.composite");<BR>
dasCompanyService = scaDomain.getService(CompanyService.class, "CompanyComponent/CompanyServiceComponent");</P>
<P>scaDomain2 = SCADomain.newInstance("jmscustomer.composite");<BR>
jmsCustomerService = scaDomain.getService(jmsCustomerService.class, "jmsCustomerComponent/jmsCustomerServiceComponent");</P>
<P>dasCompanyService.updateCompanies(); //RM1 DBMS<BR>
jmsCustomerService.updateCustomers(); //RM2 JMS<BR>
--------------------------------------------------------------------------------------------------------------------------------------------------<BR>
The Table2 from Tx Policy Draft needs to be considered.</P>
<P>As the knowledge about das.implemnetation intent is at the construction of DASImplementationProvider(), but the knowledge of service level intent<BR>
is at DASImplementationProvider.createInvoke() level, createInvoker() is the place which can take decision about tx control.</P>
<P>The ConnectionInfo - finally present inside das (may it be from config.xml or .composite) should be in accordance with what is expected in the <BR>
effective intents.</P>
<P>DataAccessImplementationProvider.createInvoker() when calls getDAS() should pass as IN params the effective intents.</P>
<P>When caller wants to pass xads (in case of global tx)/connection (in case of local tx), it needs a way to inject it (i.e. inject tx context) in <BR>
the service. Some possible ways -<BR>
**All DAS based services - can say mandatorily have a method setTransactionContext(Object ctx) (ctx can be Connection/XADS based on local<BR>
or global). This should be invoked by the caller before calling any business method for the service. <BR>
**Another way, from JIRA-1816 work - say the caller does<BR>
GlobalTransactionContext.setContext(XADS) OR LocalTransactionContext.setContext(Connection).<BR>
with this the thread context will have info to be used inside SCA component/services.<BR>
DataAccessImplementationProvider will do getContext() and if it is available (i.e. caller did setContext), will pass it to the getDAS(),<BR>
so das instance will get Connection during construction. </P>
<P>---------------------------------------------------------------------------------------------------------------------------------------------------<BR>
<B>I] propagatesTransaction + managedTransaction.global</B></P>
<P>MEANING: caller will ideally start tx and pass the tx context to sca runtime. the tx is distributed xa tx.</P>
<P>FLOW: <BR>
i) during DataAccessImplementationProvider.createInvoker() <DIV class="error"><SPAN class="error">Unknown macro: {das=getDAS()}</SPAN> </DIV>, inents will be passed in as well as necessary info from<BR>
txn context will be passed in by DataAccessImplementationProvider.<BR>
ii) das will get constructed with passing "new" connection to FACTORY.createDAS(). Also set managedtx=false to enalble non-das tx management.</P>
<P>the caller will be responsible to handle the txn (i.e. managed shared global txn pattern)</P>
<P><B>example</B></P>
<P>XADS= GlobalTransactionManager.getXADataSource(pass in properties);<BR>
GlobalTransactionContext.setContext(XADS tied to XID); //due to threadlocal, this context is referenceable by DataAccessImplementationProvider now.<BR>
GlobalTransactionManager.begin(GlobalTransactionContext.getContext());</P>
<P>scaDomain = SCADomain.newInstance("company.composite");<BR>
dasCompanyService = scaDomain.getService(CompanyService.class, "CompanyComponent/CompanyServiceComponent");//needs XADS1 tied with same XID</P>
<P>dasCustomerService = scaDomain.getService(CustomerService.class, "CompanyComponent/CustomerServiceComponent");//needs XADS2 tied with same XID</P>
<P>dasCompanyService.updateCompanies();//RM0 - das0 <BR>
dasCustomerService.updateCustomers();//RM0 - das1</P>
<P>GlobalTransactionManager.commit(context);//see that XID has 2 XADS tied to it and does necessaty actions for 2PC<BR>
--------------------------------------------------------------------------------------------------------------------------------------------------<BR>
Now for the case that, the caller is not having a ongoing tx and so does not inject tx context in sca runtime.</P>
<P>When DASImplementationProvider detects there is no tx context set , inside createInvoker(), it can first instantiate das without a connection<BR>
(some changes needed in tuscany-das-rdb for this), and then use das.getConfig() to get necessary config props and construct a tx context <BR>
to be used by the current DASInvoker. Say we create a new DASTransactionCoordinator() for this work.</P>
<P>DASTransactionCoordinator {</P>
<P> GlobalTransactionContext setTxContext(dasConfig)<DIV class="error"><SPAN class="error">Unknown macro: {
XADS= GlobalTransactionManager.getXADataSource(pass in properties);
GlobalTransactionContext.setContext(XADS); //due to threadlocal, this context is referenceable by DataAccessImplementationProvider now.
GlobalTransactionManager.begin(GlobalTransactionContext.getContext());//starts tx, this tx will be shared by all invokers.
}</SPAN> </DIV></P>
<P> //multiple XADS will need to be tied to single xid to make them part of 1 xa tx.<BR>
//more methods here for getContext, enqueXAResourceInXID, dqueue XAResource from XID, XID based 2PhaseCommit... <BR>
}</P>
<P>and will also pass "new" conection from the tx context to each new das instance.</P>
<P>Also DASImplementationProvider() in this case will need to terminate tx. This can be done in stop() of DASImplementationProvider();<BR>
start() can not be used to start a tx as at that time, there is no existing tx context.</P>
<P>Questions:<BR>
Now are my confusions. In DASImplementationProvider.stop() what is the way to know whether to commit/rollback? i.e. how stop() method will know about the invoke() having exceptions? Or otherwise each DASinvoker will need access to xid which is shared by all XAResources in the global tx<BR>
and the DASInvoker is supposed to call DASTransactionCoordinator.rollback() for case of exception?</P>
<P>Also, this whole story relates to only one RuntimeComponent (i.e. multiple services and multiple operations in each services but all in same <BR>
component. Thus the tx can be encompassed by DASImplementationProvider.) What to do for the case when the global tx needs to span multiple <BR>
components?<BR>
------------------------------------------------------------------------------------------------------------------------------------------------<BR>
<B>II] suspendsTransaction + managedTransaction.global</B><BR>
Here even if caller has a tx, it will be ignored and DASImplementationProvider+DASTransactionCoordinator will create a new Tx context and <BR>
will manage tx. Same questions as I]<BR>
-------------------------------------------------------------------------------------------------------------------------------------------------<BR>
<B>III] suspendsTransaction + managedTransaction.local</B></P>
<P>DASImplementationProvider() will pass DASConfig.connectionInfo() to LocalTransactionManager.getDataSource() and setContext() to get <BR>
java.sql.Connection (can be DriverManager or DataSource - in case of DataSource, the external env. is responsible for the JNDI initialization.)<BR>
(As local tx, no question of XADS). Same question - how to communicate exception occuring in DASInvoker.invoke() to stop()?<BR>
to decide whether to commit/rollback? Also as these are mere Connections and not XID/XADS etc. is it better for the DASInvoker() to control<BR>
the commit/rollback of tx? i.e. each DASInvoker() thread will be a Local Tx.<BR>
--------------------------------------------------------------------------------------------------------------------------------------------------<BR>
<B>IV] suspendsTransaction + noManagedTransaction</B><BR>
this is equivalent to a das config with managedtx=true.</P>
<P>Now say in case, there are das1 and das2 involved from 2 different .composites in a caller's business method<BR>
and das1 has IV] / managedtx=true and das2 has I], how will we be able to dectate that , because das1 is das managed tx, das2 should behave in <BR>
same way?<BR>
-------------------------------------------------------------------------------------------------------------------------------------------------<BR>
Also, need to specify behavior for cases when only impl intent is present or only interaction intent is present.</P>
<P>CASE2) and CASE4) in case of I] need the caller to manage tx. If this is not happening, how implementation.das will be able to manage tx <BR>
(if there are multiple components involved)</P>
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