Fabio, the situation that I am working with is probably not that common, but I will describe it, and maybe you can offer some advice.
There is a very large legacy application that predated NH and has gone through several design iterations, such that it has several data access abstractions on top of ADO.NET. (calling SqlClient.* direcly, through ApplicationBlock.Data, etc.) NHibernate is being introduced gradually, and until the conversion is complete, we have this mixed environment where some stuff is NH-enabled and some is not. One of the areas where this is cumbersome is transaction management. A fair bit of object interaction is abstracted into higher-order components. The choice of which transaction mechanism is appropriate is not always obvious, thus making TransactionScope really attractive. If we could just use that, and rely on everything down the line to play nicely with it, it would dramatically simplify working with this environment. In other words, it would be very attractive for me to *not* have to call session.BeginTransaction explicitly. Does that make sense? Thanks! -Michael ________________________________ From: [email protected] [[email protected]] On Behalf Of Fabio Maulo [[email protected]] Sent: Monday, March 23, 2009 10:38 AM To: [email protected] Subject: [nhibernate-development] Re: More DTC issues When you are calling session.BeginTransaction you don't know if it happen inside a DTC or no, right ? You don't know if/when/who start a DTC. >From Oren example 1/ low level infrastructure - dtc 2/ high level infarstruture - nh 3/ business code - your stuff 3/ your stuff end 2/ session.Flush, nh-transaction commit, session.Dispose 1/ Complete but you don't know if NH-code is running inside a DTC, as "your-stuff", or part of it, don't know that it is running inside DTC+NH. What you do in the "high level infarstruture" is openSession+session.BeginTransaction without take care if a "low level infrastructure" component start a DTC. Or you want put something like if(DTC) {aBehaviorOfNhSession+Transaction} else {anotherBehaviorOfNhSession+Transaction} ? hopefully no. The user don't need to know to call session.BeginTransaction because call it is a simple best/required-practice. The user should call session.BeginTransaction always without take care about DTC. 2009/3/23 Michael Teper <[email protected]<mailto:[email protected]>> But *does* the user need to know to call session.BeginTransaction? In my example, are you saying that I would need to explicitly manage bot the TransactionScope and NH ITransaction ? Thanks!! -Michael ________________________________ From: [email protected]<mailto:[email protected]> [[email protected]<mailto:[email protected]>] On Behalf Of Fabio Maulo [[email protected]<mailto:[email protected]>] Sent: Monday, March 23, 2009 10:13 AM To: [email protected]<mailto:[email protected]> Subject: [nhibernate-development] Re: More DTC issues For those reasons the ITransaction shouldn't be a merely "ADO.NET<http://ADO.NET> transaction wrapper" (or so near to it). session.BeginTransaction should know which is the environment, it should know if it should run in a nested DTC transaction ... and so on. The user only need to know that i must call session.BeginTransaction, NH should to the right thing. 2009/3/23 Michael Teper <[email protected]<mailto:[email protected]>> Fabio, Ayende, Another thing to consider is the nested transaction scenario like this: using (var scopeOuter = new TransactionScope()) { // load / change some object(s) using (var innerScope = new TransactionScope()) { try { // load / change something else innerScope.complete(); } catch { // do something } } outerScope.complete(); } This may look silly but if the inner transaction is encapsulated in a different class, this is a very plausible scenario. Wherever NH keeps track of the current transaction scope, it needs to be aware of potential for nesting. Thanks! -Michael ________________________________ From: [email protected]<mailto:[email protected]> [[email protected]<mailto:[email protected]>] On Behalf Of Fabio Maulo [[email protected]<mailto:[email protected]>] Sent: Monday, March 23, 2009 9:45 AM To: [email protected]<mailto:[email protected]> Subject: [nhibernate-development] Re: More DTC issues 2009/3/23 Ayende Rahien <[email protected]<mailto:[email protected]>> The problem is that usually the DTC is opened by a lower level component, and my code has no control over it. More than that, I usually don't have control over NH's code as well. It goes like this: 1/ low level infrastructure - dtc 2/ high level infarstruture - nh 3/ business code - my stuff and then 3 -end 2- end 1-end If 2 don't know about 1, 2 should use session.BeginTransaction and session.Transaction.Commit(). I don't want to be aware of all of this issues, I just want to make this work. So explicitly flushing is an option that I would generally be against. Making NH's transaction equal to the dtc is also not a good option, because the use of the DTC is to manage several resources, not just NH. You know... I never said dtc=nhTx What I would like to avoid is If(DTC) {something} else {somethingelse} inside NH-Core. -- Fabio Maulo -- Fabio Maulo -- Fabio Maulo
