Re: Nesting Transactions

I actually just want to do real nesting of the transactions, I don't  
want to violate the ideas, I want to extend them by starting a  
serialization ( I get that the transaction is itself serialized to the  
journal),  lumping them all in until done and then writing it out.     
Almost like how serialization recurses through containers.

In general, I want to tie together multiple smaller transactions for  
rollback or commit en masse and I could hide all of the complexity  
with start and end transactions.   I am exposing a public API that has  
both simple CRUD operations and larger operations (like various mass  
importers).    I would like to compose the larger actions out of  
smaller ones but roll back on any fail.      I would also like my  
consumers to be able delineate those transactions themselves, but  
don't really want to have to explain the pattern to them.

  Sure.. as Klaus points out, I can construct an anonymous  
transaction.    I figured that would make it possible to simply set a  
"start" point ..  do a bunch of transactions and then commit them.      
I can live without it but it would have been nice for 3rd party  
consumers of my API to build transactions in a way they are used to.

R


On Jun 30, 2009, at 6:11 PM, Justin T. Sampson wrote:

> That's kind of the opposite of Prevayler's design. :)
>
> Prevayler's whole architecture is based on the fact that  
> transactions are encapsulated into objects. This allows transactions  
> to be journaled, replicated, and executed in a streamlined  
> concurrent pipeline.
>
> Could you say more about why you don't want to write a "composite  
> transaction"? There may be other things people have done to address  
> similar concerns.
>
> Cheers,
> Justin
>
>
> On Tue, Jun 30, 2009 at 2:40 PM, Ross Rick <[email protected]> wrote:
> Hi all,
>
> I wonder if anyone has tried nesting transactions with prevayler  
> before.
>
> To be specific, lets imagine two calls to the same transaction done  
> sequentially.
>
> LocalList.add( prevayler.execute ( new  
> GetNutsTransaction( "Walnuts") ;
> LocalList.add( prevayler.execute ( new GetNutsTransaction ("Pecans") ;
>
> What I would like to do is make those two calls within the same  
> transaction without being forced to code a sort of composite  
> transaction.   Of course, what I am really getting at is the ability  
> to arbitrarily start a transaction and then have that bundle all of  
> the smaller transactions until I explicitly commit.   As a more  
> realistic example, I would want to do something like this :
>
> public void increaseNutPurchases(String[] nutTypes, int pctIncrease) {
>
>     Transaction txn = startLongishTransaction();
>
>     try {
>         for (String nutType : nutTypes) {
>
>             List growers = prevayler.execute(new  
> GetGrowerQuery(nutType));
>             for (Grower grower : growers) {
>
>                 prevayler.execute(new  
> UpdateBuyQuantityTransaction(grower, pctIncrease));
>
>             }
>         }
>     }
>
>     catch (Exception e) {
>         txn.rollback();
>     }
>     txn.commit():
>
> }
>
>
> Has anyone tried this ??   Known issues?   Any red flags pop up for  
> you looking at this?
>
> Thx,
>
> Rick
>
>
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