Revision: 1245
Author: dhanji
Date: Thu Sep 16 14:42:05 2010
Log: Edited wiki page Transactions through web user interface.
http://code.google.com/p/google-guice/source/detail?r=1245
Modified:
/wiki/Transactions.wiki
=======================================
--- /wiki/Transactions.wiki Thu Sep 16 14:37:57 2010
+++ /wiki/Transactions.wiki Thu Sep 16 14:42:05 2010
@@ -40,12 +40,21 @@
== Units of Work ==
-A unit of work is roughly the lifespan of an `EntityManager` (in JPA). It
is the _session_ referred to in the `session-per-*` strategies. We have so
far seen how to create a unit of work that spans a single transaction, and
one that spans an entire HTTP request.
+A unit of work is roughly the lifespan of an `EntityManager` (in JPA). It
is the _session_ referred to in the `session-per-*` strategies. We have so
far seen how to create a unit of work that spans a single transaction:
+
+http://warp-persist.googlecode.com/svn/wiki/txn_unitofwork.png
+
+...and one that spans an entire HTTP request:
+
+http://warp-persist.googlecode.com/svn/wiki/request_unitofwork.png
Sometimes you need to define a custom unit-of-work that doesn't fit into
either requests or transactions. For example, you may want to do some
background work in a timer thread, or some initialization work during
startup. Or perhaps you are making a desktop app and have some other idea
of a unit of work.
+http://warp-persist.googlecode.com/svn/wiki/custom_unitofwork.png
+
To start and end a unit of work arbitrarily, inject the `UnitOfWork`
interface:
+{{{
public class MyBackgroundWorker {
@Inject private UnitOfWork unitOfWork;
@@ -59,5 +68,6 @@
}
}
}
+}}}
You are free to call any `...@transactional` methods while a unit of work is
in progress this way. When `end()` is called, any existing session is
closed and discarded. It is safe to call `begin()` multiple times--if a
unit of work is in progress, nothing happens. Similarly, if one is ended
calling `end()` returns silently. `UnitOfWork` is threadsafe and can be
cached for multiple uses or injected directly into singletons.
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