Are those manual transactions? (I.e. how does it happen that
transaction scopes overlap between two queries?)
Also you can reuse the current thread transaction between multiple
domains. As I said, connections are scoped by DataNode name, so the
same transaction will return 2 separate connections for 2 queries run
against 2 different nodes.
Andrus
On Dec 1, 2009, at 3:27 PM, Evgeny Ryabitskiy wrote:
Problem in multiple Domains.
When I am creating transaction I am creating it's for specific
DataDomain (like a DataContext).
When I have 2 Modules with dedicated DataDomains (so it will be 2
DataDomains) I can create 2 Transactions
(domain.createTransaction()).
But to thread I can bind only one. Then when I start performing
queries I got:
1)First Domain Transaction is binded and handled normally
2)Second Domain Transaction is override by first DataDomain. So when I
perform query for second: ThreadLocals return Transaction for firs
Domain.
Evgeny
2009/12/1 Andrus Adamchik <[email protected]>:
Singletons are bad in a general purpose framework, like Cayenne. No
question
about that. Per your description even thread-local singletons can
be a
problem, which is less obvious to me, but I guess real in some
circumstances. So let's see what those are.
2)DataContext.getThreadLocal()
Solved by own ThreadLocal for each module. (modules can work in one
thread)
//also spend some time
This is just a convenience in Cayenne. Nobody's forced to use it. I
will go
as far as to suggest to remove it from Cayenne 3.1 as a built-in
feature,
and just document it as a possible design pattern in a user
application.
3)Transaction.getThreadTransaction()
this is killing one!!!
using of own ThreadLocal doesn't help.
It's hard-coded in performing Query to use this singleton
Transaction.getThreadTransaction()
And that is really huge problem for me.
J2EE pattern of tying a transaction to an execution thread, even if
multiple
data sources are involved, makes sense as it allows to commit/
rollback
multiple things at once. Cayenne Transaction sort of follows that.
JDBC
connections within the transaction are scoped by DataNode name. So
what
exactly is the problem?
Andrus
On Dec 1, 2009, at 2:44 PM, Evgeny Ryabitskiy wrote:
Hello 2 everyone!
Today I one more time thinking about singleton pattern and it's hard
usssage in Cayenne.
So.. I have several modules, each has own DomainConfig file and
connection to it's DataBase. Sometimes there can be used different
DB
servers and even different DB types (usually it's Oracle and MS SQL,
sometimes Sybase).
Singletons:
1) Configuration.getSharedConfiguration()
This problem is solved:
DefaultConfiguration conf = new
DefaultConfiguration("module1-cayenne.xml");
conf .initialize;
conf.getDomain();
//spend some time to find solution... everywhere examples with
SharedConfiguration
2)DataContext.getThreadLocal()
Solved by own ThreadLocal for each module. (modules can work in one
thread)
//also spend some time
3)Transaction.getThreadTransaction()
this is killing one!!!
using of own ThreadLocal doesn't help.
It's hard-coded in performing Query to use this singleton
Transaction.getThreadTransaction()
And that is really huge problem for me.
So me suggestion is to move this ThreadLocal to DataDomain. Still
can
use singleton API for standalone applications.
Also we can move DataContext to DataDomain.
Evgeny.
