On 2002.02.14 03:30:25 -0500 Edward Q. Bridges wrote:
can this be both possible and useful?
It's definitely possible. Useful is another question.
Normally a jca connector is useful when you want to communicate with
something that has:
--limited, resource-expensive resources required for a communication
channel
--some notion of transactions
--some notion of security.
As I tried to hint, none of these seem to apply very well to a file system.
The only behaviour I thought of that could be useful is preventing
simultaneous write access to a file. Supplying an anonymous temp directory
is as you point out another possible function. If we can mangle file names
(and don't try to read files we didn't create) we could implement
transactional behavior by including a version number in each file name. In
this case we could also implement some kind of security.
david jencks
as far as i can tell from reading a tutorial on JCA, when the server
starts up it spawns several connections to a resource via the
ManagedConnectionFactory. then the client requests one of these
connections via a ConnectionFactory.
This is a little oversimplified. The degree of pooling depends on the
ConnectionManager, part of the environment (JBoss in our case)
the connections are (apparently) made anonymously to a datasource
configured in a config file that the server reads in at startup.
??Connections are normally made under a security context. Unless that
context is constant (all connections made as the same db user), they
can't be made until the security context is known. I'm not sure what you
mean by datasource. The ManagedConnectionFactory is normally configured at
startup, the ConnectionFactory is what the user gets the connections from
(for jdbc this is usually a javax.sql.DataSource), however in most
circumstances the resource manager is remote and configured through its own
mechanism (e.g. Oracle)
in this regard, how useful is this really when considering files. in
this context how is it possible to create connections to arbitrary files
or network connections? (IMHO this would be the the truly useful aspect
of such a service). the most useful application of this would be to
create a tempfile service that provides a connection to an anonymous
file on the filesystem.
I'm starting to think that might be useful as well.
On Wed, 13 Feb 2002 16:00:46 -0500, David Jencks wrote:
I think the only useful thing you can impelement with a file system
connector is serialization: keep connections from accessing the same
file
at the same time. Transactions without versioning would be very
difficult.
I don't really see any place for security.
If you are interested in an example that is only a little more
complicated
than what would be necessary for a filesystem connector, I can send you
my
javaspace adapter. I haven't been able to test it, however based on the
other (3) adapters I've written I think everything important is
implemented. I'd also be happy to answer questions and review code.
Aside from the spec, the recent jca book is somewhat informative, but
copying an existing adapter will be much easier.
david jencks
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