I did notice that when a client connects to the network server, there is code that creates a connection number by incrementing a variable in DB2jServerImpl (it's disconcerting that it's not synchronized), and that this number is passed to the Session object, and that Session appears to use this when outputting traces (but I was a bit lost by then).
But this is not the same as what Kathey is looking for. Perhaps it could be found by EmbedConnection (I actually hope not, as that would indicate circular dependencies), but even so it would only be available for EmbedConnections that were created to service a session from a remote client.
Is there a preference to have the unique id to be in the ConnectionContext rather than in the Connection? I don't fully understand the roles and responsibilities of Context vs. the object it "contextizes" :) so I'd appreciate the guidance. My intuition says simplicity dictates it goes in the Connection, but let me know if I'm wrong...
I will note that in general the approach for generating unique ids appears to be incrementing variables rather than using UUID. In my searches for the mysterious session id, I saw two instances of this
GenericLanguageConnectionFactory.getNextLCCInstanceNumber()
and
DB2jServerImpl.getNewConnNum()
this latter one is called whenever a new client thread is created, I am pretty sure this is Mike's "session id".
So, I am leaning towards the increment approach for generating a new connection id rather than using UUID, especially since it will work in the client code as well.
Thanks,
David
Mike Matrigali wrote:
I am not sure where the following information is contained, but somehow
the log statement text trace in a network server connection use to associate a "session id" with a connection. So derby.log statments
would be tagged with this info. This is what I always used
to understand the path of a connection within the log (often people will
use thread id which can work, but does not work if connection pooling
is involved). This did not provide any sort of unique id for a given
network server, though I don't know if that is necessary.
Maybe someone knows if this info is available to the EmbedConnection class, maybe from the context manager?
David Van Couvering wrote:
Hi, Kathey. Currently the connection classes don't appear to have a unique identifier that could be made available in toString(). Do I take it you would like me to find an approach that generates one?
I noticed Derby has a UUID service (very nice!). Is it OK if I use that here to generate a UUID for the connection? If I don't hear otherwise, I'll assume this approach is OK, e.g.
public class EmbedConnection { private UUID UUIDValue; private String UUIDString;
public EmbedConnection() { UUIDFactory uuidFactory = Monitor.getMonitor().getUUIDFactory(); UUIDValue = uuidFactory.createUUID(); UUIDString = this.getClass().getName() + ":" + UUIDValue.toString(); ... }
public String toString() { UUIDString; } }
=====
The connection classes I found are as follows. Please let me know if I missed any. An indented class implies it extends the unindented class above it.
EMBEDDED (org.apache.derby.engine.*) BrokeredConnection (implements java.sql.Connection) BrokeredConnection30 EmbedConnection (implements java.sql.Connection) EmbedConnection30 EmbedPooledConnection (implements java.sql.PooledConnection) EmbedXAConnection
CLIENT (org.apache.derby.client.*_ Connection (abstract class, implements java.sql.Connection)) NetConnection NetXAConnection ClientXAConnection (implements java.sql.XAConnection) ClientPooledConnection (implements java.sql.PooledConnection) LogicalConnection (implements java.sql.Connection)
On the client side, I first need to understand: is derbyclient.jar supposed to be standalone (meaning it can't depend upon things in derby.jar like the Monitor and the UUID class). If so, I suppose I could cut/paste the BasicUUID class into the client packages for use on the client side (shiver). Alternately we could have a derbyutils.jar that is shared between client and server (Big Change, not sure if I want to take that on). Advice here would be most appreciated.
Thanks,
David
Kathey Marsden (JIRA) wrote:
[ http://issues.apache.org/jira/browse/DERBY-243?page=all ]
Kathey Marsden updated DERBY-243: ---------------------------------
Summary: connection toString should uniquely identify the connection (was: connection toString doesn't give enough information)
Description: The toString() on the Derby connection doesn't print unique information.
for example System.out.println(conn) prints:
EmbedConnection in the case of derby embedded
It would be great if the toString() method for connections could be used to differentiate one connection from another.
was: The toString() on the Derby connection doesn't print unique information. for example System.out.println(conn) prints: EmbedConnection in the case of derby embedded
I am not sure if XA Connections and Pooled Connections have the same issue. I didn't immediately see an override of the toString() method in BrokeredConnection.java like there is for EmbedConnection
connection toString should uniquely identify the connection -----------------------------------------------------------
Key: DERBY-243 URL: http://issues.apache.org/jira/browse/DERBY-243 Project: Derby Type: Improvement Components: JDBC Reporter: Kathey Marsden Assignee: David Van Couvering Priority: Trivial Fix For: 10.0.2.1, 10.0.2.0, 10.0.2.2, 10.1.0.0
The toString() on the Derby connection doesn't print unique information.
for example System.out.println(conn) prints:
EmbedConnection in the case of derby embedded
It would be great if the toString() method for connections could be used to differentiate one connection from another.
