RE: GlobalNamingResouces used by other GlobalNamingResources
sorry, can't answer specific Q on whether you can access datasource from generator. but it sounds like you are trying to uniquely ID rows in a database? if so then the simplest way seems to be to use auto_increment fields and let the database handle it. or are you saying that that isn'y working - is this what you mean by not supporting the database-generated id-numbers? if so please say more about why its not working. what database? code sample? -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 11:49 To: TomcatUsers Subject: GlobalNamingResouces used by other GlobalNamingResources Hello again! Sorry to bother in this topic again but I need to strait out one more thing. I have my Datasource now as GlobalNamingContext (and a big post-it saying that I shall change the resource-link from DefaultContext). Since JDBC doesn't generate id-numbers and not supporting the database-generated id-numbers I have written an id-generator that takes care of the problem. It works fine for a single web-app using its own private database but is trouble when two web-apps uses the same database since it's awful hard to keep the generators synchronized (even worse using to tomcat-instances). So, for a breif moment I thought that I had the solution putting the id-generator as a Resource under GlobalNamingResources. And that would have worked if I didn't the init the id-generator with a call to my datasource that also is in the GlobalNamingContext. javax.naming.NameNotFoundException: Name comp:java is not bound in this Context was the result. So, before I start to rewrite my id-generator i would like to get a few things clarified. 1) Can I in any part of my id-generator (assuming that it is defined in the GlobalNamingResources) use my datasource. For example after the user have done a lookup and calling the generate-method? What context will be used in that case? 2) Since we are closing in on the fact that or single tomcat-server sone will not cope with the load its carrying in the peeks. Would there be a better way to implement the id-generator? (rmi, webservice etc etc)? Thank you very much in advance Roland Carlsson - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: GlobalNamingResouces used by other GlobalNamingResources
OK now I see your problem. I have the same issue. I've worked around it with a bit of a hack I'm afraid, and just used the MySQL non-jdbc solution. As you say I will pay the price for this sin later, if I ever need to swap database. However I've taken a view that for my specific situation, this is unlikely in the medium term. So instead of investing time in making the code completely portable to another database, I've invested time in mitigating the impact by genericising my code so that there is only one place I will need to make changes. (Essentially, I've beanified all my database tables so that I have a single method that creates rows in any table in the database and returns the ID). I think portability and re-use are worth investing time and effort in, but there is a limit to that, and sometimes, you need to make compromises and move on, otherwise you can spend days trying to work around a problem that might never happen. -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 13:03 To: TomcatUsers Subject: Sv: GlobalNamingResouces used by other GlobalNamingResources Hi Steve and thanks for you answer. Try the following scenario. The problem is to get back the primary key when doing an insert. Say that you have a master/slave relation between two tables. You insert a row into master. Then you are going to insert a few rows connected to the master into slave. How do you know the id-number of your master? I know that mysql has a non-jdbc soloution for this but since one of our general design goals are portable code.. So, we have desided to take the same apporach as Object-Relational Bridge. We created our own id-generator to handle the problem. But its has created a new set of problems now when we are going to use multiple web-apps and (in a not so distant future) mutiple servers. Regards Roland Carlsson Den 04-10-27 13.48, skrev Steve Kirk [EMAIL PROTECTED]: sorry, can't answer specific Q on whether you can access datasource from generator. but it sounds like you are trying to uniquely ID rows in a database? if so then the simplest way seems to be to use auto_increment fields and let the database handle it. or are you saying that that isn'y working - is this what you mean by not supporting the database-generated id-numbers? if so please say more about why its not working. what database? code sample? - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: GlobalNamingResouces used by other GlobalNamingResources
Sorry - can't answer that one for sure. Does look a bit strange. I could only guess that it might be to do with classloading? I seem to remember that a class abc.def.MyClass loaded by classloader A is deemed to be different to the same class abc.def.MyClass loaded by classloader B, so I would guess that this might lead to casting problems. I haven't used JNDI much apart from in the context of DBCP, so I'm not sure exactly how it works - could it maybe be using a different classloader to the one loading your servlet classes? Then again that could be complete rubbish :) -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 13:41 To: TomcatUsers Subject: Sv: GlobalNamingResouces used by other GlobalNamingResources Hello Steve! I have done some trial and error and come to the following (if not somewhat shaky) conclusion. If I make the call to the datasource in the consturctor of my object it will fail, since the caller is the server itself and it has no context. If I make the call to the datasource as a method after have looked up my object and retrived as a user it will run in the context of the user (web-app) and therefore work. Perhaps Yoav can confirm this? So, I manage to get my object...but get a strange class cast error This code: System.out.println(o); se.alfamoving.file.db.FileIdGenerator fg = (se.alfamoving.file.db.FileIdGenerator) o; Gives this output: [EMAIL PROTECTED] java.lang.ClassCastException snip/ But I'll guess that I spelled badly somewhere :-/ The happy moments never seems to last :-) Thank you very much for your time and effort! Regards Roland Carlsson Den 04-10-27 14.28, skrev Steve Kirk [EMAIL PROTECTED]: OK now I see your problem. I have the same issue. I've worked around it with a bit of a hack I'm afraid, and just used the MySQL non-jdbc solution. As you say I will pay the price for this sin later, if I ever need to swap database. However I've taken a view that for my specific situation, this is unlikely in the medium term. So instead of investing time in making the code completely portable to another database, I've invested time in mitigating the impact by genericising my code so that there is only one place I will need to make changes. (Essentially, I've beanified all my database tables so that I have a single method that creates rows in any table in the database and returns the ID). I think portability and re-use are worth investing time and effort in, but there is a limit to that, and sometimes, you need to make compromises and move on, otherwise you can spend days trying to work around a problem that might never happen. -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 13:03 To: TomcatUsers Subject: Sv: GlobalNamingResouces used by other GlobalNamingResources Hi Steve and thanks for you answer. Try the following scenario. The problem is to get back the primary key when doing an insert. Say that you have a master/slave relation between two tables. You insert a row into master. Then you are going to insert a few rows connected to the master into slave. How do you know the id-number of your master? I know that mysql has a non-jdbc soloution for this but since one of our general design goals are portable code.. So, we have desided to take the same apporach as Object-Relational Bridge. We created our own id-generator to handle the problem. But its has created a new set of problems now when we are going to use multiple web-apps and (in a not so distant future) mutiple servers. Regards Roland Carlsson Den 04-10-27 13.48, skrev Steve Kirk [EMAIL PROTECTED]: sorry, can't answer specific Q on whether you can access datasource from generator. but it sounds like you are trying to uniquely ID rows in a database? if so then the simplest way seems to be to use auto_increment fields and let the database handle it. or are you saying that that isn'y working - is this what you mean by not supporting the database-generated id-numbers? if so please say more about why its not working. what database? code sample? - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -
RE: GlobalNamingResouces used by other GlobalNamingResources
Hi, Yeah, Steve's advice on classloading is right on the mark... I don't have time to check this out in depth, but I'd be surprised if he's wrong. com.foo loaded from common/lib is not the same as com.foo loaded from WEB-INF/lib. Yoav Shapira http://www.yoavshapira.com -Original Message- From: Steve Kirk [mailto:[EMAIL PROTECTED] Sent: Wednesday, October 27, 2004 8:58 AM To: 'Tomcat Users List' Subject: RE: GlobalNamingResouces used by other GlobalNamingResources Sorry - can't answer that one for sure. Does look a bit strange. I could only guess that it might be to do with classloading? I seem to remember that a class abc.def.MyClass loaded by classloader A is deemed to be different to the same class abc.def.MyClass loaded by classloader B, so I would guess that this might lead to casting problems. I haven't used JNDI much apart from in the context of DBCP, so I'm not sure exactly how it works - could it maybe be using a different classloader to the one loading your servlet classes? Then again that could be complete rubbish :) -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 13:41 To: TomcatUsers Subject: Sv: GlobalNamingResouces used by other GlobalNamingResources Hello Steve! I have done some trial and error and come to the following (if not somewhat shaky) conclusion. If I make the call to the datasource in the consturctor of my object it will fail, since the caller is the server itself and it has no context. If I make the call to the datasource as a method after have looked up my object and retrived as a user it will run in the context of the user (web-app) and therefore work. Perhaps Yoav can confirm this? So, I manage to get my object...but get a strange class cast error This code: System.out.println(o); se.alfamoving.file.db.FileIdGenerator fg = (se.alfamoving.file.db.FileIdGenerator) o; Gives this output: [EMAIL PROTECTED] java.lang.ClassCastException snip/ But I'll guess that I spelled badly somewhere :-/ The happy moments never seems to last :-) Thank you very much for your time and effort! Regards Roland Carlsson Den 04-10-27 14.28, skrev Steve Kirk [EMAIL PROTECTED]: OK now I see your problem. I have the same issue. I've worked around it with a bit of a hack I'm afraid, and just used the MySQL non-jdbc solution. As you say I will pay the price for this sin later, if I ever need to swap database. However I've taken a view that for my specific situation, this is unlikely in the medium term. So instead of investing time in making the code completely portable to another database, I've invested time in mitigating the impact by genericising my code so that there is only one place I will need to make changes. (Essentially, I've beanified all my database tables so that I have a single method that creates rows in any table in the database and returns the ID). I think portability and re-use are worth investing time and effort in, but there is a limit to that, and sometimes, you need to make compromises and move on, otherwise you can spend days trying to work around a problem that might never happen. -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 13:03 To: TomcatUsers Subject: Sv: GlobalNamingResouces used by other GlobalNamingResources Hi Steve and thanks for you answer. Try the following scenario. The problem is to get back the primary key when doing an insert. Say that you have a master/slave relation between two tables. You insert a row into master. Then you are going to insert a few rows connected to the master into slave. How do you know the id-number of your master? I know that mysql has a non-jdbc soloution for this but since one of our general design goals are portable code.. So, we have desided to take the same apporach as Object-Relational Bridge. We created our own id-generator to handle the problem. But its has created a new set of problems now when we are going to use multiple web-apps and (in a not so distant future) mutiple servers. Regards Roland Carlsson Den 04-10-27 13.48, skrev Steve Kirk [EMAIL PROTECTED]: sorry, can't answer specific Q on whether you can access datasource from generator. but it sounds like you are trying to uniquely ID rows in a database? if so then the simplest way seems to be to use auto_increment fields and let the database handle it. or are you saying that that isn'y working - is this what you mean by not supporting the database-generated id-numbers? if so please say more about why its not working. what database? code sample? - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED
RE: GlobalNamingResouces used by other GlobalNamingResources
I'm not sure if this will solve it or is even accurate - but probably worth you checking out. Specifically, look at msterjev's post re use of URLClassLoader near the bottom of the thread: http://www.experts-exchange.com/Programming/Programming_Languages/Java/Q_207 10542.html -Original Message- From: Shapira, Yoav [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 14:03 To: Tomcat Users List Subject: RE: GlobalNamingResouces used by other GlobalNamingResources Hi, Yeah, Steve's advice on classloading is right on the mark... I don't have time to check this out in depth, but I'd be surprised if he's wrong. com.foo loaded from common/lib is not the same as com.foo loaded from WEB-INF/lib. Yoav Shapira http://www.yoavshapira.com -Original Message- From: Steve Kirk [mailto:[EMAIL PROTECTED] Sent: Wednesday, October 27, 2004 8:58 AM To: 'Tomcat Users List' Subject: RE: GlobalNamingResouces used by other GlobalNamingResources Sorry - can't answer that one for sure. Does look a bit strange. I could only guess that it might be to do with classloading? I seem to remember that a class abc.def.MyClass loaded by classloader A is deemed to be different to the same class abc.def.MyClass loaded by classloader B, so I would guess that this might lead to casting problems. I haven't used JNDI much apart from in the context of DBCP, so I'm not sure exactly how it works - could it maybe be using a different classloader to the one loading your servlet classes? Then again that could be complete rubbish :) -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 13:41 To: TomcatUsers Subject: Sv: GlobalNamingResouces used by other GlobalNamingResources Hello Steve! I have done some trial and error and come to the following (if not somewhat shaky) conclusion. If I make the call to the datasource in the consturctor of my object it will fail, since the caller is the server itself and it has no context. If I make the call to the datasource as a method after have looked up my object and retrived as a user it will run in the context of the user (web-app) and therefore work. Perhaps Yoav can confirm this? So, I manage to get my object...but get a strange class cast error This code: System.out.println(o); se.alfamoving.file.db.FileIdGenerator fg = (se.alfamoving.file.db.FileIdGenerator) o; Gives this output: [EMAIL PROTECTED] java.lang.ClassCastException snip/ But I'll guess that I spelled badly somewhere :-/ The happy moments never seems to last :-) Thank you very much for your time and effort! Regards Roland Carlsson Den 04-10-27 14.28, skrev Steve Kirk [EMAIL PROTECTED]: OK now I see your problem. I have the same issue. I've worked around it with a bit of a hack I'm afraid, and just used the MySQL non-jdbc solution. As you say I will pay the price for this sin later, if I ever need to swap database. However I've taken a view that for my specific situation, this is unlikely in the medium term. So instead of investing time in making the code completely portable to another database, I've invested time in mitigating the impact by genericising my code so that there is only one place I will need to make changes. (Essentially, I've beanified all my database tables so that I have a single method that creates rows in any table in the database and returns the ID). I think portability and re-use are worth investing time and effort in, but there is a limit to that, and sometimes, you need to make compromises and move on, otherwise you can spend days trying to work around a problem that might never happen. -Original Message- From: Roland Carlsson [mailto:[EMAIL PROTECTED] Sent: Wednesday 27 October 2004 13:03 To: TomcatUsers Subject: Sv: GlobalNamingResouces used by other GlobalNamingResources Hi Steve and thanks for you answer. Try the following scenario. The problem is to get back the primary key when doing an insert. Say that you have a master/slave relation between two tables. You insert a row into master. Then you are going to insert a few rows connected to the master into slave. How do you know the id-number of your master? I know that mysql has a non-jdbc soloution for this but since one of our general design goals are portable code.. So, we have desided to take the same apporach as Object-Relational Bridge. We created our own id-generator to handle the problem. But its has created a new set of problems now when we are going to use multiple web-apps and (in a not so distant future) mutiple servers. Regards Roland Carlsson Den 04-10-27 13.48, skrev Steve Kirk [EMAIL PROTECTED]: sorry
RE: GlobalNamingResouces used by other GlobalNamingResources
I've just noticed another (more elegant) solution from another post, and
will be changing my code to use it. As long as your database driver
supports it, try using statement.getGeneratedKeys()
I got this example from
http://www.datadirect.com/products/jdbc/docs/jdbc30feats/index.ssp
Int rowcount = stmt.executeUpdate (
insert into LocalGeniusList (name) values ('Karen'),
employeeID);
ResultSet rs = stmt.getGeneratedKeys (); // Karen's employeeID value is now
available
-Original Message-
From: Steve Kirk [mailto:[EMAIL PROTECTED]
Sent: Wednesday 27 October 2004 13:29
To: 'Tomcat Users List'
Subject: RE: GlobalNamingResouces used by other GlobalNamingResources
OK now I see your problem. I have the same issue. I've
worked around it
with a bit of a hack I'm afraid, and just used the MySQL
non-jdbc solution.
As you say I will pay the price for this sin later, if I ever
need to swap
database. However I've taken a view that for my specific
situation, this is
unlikely in the medium term. So instead of investing time in
making the
code completely portable to another database, I've invested time in
mitigating the impact by genericising my code so that there
is only one
place I will need to make changes. (Essentially, I've
beanified all my
database tables so that I have a single method that creates
rows in any
table in the database and returns the ID).
I think portability and re-use are worth investing time and
effort in, but
there is a limit to that, and sometimes, you need to make
compromises and
move on, otherwise you can spend days trying to work around a
problem that
might never happen.
-Original Message-
From: Roland Carlsson [mailto:[EMAIL PROTECTED]
Sent: Wednesday 27 October 2004 13:03
To: TomcatUsers
Subject: Sv: GlobalNamingResouces used by other
GlobalNamingResources
Hi Steve and thanks for you answer.
Try the following scenario.
The problem is to get back the primary key when doing an
insert. Say that
you have a master/slave relation between two tables.
You insert a row into master. Then you are going to insert
a few rows
connected to the master into slave. How do you know the
id-number of your
master?
I know that mysql has a non-jdbc soloution for this but since
one of our
general design goals are portable code.. So, we have
desided to take the
same apporach as Object-Relational Bridge. We created our own
id-generator
to handle the problem. But its has created a new set of
problems now when we
are going to use multiple web-apps and (in a not so distant
future) mutiple
servers.
Regards
Roland Carlsson
Den 04-10-27 13.48, skrev Steve Kirk
[EMAIL PROTECTED]:
sorry, can't answer specific Q on whether you can access
datasource from
generator. but it sounds like you are trying to uniquely
ID rows in a
database?
if so then the simplest way seems to be to use
auto_increment fields and let
the database handle it. or are you saying that that isn'y
working - is this
what you mean by not supporting the database-generated
id-numbers? if so
please say more about why its not working. what database?
code sample?
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
Re: GlobalNamingResouces used by other GlobalNamingResources
Hi Steve!
That is a quite sweet function. I'll try it out as soon as I can when
comming to work tomorrow.
Thanks for the tip
Regards
Roland Carlsson
- Original Message -
From: Steve Kirk [EMAIL PROTECTED]
To: 'Tomcat Users List' [EMAIL PROTECTED]
Sent: Wednesday, October 27, 2004 6:20 PM
Subject: RE: GlobalNamingResouces used by other GlobalNamingResources
I've just noticed another (more elegant) solution from another post, and
will be changing my code to use it. As long as your database driver
supports it, try using statement.getGeneratedKeys()
I got this example from
http://www.datadirect.com/products/jdbc/docs/jdbc30feats/index.ssp
Int rowcount = stmt.executeUpdate (
insert into LocalGeniusList (name) values ('Karen'),
employeeID);
ResultSet rs = stmt.getGeneratedKeys (); // Karen's employeeID value is
now
available
-Original Message-
From: Steve Kirk [mailto:[EMAIL PROTECTED]
Sent: Wednesday 27 October 2004 13:29
To: 'Tomcat Users List'
Subject: RE: GlobalNamingResouces used by other GlobalNamingResources
OK now I see your problem. I have the same issue. I've
worked around it
with a bit of a hack I'm afraid, and just used the MySQL
non-jdbc solution.
As you say I will pay the price for this sin later, if I ever
need to swap
database. However I've taken a view that for my specific
situation, this is
unlikely in the medium term. So instead of investing time in
making the
code completely portable to another database, I've invested time in
mitigating the impact by genericising my code so that there
is only one
place I will need to make changes. (Essentially, I've
beanified all my
database tables so that I have a single method that creates
rows in any
table in the database and returns the ID).
I think portability and re-use are worth investing time and
effort in, but
there is a limit to that, and sometimes, you need to make
compromises and
move on, otherwise you can spend days trying to work around a
problem that
might never happen.
-Original Message-
From: Roland Carlsson [mailto:[EMAIL PROTECTED]
Sent: Wednesday 27 October 2004 13:03
To: TomcatUsers
Subject: Sv: GlobalNamingResouces used by other
GlobalNamingResources
Hi Steve and thanks for you answer.
Try the following scenario.
The problem is to get back the primary key when doing an
insert. Say that
you have a master/slave relation between two tables.
You insert a row into master. Then you are going to insert
a few rows
connected to the master into slave. How do you know the
id-number of your
master?
I know that mysql has a non-jdbc soloution for this but since
one of our
general design goals are portable code.. So, we have
desided to take the
same apporach as Object-Relational Bridge. We created our own
id-generator
to handle the problem. But its has created a new set of
problems now when we
are going to use multiple web-apps and (in a not so distant
future) mutiple
servers.
Regards
Roland Carlsson
Den 04-10-27 13.48, skrev Steve Kirk
[EMAIL PROTECTED]:
sorry, can't answer specific Q on whether you can access
datasource from
generator. but it sounds like you are trying to uniquely
ID rows in a
database?
if so then the simplest way seems to be to use
auto_increment fields and let
the database handle it. or are you saying that that isn'y
working - is this
what you mean by not supporting the database-generated
id-numbers? if so
please say more about why its not working. what database?
code sample?
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
