Jim,
Thanks for the reply. I have not looked over the 2.0 spec. in detail yet
but I will.
Are you mapping cmp entity beans to an existing db structure most of the time?
Cory
At 07:28 PM 10/21/00 -0400, you wrote:
>Hi Cory...
>
>I doubt we'll see anything thats database engine specific supported in CMP.
>I agree that sequences are extremely usefull and wish that there was a
>standard way on implementing them on database engines so that JDBC (and
>therefore J2EE) could take full advantage. PostgreSQL has a sequence and MS
>SQL Server has an identity field and so on. Unfortunatly, database vendors
>have no standard for implementing them.
>
>You can write code to generate a unique value for a primary key. You could
>code up a session bean that uses JDBC to create a new record in a table
>with no fields but the identity field. Of course, this bean would be
>database specific and it would be used by the non-database specific CMP
>entity beans.
>
>Orion makes a key generator available called counter.jar, which you can
>read about in the Orion FAQ (although I don't know what its licensing terms
>are - check this before you rely on it in your app).
>
>Setting aside the question of sequence types and primary key generation, I
>have not yet run into a RDBMS data structure I don't think I could
>replicate using EJB 2.0 CMP. Even if I did, I could isolate part with BMP
>or session beans and use CMP for the rest. I expect if I found something so
>strange 2.0 CMP could not handle it that I would try to redesign it so that
>it could be handled. I would probably end up with a better and simpler
>design.
>
>With EJB 2.0 CMP, I have a very good chance of getting my J2EE app to run
>on whatever database on whatever compliant server on whatever operating
>system. And, all the work it does for me is nice as well. Also, with EJB
>2.0, its entirely possible to create a tool that would let you draw a UML
>diagram and generate almost the entire back end of an app - deployment
>descripters, code, maybe everything but the QL- automatically and then make
>changes a snap. There is no such tool now, but give some time.
>
>The best source of how to do CMP, unfortunatly, is still the spec.
>
>Anyhow, I thought EJB 1.1 was of limited utility. I think 2.0 is much, much
>better and can probably handle most systems. Just my opinion.
>
>Jim
>
>
>--On Saturday, October 21, 2000 3:11 AM -0400 Cory Adams
><[EMAIL PROTECTED]> wrote:
>
>> Jim,
>>
>> How could a CMP managed entity bean handle a create for say an Oracle
>> database table that used db specific sql for describing the key using a
>> sequence?
>>
>> Where the sql itself might look like
>>
>> insert into customer (id, name, address) values(cust_sequence.NEXTVAL,
>> "Jim" "12 Willow Street");
>>
>> Maybe this is trivial.....
>>
>> Better yet could I ask you to provide some of the sources of information
>> that you use to help all of us better understand how to do CMP with
>> perhaps complex RDBMS entity relationships?
>>
>> Thanks,
>>
>> Cory
>>
>> At 09:07 PM 10/20/00 -0400, Jim Archer wrote:
>>> What types of relationships do you feel EJB 2.0 can't adequately
>>> support? I have been studying 2.0 CMP carefully, and it seems to be
>>> quite powerfull. There may be holes in it, but it can handle the
>>> majority of real works cases.
>>>
>>> Jim
>>>
>>>
>>> --On Friday, October 20, 2000 12:28 PM -0700 [EMAIL PROTECTED] wrote:
>>>
>>>> If you don't use an object-relational mapping tool you're still in for a
>>>> lot of hurt with EJB if you have a complex data model. I don't think CMP
>>>> really addresses the kind of data models large systems have. Nor does
>>>> the relationship support in EJB 2.0 either. I think you'll end up doing
>>>> JDBC BMP with your Session and Entity beans. Performance is only an
>>>> issue when you make everything a stateful session bean or an entity
>>>> bean. There are rules for when it's appropriate to make things entity
>>>> beans. There still isn't a whole lot of useful information around on
>>>> design EJBs yet though with most of it only explaining the basics
>>>> including the ORA book.
>>>>
>>>> On Fri, 20 Oct 2000, Duffey, Kevin wrote:
>>>>
>>>>> Thanks.
>>>>>
>>>>> I only meant to use the /classes folder because my ejb code is in the
>>>>> same project as the rest of my code (Servlets, javabeans, action
>>>>> classes, etc). Since it all compiles to the same one folder, I assume I
>>>>> will have to "move" the ejb compiled classes every time I compile them.
>>>>> What I was hoping for was a way to not have to do this..instead, just
>>>>> let the whole project compile to the WEB-INF/classes folder (all my
>>>>> code), and then have Orion pick up on the ejb changes from that point.
>>>>> It appears to me from what everyone is saying I will have to use some
>>>>> sort of script every time I make a change to an ejb, which my first
>>>>> thoughts is a pain in the ass. Its very easy to develop servlets,
>>>>> action classes, javabeans, core classes, but ejb not only requires 3
>>>>> classes per component, but lots of "special" work just to get the thing
>>>>> deployed. Then, every time you make a change, it requires the same
>>>>> process. I would think turn-around time for ejb development is on the
>>>>> order of a couple of minutes for every change you make. That results in
>>>>> a lot slower development cycle than I am currently using.
>>>>>
>>>>> Worse, I have started hearing alot of people turn away from ejb and
>>>>> going back to servlets because of development time, and performance.
>>>>> Supposedly the ejb stuff isn't living up to all the hype. However, I
>>>>> look at what the ejb container does for you (connection pooling,
>>>>> transactions, security, instance pooling, etc) and it seems there is
>>>>> alot of stuff I wont have to do on the side of persistence,
>>>>> transactions and security..so maybe the extra time is worth it? ;)
>>>>>
>>>>> Anyways..I did as one person suggested in this list, I set up in my
>>>>> application.xml like so:
>>>>>
>>>>> <module>
>>>>> <ejb>/path/www/WEB-INF/classes/</ejb>
>>>>> </module>
>>>>>
>>>>> and Orion seems to be finding the classes (the ejb). However, I keep
>>>>> seeing an error appear. It says something like:
>>>>>
>>>>> Error compiling class c:/path/www/WEB-INF/classes/ Login.java
>>>>> LoginBean.java LoginHome.java can't find method create()in
>>>>> LoginBean.java
>>>>>
>>>>> Its a very strange message to me. If I change the <module> path, it
>>>>> tells me it can't find the classes. If I delete the classes, it also
>>>>> tells me it can't find them. So I assume the path is set correctly in
>>>>> the module <ejb> tag..as it is finding the classes. I am just not sure
>>>>> why the heck its giving me some compiler error..or why its even trying
>>>>> to compile them..they are already compiled.
>>>>>
>>>>> Anyways..I'll keep plugging away.
>>>>>
>>>>>
>>>>> > -----Original Message-----
>>>>> > From: Stanislav Maximov [mailto:[EMAIL PROTECTED]]
>>>>> > Sent: Thursday, October 19, 2000 6:34 PM
>>>>> > To: Orion-Interest
>>>>> > Subject: RE: EJB Help..
>>>>> >
>>>>> >
>>>>> > Kevin,
>>>>> > look inside the news-application example bundled with Orion,
>>>>> > lots of things
>>>>> > will become clear for you after that.
>>>>> > <www-dir>/WEB-INF/classes directory is for servlet classes,
>>>>> > not for EJBs.
>>>>> > You'll see how to deploy EJBs in that example and in
>>>>> > documentation as well.
>>>>> >
>>>>> > stas@
>>>>> >
>>>>> > > -----Original Message-----
>>>>> > > From: [EMAIL PROTECTED]
>>>>> > > [mailto:[EMAIL PROTECTED]]On Behalf Of
>>>>> > Duffey, Kevin
>>>>> > > Sent: Friday, October 20, 2000 3:45 AM
>>>>> > > To: Orion-Interest
>>>>> > > Subject: RE: EJB Help..
>>>>> > >
>>>>> > >
>>>>> > > Thanks for the note. One thing..since I compile all of my
>>>>> > classes into the
>>>>> > > www/WEB-INF/classes dir, should I put a META-INF in the
>>>>> > /classes dir, and
>>>>> > > just point the module to the WEB-INF/classes folder? Would
>>>>> > that work?
>>>>> > >
>>>>> > > Not that I want you to tell me everything, ok..I do, but
>>>>> > what exactly do I
>>>>> > > need to get EJB deployed in that way? My first stab that I
>>>>> > want to do is
>>>>> > > create a login process. I would like to use statless session
>>>>> > > beans, and also
>>>>> > > use an entity bean..using CMP. I created 3 classes, Login,
>>>>> > LoginBean and
>>>>> > > LoginHome. I have them in com.mycompany.ejb package. That
>>>>> > compiles to
>>>>> > > www/WEB-INF/classes dir. So do I make application.xml like so:
>>>>> > >
>>>>> > > <module>/www/WEB-INF/classes</module>
>>>>> > >
>>>>> > > where the com folder starts? Or do I actually have to point them
>>>>> > > directly to
>>>>> > > the .class files themselves? If the classes are compiled in
>>>>> > a package, I
>>>>> > > assume I need to point the ejb module setting to the root
>>>>> > package right?
>>>>> > > Furthermore, do I need that ejb.xml file in META-INF? If so, what
>>>>> > > should it
>>>>> > > be set to if I am using an expanded dir? Lastly, how the
>>>>> > heck to I get the
>>>>> > > entity bean added..is that a forth class, or a whole set of
>>>>> > 3 different
>>>>> > > classes, one being the entity bean, the other two being
>>>>> > like the home and
>>>>> > > remote objects? It seems kind of silly that I would need 6
>>>>> > > classes to do the
>>>>> > > login process..3 for the session/logic stuff, and 3 for the
>>>>> > > entity/database
>>>>> > > mapping.
>>>>> > >
>>>>> > > Thanks so much..I appreciate the help.
>>>>> > >
>>>>> > >
>>>>> > > > -----Original Message-----
>>>>> > > > From: Mike Cannon-Brookes [mailto:[EMAIL PROTECTED]]
>>>>> > > > Sent: Thursday, October 19, 2000 3:39 PM
>>>>> > > > To: Orion-Interest
>>>>> > > > Subject: RE: EJB Help..
>>>>> > > >
>>>>> > > >
>>>>> > > > Kevin,
>>>>> > > >
>>>>> > > > With any *ar file in Orion, you can use a directory instead.
>>>>> > > >
>>>>> > > > eg
>>>>> > > > <module>
>>>>> > > > <ejb>./myejbs.jar</ejb>
>>>>> > > > </module>
>>>>> > > >
>>>>> > > > can just be
>>>>> > > >
>>>>> > > > <module>
>>>>> > > > <ejb>./myejbs</ejb>
>>>>> > > > </module>
>>>>> > > >
>>>>> > > > where ./myejbs is a directory structure which has the
>>>>> > same structure
>>>>> > > > (META-INF directories etc) as inside the myejbs.jar
>>>>> > > >
>>>>> > > > Mike
>>>>> > > >
>>>>> > > > -----Original Message-----
>>>>> > > > From: [EMAIL PROTECTED]
>>>>> > > > [mailto:[EMAIL PROTECTED]]On Behalf Of
>>>>> > > > Duffey, Kevin
>>>>> > > > Sent: Friday, October 20, 2000 5:37 AM
>>>>> > > > To: Orion-Interest
>>>>> > > > Subject: EJB Help..
>>>>> > > >
>>>>> > > >
>>>>> > > > Hi all,
>>>>> > > >
>>>>> > > > I am trying my hand at EJB with Orion, and I am wondering if
>>>>> > > > there is any
>>>>> > > > way to avoid the hassle of always having to package the ejb
>>>>> > > > classes into a
>>>>> > > > .jar file, and so on. Is there any way at all to develop and
>>>>> > > > deploy ejbs
>>>>> > > > using an expanded dir structure, much like in the development
>>>>> > > > of a .war
>>>>> > > > file..where you have the whole www dir, WEB-INF, etc
>>>>> > > > expanded..but then jar
>>>>> > > > it up and rename it to .war for deployment? It seems rather
>>>>> > > > tedious on ejb
>>>>> > > > development every time a change is made, the whole thing has to
>>>>> > > > be repackaged and deployed. I know there are some tools, such as
>>>>> > > > JBuilder,
>>>>> > > > VisualCafe, etc that do this for you somewhat nicely..but
>>>>> > > > even those take a
>>>>> > > > little bit of time to do it. So, for the purposes of
>>>>> > > > development, where many
>>>>> > > > changes are happening on any regular basis, how can I quickly
>>>>> > > > develop and
>>>>> > > > test ejb, with Orion, or any app server for that matter.
>>>>> > I do want the
>>>>> > > > ability for the context.lookup() call to work. The reason
>>>>> > > > is..I have two
>>>>> > > > computers, networked. I want to develop the ejbs on one
>>>>> > > > computer, and have
>>>>> > > > my www stuff on the other hitting them over the network so
>>>>> > > > that i can get
>>>>> > > > some kind of feel of the performance. I have a 4-way
>>>>> > switch, so I can
>>>>> > > > develop www stuff, then switch over to the other computer and
>>>>> > > > do some ejb
>>>>> > > > stuff. I will run one instance of Orion on each computer.
>>>>> > > > However, I don't
>>>>> > > > mind also being able to run www and ejb stuff in the same on
>>>>> > > > instance on one
>>>>> > > > computer, as long as the lookup stuff is used the same way,
>>>>> > > > even though the
>>>>> > > > ejb's are running locally.
>>>>> > > >
>>>>> > > > Any pointers on how to set up Orion to do this, including the
>>>>> > > > application.xml <module> tag (how to point it to the right
>>>>> > > > place instead of
>>>>> > > > the ejb.jar file, for example so that the ejbs will get
>>>>> > > > picked up by the
>>>>> > > > server), web.xml, orion-web.xml, server.xml, etc..anything
>>>>> > > > that needs to be
>>>>> > > > done to get this to work.
>>>>> > > >
>>>>> > > > Thanks so much for any help.
>>>>> > > >
>>>>> > > >
>>>>> > >
>>>>> >
>>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>
>
>
>
>
>
>
