Uaually, I need to build on top of legacy code. If I had time I would build
a tool to generate the 2.0 entity beans and descriptors from a database
schema, but I don't have time. I have seen these tools for 1.1, so someone
will be doing it.
Currently, my project is to build something brand new.
Jim
--On Saturday, October 21, 2000 8:23 PM -0400 Cory Adams
<[EMAIL PROTECTED]> wrote:
> 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.
>>>>>> > > >
>>>>>> > > >
>>>>>> > >
>>>>>> >
>>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>>
>>
>>
>>
>>
