Personally I think it is a very good approach to use stateless SessionBeans as a kind
of firewall to the session. You can avoid too much traffic over your networkcable.
However, it makes no sense to me to have such a flexible solution and then not using
all the benefits you can gain.
If you have only session beans (no data persist in here) and you do not have any
underlying concept for persistent storage of your data (EntityBeans) why do you want
to use EJB-Technology? The big improvement for using this technology is that you as
coder write your SessionBeans and EntityBeans the way your design needs it and then
you just deploy them. You do not have to worry about
- will my data be persistent
- where are my data stored
- how are my data stored
- how do I have to access them
This is the strength of Container Based Persistency: You write your beans and let the
container do the rest of the work. Ideally you can also combine several underlying
databases and nobody will know this.
As perfect scenario for EJB-Applications I suggest to have
- one client which is talking to one or more SessionBeans
- one or more SessionBeans coordinating the requests coming from one or more clients.
These session beans are talking to one or more EntityBeans
- one or more EntityBeans are accessed by the logic of the SessionBeans and the client
does not know anything about them. He does not know whether his data are stored in an
ODBMS or RDBMS, he does not know whether his data are stored in one or more
EntityBeans and he does even not know that these EntityBeans are existing.
As a very well running vehicle for this scenario you should try to use Versant's enJin
which gives you all these advantages (and even more) and it works smoothly together
with Weblogic (and also WebSphere).
Viele Gruesse
Stefan Niantschur
Support Engineer, MIS
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-----Ursprungliche Nachricht-----
Von: A mailing list for Enterprise JavaBeans development
[mailto:[EMAIL PROTECTED]] Im Auftrag von Bert Robben
Gesendet am: Mittwoch, 1. Marz 2000 19:44
An: [EMAIL PROTECTED]
Betreff: Re: EJB and ODBMS
> Is someone has already made a design with an appserver and a ODMS?
> In particular, have you use
> * Only Session bean,
> * Some Entity bean
> * what type of ODBMS ?
Yes, we're setting up such an architecture. We want to build collaborative
applications with complex business objects and constraints.
We are planning to use no entity beans and only stateless session beans.
Reasons:
* entity beans constrain us too much (for instance w.r.t. querying, db
clustering, indexing)
* relationships/inheritance is too difficult with entity beans
=> we prefer to use persistent objects as domain objects
* relative benefits w.r.t. OODB are minor (for instance no O/R mapping)
And yes, we do need to write a large amount of support software on top of
EJB before we can write applications (for instance business constraints,
client caching, ...).
I am happy to discuss this in more detail if people are interested.
regards,
Bert
PS: For products, we're considering Weblogic + ObjectStore/Javlin
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