[JBoss Seam] - Application Context availability
by harpritt
Hiya gents and ladies.... (i wish there were more female programmers)
My Seam app is coming along really really well... im extreamly chuffed with it.... i actually feel a bit guilty for having had so much fun using SEAM.....
anyway, im writting a servet that gets initialized durring application start to act as a global notifier of resource availability.
what i want it to do is simply check a resource e.g. my cvs server and it to add a parameter to the application context indicating its status.
i can then check the application context from anywhere in my app for resource status.
im having a shed load of trouble trying to get a hold of the Application context
public void init(ServletConfig config) throws ServletException {
|
| // Add parameter to Application context ... ARGGHHH!
|
| }
.. ive got myself very confused... to the point where i cant even remember what the difference between the application scope and context are... google aint helping....
Anyway .... all help as allways is greatly apprieciated.
H
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18Â years, 9Â months
[JBoss Seam] - multiple data sources
by gstacey
A new project I am working on requires multiple data sources and switching between them programmatically. These data sources contain the same entites, but different data. I set up some of the basics of the project with one datasource and a managed persistence context and it works great, but I'm having trouble with the multiple sources part. I've done a bit of searching through docs and forums, but I haven't found any answers so far.
My questions:
1) Do I need to declare a persistence unit in my persistence.xml for each of these data sources?
In the long run I'd like to be able to add a new datasource without having to redeploy the application, so it would be nice to avoid this.
2) How can i programmatically set a managed persistence context in a bean?
The persistence:managed-persistence-context component seems tied to a specific persistence unit via the factory jndi name in the persistence.xml. I couldn't do simple injection then because I would be tied to that unit right? I tried passing in an EntityManager instead of injecting it and I could retrieve data but I got 'no active transaction' errors when I actually tried to do anything, so it seems the conversation piece wasn't working.
I'm looking into overriding EntityManagerFactory to possibly create the correct Entitymanager on login (when the source is chosen) and put it into the session at that point. Does this seem like a viable approach?
Any help appreciated.
Thanks,
Greg
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18Â years, 9Â months
[JBoss Seam] - Some thoughts about abstracting everything from everything
by oleg_p
Hello,
For the last 3-4 months I've been picking JBoss Seam as the framework for my Java EE projects,
before this I was using some plain EJB3 + JPA approaches.
The overall stack of technologies looks like this (from Presentation Tier downto Resource Tier):
RichFaces
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Facelets
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JSF
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EJB3
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JPA
....with Seam being present somewhere throughout all these technologies.
Everything seems to be cool - the need for introducing some "glueing" components such as DAOs, DTOs, Service Locators etc.
seems to evaporate and all layers seem to cooperate pretty much well. BUT....
I really need (have) to keep a certain level of independence and loose coupling among the technologies used throughout the application tiers.
To my opinion the main issue with JBoss Seam seems to be the following:
The common practices assume the presence of Seam-specific annotations and JPA invocations in Session Beans,
which are being later called by JSF
Considering that Session Beans contain almost all the business logic of our application (for the case of Seam application),
this means that this business logic is coupled with both Seam by using at least its context management services
(e.g. @In @Out annotations for injecting/outjecting Seam components) and JPA by calling EntityManager methods directly
inside the methods of Session Beans
What I really need (have to) is the following:
Independence from the technologies in Persistence Layer (EIS Integration Tier):
My "data feeders" can be anything the human mind can imagine: RDBMS, XML Database, Plain Files, Legacy Systems via Proprietary Protocols etc.
Independence from Seam in my CORE business logic.
At the same time - keeping all the infrastructural services provided by Seam and EJB3
>From my side I can suggest the following solution to this architectural problem:
To keep Session Bean sublayer dependent on Seam - there is no other way out,
I will call this sublayer "Seam Business Logic Integration Layer".
It's main purpose will be to integrate Business Logic Tier with Seam and EJB3 infrastructural services.
To move the core business logic into POJI/POJO implementations,
which will not use Seam/EJB3 annotations or other services + they will also not use JPA invocations.
Considering that we will not use @Name annotation for these POJOs and
that we will still need to inject them into Session EJBs, all these POJOs will be configured in components.xml as Seam components.
To introduce something called "Domain Model Facade" - abstraction from the underlying persistence technologies.
This facade will be presented as POJI for the core business logic (implemented as POJOs) and will provide
the basic methods related to data access operations (e.g. save, load, find etc.).
The underlying implementations will provide JPA, XML or JCA versions according to the configurations.
I will call this sublayer "Seam Domain Model Integration Layer".
Domain Model itself will be exposed to the core business logic as POJI/POJO combinations.
While at the same time - these classes can be configured in components.xml as Seam components
for enabling the context management services provided by Seam + referencing them in JSF pages.
What I really want to ask is the following:
Will this work?
For the case if it will work - maybe there are some existing and better approaches to this issue?
For example: something with Spring integration into all this mess for enabling the loose coupling between layers?
Or maybe it will introduce some much bigger mess...
Thanks in advance,
Oleg
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18Â years, 9Â months