Multiple Database Pooling using Entity Bean

Hi,
Can anyone come across this problem? I have an entity bean (BMP). I want to connect to multiple databases(Oracle, My-SQL, MS-SQL Server). The application is like this. if a request come from the client i have to identify the client request and connect to the database. How to do this. How to connect to get the pool from the connection pooling. Please reply its urgent.
thanks
Prem

Thanks for ur reply.
what the point is i want to identify the client request and send this request to that bean. i have developed 30 cmp beans, if i have to identify i have to change all cmp to bmp, is there any solution to this.

Similar Messages

Database access using Entity Beans

How does it work? In the examples I've seen, there is no SQL statement
being generated, and I no code establishing the JDBC bridge...
What am I missing? How do I look up a record in a database using an
entity bean?
Thanks!!!
-Dan

The Entity Bean remote interface methods access the database.
InitialContext ic=new InitialContext();
EntityBHome eh = (EntityBHome)ic.lookup("com.ejb.EntityBHome");
EntityB entityB=eh.findByPrimaryKey(primarykey pk);
[email protected] (Dan M) wrote:
How does it work? In the examples I've seen, there is no SQL statement
being generated, and I no code establishing the JDBC bridge...
What am I missing? How do I look up a record in a database using an
entity bean?
Thanks!!!
-Dan

Insert data into table from JSP page using Entity Beans(EJB 3.0)

I want to insert data into a database table from JSP page using Entity Beans(EJB 3.0).
1. I have a table 'FRIENDS', (in Oracle 10g database).
2. It has two columns, 'NAME' and 'CITY'. Both have datatype strings(varchar2).
3. Now from a JSP page, having two textfields, 'NAME' and 'CITY', I want to insert data into table 'FRIENDS'.
4. In between JSP and database is a Entity Bean(EJB 3.0) and a stateless session bean.
5. I am using JDev as editor.
Please provide me code ASAP or link with similar example.
Thank you.
Anurag

Hi,
I am also trying that scenario. So u can
Post the jsp form data to a Servlet which will act as a Controller.
In the servlet invoke the business method.
Similar kind of app is in www.roseindia.net
Hope this would help u.
Meanwhile if u get any optimal solution, pls post it.
Thanks,
Happy Java Coding.

Data Warehouse report query using Entity Beans

I have used the EJB technology on one project, so I am not all that familiar with
best practices.
In my new project, I have to produce reports using a query that goes against a
dimensional database. I am wondering what options I have to run the query and
extract the results given that the application will run on WebLogic.
1) Straight JDBC
2) BMP
3) CMP (could be a problem because the quety is a join query, but I am not sure
if WebLogic requires that the query is against a table rather than a view)
The query is read-only. I am more interested in ease of coding and code management
rather than application performance at this point because I think the query will
spend a relatively large time executing on the Oracle database.
I would like to hear the best practices to be employed in this case. Thanks very
much!
Ravi.

Don't use entity beans for this. Straight JDBC is not perfect either, but it
is preferable to entity beans for this type of work.
Peace,
Cameron Purdy
Tangosol, Inc.
Clustering Weblogic? You're either using Coherence, or you should be!
Download a Tangosol Coherence eval today at http://www.tangosol.com/
"Ravi Navanee" <[email protected]> wrote in message
news:3c92693d$[email protected]..
>
I have used the EJB technology on one project, so I am not all thatfamiliar with
best practices.
In my new project, I have to produce reports using a query that goesagainst a
dimensional database. I am wondering what options I have to run the queryand
extract the results given that the application will run on WebLogic.
1) Straight JDBC
2) BMP
3) CMP (could be a problem because the quety is a join query, but I am notsure
if WebLogic requires that the query is against a table rather than a view)
The query is read-only. I am more interested in ease of coding and codemanagement
rather than application performance at this point because I think thequery will
spend a relatively large time executing on the Oracle database.
I would like to hear the best practices to be employed in this case.Thanks very
much!
Ravi.

Disadvantages of using entity beans.

can I know the disadvantages of using entity beans.

sigh I guess if someone puts it on a website it must be true...
"Forces the use of a heavy component mechanism for fine grained business objects."
Heaviness is not some arbitrary side-effect. It is directly due to the services provided by the EntityBeans (transactions, etc). If you need those services, you pay the price. If you don't then you shouldn't be using EJB to begin with. Also with the advent of LocalInterfaces, fine-grainedness is no longer a liability.
"More complex than JDO limiting developer productivity."
Perhaps it has less to do with limited productivity, and more to do with limited developers.
"More difficult to achieve good performance."
Compared to a simple data storage mechanism, sure.
"Inheritance not supported."
Really? Wow, I guess all the EJB code I've written for the last 3 years doesn't really work.
"Cannot be used for persistence in non-application server environments."
Uhh, yeah, but seeing as how the decision to use EJBs is not limited to the persistance scheme, the non-use of an application server is moot.
"There is no dynamic query mechanism to lookup entity beans (finders are specified at compile time)."
And what compiled business process (i.e SessionBeans) requires dynamic lookup of arbitrary data? Humans performing search functions can be done via entity beans, but probably should not be done since a large searches do not (or very rarely) need to be transactional.
"It is not easy to write unit tests for beans as it is not possible to use them outside of the application server."
For a long time this was true, but there are now many unit test suites designed for J2EE.
"No support for automatic primary key generation."
In the spec, no. But it's fairly trivial to implement on your own.
"Only relational databases are supported."
If you use CMP, yes. If you use BMP, you can do whatever you want inside your ejbLoad()/ejbStore() methods. Another reason to not use CMP.

Pooling of Entity beans

Hi,
How is pooling of entity beans supported in Weblogic? If a value is provided for
max_beans_in_free_pool, then the Weblogic server creates a particular number of
entity bean instances in the pool? What's the role of max-beans-in-cache?
Regards,
Indhu

Thanks Seth for your info
Indhu
Seth White <[email protected]> wrote:
>
The docs are incorrect. You may configure a pool for your entity beans.
Seth
indhu wrote:
Hi Ryan,
Thanks for your reply.
In the entity-descriptor element of weblogic-ejb-jar.xml, pool elementis there,
which consists of max-beans-in-free-pool and initial-beans-in-free-pool.The document
says that the pool element configures the behavior of the WebLogicServer free
pool for stateless session and message driven EJBs.It means that wecan't use
those elements to set free pool for entity beans?
Regards,
Indhu
"Ryan LeCompte" <[email protected]> wrote:
Hello Indhu,
Refer to the following links for answers to your questions:
http://edocs.bea.com/wls/docs70/ejb/EJB_environment.html#1135029
http://edocs.bea.com/wls/docs70/ejb/reference.html#1071069
http://edocs.bea.com/wls/docs70/ejb/reference.html#1071125
Best regards,
Ryan LeCompte
[email protected]
http://www.louisiana.edu/~rml7669
"indhu" <[email protected]> wrote:
Hi,
How is pooling of entity beans supported in Weblogic? If a value
is
provided
for
max_beans_in_free_pool, then the Weblogic server creates a particular
number of
entity bean instances in the pool? What's the role of max-beans-in-cache?
Regards,
Indhu

How to handle multiple tables data in Entity Beans?

How to handle multiple tables data in Entity Beans?
i mean, my bean (non trivial) is responsible for frequent
insertion in one table and some deletion on another table.
Can anyone of you...please..?

Is your data model right? If you are adding in one and deleting in another it sounds to me more like a process that an entity, in which case you may revisit your data model and simplify it, add in a session bean with the process method to co-ordinate between the two.
However, if you want to map multiple different tables within a single entity bean it is possible and just part of the mapping. How you actualyl specify it depends on which implementation you are working with.
Cheers,
Peter.

Can anyone describe using entity beans for persitance in Software Architect

Can anyone describe using entity beans for persitance in Software Architecture you built for a product?

Although this forum is supposed to help you gain knowledge on entity beans, its not a free rider that's supposed regurgitate everyone's knowledge to you.
Read something first and then clarify your thoughts with this forum.

Mapping of an entity EJB to multiple database tables using CMP?

Can one entity EJB have attributes split between (mapped to) multiple databse tables?
Would CMR work properly between two such entity EJBs (both mapped to multiple database
tables).

Hi Milos.
Can one entity EJB have attributes split between (mapped to) >>multiple databasetables?
A CMP Entity should be always mapped a record in a single DB table.
Thanks.
Ji Zhang
Developer Relations Engineer
BEA Support

To use Entity Bean or Oracle stored Package?

Currently, in my project, Weblogic8.1 and Oracle is used, but lots of business logic is implemented using Oracle stored Packages, many of these packages have a package level readonly lookup table(like index-by table or nested table), which is populated with data from database, once the package is called, and is accessed very often in subsequent calls of stored procedures.
Since, in Weblogic server, a connection pool is maintained, and those package level lookup tables would be stored as session data in oracle PGA, I'm afraid this might cause oracle database server to be overloaded.
to fully take advantage of middleware cache service that weblogic provide, should I move those business logic out of oracle and implement them using like read only entity bean?
any help appreciated!

Its very hard to say without knowing the usage patterns of the data. It sounds like you have a lot of read-only entities. These could be spread around a WLS cluster, therefore there is more scalability and performance with this option. However, I would not neccessarily rewrite business logic from SP into EJB just for middle-tier caching.
If its a DB intensive app with lots of SQL, then if the calls are within SP's, there is only 1 call from WLS and the DBA ought o be able to tune the DB usin read-ahead and other DBA semantics. If there is locality of reference in the data, again, DB can use read-ahead better than WLS, although RO cache in middle is more scalable than DBMS.
I wouldnt rewrite business logic from SP to EJB/Entity beans to take advantage of cache, especially if there is no locality of read-only reference to data. Oracle could do this better in my opinion, especially if SP's already exist
Need for information on the usage patterns of the data - how is it CRUD'd.
I would use-case the steel threads and put them under test load to see if the SP's really are an issue, since this is an architecture decision. What state is the project at? Live/Dev? Inception?

Multiple create methods of entity beans in single transcation

Hi,
I have some entity beans with CMR. I am managing these entity beans with a Stateful session bean whose transaction type is Container Managed for all its methods.
In one particular method of this Session bean I am calling two entity bean's create method. i.e I am creating two entity beans through home.create() methods. There are two home.create() methods one after another inside a try catch block.
I want that the entire operation be under just one transcation so i have also given the transaction attribute as Required for all methods of Session bean and Entity Beans.
However if i pass invalid parameters to second create method so that it generates exception then still the first create statement is successful and database is updated.
what i want is that the first create also should be roll backed.
How can i acheive this through Container Managed Transaction Session Bean?

Hi Ashwini,
"Ashwini" <[email protected]> wrote in message news:400291af$[email protected]..
I have some entity beans with CMR. I am managing these entity beans with a Stateful session bean whose transactiontype is Container Managed for all its methods.
>
In one particular method of this Session bean I am calling two entity bean's create method. i.e I am creatingtwo entity beans through home.create() methods. There are two home.create() methods one after another inside a try catch
block.
>
I want that the entire operation be under just one transcation so i have also given the transaction attribute asRequired for all methods of Session bean and Entity Beans.
>
However if i pass invalid parameters to second create method so that it generates exception then still the firstcreate statement is successful and database is updated.
what i want is that the first create also should be roll backed.
How can i acheive this through Container Managed Transaction Session Bean?o Do you use TXDatasource with your entity beans?
o In CMT transactions are automatically rolled back only when RuntimeExceptions
are thrown. What kind of exception is thrown in your case?
Regards,
Slava Imeshev

Multiple database users, ORM, entity framework, best practices

Hello everyone!
You've already helped me several times, however I must ask for an advice once more.
I was assigned to develop .NET application with Data Access Layer and I've decided to use Oracle Database Software to provide sample data.
As I'm absolute novice considering creating DAL I'd be grateful if you can examine my plan in terms of security and reliability:
My database:
1) I've created database with sample tables and relations between them. All tables belongs to databaseAdmin.
2) I've created HR and Manager database users and granted them some privileges on certain databaseAdmin's tables. My intention is to reduce access to unnecessary tables. If my application user want to make some changes to Customers table it should be enough to connect to database as HR.
And now I'd like to map my database using Entity Framework in my application. And that's where I have a problem:
-If I create Entity Model basing on databaseAdmin tables I get perfect model, however every Entity SQL query would be executed on behalf of databaseAdmin, which breaks my idea of hiding unnecessary tables.
-If I create Entity Model for HR and Manager users, my models could overlap on tables that both users have access to and no connection between tables would be generated (as from their point of view those tables are just some tables that belong to databaseAdmin)
Could you help me with this deadlock? Or maybe my assumptions about multiple database users are incorrect? Please, bear in mind I'm a novice.
I was trying to find a solution in web, and there're tons of data discussing technical aspects of Entity Framework etc., but not so many documents about conceptual model of database.

hi Michael,
Thanks for you posting!
Sorry for I am not totally understanding your issue. Maybe two points need your confirm:
1. I confuse with the "Service controller"? IS your meaning MVC controller? Or ServiceController(http://www.codeproject.com/Articles/31688/Using-the-ServiceController-in-C-to-stop-and-start
2.whether The type of ID in the model is match to the database ? In other words, Is the type of IDin .edmx matched to the database?
By the way, it seems that this issue is more related to EF. You could post this issue on EF discussion for better support.
Thanks & Regards,
Will
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Problems accessing tables in oracle database with ejb entity bean

I have created a simple server application that uses an entity bean (version 2.0) for an existing table in oracle database, and a session bean that is used as an outside interface for performing operations on that table.
after deploying the server and client application the client attempts to perform an operation with the session bean remote interface it obtained.
The session bean uses a locale interface to communicate with the entity bean, but when it tries to use its methods (create, findByXXX) it always get the following Exception: java.sql.SQLException: ORA-00942: table or view does not exist.
the table of course exists, and the username password I'm using has all the permissions needed for this table.
note - I'm using the Forte enterprise edition 4.0 as developer tool.
I'll be glad to get some help.
Here is the full stack trace of the exception:
javax.ejb.TransactionRolledbackLocalException: Exception thrown from bean; nested exception is: javax.ejb.EJBException: nested exception is: java.sql.SQLException: ORA-00942: table or view does not exist
javax.ejb.EJBException: nested exception is: java.sql.SQLException: ORA-00942: table or view does not exist
java.sql.SQLException: ORA-00942: table or view does not exist
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:168)
at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:208)
at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:543)
at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1405)
at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteDescribe(TTC7Protocol.java:643)
at oracle.jdbc.driver.OracleStatement.doExecuteQuery(OracleStatement.java:1674)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1870)
at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:363)
at oracle.jdbc.driver.OraclePreparedStatement.executeQuery(OraclePreparedStatement.java:314)
at com.sun.ejb.persistence.SQLEngine.ejb20Finder(SQLEngine.java:226)
at com.sun.ejb.persistence.PartitionImpl.ejbFinder(PartitionImpl.java:736)
at com.cti2.telco.core.ejb.entity.userInfo.UserInfoEJB_PM.ejbFindByEmail(UserInfoEJB_PM.java:393)
at com.cti2.telco.core.ejb.entity.userInfo.UserInfoEJB_PM_LocalHomeImpl.findByEmail(UserInfoEJB_PM_LocalHomeImpl.java:64)
at com.cti2.telco.core.ejb.UserManagerEJB.authenticate(UserManagerEJB.java:77)
at com.cti2.telco.core.ejb.UserManagerEJB.authenticate(UserManagerEJB.java:68)
at com.cti2.telco.core.ejb.UserManagerEJB_EJBLocalObjectImpl.authenticate(UserManagerEJB_EJB
LocalObjectImpl.java:63)
at com.cti2.telco.core.ejb.dispatch.TelcoFacadeEJB.userLogin(TelcoFacadeEJB.java:80)
at com.cti2.telco.core.ejb.dispatch.TelcoFacadeEJB_EJBObjectImpl.userLogin(TelcoFacadeEJB_EJBObjectImpl.java:24)
at com.cti2.telco.core.ejb.dispatch._TelcoFacadeEJB_EJBObjectImpl_Tie._invoke(Unknown Source)
at com.sun.corba.ee.internal.POA.GenericPOAServerSC.dispatchToServant(GenericPOAServerSC.java:519)
at com.sun.corba.ee.internal.POA.GenericPOAServerSC.internalDispatch(GenericPOAServerSC.java:204)
at com.sun.corba.ee.internal.POA.GenericPOAServerSC.dispatch(GenericPOAServerSC.java:112)
at com.sun.corba.ee.internal.iiop.ORB.process(ORB.java:273)
at com.sun.corba.ee.internal.iiop.RequestProcessor.process(RequestProcessor.java:84)
at com.sun.corba.ee.internal.orbutil.ThreadPool$PooledThread.run(ThreadPool.java:99)
...

Well it seems like the problems has a simple explanation. The Forte assigns a default table name (<entityName>EJBTable) when creating an entity bean from an existsing table in DB (which is not the same as the one it was created from !!!). Also, for reason unknown, when you deploy these entity beans, it doesn't even create the new table under its new name (even if instructed to).
So using the Forte we managed to use successfuly only entity beans that were created "from scretch" (when deployed their tables are created).
Does anyone know how to change the default name the Forte uses, and make it work properly with entity beans created from an existsing table (without going over the xml's) ?

Seeding multiple databases with single Entity Framework context

I am developing a single-instance, multi-tenant web application, with a SQL database using Entity Framework 6 Code-First.
I want to have a separate database for each client, generated from the same EF models, with a single DbContext. The database to connect to will be determined by the subdomain that the client is using the web app from.
This seems to work fine and the correct database is connected to depending on the subdomain. However my issue is seeding the databases with data. This is the code I have:
foreach (var connString in ConfigurationManager.ConnectionStrings.Cast<ConnectionStringSettings>()))
Configuration.PerformDatabaseMigration(connString.Name);
This then calls the PerformDatabaseMigration method:
public class Configuration : DbMigrationsConfiguration<DataContext>
public Configuration()
AutomaticMigrationsEnabled = false;
AutomaticMigrationDataLossAllowed = false;
public static void PerformDatabaseMigration(string connStringName)
var databaseInitialiser = new Configuration { TargetDatabase = new DbConnectionInfo(connStringName) };
var dbMigrator = new DbMigrator(databaseInitialiser);
dbMigrator.Update();
protected override void Seed(DataContext context)
base.Seed(context);
var superAdmin = new User { Id = 1, UserName = "SuperAdmin" };
context.Users.AddOrUpdate(superAdmin);
The issue is that when seeding this data for the second database, the context passed into the Seed method already has the admin user added to the `DbSet<User>` property of the context, even though the context is for the second databse connection, not
the first. It appears that the context is not being cleared from seeding the first database, and so I receive a `DbUpdateException`, as my User.Username field is a unique index.
Cannot insert duplicate key row in object 'dbo.Users' with unique index 'IX_UserName'. The duplicate key value is (SuperAdmin).\r\nThe statement has been terminated.
public class User : ModelBase, IUserIdentity, IPrincipal, IIdentity
[Index(IsUnique = true)]
[Required]
[StringLength(40)]
public string UserName { get; set; }

Hello Attune,
>>This seems to work fine and the correct database is connected to depending on the subdomain. However my issue is seeding the databases with data.
Is that you firstly create these databases and then call the PerformDatabaseMigration method to seed these database with data? Do you have a try to seed these database data when creating the database with AutomaticMigrationsEnabled = true; with your provided
configuration class, I tested it and it could work as seeding same data to different database:
internal sealed class Configuration : DbMigrationsConfiguration<CFs.CFContext>
public Configuration()
AutomaticMigrationsEnabled = true;
public static void PerformDatabaseMigration(string connStringName)
var databaseInitialiser = new Configuration { TargetDatabase = new DbConnectionInfo(connStringName) };
var dbMigrator = new DbMigrator(databaseInitialiser);
dbMigrator.Update();
protected override void Seed(CFs.CFContext context)
base.Seed(context);
var superAdmin = new ApplicationUser() { ApplicationUserID = 1, FirstName = "", LastName = "" };
context.ApplicationUsers.AddOrUpdate(superAdmin);
Regards.
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How can i execute multiple database operations using multiple objects

i have data in files which i need to read/parse and insert/update the database. can someone tell me how can i read multiple statements at a time and process using multiple objects.

This doesn't seem like too much of a JDBC question or at least the answer as I see it isn't unique or specific to JDBC.
If you want to run multiple processes within your single program then you need to use Java threads. I would recommend you read up on how to properly code Java threads and if you have questions unique to your multi-threaded JDBC implementation come back and ask those questions.
You may also want tot take advantage of a transaction manager that includes a database connection pool that will handle most of the complexity for you. Depending on the flexibility of your architecture you may not have to do any thread coding at all when using a transaction manager.

Multiple Database Pooling using Entity Bean

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