Limit datasource/pool to use by EJBs only

In an enterprise application database access is done via entity ejbs. You
normally don't want users to bypass the ejbs and use the datasource or
connection pool directly.
Is there some configuration option to restrict the use of datasources or
connection pools to calls from within the server ?
Thanks for your hints / ideas.
Dirk

Hi Dirk,
You will need to set up corresponding ACLs and users to limit
access to DataSources from cetain callers anly, and then set
up security definitions for EJBs.
The problem is, it's not true that access to DS is limited by EJBs
only. You may what to acces it from let say servlets and jsps while
impelementig fast lane reading, etc...
Regards,
Slava Imeshev
"Dirk Weil" <[email protected]> wrote in message
news:[email protected]..
In an enterprise application database access is done via entity ejbs. You
normally don't want users to bypass the ejbs and use the datasource or
connection pool directly.
Is there some configuration option to restrict the use of datasources or
connection pools to calls from within the server ?
Thanks for your hints / ideas.
Dirk

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we are coming up with a much clearer and simpler to use data-sources story, which, for now, is the following:
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I m not getting connected to oracle 9i database using my ejb...

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Deployment failed:nested exception
resolution:
base exception:
com.evermind.server.rmi.OrionRemoteException
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the code i am using for EJB class is as follows
package Simpapp;
import javax.ejb.*;
import java.sql.*;
import javax.naming.*;
import javax.sql.DataSource;
public class SimpappBean implements SessionBean {
    static final String DATASOURCE = "bajaj";
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    DataSource ds;
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         //sql.setString (1, input);
         ResultSet results = sql.executeQuery (SQL);
         if (results.next () == false) {
          System.out.println ("No rows for "+ input);
              throw new java.rmi.RemoteException ("SQL failure");
         } // if
         String result = results.getString ("username");
         results.close ();
         sql.close ();
         conn.close ();
         if (result == null) {
          System.out.println ("NULL result for "+ input);
              throw new java.rmi.RemoteException ("SQL failure");
         } else
          return (result);
     } catch (SQLException sqle) {
         System.err.println ("While executing SQL: " +
          sqle.getMessage ());
         throw new java.rmi.RemoteException ("SQL failure");
        } catch (Exception e) {
         System.err.println ("Unknown Exception: " +
          e.getMessage ());
         throw new java.rmi.RemoteException ("Bean Exception: " +
          e.getMessage ());
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Context ic = new InitialContext();
DataSource ds (DataSource) ic.lookup("jdbc/OracleDS")
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...to our code.
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The app generates an exception when trying to locate the OracleDS, however.
We have also tried replacing the "com.evermind.sql.DriverManagerDataSource" class with "oracle.jdbc.pool.OracleConnectionCacheImpl" as per another post's recommendation.
It appears that others have had similar problems (prior to 903?), but many have, in fact, (now) got this working successfully -- what are we missing please......?
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Crosstab query using pure SQL only

Hi all,
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Name Date Amount
Alex 2005-06-10 1000
Alex 2005-06-20 1000
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Alex 2005-07-20 1000
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Alex 2005-08-20 1000
John 2005-06-10 2000
John 2005-06-20 2000
John 2005-07-10 2000
John 2005-07-20 2000
John 2005-08-10 2000
John 2005-08-20 2000
And I need to transform it into:
Name 06-2005 07-2005 08-2005
Alex 2000 2000 2000
John 4000 4000 4000
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Thanks!

Hi,
I couldn't resist the intellectual challenge of a pure SQL solution for a pivot table with a dynamic number of columns. As Laurent pointed out, a SQL query can only have a fixed number of columns. You can fake a dynamic number of columns, though, by selecting a single column containing data at fixed positions.
 
 
If it were me, I'd use a PL/SQL solution, but if you must have a pure SQL solution, here is an admittedly gruesome one. It shows the sum of all EMP salaries per department over a date range defined by start and end date parameters (which I've hardcoded for simplicity). Perhaps some of the techniques demonstrated may help you in your situation.
 
 
set echo off
set heading on
set linesize 100
 
select version from v$instance ;
 
set heading off
 
column sort_order noprint
column sal_sums format a80
 
select -- header row
1 as sort_order,
'DEPTNO' as DEPTNO ,
sys_connect_by_path
 ( rpad
 ( to_char(month_column),
 10
 ' | '
 ) as sal_sums
from
 select
 add_months( first_month, level - 1 ) as month_column
 from
 ( select
 date '1981-01-01' as first_month,
 date '1981-03-01' as last_month,
 months_between( date '1981-03-01', date '1981-01-01' ) + 1 total_months
 from dual
 connect by level < total_months + 1
) months
where
connect_by_isleaf = 1
connect by
month_column = add_months( prior month_column, 1 )
start with
month_column = date '1981-01-01'
union all
select -- data rows
2 as sort_order,
deptno,
sys_connect_by_path( sum_sal, ' | ' ) sal_sums
from
select
 dept_months.deptno,
 dept_months.month_column,
 rpad( to_char( nvl( sum( emp.sal ), 0 ) ), 10 ) sum_sal
from
 select
 dept.deptno,
 reporting_months.month_column
 from
 dept,
 ( select
 add_months( first_month, level - 1 ) as month_column
 from
 ( select
 date '1981-01-01' as first_month,
 date '1981-03-01' as last_month,
 months_between( date '1981-03-01', date '1981-01-01' ) + 1 total_months
 from
 dual
 connect by level < total_months + 1
 ) reporting_months
 ) dept_months,
 emp
where
 dept_months.deptno = emp.deptno (+) and
 dept_months.month_column = trunc( emp.hiredate (+), 'MONTH' )
group by
 dept_months.deptno,
 dept_months.month_column
) dept_months_sal
where
month_column = date '1981-03-01'
connect by
deptno = prior deptno and
month_column = add_months( prior month_column, 1 )
start with
month_column = date '1981-01-01'
order by
1, 2
 
VERSION
10.1.0.3.0
 
DEPTNO | 81-01-01 | 81-02-01 | 81-03-01
10 | 0 | 0 | 0
20 | 0 | 0 | 0
30 | 0 | 2850 | 0
40 | 0 | 0 | 0
 
Now, if we substitute '1981-03-01' with '1981-06-01', we see 7 columns instead of 4
 
DEPTNO | 81-01-01 | 81-02-01 | 81-03-01 | 81-04-01 | 81-05-01 | 81-06-01
10 | 0 | 0 | 0 | 0 | 0 | 2450
20 | 0 | 0 | 0 | 2975 | 0 | 0
30 | 0 | 2850 | 0 | 0 | 2850 | 0
40 | 0 | 0 | 0 | 0 | 0 | 0
 To understand the solution, start by running the innermost subquery by itself and then work your way outward.

EJBs only for session facade?

Hi all,
With EJB 2.1 many were saying that it is good to place POJOs behind a session facade of ejbs for a distributed application.
This will allow a developer to test his business logic outside the container.
But with EJB 3.0, all ejbs are pojos, so can i use ejbs for all my business logic?
Is it advisable?
Will this have any performance problem?
Kindly suggest.

Hi,
Thanks for your reply.
I have a distributed application with numerous web clients as well as a few multithreaded application clients accessing the business logic layer.
Definitely there will be a huge load especially if the number of clients increase.
So there will be a lot of distributed transactions.
I have no doubt whether i should use ejbs or not.
I must because the business logic layer must support remote access.
Considering this scenario, should i use ejbs beyond the session facade layer?
I understand that by using ejbs only in the session facade layer is an adavantage as that will not tie my business logic to a framework.
But considering the scope of the application, kindly provide your suggestions.
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James.

Difference between using app server connection pooling and using the driver

Hi all,
How to get connection pooling with out application server and tomcat also?
What is the difference between using app server connection pooling and using the driver supported connection pooling?
Regards,
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Ok, I have deleted EVERYTHING off my 16gb ipad. Photos, music, apps. All I have are the standard apps. It says I have used 11gb and only have 1.6 left. When I first bought it I had up to 4 movies and lots of apps, no problems. What's going on please!?

How much space is used by your Other? You may be able to reduce.
How Do I Get Rid Of The “Other” Data Stored On My iPad Or iPhone?
http://tinyurl.com/85w6xwn
With an iOS device, the “Other” space in iTunes is used to store things like documents, settings, caches, and a few other important items. If you sync lots of documents to apps like GoodReader, DropCopy, or anything else that reads external files, your storage use can skyrocket. With iOS 5/6, you can see exactly which applications are taking up the most space. Just head to Settings > General > Usage, and tap the button labeled Show All Apps. The storage section will show you the app and how much storage space it is taking up. Tap on the app name to get a description of the additional storage space being used by the app’s documents and data. You can remove the storage-hogging application and all of its data directly from this screen, or manually remove the data by opening the app. Some applications, especially those designed by Apple, will allow you to remove stored data by swiping from left to right on the item to reveal a Delete button.
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I'm trying to set up my iPad2. I am entering my Apple ID and get a message that says "try another apple id, this ID is already being used. The only time I've used this Apple ID (my email), is when I bought a mac for my college student.

I'm trying to set up my iPad2. I am entering my Apple ID and get a message that says "try another apple id, this ID is already being used. The only time I've used this Apple ID (my emal) was when I purchased a mac for my college aged child.

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How to create a cache for JPA Entities using an EJB

Hello everybody! I have recently got started with JPA 2.0 (I use eclipseLink) and EJB 3.1 and have a problem to figure out how to best implement a cache for my JPA Entities using an EJB.
In the following I try to describe my problem.. I know it is a bit verbose, but hope somebody will help me.. (I highlighted in bold the core of my problem, in case you want to first decide if you can/want help and in the case spend another couple of minutes to understand the domain)
I have the following JPA Entities:
@Entity Genre{
private String name;
@OneToMany(mappedBy = "genre", cascade={CascadeType.MERGE, CascadeType.PERSIST})
private Collection<Novel> novels;
@Entity
class Novel{
@ManyToOne(cascade={CascadeType.MERGE, CascadeType.PERSIST})
private Genre genre;
private String titleUnique;
@OneToMany(mappedBy="novel", cascade={CascadeType.MERGE, CascadeType.PERSIST})
private Collection<NovelEdition> editions;
@Entity
class NovelEdition{
private String publisherNameUnique;
private String year;
@ManyToOne(optional=false, cascade={CascadeType.PERSIST, CascadeType.MERGE})
private Novel novel;
@ManyToOne(optional=false, cascade={CascadeType.MERGE, CascadeType.PERSIST})
private Catalog appearsInCatalog;
@Entity
class Catalog{
private String name;
@OneToMany(mappedBy = "appearsInCatalog", cascade = {CascadeType.MERGE, CascadeType.PERSIST})
private Collection<NovelEdition> novelsInCatalog;
The idea is to have several Novels, belonging each to a specific Genre, for which can exist more than an edition (different publisher, year, etc). For semplicity a NovelEdition can belong to just one Catalog, being such a Catalog represented by such a text file:
FILE 1:
Catalog: Name Of Catalog 1
"Title of Novel 1", "Genre1 name","Publisher1 Name", 2009
"Title of Novel 2", "Genre1 name","Pulisher2 Name", 2010
FILE 2:
Catalog: Name Of Catalog 2
"Title of Novel 1", "Genre1 name","Publisher2 Name", 2011
"Title of Novel 2", "Genre1 name","Pulisher1 Name", 2011
Each entity has associated a Stateless EJB that acts as a DAO, using a Transaction Scoped EntityManager. For example:
@Stateless
public class NovelDAO extends AbstractDAO<Novel> {
@PersistenceContext(unitName = "XXX")
private EntityManager em;
protected EntityManager getEntityManager() {
return em;
public NovelDAO() {
super(Novel.class);
//NovelDAO Specific methods
I am interested at when the catalog files are parsed and the corresponding entities are built (I usually read a whole batch of Catalogs at a time).
Being the parsing a String-driven procedure, I don't want to repeat actions like novelDAO.getByName("Title of Novel 1") so I would like to use a centralized cache for mappings of type String-Identifier->Entity object.
Currently I use +3 Objects+:
1) The file parser, which does something like:
final CatalogBuilder catalogBuilder = //JNDI Lookup
//for each file:
String catalogName = parseCatalogName(file);
catalogBuilder.setCatalogName(catalogName);
//For each novel edition
String title= parseNovelTitle();
String genre= parseGenre();
catalogBuilder.addNovelEdition(title, genre, publisher, year);
//End foreach
catalogBuilder.build();
2) The CatalogBuilder is a Stateful EJB which uses the Cache and gets re-initialized every time a new Catalog file is parsed and gets "removed" after a catalog is persisted.
@Stateful
public class CatalogBuilder {
@PersistenceContext(unitName = "XXX", type = PersistenceContextType.EXTENDED)
private EntityManager em;
@EJB
private Cache cache;
private Catalog catalog;
@PostConstruct
public void initialize() {
catalog = new Catalog();
catalog.setNovelsInCatalog(new ArrayList<NovelEdition>());
public void addNovelEdition(String title, String genreStr, String publisher, String year){
Genre genre = cache.findGenreCreateIfAbsent(genreStr);//##
Novel novel = cache.findNovelCreateIfAbsent(title, genre);//##
NovelEdition novEd = new NovelEdition();
novEd.setNovel(novel);
//novEd.set publisher year catalog
catalog.getNovelsInCatalog().add();
public void setCatalogName(String name) {
catalog.setName(name);
@Remove
public void build(){
em.merge(catalog);
3) Finally, the problematic bean: Cache. For CatalogBuilder I used an EXTENDED persistence context (which I need as the Parser executes several succesive transactions) together with a Stateful EJB; but in this case I am not really sure what I need. In fact, the cache:
Should stay in memory until the parser is finished with its job, but not longer (should not be a singleton) as the parsing is just a very particular activity which happens rarely.
Should keep all of the entities in context, and should return managed entities form mehtods marked with ##, otherwise the attempt to persist the catalog should fail (duplicated INSERTs)..
Should use the same persistence context as the CatalogBuilder.
What I have now is :
@Stateful
public class Cache {
@PersistenceContext(unitName = "XXX", type = PersistenceContextType.EXTENDED)
private EntityManager em;
@EJB
private sessionbean.GenreDAO genreDAO;
//DAOs for other cached entities
Map<String, Genre> genreName2Object=new TreeMap<String, Genre>();
@PostConstruct
public void initialize(){
for (Genre g: genreDAO.findAll()) {
genreName2Object.put(g.getName(), em.merge(g));
public Genre findGenreCreateIfAbsent(String genreName){
if (genreName2Object.containsKey(genreName){
return genreName2Object.get(genreName);
Genre g = new Genre();
g.setName();
g.setNovels(new ArrayList<Novel>());
genreDAO.persist(t);
genreName2Object.put(t.getIdentifier(), em.merge(t));
return t;
But honestly I couldn't find a solution which satisfies these 3 points at the same time. For example, using another stateful bean with an extended persistence context (PC) would work for the 1st parsed file, but I have no idea what should happen from the 2nd file on.. Indeed, for the 1st file the PC will be created and propagated from CatalogBuilder to Cache, which will then use the same PC. But after build() returns, the PC of CatalogBuilder should (I guess) be removed and re-created during the succesive parsing, although the PC of Cache should stay "alive": shouldn't in this case an exception being thrown? Another problem is what to do when the Cache bean is passivated. Currently I get the exception:
"passivateEJB(), Exception caught ->
java.io.IOException: java.io.IOException
at com.sun.ejb.base.io.IOUtils.serializeObject(IOUtils.java:101)
at com.sun.ejb.containers.util.cache.LruSessionCache.saveStateToStore(LruSessionCache.java:501)"
Hence, I have no Idea how to implement my cache.. Can you please tell me how would you solve the problem?
Many thanks!
Bye

Hi Chris,
thanks for your reply!
I've tried to add the following into persistence.xml (although I've read that eclipseLink uses L2 cache by default..):
<shared-cache-mode>ALL</shared-cache-mode>
Then I replaced the Cache bean with a stateless bean which has methods like
Genre findGenreCreateIfAbsent(String genreName){
Genre genre = genreDAO.findByName(genreName);
if (genre!=null){
return genre;
genre = //Build new genre object
genreDAO.persist(genre);
return genre;
As far as I undestood, the shared cache should automatically store the genre and avoid querying the DB multiple times for the same genre, but unfortunately this is not the case: if I use a FINE logging level, I see really a lot of SELECT queries, which I didn't see with my "home made" Cache...
I am really confused.. :(
Thanks again for helping + bye

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Limit datasource/pool to use by EJBs only

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