First of all I want to clarify that I am not using entity beans to access
database. I
appreciate your understanding about the usage of J2EE pattern. This pattern
is all about
resource independency, that means, after using that pattern, I need not
worry whether my
query is being processed by Oracle, Sybase, XML datastore etc. But I think
that is a separate
issue (resource independency).
Here what I am worried of is, it may mean as many classes (read
implementation classes) as
there are tables and queries. It may become difficult to manage when we
have a large database
and schema. May be I am going to same line where you are. I want to put
that kind of
implementation in native SQL instead of Java classes. That means, there
should be some kind
of common interface which could interact with the query parameter, query
identifier; and just
pass them to corresponding implemention of SQL. The interface should be
single controller to
manage it. I don't know how far is it possible. Any takers............
-ShriKant
"A mailing list for discussion about Sun Microsystem's Java Servlet API
Technology." wrote:
> Well. It all depends on how you access the DB whether thru Entity beans,
> direct Sql drivers etc., As you might know there is a j2ee pattern called
> "Data Access Objects(DAOs)" using which you can do these. It's nothing
but
> kind of using the power of interfaces in Java. For example, you can
declare
> an interface with business methods. Let's say you need to access a user
> table. Then you may have,
>
> public interface DBAccess{
> public void addUser(UserInfo ui) throws SQLException;
> public void deleteUser(String userId)throws SQLException;
> public void modifyUser(UserInfo modifiedUser)throws SQLException;
> public UserInfo getUser(String userId) throws SQLException;
> public void getUsers()throws SQLException;
> }
>
> You can write implementaion classes for this interface depends on the
> Database you use. The code to add/modify/delete data into/from a database
> will reside in a single place(implementation classes) which will lead you
> to a better maintainalbe code.
>
> For example, you may use a RDBMS, ordinary DBMS even flat files. As long
as
> your code talks to an interface, you can plug in the implementations.
>
> For example you use two kinds of DBs in your code. Then,
> DBAccess db = DBAccessFactory.getInstance("Oracle");
> UserInfo ui = db.getUser("shri");
> db.deleteUser("shri");
> db = DBAccessFactory.getInstance("SQLServer");
> db.addUser(ui);
>
> So even if you change the implementation classes, your code still works.
> I don't prefer going for stored procedures and writing methods which
takes
> a Query as an argument. If you want this only, then that is what your
> statement/prepared statements do.
>
> -----Original Message-----
> From: ShriKant Vashishtha [mailto:[EMAIL PROTECTED]]
> Sent: Monday, January 28, 2002 5:37 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Connection in JSPs?
>
> Is there a generic approach/pattern/framework by which we just need to
> specify the query
> parameter and that will give us the respective response. I want to use a
> common interface
> (and put it into a Class) for all the sql ueries for all the JSP which
> should not be
> dependent upon the query parameter and type of query. One possible
solution
> I can think of to
> use the stored procedure for all JDBC related work and pass them the
> necessary parameters
> required and get the response in return. But at present I am not very
sure
> of the pros and
> cons of this strategy. Is there any other possible solution. Please
> enlighten...........
>
> -ShriKant
>
> "A mailing list for discussion about Sun Microsystem's Java Servlet API
> Technology." wrote:
>
> > You can write an utility class kind of thing like ConnectionPool.java
> which
> > has methods like public Connection getFreeConnection() and public void
> > returnConnection(Connection c).
> > Make sure that you don't close the connections in your JSPs after use.
> Let
> > the same utility class close the connections when it decides they are
not
> > necessary.
> > So that you can have the code two aquire a DB connection in one place
> > which will be easier when you might change the server/driver etc in
> future.
> > -----Original Message-----
> > From: Sumit Mishra [mailto:[EMAIL PROTECTED]]
> > Sent: Monday, January 28, 2002 10:31 AM
> > To: [EMAIL PROTECTED]
> > Subject: Connection in JSPs?
> >
> > Hi,
> >
> > What can be the best way of taking connection in a JSP when u have to
> fire
> > a query in almost every JSP? Is the useBean approach ok??
> >
> > Regards,
> > Sumit
>
>
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