[raghav]

1. WHAT IS CLONNEABLE INTERFACE IN JAVA.? Is it implemented by the ProtoType Design pattern.?


2. which drivers we are currently using in jdbc. and why.?


3.what are the references availble in java, How they work.?


reply plz..

[sowmya571]

hello







2. which drivers we are currently using in jdbc. and why.?







JDBC is a set of Java API
for executing SQL statements. This API consists of a set of classes and
interfaces to enable programs to write pure Java Database applications.





There are two types of
JDBC Driver Models and they are:


a) Two tier model and


b) Three tier model


Two
tier model:

In this model, Java applications interact directly with the
database.

A JDBC driver is required to communicate with the particular database
management system that is being accessed.


SQL statements are sent to the
database and the results are given to user.


This model is referred to as
client/server configuration where user is the client and the machine that has
the database is called as the server.


Three tier model: A middle tier is
introduced in this model. The functions of this model are:


a) Collection of SQL
statements from the client and handing it over to the database,


b) Receiving
results from database to the client and c) Maintaining control over accessing
and updating of the above.




a) JDBC-ODBC Bridge driver
b) Native API Partly-Java driver c) JDBC-Net Pure Java driver d)
Native-Protocol Pure Java driver

u use these driving depending on ur achitechture and application requirements

[raghav]

Thank you very much sowmya..


one more doubt..plz clarify


In real time scenario which drivers you people are currently using..?


Is there any particular cause..?

[sowmya571]

hello



It dep[ends on the Application requirements ..



If u need a socket then Use last 2 type drivers



else we used JDBC-ODBC bridge driver for our application



bye



sowmya

[saivasu]

in real time applications we use type-4 driver

[sowmya571]

hello



well that can be any one . In polaris we used JDBC-ODBC bridge one ya

donno ab others



can u please specify what are the major advantages and dis advantages



of using driviers depending on performance and stuff SAIVASU



waiting 4 ur reply sir



please do so



bye



sowmya

[sk_kireeti]

Type 4 dirvers are provided by the DB vendor and are customized by the Database vendor. There can be different drivers for different versions of Database. Because of the customization, the in performance wise they are better. And also independent of plaform ( still, vendor specific restrictions are applicable on DB).

Thanks,
Krishna

[sk_kireeti]

Also, we make use of jdbc-odbc driver only when the development and production environments are windows based.

Also jdbc-odbc is a little slower version (but simple in structure). Because we are intruducing a new layer called odbc which keeps us much far from the DB in the application architecture.

Thanks,
Krishna

[sowmya571]

hello



can u please say ab the other drivers performance and where we use them ie i mean which scenarios we use them



bye



sowmya

[saivasu]

Hello,





JDBC Drivers: A comparative Study


To connect with individual databases, JDBC requires drivers for each database. The driver gives out the connection to the database and implements the protocol for transferring the query and result from clint to databse.

• Type 1 Driver: JDBC-ODBC Driver
  
  
  
  • Translates query obtained by JDBC into corresponding ODBC query, which is then handled by the ODBC driver.
    
  • Sun provides a JDBC-ODBC Bridge driver. sun.jdbc.odbc. JdbcOdbcDriver. This driver is native code and not Java, and is closed source.
    
  • Client -> JDBC Driver -> ODBC Driver -> Database
    
  • There is some overhead associated with the translation work to go from JDBC to ODBC.
    
  • Advantages:
    
    
    
    • Almost any database for which ODBC driver is installed, can be accessed.
    [/list]
    • Disadvantages:
      
      
      
      • Performance overhead since the calls have to go through the JDBC overhead bridge to the ODBC driver, then to the native db connectivity interface.
        
      • The ODBC driver needs to be installed on the client machine.
        
      • Considering the client-side software needed, this might not be suitable for applets.
      [/list][/list][/list]
      
      
      • Type 2 Driver: Native-API Driver
        
        
        
        • This type of driver converts JDBC calls into calls to the client API for that database.
          
        • Client -> JDBC Driver -> Vendor Client DB Library -> Database
          
        • Advantage:
          
          
          
          • + Better performance than Type 1 since no jdbc to odbc translation is needed.
          [/list]
          • Disadvantages:
            
            
            
            • The vendor client library needs to be installed on the client machine.
              
            • Cannot be used in internet due the client side software needed.
              
            • Not all databases sgive the client side library.
            [/list][/list][/list]
            
            
            • Type 3 driver: Open Net Protocol Driver
              
              
              
              • Follows a three tier communication approach.
                
              • Can interfere to multiple databases - Not vendor specific.
                
              • The JDBC Client driver written in java, communicates with a middleware-net-server using a databse independent protocol, and then this net server translates this request into database commands for that database.
                
              • Thus the client driver to middleware communication is database independent.
                
              • Client -> JDBC Driver -> Middleware-Net Server -> Any Database
                
              • Advantages:
                
                
                
                • Since the communication between client and the middleware server is database independent, there is no need for the vendor db library on the client machine. Also the client to middlware need'nt be changed for a new database.
                  
                • The Middleware Server (Can be a full fledged J2EE Application server) can provide typical middleware services like caching (connections, query results, and so on), load balancing, logging, auditing etc..
                  
                • eg. for the above include jdbc driver features in Weblogic.
                [/list]
                • Can be used in internet since there is no client side software needed.
                  
                • At client side a single driver can handle any database. (It works provided the middlware supports that database!!)
                  
                • Disadvantages:
                  
                  
                  
                  • Requires database-specific coding to be done in the middle tier.
                    
                  • An extra layer added may result in a time-bottleneck. But typically this is overcome by providing efficient middleware services described above.
                  [/list][/list][/list]
                  
                  
                  • Type 4: Proprietary Net protocol driver
                    
                    
                    
                    • Type 4 drivers are entirely written in Java that communicate directly with vendor's database through socket connection. Here no translation or middleware layer, are required which improves performance.
                      
                    • The driver converts JDBC calls into the vendor-specific database protocol so that client applications can communicate directly with the database server.
                      
                    • Completely implemented in Java to achieve platform independence.
                      
                    • e.g include the widely used Oracle thin driver - oracle.jdbc.driver. OracleDriver which connect to jdbc:oracle:thin URL format.
                      
                    • Client Machine -> Native protocol JDBC Driver -> Database server
                      
                    • Advantages:
                      
                      
                      
                      • These drivers don't translate the requests into db request to ODBC or pass it to client api for the db, nor do they need a middleware layer for request indirection. Thus the performance is considerably improved.
                      [/list]
                      • Disadvantage:
                        
                        
                        
                        • At client side, a separate driver is needed for each database.
                        [/list][/list][/list]
                        Thanks
                        
                        
                        sai vasu.g

[sowmya571]

hello



Thanks u so much sai. Very gud info n clearly put



bye



sowmya

[hariprasad]

HI,

Hoe to call EJB in struts frame work ? what are the ateps for service locator ? where we call to which class ?