Friday, 16 July 2010

ODBC (OPEN DATA BASE CONNECTIVITY)

What is ODBC?
ANS: it is a standard abstraction for applications accessing the tabular datastores.
Who introduced and maintain ODBC?
Ans:
·         The ODBC standards (specifications) is introduced and maintained by ODBC COMMUNITY.
·         THE ODBC community is formed by Microsoft collaboration with all the major  db vendors includes Oracle and IBM.
·         The single agenda of this standard is to provide a unified abstraction for accessing the tabular datastores/database servers)

Fig: Option-3.jpg
The ODBC includes 2 (two) parts:
1.       ODBC API: This provides a standard abstraction for accessing the ODBC Driver
2.       ODBC Drivers: this implements the ODBC (Services i.e: communicating with DB Server)
The ODBC Driver is implemented by 3rd party vendors i.e: any vendor.
·          
Note: The ODBC API is provided in C –Language.
Problems with this Approach:
1.       The availability of ODBC is very less out of the windows environment.
2.       Because of no frequent updations to the specifications to in the recent years; many new and Database specific features are not represented by the ODBC API.
Because of these reasons we still find the existence of Database Native Drivers in the market.
About Option-3:
Fig: option-3.jpg

·         This option makes the system database independent, howeer this also requires to implement native methods.
·         After working into these 3 options we find that we need a specialized support for java applications accessing the database servers; which is introduced in the form of JDBC



JDBC


Fig: JDBC1-JPG
From the above Fig: JDBC1-JPG architecture we understand the JDBC consist of two important elements:
1.       JDBC Driver: is a well defined set of objects implementing the JDBC services.
·         This is provided by 3rd party vendors, following the JDBC specification standards.
2.       JDBC API: is a standards (unified) abstraction (interface) to program java applications accessing the JDBC Services.
Note:
1.       The JDBC specification is from Java Community Process (JCP).
2.       THE JCP has never described JDBC as Java Database Connectivity, it is just some authors started referred it such.



UNDERSTANDING THE JDBC Driver:

·         As said the JDBC Driver is responsible to communicate with database server.
·         To do this JDBC Driver follows any of the 4 approaches, based on which we categorize JDBC Driver into the following 4 types:
1.       Type -1
2.       Type -2
3.       Type -3
4.       Type -4
Note:
At present we have 300+ registered JDBC drivers from different vendor accessing different databases. These 300+ are categorized into 4 types.

·         JDBC is an abstraction, and java application uses this JDBC.

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