Explain Characteristics & components of DDBMS ?

In DDBMS the data and processing functions are distributed among several sites.

A DBMS must have at least the following functions to be classified & distributed.

1. Application Interface : used to interact with the end user application programs & other DBMS with in the DBMS.

2. validation : To analyze data requests for syntax correctness.

3. Transformation : To decompose complex requests in to small data request components.

4. Query optimization : to find best access strategy.

5. Mapping : To determine the data location of local & remote fragments.

6. I/O Interface : To read (or) write data from (or) to permanent local storage.

7.  security : Provide data privacy at both local & remote data base.

8. Backup & recovery : To ensure the availability & recoverability of the data base in case of a failure.

9. Concurrency control : Manage simultaneous data access & to ensure data consistency.

DDBMS also perform :

1. Receive an applications  request.

2. Validate analyze & decompose the request.

3. Map the request logical to physical data components.

4. Search for locate read & validate the data.

5. Ensure data base consistency security.

DDBMS components :

1. computer work stations: ( sites ) ® network system.   DDBMS must be independent of the computer system hardware.

2. Network hard ware & software components : This is present in each work station . The network components allows all sites to internet & exchange data.

Because the components like computers, as network hard ware & so on to be supplied by different vendors so that’s why DDBMS functions can be run on multiple platforms.

3. communication media : This carry the data from one workstation to another. The DDBMS must be communications media independent.

It able to support several types of communication media.

4. Transaction processor (TP): It is a software component found in each computer that requests data.

TP receive & process the applications data requests.

TP also known as application processor (AP) or the Transaction manager(TM).

5. Data processor  (Dp) : It is a software component found in each computer that stores & retrieves data located at the size.

DP also known as data manager (DM).

DTP & TPS can be added to the system without affecting the operation of the other components.