Thursday, August 11, 2011

Centralized and Distributed Database

Distributed and Centralized Databases
Distributed data is defined as collection of logically distributed database which are connected with each other through a network. A distributed database management system is used for managing distributed database. Each side has its own database and operating system.

A centralized database has all its data on one place. As it is totally different from distributed database which has data on different places. In centralized database as all the data reside on one place so problem of bottle-neck can occur, and data availability is not efficient as in distributed database. Let me define some advantages of distributed database, it will clear the difference between centralized and distributed database.

Users can issue commands from any location to access data and it does not affect the working of database. Distributed database allows us to store one copy of data at different locations. Its advantage is that if a user wants to access data then the nearest site (location) will provide data so it takes less time.

There are multiple sites (computers) in a distributed database so if one site fails then system will not be useless, because other sites can do their job because as I earlier said that same copy of data is installed on every location. You will not find this thing in centralized database.

Any time new nodes (computers) can be added to the network without any difficulty.
Users do not know about the physical storage of data and it is known as distribution transparency, as we know that ideally, a DBMS must not show the details of where each file is stored or we can say that a DBMS should be distribution transparent.

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Wednesday, August 10, 2011

Software Process in Software Engineering

Process : Process is the set of sequences that include
  • Activities
  • Constraint
  • Process
     That produces the intended result. 
  • Process are composed of sub processes
  • Process have entry and exit criteria.
Software Process :
                            Software process encompasses of set of activities and process that evolved or developed the software systems.
Process
1)Process Management Processes
2)Project Development Process

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