An architecture of Distributed Information System

Q. Short note on : An architecture of Distributed Information System. ( December 2018 ) ( 10 Marks )
Ans -

1. Distributed information systems represent an increasingly important trend to computer users. 
2. Distributed processing is a technique for implementing a single logical set of processing functions across a number of physical devices, so that each performs some part of the total processing required. 
3. Distributed processing is often accompanied by the formation of a distributed database. 
4. A distributed database exists when the data elements stored at multiple locations are interrelated, or if a process (program execution) at one location requires access to data stored at another location. 
5. Examples of how these techniques are being used are provided, with comments on the advantages and disadvantages of the distribution of processing and databases in the current state-of-the-art.

Separation of functionality into three conceptual layers

1.  Presentation

• interacts with client

1. present information
2. accept requests
3. graphical user interface, or module that formats/transforms data, or ...

  2. Application logic

1.   programs that implement the services offered by the IS
2.   often retrieves/modifies data

 3. Resource management

• manages the data sources of the IS

1.  DBMSs
2. file system
3. any "external" systemn