Distributed Heterogeneous Applications and CORBA

Distributed Heterogeneous Applications and CORBA

Heterogeneity in DS

- Heterogeneous computing refers to systems which use more than one kind of processor or cores.
- Because of dissimilar coprocessor, such system gain performance or energy efficiency.
- Distributed system contains different kinds of hardware and software working together co-operatively to solve problems.
- Distributed applications are heterogeneous in terms of:
a) software = UNIX, Window, Real time OS
b) hardware = PC, Server, Workstation, Mainframe
c) unconventional devices = Teller machine, Telephone switch, Robots
d) Diverse network = Ethernet, FDDI, ATM
- Different users which have to interact with the applications decide for different hardware and software solutions.
- The integration of heterogeneous components implies construction of distributed system.
- Communication for heterogeneity support should be resolved.

Middleware

Role of middleware in Distributed System

- Middleware is a software that provides services which are not provided by the OS to enable various components of distributed system to communicate and manage data.
- The major role of middleware is to handle communication between components of the system, without making any assumptions of the contents if the receiver could understand the contents.
- Middleware is also responsible for load management such as starting and stopping services and managing loads directed to them.
- It also provides other services such as authentication and authorization, audit and logging.
- It provides interoperability between applications that run on different operating system.

Objects in Distributed System

- A distributed system is a collection of objects like UI, database, etc.
- Each object has its own attributes and methods which define its behavior.
- Object Request Broker (ORB) allows objects to find each other and interacts between them over the network.

Interface Definition Language

- An interface specifies the API used by the clients to invoke operations on objects.
- Each object can have one or more interfaces.
- Interfaces are defined with the help of Interface Definition Language (IDL).
- Middleware supports parsing of IDL of an interface with the help of interface compiler.
- IDL only specify declaratives, not the executable codes.
- IDL should be independent of the implementation language.