Basic Principles Of Jini
Jini's key aim is to create a network which has the advantages of interconnected computers such as the Internet, and the advantages of an individual computer. This results in a system which has the flexibility of a desktop computer, but also allows easy access to and sharing of every other device on the system. To do this, Jini deals with seven different aspects.
1. Services
A Service is the most important aspect of a Jini network. It can represent any entity on the network that offers some function to the rest of the network. This can cover many areas from hardware (e.g. a network printer or central file server) to software (e.g. applications).
For a Service to operate, it needs a software implementation. To do this, we must have a Java program called an Object that can perform the required functions. This Object will also have Attributes which are values that define what it is and what it does.
2. Look-Up Service
This is another key element of the network that works in conjunction with Services. The Look-Up Service is what allows devices on the network to find a service then use it.
A Service can be added to a look-up service by using two protocols: Discovery and Join:
- Discovery allows a Service Provider to find a Look-Up Service.
- Join allows it to take a copy of the Service and store it.
3. Java RMI
RMI stands for Remote Method Invocation. In simple terms, it is a mechanism that allows Java to execute and move code around the network by communicating between two or more devices. An example would be a Java method (code that is written to perform a task) on device 1 calling another Java method on device 2 to do something, then the result of this being passed back to device 1.
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