Basic Principles Of Jini
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4. Security
Security within Jini relies on two aspects: the Principal and an Action Control List.
- The Principal represents whatever entity accessed the system or network, so this is normally the user.
- The Action Control List details the privileges that whatever or whoever may have when making use of a Service. The content of the Action Control List will decide if a Service is allowed to be used.
5. Leasing
Leasing is a mechanism that allows an entity guaranteed access to a Service for a set time period. There are two forms of lease: Exclusive and Non-Exclusive.
- An Exclusive lease means that, while in operation, no other user or entity may use the resource that the lease is for. If a Service were using a backing storage device to write a file, then no other user may use that backing storage device while this is happening.
- A Non-Exclusive lease allows the opposite to happen. A resource is available to everyone at any time. An example would be a networked printer on which anyone can print at all times.
6. Transactions
Many operations will need to access more than one Service at a time to complete a task. A Transaction allows a series of multiple operations to access the required Services to be treated as one entity.
7. Events
When something happens within the network ,this is known as an Event. Objects within the network can register interests in a particular event - they are notified if it occurs. An example of this could be if a printer has been disconnected from the network. All services which rely on this printer could subscribe to this event and be notified of disconnection. They might then remove this printer from the list they offer.
