reference from：http://www.cs.bgu.ac.il/~spl051/Personal_material/Practical_sessions/Ps_12/ps12.html
- Java server class with multiple client connections: one-to-one ratio of threads to clients, therefore enormous thread overhead, resulted in performance problems and lack of scalability. The main problem is blocking I/O calls.
- JDK 1.4 supports non-blocking I/O calls (java.nio and java.nio.channels). These packages were designed principally according to Reactor design pattern (Using Design Patterns to Develop Reusable Object-Oriented Communication Software by Douglas C. Schmidt).
The actors in Reactor pattern are:
• Handles, which identify resources (such as network connections, open files, and synchronization
objects) that are managed by an operating system.
• Reactor, which defines an interface for registering, removing, and dispatching Event Handler
objects. An implementation of the Reactor interface provides a set of application-independent
event demultiplexing and dispatching mechanisms. These mechanisms dispatch application-specific
Event Handler in response to events occurring on one or more Handles.
• Event Handler, which specifies an interface used by the Reactor to dispatch callback methods
defined by objects that are pre-registered to handle certain types of events (such as input events,
output events, and signals).
• Concrete Event Handler, which implements the customized callback method(s) that process events
in an application-specific manner.
Using Reactor in Communication Software
- Short tutorial
- Important classes in java.nio.channels:
- SocketChannel, ServerSocketChannel
- Selector (Reactor)
- SelectionKey
- java.nio: ByteBuffer
Example
- Reactor
- ConnectionAcceptor (Event Handle)
- ConnectionReader (Event Handle)
- MessageProcessorTask
- SimpleClient
- ThreadPool