monq.net

Class FilterServiceFactory

java.lang.Object

monq.net.FilterServiceFactory

All Implemented Interfaces:

ServiceFactory

public class FilterServiceFactory
extends java.lang.Object
implements ServiceFactory

sets up a filter service as returned by any ServiceFactory as an element of a distributed pipe. A filter denotes a method thats reads from an InputStream and writes to an OutputStream. A ServiceFactory creates such a filter and is normally used by TcpServer to create a new filter instance for every connection it receives. This class is a filter service which fetches input from another server further upstream. Details can be found in the description of createService().

A typical use involves the following steps:

1. Write a class that implements a Service, i.e. it has a run() method that reads data from an InputStream, possibly manipulates it, and then sends it to an OutputStream. Lets call this class Blorg. Normally it will have a constructor like

   Blorg(InputStream, OutputStream)

2. Create an object of FilterServiceFactory:

   FilterServiceFactory fsf = 
      new FilterServiceFactory(new ServiceFactory() {
        public Service createService(InputStream in, 
                                     OutputStream out) {
          return new Blorg(in, out);
        }
      });

3. Set up the server with a TcpServer:

    int port = 3344;
    new TcpServer(port, fsf).setLogging(System.err).serve();

Author:

© 2004-2016 Harald Kirsch

Constructor Summary

Constructors

Constructor and Description
FilterServiceFactory(ServiceFactory clientFactory) create a filter service factory to connect services created by clientFactory to an upstream server.

Method Summary

Modifier and Type	Method and Description
Service	createService(java.io.InputStream controlIn, java.io.OutputStream filterOut, java.lang.Object param) contacts an upstream server and connects a service to the resulting input and the given output.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FilterServiceFactory

public FilterServiceFactory(ServiceFactory clientFactory)

create a filter service factory to connect services created by clientFactory to an upstream server.

Method Detail

createService

public Service createService(java.io.InputStream controlIn,
                             java.io.OutputStream filterOut,
                             java.lang.Object param)
                      throws ServiceCreateException

contacts an upstream server and connects a service to the resulting input and the given output. The following steps are performed.

1. Read a request from controlIn. The request must originate from a PipelineRequest, i.e. it was typically send with a DistPipeFilter.
2. The upstream server is contacted. As a result there is an input stream available from the upstream server.
3. The client service factory specified in the constructor is called to create a service. It will have its input from the upstream server and its output is filterOut Any key value pairs read from controlIn orgininating from a PipelineRequest object will be passed as a Map to the client service factory.

The resulting service is returned.

Specified by:

createService in interface ServiceFactory

Parameters:

param - is ignored because parameters for the client service factory are read from controlIn.

Throws:

ServiceCreateException - as thrown by the client service factory

ServiceUnavailException - as thrown by the client service factory