Package org.catnets.p2pagent.apiSamples.Echoes

Echoes Sample Application

See:
Description

Class Summary

EchoClient	This class implements a simple requestor that executes a serie of request to a EchoServer and registers the time to completation of each request, computing an average at the end of this serie.
EchoesMainApp	Main application that initiates the EchoServer and EchoServer agents passing the appropiate parameters.
EchoServer	Receives a message and replies to the originator with the same message, after waiting for a random time, wich simulates the server's response time.

Package org.catnets.p2pagent.apiSamples.Echoes Description

Echoes Sample Application

Author: Pablo Chacin

Version. 1.0

Created: Feb 23, 2006

(c) Technical University of Catalonya 2006

Overview

This sample application presents a simple, yet very complete example of the main functionalities provided by the P2pAgents API, a fundamental part of the Grid Market Middleware.

The application shows two agents, EchoesServer and EchoesClient, which engage in a multiple communications of the type send/reply to implement a sort of "ping" command, as provided for TCPIP in most platforms. Along this process, the EchoesClient determines the average response time of the sever.

Throught this example we can show how the following functionalities are implemented:

• Crete an agent and pass initialization parameters
• Wait for an agent to complete and get results from it
• Retrieve parameters passed to an agent and pass back results
• Send and receive messages
• Reply to an message received from other agent
• Schedulle events to be executed in the future and handle them when the time expires
• Report execution metrics that can be externaly analyzed
• Keep a record of agent's the execution by means of log entries

Components

• EchoesMainApp: is the main application that starts the client and server agents and pass to them the required parameters, as specified below.
• EchoServer respond to requests received from cliets after waiting for a random delay that simulates the response time of the server. The delay is implemented by a schedulled event with a random delay time. When the event expires, the server replies to the client with the same message it received.

  The server receives as parameters:

  • Average delay time
  • Variation on the delay time.
• EchoClient send a series of requests to the EchoServer and records the response time of each request. The client for responses until either a minimun number of responses have been received or a timeout expiries. Upon finalization, calculates the average response time, reports it as a "ResponseTime" metrics and returns as a result argument to the caller application.

  The client receives as parameters:

  • Number of requests tp be sent
  • A P2PAgentReference to contact the EchoServer.

Executing the application

The Echoes application components are contained in the EchoesSample project. This project contains the following directories:

• src/ source files
• lib/ libraries required by the middleware

Also in the project's root directory there is a configuration file HostingConfig.properties.

In Eclipse

1. Import the Echoes project
2. run the class EchoesMainApp, passing the following command line parameters:
   config.node EchoClient config.port 8051 config.workdirectory ./Echoes

Execution Results

After executing the application a trace should be shown in the console. This trace can also be seen in the file log.txt in the project's root directory. The trace should look as follows:

Timestamp: 1140713385943
Severity: INFO
AgentName: EchoServer
ClassName: Server
Method: handleEvent
Message: Event expired

Timestamp: 1140713385944
Severity: INFO
AgentName: EchoClient
ClassName: EchoRequestor
Method: Request completation
Message: Request execution time 1875

Timestamp: 1140713385944
Severity: INFO
AgentName: EchoClient
ClassName: EchoRequestor
Method: makeRequest
Message: Making request number: 3

Also, in the project's root directory there should be a file named ResponseTime.txt with a series of rows, each with the response time of each echo request sent by the client to the server. This file should look as follows:

1140714229886,EchoClient,ResponseTime,1565
1140714231382,EchoClient,ResponseTime,1495
1140714233083,EchoClient,ResponseTime,1701
1140714234642,EchoClient,ResponseTime,1559