Irrigator-pinger is a project mainly written in JavaScript, it's free.
Interview project
This project is made to illustate possibilities of asynchronous I/O.
Well, it is a task I got during my interview.
Emulator is a simple TCP-server that emulates a remote irrigation controller.
In this experiment an emulator actually represents several devices.
Each can run on its own host:port, see emulator/dev-config.js.
Pinger is a TCP client utility to check a number of device instances.
Pinger sends string 'connect_1', then waits for 0x55 byte from device.
The connections to devices are made asynchronously, so response waiting
stage does not freeze the client process and several checks at once are
possible.
Install node.js 0.4.11 or later.
Under UNIX - go to this directory and type:
./emulator
This will run emulation servers.
Open new console and type:
./pinger
This will run pinger.
Currently you can configure a set of host:port values.
Go to lib/pinger/dev-config.js to set up servers you want to check.
Go to lib/emulator/dev-config.js to set up devices you want to emulate.
The client connects to the server.
The client sends command connect_1\n.
If server responds with byte 0x55 during 10s timeout the server is considered alive.
Otherwise - or in case of connection refused - the server is considered dead.
Connections to all servers are made simultaneously. This is achived by asynchronous architecture of Node.js, that means that every long-running I/O operation is made by OS with corresponding callbacks to main process in case of operation success or failure.
The system is production ready.
You can modify pinger to handle report data as you wish.
You can modify lib/pinger/client to match real-life device protocol.