When Quasar is running in production, we assume the printer(s)/LED sign is at a certain IP address and forward requests to it, no questions asked. This risks having a request be forwarded to a non existent device and then the SQS message deleted meaning we cannot recover the failed request.
The ping command can be used to check if a device is up at a certain IP address. To run the ping command from Node, we can use exec. An example is below:
const { exec } = require('child_process');
exec('ping <ip address>', function(error, stdout, stderr) {
// do something with error, stdout, stderr
});If you're unfamiliar with ping, check out this animated YouTube video.
Some things to consider
- How do we know when the device is up/down?
- hint: observe how the three callback function params (error, stdout, stderr) change depending on device status
ping normally "pings" an IP address until stopped. how do we specify only a limited number of packets?
Ideal workflow
- watch the youtube video
- address the above section on things to consider
- create a function in a separate file that makes use of
exec to ping a device
- The function should return a promise, resolving true/false depending if the device is up or not.
- If you're unfamiliar with Promises, check out this simple video.
- incorporate your new function into the LED/Print handlers.
When Quasar is running in production, we assume the printer(s)/LED sign is at a certain IP address and forward requests to it, no questions asked. This risks having a request be forwarded to a non existent device and then the SQS message deleted meaning we cannot recover the failed request.
The
pingcommand can be used to check if a device is up at a certain IP address. To run thepingcommand from Node, we can use exec. An example is below:If you're unfamiliar with
ping, check out this animated YouTube video.Some things to consider
pingnormally "pings" an IP address until stopped. how do we specify only a limited number of packets?Ideal workflow
execto ping a device