For details about IRTA and modifications done on MQTT, please refer to the PDF found in this repository. There is an online demo available too.
In this example we will use a feature of IRTA which consists on merging, at broker level, two incoming messages and transforming them into one single message by applying a custom function to them.
Go to examples/test1-merging-2-topics
In this example there is a publisher sending a message every 1 minute under the topic pumpFlow and the subscriber expecting messages under the same topic, but every 3 minutes. Thus, the broker with IRTA discards 2 out of 3 messages because they are not needed.
Go to examples/test2-discard-out-of-period
In this example there is a publisher sending a message with a simlated latency of 2 minutes under the topic pumpFlow and the subscriber expecting messages under the same topic, but with a latency not greater than 1 minute. Thus, the broker with IRTA discards all the messages because they don't meet the latency requirements of the broker.
Go to examples/test3-discard-out-of-latency
If you would like to try IRTA without installing anything, please check out our online demo.
- Node.js (tested with v10.14.1): https://nodejs.org/es/download/
- Tested on Linux
IRTA is based on the MQTT protocol, but it modifies its packet structure and flow to be able to meet time and functional requirements. For this reason, popular JS libraries and modules have been modified. For the moment, these are found inside the node_modules folder, so you need to rebuild them so they can work on your architecture. 1. On the root folder, run:
$ npm rebuild
Once rebuilt, you are able to create a broker using Mosca and IRTA, and subscribers and publishers. Please, refer to the examples section to see how this is done.
function lambda (irta, packet) {
// do something
return true
}
The function receives 2 arguments:
- The first one is the irta object
- The second one is the packet to be analyzed and processed
The payload can be found at packet.payload and is in Buffer type. In case we want to process and replace the payload of the current message, we need to overwrite it. If we want to prevent that message from being sent, we return false, otherwise we return true.
This means that the port 1883 is being used by other process. Probably you have another MQTT broker running (Mosquitto?). Make sure to either stop that process or change the broker port (found on settings in the broker file).