In this step, we will create a very simple chat application that leverages on the dissemination and membership protocols from the previous steps.
First, we will alter the dissemination protocol to receive requests to send messages (instead of relying on a timer) and to send a notification every time a message is received. To do this we need to:
- Create a
BroadcastRequestthat will be sent by the chat application and received by the dissemination protocol. - Create a
DeliverNotificationthat will be triggered by the dissemination protocol when a message is received. - Remove the timer from the dissemination protocol, and instead, use the
BroadcastRequesthandler to trigger the dissemination of new messages. - Trigger the
DeliverNotificationwhen a message is received.
Our chat application will be implemented as a Babel protocol. However, as we are building an interactive application, our protocol will be a bit different from the ones we have seen so far. In particular, we will create a new thread that will be responsible for reading user input and sending the requests to the dissemination protocol.
Other than this, all the protocol needs is to subscribe to the DeliverNotification and print the received messages.
You can check the source code of step B as an example.
To compile your code, run the following commands:
mvn clean packagedocker build -t babel-tutorial/e-chat .
You need to create a docker network for the tutorial:
docker network create babel-tutorial-net
To remove the network:
docker network rm babel-tutorial-net
docker run --network babel-tutorial-net --rm -h node-1 --name node-1 -it babel-tutorial/e-chat
docker run --network babel-tutorial-net --rm -h node-2 --name node-2 -it babel-tutorial/e-chat contact=node-1:8000
docker run --network babel-tutorial-net --rm -h node-3 --name node-3 -it babel-tutorial/e-chat contact=node-1:8000
docker run --network babel-tutorial-net --rm -h node-4 --name node-4 -it babel-tutorial/e-chat contact=node-1:8000