example/README.md

PubSub Chat Example #

This directory contains a simple command-line chat application that demonstrates the core features of the dart-libp2p-pubsub library.

Features Demonstrated #

• Creating a libp2p Host.
• Initializing the PubSub service with GossipSubRouter.
• Connecting to a peer using a MultiAddr.
• Subscribing to a topic.
• Publishing messages from standard input.
• Receiving and displaying messages from the network.
• Graceful shutdown.

How to Run #

Prerequisites #

You need to have the Dart SDK installed.

The example code in chat.dart relies on a helper function, createLibp2pNode, which is fully implemented in the project's test suite at test/real_net_stack.dart. To make this example runnable, you would need to:

1. Copy test/real_net_stack.dart into the example/ directory.
2. Update example/chat.dart to import it: import 'real_net_stack.dart';.
3. Replace the dummy createLibp2pNode function at the bottom of chat.dart with the actual implementation.

Running the Chat #

After setting up the createLibp2pNode function, you can run the chat application.

1. Open two terminal windows.

2. In the first terminal, start the first chat node:

   dart run example/chat.dart
   

   The application will start and print its listen address, which includes its unique PeerId. It will look something like this:

   INFO: 2023-10-27 10:30:00: ChatExample: Listen addresses: [/ip4/127.0.0.1/udp/54321/udx/p2p/12D3KooW...somePeerId]
   

3. Copy the full listen address from the first terminal.

4. In the second terminal, start the second node and pass the first node's address as an argument:

   dart run example/chat.dart <paste_address_from_first_terminal_here>
   

   For example:

   dart run example/chat.dart /ip4/127.0.0.1/udp/54321/udx/p2p/12D3KooW...somePeerId
   

5. The two nodes will connect. You can now type a message in either terminal and press Enter to send it. The message will appear on the other node's screen.

6. To exit, press Ctrl+C in either terminal.