Internet Computer Pub/Sub

Pub/Sub with Rust Canister Development Kit. This example demonstrates how functions may be passed as arguments of inter-canister calls to be used as callbacks. Also, with canister upgrade mechanism, we can upgrade the canister code without losing the state.

Overview

This sample project demonstrates how functions may be passed as arguments of inter-canister calls to be used as callbacks.

A common problem in both distributed and decentralized systems is keeping separate services (or canisters) synchronized with one another. While there are many potential solutions to this problem, a popular one is the Publisher/Subscriber pattern or "PubSub". PubSub is an especially valuable pattern on the Internet Computer as its primary drawback, message delivery failures, does not apply.

Prerequisites

This example requires an installation of:

Install the IC SDK.

Begin by opening a terminal window.

Step 1: Navigate into the folder containing the project's files and start a local instance of the Internet Computer with the command:

cd examples/rust/pub-sub
dfx start --background

Step 2: Deploy the canister:

dfx deploy

Step 3: Subscribe to the "Apples" topic:

dfx canister call sub init '("Apples")'

Step 4: Publish to the "Apples" topic:

dfx canister call pub publish '(record { "topic" = "Apples"; "value" = 2 })'

Step 5: Receive your subscription:

dfx canister call sub getCount

The output should resemble the following:

(2 : nat)

More information

adamcanray/IC-Rust-PubSub