Pamoja.Bus 0.1.17

Pamoja.Bus

An in-memory typed publish and subscribe event bus. One capability of pamoja, one memory-safe Rust core with bindings for TypeScript, Python, and C#.

Install

dotnet add package Pamoja.Bus

using Pamoja.Bus;

This pulls in Pamoja.Native, the compiled engine, and Pamoja.Codec. dotnet add package Pamoja is the whole framework in one package.

Example

The guide project's example, spliced here as it ran in CI.

From bindings/dotnet/samples/Pamoja.Guides/BusGuide.cs:

// A sampler announces something and whatever cares picks it up, with neither side
// holding a reference to the other. This is how the parts of one node are wired.
using EventBus hub = new EventBus(8);
using EventBus control = hub.Subscribe();
using EventBus logger = hub.Subscribe();

await hub.PublishAsync("battery.low"u8.ToArray());
byte[] toControl = (await control.NextAsync())!;
byte[] toLogger = (await logger.NextAsync())!;
Console.WriteLine(
    $"control saw {System.Text.Encoding.UTF8.GetString(toControl)},"
    + $" the logger saw {System.Text.Encoding.UTF8.GetString(toLogger)}");

// A subscriber taken later starts from the next event, so it never sees what went
// out before it existed.
using EventBus late = hub.Subscribe();
await hub.PublishAsync("link.up"u8.ToArray());
byte[] firstSeen = (await late.NextAsync())!;
Console.WriteLine(
    $"the late subscriber's first event is"
    + $" {System.Text.Encoding.UTF8.GetString(firstSeen)}");

// The buffer is per subscriber and bounded, so one further behind than the
// capacity drops what it missed and resumes with the most recent events. A slow
// reader costs itself, not the publisher.
using EventBus slow = new EventBus(2);
using EventBus reader = slow.Subscribe();
for (byte count = 0; count < 5; count++)
{
    await slow.PublishAsync(new byte[] { count });
}

byte[] resumed = (await reader.NextAsync())!;
Console.WriteLine(
    $"after five events into a buffer of two, the reader resumes at {resumed[0]}");

The same capability in every language

Documentation

• Pamoja.Bus reference, every type in this namespace.
• The Event bus guide, with the same example in Rust, TypeScript, and Python.
• Every capability, and the install page.

License

MIT