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echo

Actor system that works alongside the functional framework Language-Ext

An issue with working with C# is that no matter how much of Language-Ext functional framework you take on-board, you will always end up bumping into mutable state or side-effecting systems. A way around that is to package up the side-effects into atoms of functional computation that are attached to the mutable state (in whatever form it may take). The Actor model + functional message handling expressions are the perfect programming model for that.

Concurrent programming in C# isn't a huge amount of fun. Yes the TPL gets you lots of stuff for free, but it doesn't magically protect you from race conditions or accessing shared state, and definitely doesn't help with accessing shared external state like a database.

Documentation

Documention Description
Overview A quick guide to the core features of the Process system
tell Send a message to a Process - This should be your prefered mechanism for communicating with processes
ask Request/response for processes - use this sparingly.
Publish / Subscribe Mechanism for a Process to publish messages and state. Other processes can subscribe through their inbox or external systems can subscribe through Reactive streams (Observables).
Message dispatch The power of any actor system, especially when it comes to a changing network topology is in its message routing and dispatching
ProcessId Process address/location mechansim
Routers A router is a Process that manage sets of 'worker' processes by routing the received messages, following pre-defined behaviours, e.g. Round-robin, broadcast, etc.
Dispatchers Similar to routers but without the need for a router process, all routing is done by the sender
Registered processes A sort of DNS for Processes, can also register dispatchers
Roles A special type of dispatcher that's aware of the aliveness of cluster nodes and what their roles are

Getting started

Make sure you have the Echo.Process DLL included in your project. If you're using F# then you will also need to include Echo.Process.FSharp.

In C# you should be using static Echo.Process, if you're not using C# 6, just prefix all functions in the examples below with Process.

If you want to use it with Redis, include Echo.Process.Redis.dll. To connect to Redis use:

    // C#
    RedisCluster.register();
    ProcessConfig.initialise("sys", "web-front-end", "web-front-end-1", "localhost", "0");
  • "sys" is the 'system name', but easier to think of it as the name of the cluster as a whole. That means you can use a different value to point it at another Redis db (for multiple clusters). But for now it's easier to call it sys and leave it.
  • "web-front-end" is the role, you can have multiple nodes in a role and the role based dispatchers allow you to implement high-availability and load balancing strategies.
  • "web-front-end-1" is the name of this node, and should be unique in the cluster
  • "localhost" is the Redis connection (can be comma separated for multiple Redis nodes)
  • "0" is the Redis catalogue to use ("0" - "15")

Note, neither of those lines are needed if you're doing in-app messaging only.

Nuget

Nu-get package Description
LanguageExt.Core All of the core types and functional 'prelude'. This is the core framework that the Echo library is based upon.
Echo.Process 'Erlang like' actor system for in-app messaging and massive concurrency
Echo.Process.Redis Cluster support for the Echo.Process system for cluster aware processes using Redis for queue and state persistence
Echo.Process.Owin WebSockets gateway into the Echo.Process system. Uses Owin to register the WebSockets handler.
Echo.ProcessJS Javascript API to the Echo.Process system. Supports running of Processes in a client browser, with hooks for two-way UI binding