Orleans.Providers.ExtSqs

Overview

The SQS Stream Provider is a new implementation of a PersistentStreamProvider for Microsoft Orleans. It builds on the foundations of the Microsoft's ExtSqsStreamProvider (for more information see https://github.com/dotnet/orleans/tree/master/src/OrleansAWSUtils/Streams). However, it differs in two main ways:

1. Instead of creating its own queues it operates on ones already created. It does not created its own queues.
2. It can accept messages from external producers.

Installation

To start working with the ExtSqsStreamProvider make sure you do the following steps:

• Install-Package Orleans.Streams.ExtSqs

Example for ExtSqsStreamProvider configuration:

<Provider Type="Orleans.Providers.ExtSqs"
		Name="ExtSqsProvider"
		QueuePrefix="player" <!-- To subscribe to all player queues -->
		Version="v1"
		DataConnectionString="Service={region};AccessKey={accessKey};SecretKey={secreteKey};"
		FifoQueues="true"
		ExternalMessageIdentifier="External"/>

In code:

	var streamConfigBuilder = new ExtSqsConfigurationBuilder()
		.ConnectWith("Acce$$Key", "J007B", "eu-west-1")
		.WithQueuePrefix("player")
		.WithVersion("v1")
		.IdentifyExternallyProducedMessagesWith("External");

	config.AddSqsStreamProvider("ExtSqsProvider", streamConfigBuilder);

Implementation

The ExtSqsStreamProvider is implemented using the Orleans Guidelines to implement a new PersistentStreamProvider over the PersistentStreamProvider class (shown in this page: http://dotnet.github.io/orleans/Orleans-Streams/Streams-Extensibility).

Note: that it is built upon the foundation of Microsoft's SQSStreamProvider found here: https://github.com/dotnet/orleans/tree/master/src/OrleansAWSUtils/Streams

Queue Setup

In order for the provider to work as expected there are some constraints on the queue naming:

• Always start with a namespace - The provider will list all queues that begin with the supplied QueuePrefix in the configuration
• Following the namespace the queue index must be appended - This will be used for load balancing purposes
• Finally .fifo must be used for FIFO queues

Queue Template

{ namespace }_{ queueIndex }[ .fifo ]

Example: player-updates_0.fifo

Usage

Producing Messages

External Messages

• ExtSqs will take the MessageGroupId as the StreamId
• The QueueNamespace is the queue name without the QueueIndex and .fifo postfix
• Messages should also contain an attribute that identifies that the message is produced externally. This is configurable via the config builder's IdentifyExternallyProducesMessagesWith() with the default being "External"

Internal Messages

var streamProvider = client.GetStreamProvider("ExtSqsProvider");
var stream = streamProvider.GetStream<TestModel>(testGrain.GetPrimaryKeyString(), "player-updates");

string line;
while ((line = Console.ReadLine()) != string.Empty)
{
	stream.OnNextAsync(new TestModel
	{
		Greeting = line
	}).Wait();
}

Consuming Messages

public override async Task OnActivateAsync()
{
	var streamProvider = GetStreamProvider("ExtSqsProvider");
	var stream = streamProvider.GetStream<TestModel>(this.GetPrimaryKeyString(), "player-balances");

	await streamBalances.SubscribeAsync((message, sequence) =>
	{
		Console.WriteLine($"bal {message.Greeting}");
		return Task.CompletedTask;
	});
}

Configurable Values

These are the configurable values that the SQSStreamProvider offers to its users, the first two are required while the others have default values:

• QueuePrefix - The provider will be using the queues that are named started with the prefix supplied
• DataConnectionString - The connection string that will be used to connect toi AWS SQS
• FifoQueues - Determines whether the queues used are FIFO or not
• ExternalMessageIdentifier - This SQS Message attribute tells the provider that the message is produced by an external producer and hence it needs to apply the proper de-serialization

Additionally you have the default configuration options offered by Orleans to any PersistentStreamProvider which can be found here (under StreamProvider configuration): https://dotnet.github.io/orleans/Documentation/Orleans-Streams/Streams-Extensibility.html.