Creating a Message Module Client

Use the Scaleout.Modules.Client NuGet package’s MessageModuleClient class to send messages to your message module.

Note

The .NET MessageModuleClient class is not the only way to send messages to a message module. The Messaging REST API can also be used from other languages and platforms.

Background

In this example, we will use the MessageModuleClient class in the Scaleout.Modules.Client NuGet package to send messages to the “Flight” message module created in the prior topics.

Prerequisites

.NET 8 SDK or higher.
Scaleout.Modules.Client NuGet Package.
A deployed Message Module. This walkthrough will create a client class for the “Flight” message module project created in the previous topic.

Procedure

1. Create a client project

In a new console application project (or in any existing application/library outside of the Flight message module), add a reference to the Scaleout.Modules.Client NuGet package.

2. Define a message

Messages sent by a client must match the expected format defined in the message module. The example “Flight” module expects a specific “ArrivalTimeMessage” message (or a “PassengerAddedMessage”, if you are following the multiple message types) example.

The class definition for a message can either be redefined in your client application or put into a separate, shared library that is used by both your client and the message module.

namespace MsgModuleExampleClient
{
    public class ArrivalTimeMessage
    {
        public DateTime NewArrival { get; set; }
    }
}

3. Use the client class

The MessageModuleClient class can be used in any application that needs to interact with the Flight message module. The client application uses a GridConnection instance to connect to the ScaleOut StateServer cluster. See Connecting to a ScaleOut Data Grid for more information on using the GridConnection class.

using Scaleout.Client;
using Scaleout.Modules.Client;

namespace MsgModuleExampleClient
{
    internal class Program
    {
        static async Task Main(string[] args)
        {
            GridConnection conn = GridConnection.Connect("bootstrapGateways=localhost:721");
            MessageModuleClient flightClient = new MessageModuleClient("Flight", conn);

            var msg = new ArrivalTimeMessage
                { NewArrival = DateTime.UtcNow.AddHours(2) };

            byte[] msgBytes = System.Text.Json.JsonSerializer.SerializeToUtf8Bytes(msg);
            await flightClient.SendMessageAsync("flight123", msgBytes);
        }
    }
}