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RabbitMQ

RabbitMQ is an open-source message-broker software that originally implemented the Advanced Message Queuing Protocol and has since been extended with a plug-in architecture to support Streaming Text Oriented Messaging Protocol, Message Queuing Telemetry Transport, and other protocols.

RabbitMQ can be used in CAP as a message transporter.

Configuration

To use RabbitMQ transporter, you need to install the following package from NuGet:

PM> Install-Package DotNetCore.CAP.RabbitMQ

Next, add configuration items to the ConfigureServices method of Startup.cs.

public void ConfigureServices(IServiceCollection services)
{
    // ...

    services.AddCap(x =>
    {
        x.UseRabbitMQ(opt=>
        {
            //RabbitMQOptions
        });
        // x.UseXXX ...
    });
}

RabbitMQ Options

The RabbitMQ configuration parameters provided directly by CAP:

NAME DESCRIPTION TYPE DEFAULT
HostName Broker host address string localhost
UserName Broker user name string guest
Password Broker password string guest
VirtualHost Broker virtual host string /
Port Port int -1
ExchangeName Default exchange name string cap.default.topic
QueueArguments Extra queue x-arguments QueueArgumentsOptions N/A
ConnectionFactoryOptions RabbitMQClient native connection options ConnectionFactory N/A
CustomHeaders Custom subscribe headers Func>> N/A

ConnectionFactory Options

If you need more native ConnectionFactory configuration options, you can set it by 'ConnectionFactoryOptions' option:

services.AddCap(x =>
{
    x.UseRabbitMQ(o =>
    {
        o.HostName = "localhost";
        o.ConnectionFactoryOptions = opt => { 
            //rabbitmq client ConnectionFactory config
        };
    });
});

CustomHeaders Options

When the message sent from the RabbitMQ management console or a heterogeneous system, because of the CAP needs to define additional headers, so an exception will occur at this time. By providing this parameter to set the custom headersn to make the subscriber works.

You can find the description of Header Information here.

Example:

x.UseRabbitMQ(aa =>
{
    aa.CustomHeaders = e => new List<KeyValuePair<string, string>>
    {
        new KeyValuePair<string, string>(Headers.MessageId, SnowflakeId.Default().NextId().ToString()),
        new KeyValuePair<string, string>(Headers.MessageName, e.RoutingKey),
    };
});

How to connect cluster

using comma split connection string, like this:

x=> x.UseRabbitMQ("localhost:5672,localhost:5673,localhost:5674")