A Multi-App, Multi-Queue SqlExtension for running multiple servers for multiple applications against a single SQL Server database.

An intuitive idea of running multiple Hangfire servers for multiple applications is to run different applications in different queues, a dedicated server for each queue.

For example:

AppServer1 could run jobs defined in library AppLib1 that are registered as recurring jobs in queue AppQueue1. And AppServer2 would run jobs defined in library AppLib2 registered as recurring jobs in queue AppQueue2. And the two server executables would only load assemblies belonging to their applications and can be independent of each other.

Unfortunately, this does not work. Hangfire job queue was initially designed only for job execution, not job scheduling. In the setup above, schedulers in AppServer1 sees jobs in AppQueue2 and will not respect the queue setting. It tries to deserialize the jobs for scheduling. The deserialization will cause a dll not found exception. What's more, when the job fails and is being retried, retries will also not respect the queue setting. Jobs set for AppQueue2 will be retired by AppServer1 and will cause retry failure again.

This extension is a workaround before Hangfire supports the multiple application, multiple servers, single database setup officially.

Usage examples are provided in the examples. The necessary steps are listed below.

1. Install NuGet package Hangfire.MAMQSqlExtension: i.e. Install-Package Hangfire.MAMQSqlExtension -Version 1.0.5

2. Filter the jobs according to their queue settings before giving them to RecurringJobScheduler and DelayedJobScheduler for scheduling

GlobalConfiguration.Configuration
   .UseMAMQSqlServerStorage(connectionString, new SqlServerStorageOptions{...}, new[]{ "MyQueue" })

3. Force the job retries to respect the queue setting

[RetryInQueue("MyQueue")]
public void MethodForJob()
{
    ...
}

4. Specify queues for the BackgroundJobServer.

    var serverOptions = new BackgroundJobServerOptions
    {
        Queues = new [] {"MyQueue"},
    }
    new BackgroundJobServer(serverOptions)

5. Specify a queue when registering the job

RecurringJob.AddOrUpdate(jobID, jobAction, cron, TimeZoneInfo.Local, "MyQueue");

6. Since the dashboard is database specific, it has to be shared between the two applications. The dashboard will need to be able to deserialize jobs for both applications. This means that the Dashboard executable needs to reference all dlls that the jobs are defined in (e.g. AppLib1 and AppLib2).