Azure WebJobs SDK - in what scenarios is creation of a JobHost object required?

Question

Most of the samples associated with the Azure WebJobs SDK have startup code that looks like this:

static void Main()
{
    JobHost h = new JobHost();
    h.RunAndBlock();
}

However you can also kick off a WebJob without creating a JobHost object like this:

static void Main()
{
    // Do something...
}

In what scenarios is the JobHost necessary?

Answer 1

WebJobs and WebJobs SDK are two different things even though their name is similar.

• The WebJobs (without SDK) is a feature of Azure Websites. It is a generic, language/platform agnostic engine that can execute jobs. You can write jobs in many languages including: node, batch, C#/VB/any other .NET language
• The WebJobs SDK is a framework, only for .NET, that simplifies the task of writing code that works with Azure Storage queues, blobs, and tables, and Service Bus queues; also, it is not tied to the WebJobs feature of Web Sites - it can run in any .NET application.

The JobHost is the entry point for the Azure WebJobs SDK. It is responsible for indexing, publishing, monitoring and scheduling the functions defined using WebJobs SDK artifacts. Whenever you want to invoke a WebJobs SDK function (triggered or manual/called) you need an instance of the JobHost. If your code doesn't require Azure Storage/ServiceBus or if you want to write all the polling/logging yourself, you don't need the Azure WebJobs SDK.

Answer 2

You need the Jobs Host Configuration when you want to interact with Azure Storage (table storage, queues, blobs) or ServiceBus and if you want to expose your functions to the Azure WebJobs Dashboard.

This is some code I use in a WebJob that doesn't use JobHost

static ISubscriptions _subscriptions;

static void Main()
{
    Process();
}

public static void Process()
{
    _subscriptions.DoWork();
}