Chapter 8. Messaging with Azure Queues
Azure Queues provide reliable, asynchronous message delivery between components of a cloud-based service. Dispatching computing operations of WorkerRole projects to improve service scalability is the most common use for Azure Queues, which also can assist the Azure Fabric's load-balancing features by engaging extra nodes in computing-intensive tasks. Offloading computation to a WorkerRole can speed the response of cloud-based WebRole pages to user requests. This chapter will show you how to combine a WebRole, WorkerRole and Queue to create what's called an Azure-hosted composite application.
Queues are the simplest of the three Azure data models. A single http://servicename.queue.core.windows.net service account supports an unlimited number of uniquely named queues. Also, a queue can contain an unlimited number of messages, each of which can hold up to 8MB of string or binary payload. Your application can assign an additional 8MB maximum of custom metadata to a queue in the form of name/value pairs. Individual messages don't support custom metadata but have a maximum lifespan (time-to-live or TTL) of seven days. Like Azure Tables and Blobs, Queues offer a RESTful application programming interface (API) for enabling multiple platforms and programming languages to manipulate them when running on the Development and Azure Fabrics. Queues support both HTTP and HTTPS (secure HTTP with Transport Layer Security, TLS) protocols.
Figure 8-1 illustrates ...
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