Cloud Computing with the Windows® Azure™ Platform

Chapter 4. Scaling Azure Table and Blob Storage

Achieving high scalability requires cloud-based applications and services to be stateless so as not to rely on the data center's load balancing devices or software to route successive requests from a specific client to a particular logical node. However, most applications and services require access to data persisted in tables that share some characteristics of relational database tables, as well as individual binary large objects (blobs) for storing unstructured data such as images and text documents.

Azure Storage Services consist of highly scalable and available persistent storage for the following three types of data:

• Tables are structured tabular data stored in an Entity-Attribute-Value (EAV) data model; the maximum size of all attribute values of an entity is 1MB. Entities can be grouped into storage partitions, which are maintained in a single location.

• Blobs consist of unstructured file-based data stored in an array of bytes; containers store sets of individual blobs up to 50GB in size in hierarchical groups, which emulate a directory structure. Only blob containers and their content are available for public access.

• Queues contain an unlimited number of messages stored in tables for processing by global services (often Worker Cloud services); messages have a maximum size of 8KB. Messages usually are deleted after the process that reads them handles them. Queues are the subject of Chapter 8, "Messaging with Azure Queues."

To assure ...