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Developing Cloud Applications with Windows Azure Storage: Blobs

Blob containers

The structures used to store blobs are called blob containers. Blob containers provide a unit of organization and also of privacy sharing. By default, all blobs stored in a container share the same level of sharing, either private or public. Private containers require credentials to perform operations, whereas public containers allow anonymous read-only access to all blobs stored in the container. Creation, deletion, and update of the blobs stored in a container always require an authenticated request, irrespective of the privacy settings you assigned to the container.

An individual blob container can hold anywhere from zero to an infinite number of individual blobs. There is a limit, of course, on the total amount of storage capacity available with your account (not to mention the likely constraints you have on the money available to pay for your storage), but the limit is placed on your storage capacity, not on the number of blobs that can be placed in a single blob container. Because the capacity restrictions on an account are so large, in most situations, this number is virtually limitless.

No limit is placed on the number of containers that you can have in a single Windows Azure storage account, but just like individual blobs, the actual numerical limit is determined indirectly by the storage capacity of your Windows Azure storage account.

Blob containers allow access policies to be applied, which control access and operations performed against the individual blobs that the containers encapsulate. You’ll learn more about access policies later in this chapter.