Azure Blob Storage large file upload

Question

I am in the process of developing an application that will run on Azure and requires a user to upload very large .tiff files. We are going to use blob storage to store the files. I have been reviewing several websites to determine the correct approach to handling this situation and this link provides a good example but if I am using angular js on the frontend to grab and chunk them to the sas locator and upload via javascript, http://azure.microsoft.com/en-us/documentation/articles/storage-dotnet-shared-access-signature-part-2/ . My main confusion centers around the expiration time I should give to SAS for the user to perform the upload. I would like a distinct SAS to be created each time a user performs a file upload and for it to go away once the file is uploaded. I also would like to allow other site users to view the files as well. What is the best approach for handling these two scenarios? Also, there are examples on how to generate SAS Locator for the container and for the blob, if I need tp add a new blob to a container, which makes more sense?

Answer 1

It sounds like you may want to use a stored access policy on the container. This allows you to modify the expiry time for the SAS after the SAS has been created. Take a look at http://azure.microsoft.com/en-us/documentation/articles/storage-manage-access-to-resources/#use-a-stored-access-policy .

With the stored access policy, you could create a SAS with a longer expiry time and with write permissions only for the upload operation, and then have your application check when the file has finished uploading, and change the expiry time to revoke the SAS.

You can create a separate SAS and stored access policy with read permissions only, for users who are viewing the files on the site. In this case you can provide a long expiry time and change it or revoke it only if you need to.