Chapter 13. Valet Key Pattern
This pattern focuses on efficiently using cloud storage services with untrusted clients.
This pattern loosely models the use of valet keys from the real world. Valet keys are useful when you are willing to trust a valet parking attendant to park your car, but don't want to also give them access to areas in the car not needed for this purpose, such as the glove compartment. This pattern enables specifying that a user of your application is allowed to access very specific areas within your cloud storage account, with specific permissions, and for a limited amount of time. You can issue as many cloud storage valet keys as you like and they can all be different.
Cloud storage services simplify securely transferring data directly between untrusted clients and to secure data storage, without the data needing to pass through a trusted intermediate layer (the web tier in this case) to implement security. Both uploads and downloads are supported.
Going directly to the final storage location eliminates the need for data to unnecessarily pass through an intermediary, so these operations will be faster with lower latency, while reducing the load on the web tier. Because this pattern avoids load on the web tier, it will result in needing less capacity, which may further result in needing fewer web server nodes (thus saving money). Realize, however, that this pattern also requires the ability to securely allow access to cloud storage, typically by issuing temporary ...