无法使用我在 React Native 中通过 Rest API 构建的移动应用程序访问 Cosmos DB

Question

I am fairly new to building mobile apps and have spent days trying to solve, or at least understand, the following problem. I am building a mobile app on react native in expo. I have selected Cosmos DB as my database. Is this a good decision? Should I move to Firebase or another DB? Assuming I stick with Cosmos DB, I am unable to get an authorization string built for a REST API.

Specifically, I find every search leading to Crypto-JS. Crypto-JS is not supported in React Native (at least in expo). So, I have been trying to build the encryption on my own. To the best of my research, three steps exist to get an authorization string for my REST API.

1. translate the secret key to a word array (not sure what this is - why does it need to be an array - versus a direct Base64 encode). Need to use parse to build the array. But, I am unable to use parse in expo react native. Or am I?
2. encrypt with HMAC 256
3. decode, in Base64, with stringify (again - not supported in React Naive - Expo).

How does parse work on a key - what is the logic? For example, when I encode 'Hello world' in Base64, I get a different answer than using parse.

Base64 - SGVsbG8gd29ybGQ=

Postman using Parse - 1de965a00c28ae57 (Microsoft Cosmos API likes this answer)

How does this work? Why do I need parse. By the way, the Postman solution with Crypto-JS and parse works. How do I build an authorization string in React Native in Expo?

I would greatly appreciate insight and help as my head hurts from banging it against the wall. Thanks BC

Answer 1

Posting as answer.

There are lots of people using Cosmos DB as a database for mobile device applications. Most notably as many mobile gaming applications which like Cosmos DB because it is a distributed database. But plenty of others as well.

To connect to Cosmos DB from a mobile device where data is kept separate per tenant, you need a middle tier to serve as an auth provider for your app. For Cosmos DB this scenario centers around the use of users and permissions with resource tokens and the implementation of a token broker middle-tier service that acts as a auth provider for the mobile application. Resource tokens are issued by the token broker service for each user and can pass tokens that provide access to that users data, typically with the granularity of a partition key which is the most granularity you can have in Cosmos.

You can learn more here about Resource Tokens in Cosmos DB which includes a simple (and somewhat dated) example for how to create a token broker for a mobile device application. If you are looking for a more robust example of this you can also take a look at this example written in Java that was created by an engineer at Citrix.

Hope this helps.