问题
I've been stumbling around for a few hours trying to understand Cognito and identity management in a mobile app. I'm relatively new to mobile app development. I've made a mobile app before, but never one with a back-end. so now I'm playing around with AWS intending to try just that.
I want to make sure that each user using my app can be uniquely identified so that I can store content that they submit to the server associated with them. But I also want other users to be able to see their submitted content. I haven't decided on a data storage mechanism yet (Amazon seems to offer a few), but whatever it is will have to be an indefinitely free service since I'm not planning on spending (or earning) any money on this app.
Part of what is confusing me is the need to create App IDs with whatever service I wanted to use with federated identities. I am starting to suspect there are multiple kinds of identities that I'm getting confused. Does the App have its own identity independent of a user's identity? I didn't expect to have to create Google and Amazon App IDs just to allow users to log into my app using their Google or Amazon accounts. I suspect I'm understanding the API wrong, and I'm having a really hard time finding applicable sample code usable from Xamarin.
I have this much code (unique identifier x'd out):
CognitoAWSCredentials credentials = new CognitoAWSCredentials(
"us-east-2:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", // Identity pool ID
RegionEndpoint.USEast2 // Region
);
And that seemed to run (in a debugger) without throwing an exception at least, but I'm not clear what it has given me. I'm doubting that this credentials object uniquely identifies the user after they might reboot their device, and start the app again the next day. For that I suspect I need something more, and I'm not clear what. What's the next simplest step to get a unique identifier for a user which I can store along with their content to associate it with them?
回答1:
Are you set on having users use third part identity or do you want to provide user's their own identity? For federated identities (3rd party) you need to provide an Identity Pool ID which is created in Cognito to identify the federated identity provider. For your own identities in Cognito you create User Pools which also have an ID.
If you want to provide user sign-in and sign-up you want to use Cognito identities and not federated identities. The link below has some good references regarding this -
https://aws.amazon.com/cognito/dev-resources/
来源：https://stackoverflow.com/questions/46039811/understanding-cognito-identities