What are User Tokens and how are they associated with eBay Users and their applications?
A User token represents an authorization for an application to access eBay data (via eBay APIs) on behalf of an eBay user. An eBay user grants an application a user token by giving consent via the eBay sign-in and consent form. For more details on the process of creation of a user token refer 'Steps to generate a new and renew user token' .
A unique user token is created for every eBay user-application combination.To put it in simple words, if an eBay user owns multiple applications, each will need to use its own user token to access eBay data on the user's behalf.
Below are some illustrative use cases to explain this better.
One thing to keep in mind while going thru these illustrations is that there are 2 entities involved in creation of a unique user token - an Application (for simplicity's sake lets assume that its being maintained by a single Developer) and a customer or eBay User.
Assume there are three developers who are all members the eBay developer network and there are three different eBay users -
Each developer owns a keyset, which comprises of 3 keys: a Dev Id, an AppId and a Cert Id. In the following illustrations, lets assume our developers have the following keysets:
So, lets start with the simplest of our use cases -
A developer working for a Customer
As depicted in the table above, developer D1 working for customer C1, used his keyset to generate a unique user token T1. This token can be used by the application that is maintained by developer D1 to access eBay information on behalf of customer C1.
Now, adding a bit more complexity to the scenario we have -
A Developer working for more than one eBay Users
In this case, developer D1 used the same keyset KS1 to create a token T1 for C1 and T2 for C2.
T1 will be used by the application that D1 maintains for customer C1 and T2 will be used by the application that D1 maintains for customer C2. Both applications will be accessing eBay data on customer C2's behalf.
Similarly, we may have -
Mutiple Developers working for a Customer
In this case, each developer creates a seperate user token for C1 to use with the applictions each of them are maintaining for C1.
Finally, consider a case where -
Mutiple Developers are working for Multiple Customers
In this case, all the three developers(D1,D2,D3) are working for C1 so they created a seperate token for C1. There are 3 tokens :- T1, TT1 and TT2 that are accessing eBay data (thru some application, of course), on behalf of the same eBay user C1.