Edited to address question updates, previous answer removed
Looking over your changes to your question I think I understand the problem you are facing a bit more. As there is no field that is an identifier on your resources (just a link) you have no way to refer to that specific resource within your GUI (i.e. a link to a page describing a specific pet).
The first thing to determine is if a pet ever makes sense without an owner. If we can have a pet without any owner then I would say we need some sort of unique property on the pet that we can use to refer to it. I do not believe this would violate not exposing the ID directly as the actual resource ID would still be tucked away in a link that the REST client wouldn't parse. With that in mind our pet resource may look like:
<Entity type="Pet">
<Link rel="self" href="http://example.com/pets/1" />
<Link rel="owner" href="http://example.com/people/1" />
<UniqueName>Spot</UniqueName>
</Entity>
We can now update the name of that pet from Spot to Fido without having to mess with any actually resource IDs throughout the application. Likewise we can refer to that pet in our GUI with something like:
http://example.com/GUI/pets/Spot
If the pet does not make any sense without an owner (or pets are not allowed in the system without an owner) then we can use the owner as part of the "identity" of the pet in the system:
http://example.com/GUI/owners/John/pets/1 (first pet in the list for John)
One small note, if both Pets and People can exist separate of each-other I would not make the entry point for the API the "People" resource. Instead I would create a more generic resource that would contain a link to People and Pets. It could return a resource that looks like:
<Entity type="ResourceList">
<Link rel="people" href="http://example.com/api/people" />
<Link rel="pets" href="http://example.com/api/pets" />
</Entity>
So by only knowing the first entry point into the API and not processing any of the URLs to figure out system identifiers we can do something like this:
User logs into the application. The REST client accesses the entire list of people resources available which may look like:
<Entity type="Person">
<Link rel="self" href="http://example.com/api/people/1" />
<Pets>
<Link rel="pet" href="http://example.com/api/pets/1" />
<Link rel="pet" href="http://example.com/api/pets/2" />
</Pets>
<UniqueName>John</UniqueName>
</Entity>
<Entity type="Person">
<Link rel="self" href="http://example.com/api/people/2" />
<Pets>
<Link rel="pet" href="http://example.com/api/pets/3" />
</Pets>
<UniqueName>Jane</UniqueName>
</Entity>
The GUI would loop through each resource and print out a list item for each person using the UniqueName as the "id":
<a href="http://example.com/gui/people/1">John</a>
<a href="http://example.com/gui/people/2">Jane</a>
While doing this it could also process each link that it finds with a rel of "pet" and get the pet resource such as:
<Entity type="Pet">
<Link rel="self" href="http://example.com/api/pets/1" />
<Link rel="owner" href="http://example.com/api/people/1" />
<UniqueName>Spot</UniqueName>
</Entity>
Using this it can print a link such as:
<!-- Assumes that a pet can exist without an owner -->
<a href="http://example.com/gui/pets/Spot">Spot</a>
or
<!-- Assumes that a pet MUST have an owner -->
<a href="http://example.com/gui/people/John/pets/Spot">Spot</a>
If we go with the first link and assume that our entry resource has a link with a relation of "pets" the control flow would go something like this in the GUI:
- Page is opened and the pet Spot is requested.
- Load the list of resources from the API entry point.
- Load the resource that is related with the term "pets".
- Look through each resource from the "pets" response and find one that matches Spot.
- Display the information for spot.
Using the second link would be a similar chain of events with the exception being that People is the entry point to the API and we would first get a list of all people in the system, find the one that matches, then find all pets that belong to that person (using the rel tag again) and find the one that is named Spot so we can display the specific information related to it.
Part of the pain you feel with securing your API is that it has the wrong level of granularity. If you need to allow a user to "update user's own profile", then you should expose that specific operation on the API distinct from "update (any) user's profile". The client application should call the appropriate operation. Then you can check for permission to do that operation in a declarative way and deny it at the security border before it gets into controller code.
For example: If the client requests PUT /api/<update (any) user's profile> { profileid: ... }
. You search their permissions (e.g. claims) for "update (any) user's profile". Failing to find it, they are denied at the security border. Whereas they might be allowed to "update user's own profile", so a PUT /api/<update user's own profile> {...}
would be passed to the controller for that operation. You won't even have to specify a target profile id for this operation, because you can get it from their auth data.
REST is not simply exposing your database over HTTP nor mapping HTTP verbs to CRUD operations (or at least it shouldn't be). An API is there to focus clients on the higher-level operations. Looking at it that way also makes it easier to secure... you secure on the operation, not specific data changes.
Note: I intentionally didn't use specific naming conventions for the profile operations above. I'll leave it to someone else to argue the proper conventions for non-entity REST endpoints.
Here's another answer I did recently that may help you.
Best Answer
No. REST doesn't care about how your organize your resources, only that individual resources are identified by URLs and that resources are discoverable from other resources. If
api/competitions/{id}/teams/players
makes sense for your application then use it, as long as users can find a link to it.Roy Fielding's dissertation on Representational State Transfer, specifically sections 5.2.1.1 Resources and Resource Identifiers and 6.2 REST Applied to URI. Also look into HATEOAS (Hypertext as the Engine of Application State).
Yes, if it is both understood by and convenient for users of your application.
REST is a high-level architectural concept. It's not concerned with how you nest your identifiers. That's up to you and your application requirements. Do what makes sense and be obvious about it.