Re: [scim] [EXTERNAL] Query on a specific known resource

[Phillip Hunt <[e-mail]>]

Julien,

You are not wrong.  All queries regardless of path MUST have a ListResponse.

It may seem logical to make the jump to just returning a single resource for a query that can only return a single result, but this is not permitted in the RFC. From a protocol point of view, allowing skipping ListResponse makes the protocol more complex because it creates “exceptions” which have to be handled. For example, what happens if no filter match etc.

For the group:  For historical information, the issue is actually more complex than it seems.   For SCIM queries SCIM’s profile of HTTP overrides both HTTP GET (retrieves a resource) and HTTP POST (create a resource) to perform a search function. In the case of GET, url based filters cause privacy concerns because of the leak of confidential information in URLs. The GET method does not allow request bodies. Because of thies, SCIM also supports http POST queries. The HTTP definition suggests creation a resource.  Dual purposing these methods for search queries created necessary complexity. One of the basic rules of thumb is that whenever a “filter” shows up in a request, the request becomes a SCIM Query which mandates a ListResponse.

I discussed this at length with authors of the HTTP specifications and worked with Julian Reschke (co-author of HTTP) to submit a proposal for a HTTP SEARCH method.  This would unburden GET and POST methods and simplify protocol overall.  Julian indicated to me at the time of finalizing SCIM (around IETF93), that this issue comes up frequently for him as one of the HTTP authors.  In the end, the HTTPbis WG chose not to create a new method because there is too much water under the bridge.  See: https://httpwg.org/wg-materials/ietf93/ietf-93-httpbis-search.pdf

Phillip Hunt
@independentid
[e-mail]




> On Jul 7, 2022, at 12:57 AM, Julien Schneider <[e-mail]> wrote:
> 
> Hi Danny, hi Phillip, hi everyone,
> 
> Thanks for your answers. I think the confusing part (for me at least) is "Queries MAY be made against a single resource or a resource type endpoint ......." at the beginning of RFC7644 section 3.4.2., followed by "Responses MUST be identified using the following URI: "urn:ietf:params:scim:api:messages:2.0:ListResponse" ".
> 
> My interpretation is that "GET /Users/2819c223-7f76-453a-919d-413861904646?attributes=userName" is a query against a single resource, and should then have a "ListResponse" response? Where am I wrong here?
> 
> Thanks
> 
> Julien Schneider
> Tel: [phone]
> Fax: [phone]
> 
> http://www.audriga.com <http://www.audriga.com/> | http://www.twitter.com/audriga <http://www.twitter.com/audriga>
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> On 07/07/2022 04:51, Danny Zollner wrote:
>> Hi Julien,
>>  
>> RFC 7644 section 3.4.2 specifically is talking about queries. Retrieving or modifying known resources (i.e.: GET /Users/12345 ) does not require a ListResponse type response. A query of GET /Users?filter=displayname contains “contoso.com” or GET /Users?attributes=userName would require a ListResponse type response, as it does not identify a specific resource in the query URL via ID value (i.e.: “12345” in the previous example). On the other hand, GET /Users/12345?attributes=userName does not require the ListResponse type response as it does identify a specific resource.
>>  
>> To explicitly answer the final question in your email – the expected response to GET /Users/2819c223-7f76-453a-919d-413861904646?attributes=userNamewould be the second example you provided.
>>  
>> Cheers,
>>  
>> Danny Zollner
>>  
>> From: scim <[e-mail]> <mailto:[e-mail]> On Behalf Of Julien Schneider
>> Sent: Wednesday, July 6, 2022 3:41 AM
>> To: [e-mail] <mailto:[e-mail]>
>> Subject: [EXTERNAL] [scim] Query on a specific known resource
>>  
>> 
>> Some people who received this message don't often get email from [e-mail] <mailto:[e-mail]>. Learn why this is important <https://aka.ms/LearnAboutSenderIdentification>	
>> Hi all,
>> 
>> I have a question about queries performed against a SCIM resource object (like "/Users/{id}").
>> 
>> The RFC (https://datatracker.ietf.org/doc/html/rfc7644#section-3.4.2 <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc7644%23section-3.4.2&data=05%7C01%7Cdanny.zollner%40microsoft.com%7C29270780ce9941a0687808da5f2b53db%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637926937860837552%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=fVtTna44Hr973Z79OsTegu9U9%2FpDwRcBZignfi5Eluk%3D&reserved=0>) states: 
>> Responses MUST be identified using the following URI:
>>    "urn:ietf:params:scim:api:messages:2.0:ListResponse"
>> 
>> If I understand correctly, that means the "schemas" parameter of the response to those queries must be set to:
>> "schemas":["urn:ietf:params:scim:api:messages:2.0:ListResponse"]
>> 
>> While I understand how that applies to queries on a resource type endpoint (like "/Users") or on the SCIM server root, I don't understand how that applies to queries on a specific resource object.
>> If I understand correctly, queries on a specific resource object actually are quite identical to "retrieving a known resource" (https://datatracker.ietf.org/doc/html/rfc7644#section-3.4.1 <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fhtml%2Frfc7644%23section-3.4.1&data=05%7C01%7Cdanny.zollner%40microsoft.com%7C29270780ce9941a0687808da5f2b53db%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637926937860837552%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=DQEZdlY7XBONxFIegf1SCJfpdjpDdWzBvh5%2FzB%2B2EpQ%3D&reserved=0>) which are a GET on a specific resource, like:
>> GET /Users/2819c223-7f76-453a-919d-413861904646
>> Responses to those requests should have the "schemas" parameter set to the resource schema(s):
>> {
>>      "schemas":["urn:ietf:params:scim:schemas:core:2.0:User"],
>>      "id":"2819c223-7f76-453a-919d-413861904646",
>> ...
>> }
>> 
>> Now, how should the response to the following query should look like? And to what value should the "schemas" parameter of the response be set?
>> GET /Users/2819c223-7f76-453a-919d-413861904646?attributes=userName
>> 
>> Should it be:
>>    {
>>      "schemas":["urn:ietf:params:scim:api:messages:2.0:ListResponse"],
>>      "totalResults":1,
>>      "Resources":[
>>        {
>>          "id":"2819c223-7f76-453a-919d-413861904646",
>>          "userName":"bjensen"
>>        }
>>      ]
>>    }
>> 
>> Or something like:
>>    {
>>      "schemas":["urn:ietf:params:scim:schemas:core:2.0:User"],
>>      "id":"2819c223-7f76-453a-919d-413861904646",
>>      "meta":{
>>        "resourceType":"User",
>>        "created":"2011-08-01T18:29:49.793Z",
>>        "lastModified":"2011-08-01T18:29:49.793Z",
>>        "location":
>>    "https://example.com/v2/Users/2819c223-7f76-453a-919d-413861904646" <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fexample.com%2Fv2%2FUsers%2F2819c223-7f76-453a-919d-413861904646&data=05%7C01%7Cdanny.zollner%40microsoft.com%7C29270780ce9941a0687808da5f2b53db%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637926937860837552%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=HRI2UjMUWpVqb0IzoOcpDNA%2FVVDBG3lZ4gU6C60Gr1I%3D&reserved=0>,
>>        "version":"W\/\"f250dd84f0671c3\""
>>      },
>>      "userName":"bjensen"
>>    }
>> 
>> Thanks a lot in advance
>> 
>> -- 
>> Julien Schneider
>> Tel: [phone]
>> Fax: [phone]
>>  
>> http://www.audriga.com <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.audriga.com%2F&data=05%7C01%7Cdanny.zollner%40microsoft.com%7C29270780ce9941a0687808da5f2b53db%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637926937860837552%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=37nDJF0vyrffA22bld7R3WHNu11PnoLTmWCne%2FGCios%3D&reserved=0> | http://www.twitter.com/audriga <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.twitter.com%2Faudriga&data=05%7C01%7Cdanny.zollner%40microsoft.com%7C29270780ce9941a0687808da5f2b53db%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637926937860837552%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=P5As3bPNzRa4zSXSdYj9%2BirwGEkk6%2BYy5jkVKNAQnYw%3D&reserved=0>
>>  
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>> audriga GmbH |  Alter Schlachthof 57  | 76137 Karlsruhe
>> Sitz der Gesellschaft: Karlsruhe - Amtsgericht Mannheim - HRB 713034
>> Geschäftsführer: Dr. Frank Dengler, Dr.-Ing. Hans-Jörg Happel
>> --------------------------------------------------------------------------
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