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

[Julien Schneider <[e-mail]>]

Hi all,

Thanks a lot for your answers, it really helps.
By re-reading the RFC at the light of your responses, I think I'm 
starting to understand.

Section 3.4.2 starts with:

    The SCIM protocol defines a standard set of query parameters that can
    be used to*filter*,*sort*, and*paginate*  to return zero or more
    resources in a query response.  Queries MAY be made against a single
    resource or a resource type endpoint (e.g., "/Users"), or the service
    provider Base URI.


Here queries are defined only by filtering, sorting and pagination. 
Attributes are not part of it, which suggests that their usage do not 
fall under the "query" definition.
Now, one could wonder how would a filter/sort/pagination make sense on a 
single resource. I (personally) cannot see any use case. Maybe that 
should be clarified in the RFC, or even removed.

What is very confusing is that, although not listed in the query section 
"introduction", attributes have their own sub-section 3.4.2.5 under the 
query section. I guess (?) that was done to explicitly specify that 
attributes can be used on queries as well (and not only on basic 
operations). In that case, it would maybe be better to either:
- explicitly specify in the 3.4.2.5 subsection that attributes can be 
/used/ with/on queries, but do not define a query by themselves
- remove the 3.4.2.5 subsection and (more explicitly) specify in the 3.9 
section that attributes can be used on queries

Anyway, I think things are clearer now? Do you agree with those 
affirmations?
- attributes do not imply a query but can be used on queries
- only filtering, sorting and pagination define a query
- GET /Users/abcd?attributes=userName *is not* a query and do not 
require a ListResponse response
- GET /Users/abcd?filter=userName eq "Blah" *is* a query (which make 
little sense, but still) and requires a ListResponse response
- GET /Users?filter=userName eq "Blah" *is* a query and requires a 
ListResponse response

Thanks a lot again!

Julien Schneider
Tel: [phone]
Fax: [phone]

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On 07/07/2022 20:42, Phillip Hunt wrote:
> In practical terms, only the presence of a filter defines a query that 
> mandates a ListResponse.  The other time a ListResponse is needed is a 
> GET at the root level (which many don’t permit) or at the Resource 
> folder level.
>
> Attributes/excludedAttributes are listed under both 3.4.2 and 3.9.  In 
> practical terms, the presence of the attributes/ecludedattributes 
> qualifiers does not indicate a ListResponse.  Attributes are simply 
> permitted on any SCIM operation. POST, GET, Query, etc.  A simple GET 
> with Attributes does NOT require ListResponse (unless a filter is 
> present) as per Section 3.9 and shown in the example.
>
> Phillip Hunt
> @independentid
> [e-mail]
>
>
>
>
>> On Jul 7, 2022, at 11:04 AM, Danny Zollner 
>> <[e-mail]> wrote:
>>
>> Hi Phil,
>> I’m attempting to clarify what you’ve said here for both my own 
>> knowledge and others. Anything under a subsection of RFC 7644 3.4.2 
>> counts as a query. Query endpoints can be /Users/{id}, /Users, 
>> /Groups, and although not explicitly listed - /AnyOtherResource/{id} 
>> as well.
>> Features that fall under the label of queries and therefore require a 
>> ListResponse type response would be:
>> Filtering – i.e.: GET /x?filter=userName eq “blah”
>> Sorting
>> Pagination
>> Attributes – both ?attributes= and ?excludedAttributes=
>> Looking at 3.4.2.1, where the query endpoints are listed, the 
>> following parts of 3.4.2.x make sense and what you’re saying is 
>> apparent. From my own observations, I think there may be hundreds of 
>> implementations out there that implement ?attributes and 
>> ?excludedAttributes without a ListResponse wrapper when the query URL 
>> is a known resource such as GET /Groups/456?excludedAttributes=members.
>> I think we’re still a while away from attempting major changes to the 
>> protocol and schema RFCs, but in the future I’d be interested in 
>> having a discussion on adding an exception to the ListResponse 
>> requirement for querying known resources. The attributes queries are 
>> a bit different from the others. For filter, sort and paginate you 
>> can only really use them against the root of the server or the root 
>> of a resource (i.e.: /Users) as I understand it. I can’t think of a 
>> scenario where you’d do a filter like GET /Users/123?filter=userName 
>> eq “x” – is there a use case there that I’m missing? Similarly, I 
>> can’t think of scenarios where you’d sort or paginate results for GET 
>> /Users/123.
>> Thanks,
>> Danny
>> *From:*Phillip Hunt <[e-mail]>
>> *Sent:*Thursday, July 7, 2022 12:36 PM
>> *To:*Julien Schneider <[e-mail]>
>> *Cc:*Danny Zollner <[e-mail]>; [e-mail]
>> *Subject:*Re: [scim] [EXTERNAL] Query on a specific known resource
>> 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 
>> <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhttpwg.org%2Fwg-materials%2Fietf93%2Fietf-93-httpbis-search.pdf&data=05%7C01%7CDanny.Zollner%40microsoft.com%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=ahU2tOHPGFEjoaXkz16HWA6W50waT9m5kcYXXIIpRzA%3D&reserved=0>
>> 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  <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.audriga.com%2F&data=05%7C01%7CDanny.Zollner%40microsoft.com%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=ugCOwiY5EXLH8EfrAacwK9%2FDCGnhMp3Sh7L%2Fo8WQNOA%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%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=e6nmZrdOJiUBA%2F31N1TwKLeeQTuwCVla%2FE4UuOds7AU%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
>>
>>     --------------------------------------------------------------------------
>>
>>     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*
>>         <https://nam06.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcontoso.com%2F&data=05%7C01%7CDanny.Zollner%40microsoft.com%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=%2B7DoMHkSX3An6CfG913vNi5zgP%2BAJY28kXSnR%2FgBr80%3D&reserved=0>*”*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=userName*would
>>         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]
>>         *Subject:*[EXTERNAL] [scim] Query on a specific known resource
>>
>>         	
>>         Some people who received this message don't often get email
>>         [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%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=jbbn1Y43e0GFmChjRVbpMnTKZEqlB5TzLgiJmhz7ZRY%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%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=wbOMKvqD9T7hP5OFtruAwY2r26XrKdncriLPSapazGQ%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%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=1BDZsY%2B1DkxD3t2ZObBwf5UHRZlnoXdE9UFuuBZioS0%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%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=ugCOwiY5EXLH8EfrAacwK9%2FDCGnhMp3Sh7L%2Fo8WQNOA%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%7C61a3ef6cefda487b73ef08da603f27f4%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637928122539415111%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=e6nmZrdOJiUBA%2F31N1TwKLeeQTuwCVla%2FE4UuOds7AU%3D&reserved=0>
>>
>>           
>>
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