Network Working Group P. Hunt, Ed.
Internet-Draft Oracle
Intended status: Standards Track K. Grizzle
Expires: June 27, 2013 Sailpoint
B. Annestad
UnboundID
M. Ansari
CISCO
D. Olds
VMWare
December 24, 2012

SCIM 2.0 Token Search Extension
draft-hunt-scim-tokensearch-00

Abstract

The SCIM 2.0 Core API defines a simple profile for searching for specific resource types using filters and qualifiers in combination with the HTTP GET verb. The Token Search specification defines the following additional features:

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on June 27, 2013.

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Table of Contents

1. Introduction

The SCIM Core API is an application-level, RESTful service for provisioning and managing identity data on the web. The SCIM Core API specification[I-D.ietf-scim-api] defines methods for creation, modification, retrieval and discovery of resources. This specification extends SCIM Core API capabilities to support extended searching operations:

[Discuss: This extension specification does not propose any change in functionality to the existing GET search functions with the exception of making resourceType a searchable filter term and returning resourceType in all JSON resource representations]

[Note: this specification may be optionally combined with the SCIM core API spec]

1.1. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].

Note: For readability and space reasons, some included examples and attribute values, and UUID identifiers are shortened.

2. Search Extension

The SCIM protocol specifies well known endpoints and HTTP methods for managing resources in the core schema. In SCIM Extended Search, a virtual resource known as a "search" is defined. A "search" is a RESTful representation of a search of a set of objects in a SCIM Service Provider. A SCIM extended "search" endpoint can be appended to any normal SCIM endpoint in order to define open scope and specific resource scoped searches.

SCIM Extended Searches are defined (in ABNF [RFC5234]) as follows:

SCIMSEARCH   = scimEndpoint [scimSearch] ["/" UUID] ["?" query]

scimEndpoint = "https://" authority [path-absolute] [scimVers] 
               [scimResType] ["/" UUID]
        
scimSearch   = "/.search"

authority    = [ userinfo "@" ] host [ ":" port ]

scimVers     = "/V" 1*DIGIT

scimResType  = "/Users" / "/Groups" / "/" 1*extResChar

extResChar   = "-" / "." / "_" / DIGIT / ALPHA

Figure 1: ABNF for SCIM Search Endpoints

[Discussion: since a search within a "/Users" endpoint could be confused with a resource, do we want to have something more jarring like "xsearch" or ".search" (as in well-known urls)?]

Where:

scimSearch
Is a special path qualifier that indicates the operation is related to a search. When used with HTTP GET, scimSearch is OPTIONAL.
authority, path-absolute, userinfo, host, port
Are defined as per URI Syntax ABNF [RFC3986]
query
Is any SCIM query term as specified in section 3.2 of the SCIM Core API [I-D.ietf-scim-api].
scimVers
Is the SCIM Service Provider API version.
scimResType
Is a SCIM resource type such as "Users", "Groups" or any other schema extended resource supported by the service provider.
UUID
Identifies a unique SCIM resource or SCIM search result that is retrievable from the SCIM Service Provider (see [RFC4122]).

Example SCIM Search endpoints include:

http://example.com/scim/v2/.search

for server-wide searches
http://example.com/scim/v2/Users/.search

for searches of User resources only
http://example.com/scim/v2/Groups/.search

for searches of Group resources only
http://example.com/scim/v2/.search?searchId=607dac9b24a2;startIndex=20

to return results from a previously executed query

Token search is initiated by using either an HTTP POST or HTTP GET command (see next sections) to pass search parameters AND by setting the parameter "stateful" to "true". The server responds and returns results in a JSON result set along with a searchId token if stateful results are available.

2.1. Search Tokens

From the clients perspective, as with any HTTP is a stateless protocol. When performing searches requiring several pages of results to be returned, there is always the possibility to have inconsistent results should the underlying data change between requests. SCIM Service Providers MAY optionally maintain a stateful representation of search results that may be accessed by the client using a token.

Once a search result "searchId" token has been created, a client may peform GET requests using the parameter "searchId" and "startIndex" to return additional result pages. Any other parameters and path are IGNORED when "searchId" is present. The searchId token allows the service provider to respond with consistent stateful results, using pagination commands as defined in section 3.2.2.3 of the SCIM Core API.

[Discussion: Can an existing search result be used in combination with a new search or ordering request to sub-search within an existing set of results? E.g. would it make sense to allow a PUT against an existing search result?]

2.2. Filter Processing Across Multiple Resource Types

When the SCIM Extended Search specification is supported, Filtering, as defined in the SCIM Core API, section 3.2.2.1 is REQUIRED.

When processing search operations across endpoints that MAY include more than one SCIM resource type (e.g. a search from the server root endpoint), filters MUST be processed in the same fashion as outlined in 3.2.2.1 of the SCIM Core API. For filtered attributes that are not part of a particular resource type, the service provider SHALL treat the attribute as if there is no attribute value. For example, a presence or equality filter for an undefined attribute evaluates as FALSE.

2.3. Search Request Using HTTP POST

To create a new search result set, clients send an HTTP POST request to the desired SCIM resource endpoint (see Figure 1). The body of the POST request MAY include any of the parameters as defined in section 3.2 of the SCIM Core API.

An additional parameter "stateful" MAY be set to "true" in order to request stateful results from the server. Note that the presence of this parameter DOES NOT require that the server produce a stateful result set. Detection of stateful results is described in Section 2.5.1.

After receiving a HTTP POST request, a response is returned as specified in Section 2.5.

The following example shows an HTTP POST Search request with search parameters attributes, filter, and count included:

POST /.search
Host: example.com
Accept: application/json
Content-Type: application/json
Authorization: Bearer h480djs93hd8
Content-Length: ...

{
  "schemas": ["urn:scim:schemas:core:1.0"],
  "attributes":["displayName","username"],
  "filter":"displayName sw \"smith\"",
  "stateful":"true",
  "count":10
}

Figure 2: Example POST Search Request

[TBD - are there any cases for persistent searches?]

[TBD - should there be additional options to control where result state is maintained, lifetime, etc. Controls wheter subsequent gets cause re-queries or whether result set consistency is maintained for the life of the result set]

2.4. Search Request Using HTTP GET

When an HTTP GET request is made against a search endpoint (see Figure 1) a new search result is created. The parameters and arguments are as defined in section 3.2 of the SCIM Core API.

An additional parameter "stateful" MAY be set to "true" in order to request stateful results from the server. Note that the presence of this parameter DOES NOT require that the server produce a stateful result set. Detection of stateful results is described in Section 2.5.1.

After receiving an HTTP GET request, a response is returned as specified in Section 2.5.

The following example is the HTTP GET equivalent of the example shown in Figure 2.

GET /.search?attributes="displayName,username"
    &filter=displayName sw "smith"&count=10&stateful="true"
Host: example.com
Accept: application/json
Authorization: Bearer h480djs93hd8

Figure 3: Example GET Search Request

2.5. Search Response

2.5.1. Server Processing

If, on receiving a search request, only a single resource is matched, the server SHALL respond with an HTTP status code of 200 and include the single JSON formatted search result in the body of the response as specified in the SCIM Core API.

If multiple resources are to be returned in a single response, the server SHALL respond with an HTTP status code of 200 and a body containing an array of "Resources" in a JSON structure up to the default server limit OR the number of records specified in SCIM pagination parameter 'count'.

If more results are available than returned and the client request included the parameter "stateful" whose value is "true", Service Providers MAY support stateful paged results by returning an HTTP status code of 201 and include an attribute "searchId" specifying a token that MAY be used to obtain additional results in a stateful manner.

If the client DID NOT specify "stateful" as "true", OR Servers NOT supporting stateful results MUST return an HTTP status of 200 and a page of results as per the normal HTTP GET request of the SCIM Core API.

[Is it more appropriate in token mode for status 200 to be returned?]

Regardless of the number of resources returned or the search endpoint, the server SHALL include the following meta attributes with each resource JSON structure:

location
the permenant location URI of the returned object
resourceType
a string (scimResType) representing the type of resource returned (e.g. "User", "Group").

A search response is shown with the first page of results. For brevity reasons, only two matches are shown: one User and one Group. A status of 201 and a location header is returned with the result set identifier indicating more results are available in stateful representation. A subsequent GET to the location allows multiple pages of results to be returned while preserving the original result set using a search session identifier. As described in section 3.2.2.3, the response includes pagination response attributes: itemsPerPage, totalResults, and startIndex.

HTTP/1.1 201 Created
Content-Type: application/json
Location: https://example.com/.search
{
  "totalResults":100,
  "itemsPerPage":10,
  "startIndex":1,
  "searchId":"131dc0667e20"
  "schemas":["urn:scim:schemas:core:1.0"],
  "Resources":[
    {
      "meta":{
        "location":
          "https://example.com/Users/2819c223-7f76-413861904646",
        "resourceType":"User",
        "lastModified": ...
      }
      "username":"jsmith",
      "displayName":"Smith, James"
    },
    {
      "meta":{
        "location":
          "https://example.com/Groups/c8596b90-7539-4f20968d1908",
        "resourceType":"Group",
        "lastModified": ...
      }
      "displayName":"Smith Family"
    },
     ...
  ]
} 

Figure 4: Example POST Search Response

[Discuss: Instead of returning a location identifier for paging, how about using a "token" for paging?]

2.5.2. Client Processing

If the initial search response has status 201 and a "searchId" attribute is present, SCIM clients MAY obtain additional page results in a stateful fashion using the SCIM Core API "startIndex" pagination parameter as described in the following Section 2.6. Alternatively, SCIM clients MAY ignore the stateful results location, and request additional paged results as per the normal SCIM Core API stateless functionality which causes new results to be generated with each page request.

2.6. Querying An Existing Result

A SCIM client MAY request additional results after an initial search request has been returned with a status 201 and a "searchId" token has been provided. The client requests additional pages by using the "searchId" parameter which is set to the provided token value, along with "startIndex" and "count" parameters.

SCIM clients SHOULD NOT expect that search results will be maintained indefinitely and SHOULD request additional results in a reasonable time frame.

In the code example below, a request is made to return results starting with the 11th item in the result set identified by the identifier 2a7229cc-d9dc-4153-131dc0667e20. The identifier is used to ensure consistent results in the event the underlying data has changed since the original query was posted.

GET /v2/.search?startIndex=11&count=10
      &searchId=2a7229cc-d9dc-4153-131dc0667e20
HOST: example.com
Accept: application/json
Content-Type: application/json
Authorization: Bearer h480djs93hd8

Figure 5: Example Consistent Paged Result Set Query Request

After all results have been returned, OR after a reasonable period, the Service Provider MAY automatically delete the result set. A subsequent attempt to retrieve results from a deleted result set SHALL return an HTTP/1.1 404 NOT FOUND error.

2.7. Abandoning Search Results

If a client decides not to retrieve all results in a stateful search, a client SHOULD inform the Service Provider that it is finished with a result set by issuing an HTTP DELETE with the searchId token provided as a parameter to the endpoint where the original search was requested. Upon receiving a DELETE request, the server SHALL respond with status 200 (OK) if the search request was deleted or status 404 (NOT FOUND) if the result has already been deleted or otherwise expired.

DELETE /Users/.search?searchId=64b6efd7-6598-4dbc-ab3a-af38dad71493
Host: example.com
Authorization: Bearer h480djs93hd8


HTTP/1.1 200 OK

Figure 6: Cancelling Search Results Set

Servers MAY choose to automatically expire search results after all results have been returned or after a period of time in which no additional requests have been received for the search result. Upon automatically expiring a search result, any further request to return a result or delete a result SHOULD return a status of 404 (NOT FOUND).

2.8. ServiceProviderConfig Discovery

[TBD]

ServiceProviderConfig will require a new set of "search" attributes that indicate what is supported. For example:

  • root search
  • post search
  • stateful paged search results

3. Acknowledgements

[TBD]

4. IANA Considerations

This memo includes no request to IANA.

5. Security Considerations

Implementers should consider that the creation of search results can lead to depletion of server resources creating a vector for denial-of-service attacks. Implementers and deploiyers should take appropriate counter measures such as:

  • limiting which clients may use extended search,
  • limiting the number of extended searches any client MAY execute in a session or HTTP connection,
  • encourage clients to delete search results using the HTTP DELETE command in order to free resources,
  • limiting the time a search result is retained, and
  • purging unused or expired search results.

[Others TBD]

6. References

6.1. Normative References

[I-D.ietf-scim-api] Drake, T, Mortimore, C, Ansari, M, Grizzle, K and E Wahlstroem, "System for Cross-Domain Identity Management:Protocol", Internet-Draft draft-ietf-scim-api-00, August 2012.
[I-D.ietf-scim-core-schema] Mortimore, C, Harding, P, Madsen, P and T Drake, "System for Cross-Domain Identity Management: Core Schema", Internet-Draft draft-ietf-scim-core-schema-00, August 2012.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC3986] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005.
[RFC4122] Leach, P., Mealling, M. and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2005.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.

6.2. Informative References

[I-D.narten-iana-considerations-rfc2434bis] Narten, T and H Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", Internet-Draft draft-narten-iana-considerations-rfc2434bis-09, March 2008.

Authors' Addresses

Phil Hunt (editor) Oracle EMail: phil.hunt@yahoo.com
Kelly Grizzle Sailpoint
Bjorn Aannestad UnboundID
Morteza Ansari CISCO
Dale Olds VMWare