Cursor-based Pagination of SCIM Resources
draft-peterson-scim-cursor-pagination-01
The information below is for an old version of the document.
| Document | Type |
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|---|---|---|---|
| Authors | Matt Peterson , Danny Zollner | ||
| Last updated | 2022-10-01 | ||
| Replaced by | draft-ietf-scim-cursor-pagination | ||
| RFC stream | (None) | ||
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| Consensus boilerplate | Unknown | ||
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draft-peterson-scim-cursor-pagination-01
SCIM M. Peterson
Internet-Draft One Identity
Updates: 7643, 7644 (if approved) D. Zollner
Intended status: Informational Microsoft
Expires: 1 April 2023 28 September 2022
Cursor-based Pagination of SCIM Resources
draft-peterson-scim-cursor-pagination-01
Abstract
This document defines additional SCIM query parameters and result
attributes to allow use of cursor-based pagination in SCIM
implementations that are implemented with existing code bases,
databases, or APIs where cursor-based pagination is already well-
established.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 1 April 2023.
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document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 2
2. Query Parameters and Response Attributes . . . . . . . . . . 3
2.1. Cursors as the Only Pagination Method . . . . . . . . . . 5
3. Querying Resources Using HTTP POST . . . . . . . . . . . . . 5
4. Service Provider Configuration . . . . . . . . . . . . . . . 6
5. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The two common patterns for result pagination in HTTP-based protocols
are index-based pagination and cursor-based pagination. Rather than
attempt to compare and contrast the advantages and disadvantages of
competing pagination patterns, this document simply recognizes that
SCIM service providers are commonly implemented as an
interoperability layer on top of already existing application
codebases, databases, and/or APIs that already have a well-
established pagination pattern.
Translating from an underlying cursor-based pagination pattern to the
index-based pagination defined in Section 3.4.2.4 of [RFC7644]
ultimately requires the SCIM service provider to fully iterate the
underlying cursor, store the results, and then serve indexed pages
from the stored results. This task of "pagination translation"
dramatically increases complexity and memory requirements for
implementing a SCIM Service Provider, and may be an impediment to
SCIM adoption for some applications and identity systems.
This document defines a simple addition to the SCIM protocol that
allows SCIM service providers to reuse underlying cursors without
expensive translation. Support for cursor-based pagination in SCIM
encourages broader cross-application identity management
interoperability by encouraging SCIM service provider implementations
for applications and identity systems where cursor-based pagination
is already well-established.
1.1. Notational Conventions
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].
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2. Query Parameters and Response Attributes
The following table describes the URL pagination parameters requests
for using cursor-based pagination:
+===========+===================================================+
| Parameter | Description |
+===========+===================================================+
| cursor | The string value of the nextCursor attribute from |
| | a previous result page. The cursor value MUST be |
| | empty or omitted for the first request of a |
| | cursor-paginated query. |
+-----------+---------------------------------------------------+
| count | A positive integer. Specifies the desired |
| | maximum number of query results per page, e.g., |
| | count=10. When specified, the service provider |
| | MUST NOT return more results than specified, |
| | although it MAY return fewer results. If count |
| | is not specified in the query, the maximum number |
| | of results is set by the service provider. |
+-----------+---------------------------------------------------+
Table 1
The following table describes cursor-based pagination attributes
returned in a paged query response:
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+================+===============================================+
| Element | Description |
+================+===============================================+
| nextCursor | A cursor value string that MAY be used in a |
| | subsequent request to obtain the next page of |
| | results. Service providers supporting |
| | cursor-based pagination MUST include |
| | nextCursor in all paged query responses |
| | except when returning the last page. |
| | nextCursor is omitted from a response only to |
| | indicate that there are no more result pages. |
+----------------+-----------------------------------------------+
| previousCursor | A cursor value string that MAY be used in a |
| | subsequent request to obtain the previous |
| | page of results. Use of previousCursor is |
| | OPTIONAL. Service Providers that are unable |
| | to support a previousCursor MAY omit |
| | previousCursor when sending paged query |
| | responses. |
+----------------+-----------------------------------------------+
Table 2
For example, to retrieve the first 10 Users, use an empty cursor and
set the count to 10:
GET /Users?cursor&count=10
Host: example.com
Accept: application/scim+json
Authorization: Bearer U8YJcYYRMjbGeepD
The response to the query above returns metadata regarding pagination
similar to the following example (actual resources removed for
brevity):
{
"totalResults":100,
"itemsPerPage":10,
"nextCursor":"VZUTiyhEQJ94IR",
"schemas":["urn:ietf:params:scim:api:messages:2.0:ListResponse"],
"Rsesources":[{
...
}]
}
Given the example above, to continue pagination, set the cursor to
the value of nextCursor ("VZUTiyhEQJ94IR") and re-fetch:
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GET /Users?cursor=VZUTiyhEQJ94I&count=10
Host: example.com
Accept: application/scim+json
Authorization: Bearer U8YJcYYRMjbGeepD
If a Service Provider encounters an invalid cursor or count value (or
other error condition), the Service Provider SHOULD return
appropriate HTTP response status code and JSON detail error response
as defined in Section 3.1.2 of [RFC7644].
2.1. Cursors as the Only Pagination Method
A SCIM Service Provider MAY require cursor-based pagination to
retrieve all results for a query by including a "nextCursor" value in
the response even when the original query does not include the
"cursor" parameter.
For example:
GET /Users
Host: example.com
Accept: application/scim+json
The SCIM Service Provider may responded to the above query with a
single page of results and a "nextCursor" value as shown in the below
example (Resources omitted for brevity):
{
"totalResults":5000,
"itemsPerPage":100,
"nextCursor":"HPq72Pax3JUaNa",
"schemas":["urn:ietf:params:scim:api:messages:2.0:ListResponse"],
"Resources":[{
...
}]
}
3. Querying Resources Using HTTP POST
Section 3.4.2.4 of [RFC7644] defines how clients MAY execute the HTTP
POST verb combined with the "/.search" path extension to issue
execute queries without passing parameters on the URL. When using
"./search", the client would pass the parameters defined in Section 2
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POST /User.search
Host: example.com
Accept: application/scim+json
Authorization: Bearer U8YJcYYRMjbGeepD
{
"schemas": [
"urn:ietf:params:scim:api:messages:2.0:SearchRequest"],
"attributes": ["displayName", "userName"],
"filter":
"displayName sw \"smith\"",
"cursor": "",
"count": 10
}
Which would return a result containing a "nextCursor" value which may
be used by the client in a subsequent call to return the next page of
resources
{
"totalResults":100,
"itemsPerPage":10,
"nextCursor":"VZUTiyhEQJ94IR",
"schemas":["urn:ietf:params:scim:api:messages:2.0:ListResponse"],
"Resources":[{
...
}]
}
4. Service Provider Configuration
The /ServiceProviderConfig resource defined in Section 4 of [RFC7644]
facilitates discovery of SCIM service provider features. A SCIM
Service provider implementing cursor-based pagination SHOULD include
the following additional attribute in JSON document returned by the
/ServiceProviderConfig endpoint:
pagination A complex type that indicates pagination configuration
options. OPTIONAL.
cursor A Boolean value specifying support of cursor-based
paginations. REQUIRED.
index A Boolean value specifying support of index-based
pagination. REQUIRED.
Before using cursor-based pagination, a SCIM client MAY fetch the
Service Provider Configuration document from the SCIM service
provider and verify that cursor-based pagination is supported.
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For example:
GET /ServiceProviderConfig
Host: example.com
Accept: application/scim+json
A service provider supporting both cursor-based pagination and index-
based pagination would return a document similar to the following
(full ServiceProviderConfig schema defined in Section 5 of [RFC7643]
has been omitted for brevity):
{
"schemas": [
"urn:ietf:params:scim:schemas:core:2.0:ServiceProviderConfig"],
...
"pagination": {
"cursor": true,
"index": true
},
...
}
5. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7643] Hunt, P., Ed., Grizzle, K., Wahlstroem, E., and C.
Mortimore, "System for Cross-domain Identity Management:
Core Schema", RFC 7643, DOI 10.17487/RFC7643, September
2015, <https://www.rfc-editor.org/info/rfc7643>.
[RFC7644] Hunt, P., Ed., Grizzle, K., Ansari, M., Wahlstroem, E.,
and C. Mortimore, "System for Cross-domain Identity
Management: Protocol", RFC 7644, DOI 10.17487/RFC7644,
September 2015, <https://www.rfc-editor.org/info/rfc7644>.
Authors' Addresses
Matt Peterson
One Identity
Email: matt.peterson@oneidentity.com
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Danny Zollner
Microsoft
Email: danny.zollner@microsoft.com
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