Internet DRAFT - draft-li-scim-user-scenarios

draft-li-scim-user-scenarios






SCIM WG                                                            K. Li
Internet-Draft                                       Huawei Technologies
Intended status: Informational                                  Jan 2013
Expires: July 5, 2013


                          SCIM User Scenarios
                    draft-li-scim-user-scenarios-00

Abstract

   This document lists the user scenarios of System for Cross-domain
   Identity Management (SCIM).

Status of this Memo

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   This Internet-Draft will expire on July 5, 2013.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  SCIM User Scenarios  . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Background & Context . . . . . . . . . . . . . . . . . . .  3
     2.2.  Model Concepts . . . . . . . . . . . . . . . . . . . . . .  3
       2.2.1.  Triggers . . . . . . . . . . . . . . . . . . . . . . .  3
       2.2.2.  Actors . . . . . . . . . . . . . . . . . . . . . . . .  4
       2.2.3.  Modes & Flows  . . . . . . . . . . . . . . . . . . . .  5
       2.2.4.  Bulk & Batch Operational Semantics . . . . . . . . . .  6
     2.3.  Cloud Service Provider to Cloud Service Provider Flows
           (CSP->CSP) . . . . . . . . . . . . . . . . . . . . . . . .  6
       2.3.1.  CSP->CSP - Create Identity (Push)  . . . . . . . . . .  6
       2.3.2.  CSP->CSP - Update Identity (Push)  . . . . . . . . . .  7
       2.3.3.  CSP->CSP - Delete Identity (Push)  . . . . . . . . . .  7
       2.3.4.  CSP->CSP - SSO Trigger (Push)  . . . . . . . . . . . .  7
       2.3.5.  CSP->CSP - SSO Trigger (Pull)  . . . . . . . . . . . .  8
       2.3.6.  CSP->CSP - Password Reset (Push) . . . . . . . . . . .  8
     2.4.  Enterprise Cloud Subscriber to Cloud Service Provider
           Flows(ECS->CSP)  . . . . . . . . . . . . . . . . . . . . .  8
       2.4.1.  ECS->CSP - Create Identity (Push)  . . . . . . . . . .  8
       2.4.2.  ECS ->CSP - Update Identity (Push) . . . . . . . . . .  9
       2.4.3.  ECS ->CSP - Delete Identity (Push) . . . . . . . . . .  9
       2.4.4.  ECS ->CSP - SSO Pull . . . . . . . . . . . . . . . . .  9
   3.  Recommendations  . . . . . . . . . . . . . . . . . . . . . . .  9
   4.  Security considerations  . . . . . . . . . . . . . . . . . . .  9
   5.  IANA considerations  . . . . . . . . . . . . . . . . . . . . .  9
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  Informative References . . . . . . . . . . . . . . . . . . . . 10
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10





















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1.  Introduction

   This document describes the SCIM user scenarios.  The document's
   objective is to help with understanding of the design and
   applicability of SCIM schema [I-D.ietf-scim-core-schema] and SCIM
   protocol [I-D.ietf-scim-api].

   The following section provides the abbreviated descriptions of the
   user scenarios.


2.  SCIM User Scenarios

2.1.  Background & Context

   The Simple Cloud Identity Management (SCIM) specification is designed
   to make managing user identity in cloud based applications and
   services easier.  The specification suite seeks to build upon
   experience with existing schemas and deployments, placing specific
   emphasis on simplicity of development and integration, while applying
   existing authentication, authorization, and privacy models.  It's
   intent is to reduce the cost and complexity of user management
   operations by providing a common user schema and extension model, as
   well as binding documents to provide patterns for exchanging this
   schema using standard protocols.  In essence, make it fast, cheap,
   and easy to move users in to, out of, and around the cloud.

   The SCIM user scenarios are overview user stories designed to help
   clarify the intended scope of the SCIM effort.

2.2.  Model Concepts

2.2.1.  Triggers

   Quite simply, triggers are actions or activities that start SCIM
   flows.  Triggers may not be relevant at the protocol or the schema,
   they really serve to help identity the type or activity that resulted
   in a SCIM protocol exchange.  Triggers make use of the traditional
   provisioning C.R.U.D (Create Retrieve Modify & Delete) operations but
   add additional use case contexts like "SSO" as it is designed to
   capture a class of use case that makes sense to the actor requesting
   it rather than to describe a protocol operation.

   o  Create SCIM Identity Resource - Service On-boarding Trigger: A
      create SCIM resource trigger is a service on-boarding activity in
      which a business action such as a new hire or new service
      subscription is initiated by one of the SCIM Actors.  In the
      protocol itself, service on-boarding may well be implemented via



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      the same resource PUT method as a service change.  This is
      particular to the implementation not to the use cases that drive
      that implementation.

   o  Update SCIM Identity Resource - Service Change Trigger: An Update
      SCIM resource trigger is a service change activity as a result of
      an identity moving or changing its service level.  An Update
      Identity trigger might be the result of a change in a service
      subscription level or a change to key identity data used to denote
      a service subscription level.  Password changes are specifically
      called out from other more general identity attribute changes as
      they are considered to have specific use case differences.

   o  Delete SCIM Identity Resource - Service Termination Trigger: A
      delete SCIM resource trigger represents a specific and deliberate
      action to remove an identity from a given SCIM service point.  At
      this stage it is unclear if the SCIM protocol needs to identify
      separate protocol exchange for a service suspension actions.  This
      may be relevant as target services usually differentiate between
      these result and may require separate resource representations as
      a result.

   o  Single-Sign On (SSO) Trigger - Real-time Service Access Request: A
      SSO trigger is a special class of activity in which a Create or
      Update trigger is initiated during an SSO operational flow.  The
      implication here is that as the result of a real-time service
      access request by the end user (SSO), defined SCIM protocol
      exchanges can be used to initiate SCIM resource CRUD somewhere in
      the service cloud.

2.2.2.  Actors

   Actors are the operating parties that take part in both sides of a
   SCIM protocol exchange, and help identify the source of a given
   Trigger.  So far, we have identified the following SCIM Actors:

   o  Cloud Service Provider (CSP): A CSP is the entity operating a
      given cloud service.  In a SaaS scenario this is simply the
      application provider.  In an IaaS or PaaS scenario, the CSP may be
      the underlying IaaS/PaaS infrastructure provider or the owner of
      the application running on that platform.  In all cases, the CSP
      is the thing that holds the identity information being operated
      upon.  Put another way, the CSP really is the service that the
      end-end user interacts with.

   o  Enterprise Cloud Subscriber (ECS): An ECS represents a middle-tier
      of aggregation for related identity records.  In one of our sample
      enterprise SaaS scenarios, the ECS is "FooBar.Inc" that subscribes



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      to a cloud based CRM service "SaaS-CRM.Inc" (the CSP) for all of
      its sales staff.  The actual Cloud Service Users (CSUs) are the
      FooBar.Inc. sales staff.  The ECS actor is identified to help
      capture use cases in which a single entitle is given
      administrative responsibility for other identity accounts.  SCIM
      may not address the configuration and setup of an ECS within the
      CSP, but it does address use cases in which SCIM identity
      resources are grouped together and administers as part of some
      broader agreement or operational exchange.

   o  Cloud Service User (CSU): A CSU represents the real cloud service
      end-end user - the "person logging into and using the cloud
      service".  As described above, and ECS will typically own or
      manage multiple CSU identities where as the CSU represents the
      FooBar.Inc. employee using the cloud service to manage their CRM
      process.


                             +---------------------+
                             |   Cloud Service     |
                             |   Provider (CSP)    |
                             +---------------------+
                                       |
                      +--------------------------------+
                      |                                |
                      v                                v
              +----------------+              +----------------+
              |Enterprise Cloud|              |Enterprise Cloud|
              |Subscriber (ECS)|              |Subscriber (ECS |
              +----------------+              +----------------+
                      |                                |
              +----------------+              +----------------+
              |                |              |                |
              v                v              v                v
      +-------------+ +-------------+   +-------------+ +-------------+
      |Cloud Service| |Cloud Service|   |Cloud Service| |Cloud Service|
      |  User (CSU) | |  User (CSU) |   |  User (CSU) | |  User (CSU) |
      +-------------+ +-------------+   +-------------+ +-------------+

                           Figure 1: SCIM Actors

2.2.3.  Modes & Flows

   Modes identify the functional intent of a data-flow initiated in a
   SCIM scenario.  The modes identified so far are 'push' and 'pull'
   referring to the fact of pushing data to, or pulling data from an
   authoritative identity data store.




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   In the SCIM scenarios, Modes are often used in the context of a flow
   between two Actors.  For example, one might refer to a Cloud-to-Cloud
   Pull exchange.  Here one Cloud Service Provider (CSP) is pulling
   identity information from another CSP.  Commonly referenced flows
   are:

   o  Cloud Service Provider to Cloud Service Provider (CSP->CSP)

   o  Enterprise Cloud Subscriber to Cloud Service Provider (ECS-CSP)

   Modes & flows simply help us understand what is taking place; they
   are likely to be technically meaningless at the protocol level, but
   again they help the reader follow the SCIM scenarios and apply them
   to real work use cases.

2.2.4.  Bulk & Batch Operational Semantics

   It is assumed that each of the triggers action outlined in this
   document may be part of the larger bulk or batch operation.
   Individual SCIM actions should be able to be collected together to
   create single protocol exchanges.

   The initial focus of SCIM scenarios is on identifying base flows and
   single operations.  The specific complexity of full bulk and batch
   operations is left to a later version of the scenarios or to the main
   specification.

2.3.  Cloud Service Provider to Cloud Service Provider Flows (CSP->CSP)

   These scenarios represent flows between two Cloud Service Providers
   (CSPs).  It is assumed that each CSP maintains an Identity Data Store
   for its Cloud Service Users (CSUs).  These scenarios address various
   joiner, mover, leaver and JIT triggers, resulting in push and pull
   data exchanges between the CSPs.

2.3.1.  CSP->CSP - Create Identity (Push)

   In this scenario two CSPs (CSP-1 & CSP-2) have a shared service
   agreement in place that requires the exchange of Cloud Service User
   (CSU) accounts.  CSP-1 receives a Create Identity trigger action from
   its Enterprise Cloud Subscriber (ECS-1).  CSP-1 creates a local user
   account for the new CSU.  CSP-1 then pushes the new CSU joiner push
   request down-stream to CSU-2 and gets confirmation that the account
   was successfully created.  After receiving the confirmation from
   CSP-2, CSP-1 sends an acknowledgement to the requesting ECS.






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2.3.2.  CSP->CSP - Update Identity (Push)

   In this scenario two CSP's (CSP-1 & CSP-2) have a shared service
   agreement in place that requires the exchange of Cloud Service User
   (CSU) accounts.  The Enterprise Cloud Subscriber (ECS-1) has already
   created an account with CSP-1 and supplied a critical attribute
   "department" that is used by CSP-1 to drive service options.  CSP-1
   then receives an Update Identity trigger action from its Enterprise
   Cloud Subscriber (ECS).  CSP-1 updates its local directory account
   with the new department value.  CSP-1 then initiates a separate SCIM
   protocol exchange to push the mover change request down-stream to
   CSP-2.  After receiving the confirmation from CSP-2, CSP-1 sends an
   acknowledgment to ECS-1.

2.3.3.  CSP->CSP - Delete Identity (Push)

   In this scenario two CSPs (CSP-1 & CSP-2) have a shared service
   agreement in place that requires the exchange of Cloud Service User
   (CSU) accounts.  CSP-1 receives a Delete Identity trigger action from
   its Enterprise Cloud Subscriber (ECS-1).  CSP-1 suspends the local
   directory account for the specified CSU account.  CSP-1 then pushes a
   termination request for the specified CSU account down-stream to
   CSP-2 and gets confirmation that the account was successfully
   removed.  After receiving the confirmation from CSP-2, CSP-1 sends an
   acknowledgment to the requesting ECS.

   This use case highlights how different CSPs may implement different
   operational semantics behind the same SCIM operation.  Note CSP-1
   suspends the account representation for its service where as CPS-2
   implements a true delete operation.

2.3.4.  CSP->CSP - SSO Trigger (Push)

   In this scenario two CSPs (CSP-1 & CSP-2) have a shared service
   agreement in place that requires the exchange of Cloud Service User
   (CSU) accounts.  However, rather than pre-provisioning accounts from
   CSP-1 to CSP-2, CSP-1 waits for a service access request from the end
   Cloud Service User (CSU-1) before issuing account creation details to
   CSP-2.  When the CSU completes a SSO transaction from CSP-1 to CSP-2,
   CSP-2 then creates an account for the CSU based on information pushed
   to it from CSP-1.

   At the protocol level, this class of scenarios may result in the use
   of common protocol exchange patters between CSP-1 & CSP-2.







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2.3.5.  CSP->CSP - SSO Trigger (Pull)

   In this scenario two CSPs (CSP-1 & CSP-2) have a shared service
   agreement in place that requires the exchange of Cloud Service User
   (CSU) accounts.  However, rather than pre-provisioning accounts from
   CSP-1 to CSP-2, CSP-2 waits for a service access request from the
   Cloud Service User (CSU-1) before initiating a Pull request to gather
   information about the CSU sufficient to create a local account.

   At the protocol level, this class of scenarios may result in the use
   of common protocol exchange patterns between CSP-2 & CSP-1.

2.3.6.  CSP->CSP - Password Reset (Push)

   In this scenario two CSPs (CSP-1 & CSP-2) have a shared service
   agreement in place that requires the exchange of Cloud Service User
   (CSU) accounts.  CSP-1 wants to change the password for a specific
   Cloud Service User (CSU-1).  CSP-1 sends a request to CSP-2 to reset
   the password value for CSU-1.

   At the protocol level, this scenario may result in the same protocol
   exchange as any other attribute change request.

2.4.  Enterprise Cloud Subscriber to Cloud Service Provider
      Flows(ECS->CSP)

   These scenarios represent flows between an Enterprise Cloud
   Subscriber (ECS) and a Cloud Service Providers (CSP).  It is assumed
   that both the ECS and the CSP maintains an LDAP service for the
   relevant Cloud Service Users (CSUs).  These scenarios address various
   joiner, mover, leaver and JIT triggers, resulting in push and pull
   data exchanges between the ECS and the CSP.

   Many of these scenarios are very similar to those defined in the
   Cloud Service Provider to Cloud Service Provider section above.  They
   are identified separately here so that we may explore any differences
   and might emerge.

2.4.1.  ECS->CSP - Create Identity (Push)

   In this scenario an Enterprise Cloud Subscriber (ECS-1) maintains a
   service with a Cloud Service Provider (CSP-1) that requires the
   sharing of various Cloud Service User (CSU) accounts.  A new user
   joins ECS-1 and so ECS-1 pushes an account creation request to CSP-1,
   supplying all required base SCIM schema attribute values and
   additional extended SCIM schema values as required.





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2.4.2.  ECS ->CSP - Update Identity (Push)

   In this scenario an Enterprise Cloud Subscriber (ECS-1) maintains a
   service with Cloud Service Provider (CSP-1) that drives service
   definition from a key account schema attribute called Department.
   ECS-1 wishes to move a given CSU from Department A to Department B
   and so it pushes an attribute update request to the CSP.

2.4.3.  ECS ->CSP - Delete Identity (Push)

   In this scenario an Enterprise Cloud Subscriber (ECS-1) maintains a
   service with a Cloud Service Provider (CSP-1).  Upon termination of
   one of its employees' employment agreement, ECS-1 sends a suspend
   account request to CSP-1 (Figure 1.4.3-1).  One week later the ECS
   wishes to complete the process by fully removing the Cloud Service
   User (CSU) account and so it sends a terminate account request to
   CSP-1.

2.4.4.  ECS ->CSP - SSO Pull

   In this scenario an Enterprise Cloud Subscriber (ECS-1) maintains a
   service with a Cloud Service Provider (CSP-1).  No accounts are
   created or exchanged in advance.  However, rather than pre-
   provisioning accounts from ECS-1 to CSP-1, CSP-1 waits for a service
   access request from the Cloud Service User (CSU-1) under the control
   domain of ECS-1, before issuing an account Pull request to CSP-1.


3.  Recommendations

   The recommendation is to merge the user scenarios document into the
   use case document as section 2.


4.  Security considerations

   TBD


5.  IANA considerations

   This Internet Draft includes no request to IANA.


6.  Acknowledgements

   Authors would like to thank Darran Rolls and Patrick Harding, most of
   the texts in this document are taken from them.



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   Thanks to Bert Greevenbosch for his review and feedback.


7.  Informative References

   [I-D.ietf-scim-api]
              Drake, T., Mortimore, C., Ansari, M., Grizzle, K., and E.
              Wahlstroem, "System for Cross-Domain Identity Management:
              Protocol", draft-ietf-scim-api-00 (work in progress),
              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", draft-ietf-scim-core-schema-00 (work in
              progress), August 2012.


Author's Address

   Kepeng LI
   Huawei Technologies
   Bantian
   Shenzhen, Guangdong  518129
   China

   Email: likepeng@huawei.com
























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