Network Working Group                                    A. Backman, Ed.
Internet-Draft                                                    Amazon
Intended status: Standards Track                           M. Jones, Ed.
Expires: October 18, 2018                                      Microsoft
                                                            P. Hunt, Ed.
                                                            M. Scurtescu
                                                               M. Ansari
                                                              A. Nadalin
                                                          April 16, 2018

                Push-Based SET Token Delivery Using HTTP


   This specification defines how a series of security event tokens
   (SETs) may be delivered to a previously registered receiver using
   HTTP POST over TLS initiated as a push to the receiver.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 18, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents

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   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction and Overview . . . . . . . . . . . . . . . . . .   2
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   3
     1.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  SET Event Stream Protocol . . . . . . . . . . . . . . . . . .   4
     2.1.  Event Delivery Process  . . . . . . . . . . . . . . . . .   4
     2.2.  Push Delivery using HTTP  . . . . . . . . . . . . . . . .   5
     2.3.  Error Response Handling . . . . . . . . . . . . . . . . .   7
   3.  Authentication and Authorization  . . . . . . . . . . . . . .   8
     3.1.  Use of Tokens as Authorizations . . . . . . . . . . . . .   9
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     4.1.  Authentication Using Signed SETs  . . . . . . . . . . . .  10
     4.2.  HTTP Considerations . . . . . . . . . . . . . . . . . . .  10
     4.3.  TLS Support Considerations  . . . . . . . . . . . . . . .  10
     4.4.  Authorization Token Considerations  . . . . . . . . . . .  11
       4.4.1.  Bearer Token Considerations . . . . . . . . . . . . .  11
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Appendix A.  Other Streaming Specifications . . . . . . . . . . .  14
   Appendix B.  Acknowledgments  . . . . . . . . . . . . . . . . . .  16
   Appendix C.  Change Log . . . . . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction and Overview

   This specification defines how a stream of SETs (see
   [I-D.ietf-secevent-token]) can be transmitted to a previously
   registered Event Receiver using HTTP [RFC7231] over TLS.  The
   specification defines a method to push SETs via HTTP POST.

   This specification defines a method for SET delivery in what is known
   as Event Streams.

   This specification does not define the method by which Event Streams
   are defined, provisioned, managed, monitored, and configured and is
   out of scope of this specification.

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   [[This work is TBD by the SECEVENTS WG]]

1.1.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   For purposes of readability examples are not URL encoded.
   Implementers MUST percent encode URLs as described in Section 2.1 of
   [RFC3986] .

   Throughout this documents all figures MAY contain spaces and extra
   line-wrapping for readability and space limitations.  Similarly, some
   URI's contained within examples, have been shortened for space and
   readability reasons.

1.2.  Definitions

   This specification assumes terminology defined in the Security Event
   Token specification[I-D.ietf-secevent-token] .

   The following definitions are defined for Security Event

   Event Transmitter
      A service provider that delivers SETs to other providers known as
      Event Receivers.  An Event Transmitter is responsible for offering
      a service that allows the Event Receiver to check the Event Stream
      configuration and status known as the "Control Plane".

   Event Receiver
      A service provider that registers to receive SETs from an Event
      Transmitter and provides an endpoint to receive SETs via HTTP
      POST.  Event Receivers can check current Event Stream
      configuration and status by accessing the Event Transmitters
      "Control Plane".

   Event Stream
      An Event Stream is a defined location, distribution method and
      whereby an Event Transmitter and Event Receiver exchange a pre-
      defined family of SETs.  A Stream is assumed to have configuration
      data such as HTTP endpoints, timeouts, public key sets for signing
      and encryption, and Event Families.


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      The security subject around which a security event has occurred.
      For example, a security subject might per a user, a person, an
      email address, a service provider entity, an IP address, an OAuth
      Client, a mobile device, or any identifiable thing referenced in
      security and authorization systems.

      An Event is defined to be an event as represented by a security
      event token (SET).  See [I-D.ietf-secevent-token].

      A JSON numeric value representing the number of seconds from
      1970-01-01T00:00:00Z UTC until the specified UTC date/time,
      ignoring leap seconds.  This is equivalent to the IEEE Std 1003.1,
      2013 Edition [POSIX.1] definition "Seconds Since the Epoch", in
      which each day is accounted for by exactly 86400 seconds, other
      than that non-integer values can be represented.  See [RFC3339]
      for details regarding date/times in general and UTC in particular.

2.  SET Event Stream Protocol

   An Event Stream represents the communication channel over which a
   series of SETs are delivered to a configured Event Receiver.

2.1.  Event Delivery Process

   When an Event occurs, the Event Transmitter constructs a SET token
   [I-D.ietf-secevent-token] that describes the Event.  The Event
   Transmitter determines the Event Streams over which the SET should be
   distributed to.

   How SETs are defined and the process by which Events are identified
   for Event Receivers is out-of-scope of this specification.

   When a SET is available for an Event Receiver, the Event Transmitter
   attempts to deliver the SET based on the Event Receiver's registered
   delivery mechanism:

   o  The Event Transmitter uses an HTTP/1.1 POST to the Event Receiver
      endpoint to deliver the SET;

   o  Or, the Event Transmitter delivers the Event through a different
      method not defined by this specification.

   In Push-Based SET Delivery Using HTTP, SETs are delivered one at a
   time using HTTP POST requests by an Event Transmitter to an Event
   Receiver.  The HTTP request body is a JSON Web Token [RFC7519] with a
   "Content-Type" header of "application/secevent+jwt" as defined in

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   Section 2.2 and 6.2 of [I-D.ietf-secevent-token].  Upon receipt, the
   Event Receiver acknowledges receipt with a response with HTTP Status
   202, as described below in Section 2.2.

   After successful (acknowledged) SET delivery, Event Transmitters
   SHOULD NOT be required to maintain or record SETs for recovery.  Once
   a SET is acknowledged, the Event Receiver SHALL be responsible for
   retention and recovery.

   Transmitted SETs SHOULD be self-validating (e.g. signed) if there is
   a requirement to verify they were issued by the Event Transmitter at
   a later date when de-coupled from the original delivery where
   authenticity could be checked via the HTTP or TLS mutual

   Upon receiving a SET, the Event Receiver reads the SET and validates
   it.  The Event Receiver MUST acknowledge receipt to the Event
   Transmitter, using the defined acknowledgement or error method.

   The Event Receiver SHALL NOT use the Event acknowledgement mechanism
   to report Event errors other than relating to the parsing and
   validation of the SET.

2.2.  Push Delivery using HTTP

   This method allows an Event Transmitter to use HTTP POST
   (Section 4.3.3 [RFC7231]) to deliver SETs to a previously registered
   web callback URI supplied by the Event Receiver as part of an Event
   Stream configuration process (not defined by this document).

   The SET to be delivered MAY be signed and/or encrypted as defined in

   The Event Stream configuration defines a URI of an Event Receiver
   provided endpoint which accepts HTTP POST requests (e.g.

   The HTTP Content-Type (see Section [RFC7231]) for the HTTP
   POST is "application/secevent+jwt" and SHALL consist of a single SET
   (see [I-D.ietf-secevent-token]).  As per Section 5.3.2 [RFC7231], the
   expected media type ("Accept" header) response is "application/json".

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   To deliver an Event, the Event Transmitter generates an event
   delivery message and uses HTTP POST to the configured endpoint with
   the appropriate "Accept" and "Content-Type" headers.

   POST /Events  HTTP/1.1

   Accept: application/json
   Authorization: Bearer h480djs93hd8
   Content-Type: application/secevent+jwt

                    Figure 1: Example HTTP POST Request

   Upon receipt of the request, the Event Receiver SHALL validate the
   JWT structure of the SET as defined in Section 7.2 [RFC7519].  The
   Event Receiver SHALL also validate the SET information as described
   in Section 2 [I-D.ietf-secevent-token].

   If the SET is determined to be valid, the Event Receiver SHALL
   "acknowledge" successful submission by responding with HTTP Status
   202 as "Accepted" (see Section 6.3.3 [RFC7231]).

   In order to maintain compatibility with other methods of
   transmission, the Event Receiver SHOULD NOT include an HTTP response
   body representation of the submitted SET or what the SET's pending
   status is when acknowledging success.  In the case of an error (e.g.
   HTTP Status 400), the purpose of the HTTP response body is to
   indicate any SET parsing, validation, or cryptographic errors.

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   The following is a non-normative example of a successful receipt of a

   HTTP/1.1 202 Accepted

              Figure 2: Example Successful Delivery Response

   Note that the purpose of the "acknowledgement" response is to let the
   Event Transmitter know that a SET has been delivered and the
   information no longer needs to be retained by the Event Transmitter.
   Before acknowledgement, Event Receivers SHOULD ensure they have
   validated received SETs and retained them in a manner appropriate to
   information retention requirements appropriate to the SET event types
   signaled.  The level and method of retention of SETs by Event
   Receivers is out-of-scope of this specification.

   In the Event of a general HTTP error condition, the Event Receiver
   MAY respond with an appropriate HTTP Status code as defined in
   Section 6 [RFC7231].

   When the Event Receiver detects an error parsing or validating a
   received SET (as defined by [I-D.ietf-secevent-token]), the Event
   Receiver SHALL indicate an HTTP Status 400 error with an error code
   as described in Section 2.3.

   The following is an example non-normative error response.

   HTTP/1.1 400 Bad Request
   Content-Type: application/json

     "description":"SET already received. Ignored."


                Figure 3: Example HTTP Status 400 Response

2.3.  Error Response Handling

   If a SET is invalid, the following error codes are defined:

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   | Err Value | Description                                           |
   | json      | Invalid JSON object.                                  |
   | jwtParse  | Invalid or unparsable JWT or JSON structure.          |
   | jwtHdr    | In invalid JWT header was detected.                   |
   | jwtCrypto | Unable to parse due to unsupported algorithm.         |
   | jws       | Signature was not validated.                          |
   | jwe       | Unable to decrypt JWE encoded data.                   |
   | jwtAud    | Invalid audience value.                               |
   | jwtIss    | Issuer not recognized.                                |
   | setType   | An unexpected Event type was received.                |
   | setParse  | Invalid structure was encountered such as an          |
   |           | inability to parse or an incomplete set of Event      |
   |           | claims.                                               |
   | setData   | SET event claims incomplete or invalid.               |
   | dup       | A duplicate SET was received and has been ignored.    |

                            Table 1: SET Errors

   An error response SHALL include a JSON object which provides details
   about the error.  The JSON object includes the JSON attributes:

      A value which is a keyword that describes the error (see Table 1).

      A human-readable text that provides additional diagnostic

   When included as part of an HTTP Status 400 response, the above JSON
   is the HTTP response body (see Figure 3).

3.  Authentication and Authorization

   The SET delivery method described in this specification is based upon
   HTTP and depends on the use of TLS and/or standard HTTP
   authentication and authorization schemes as per [RFC7235].  For
   example, the following methodologies could be used among others:

   TLS Client Authentication
      Event delivery endpoints MAY request TLS mutual client
      authentication.  See Section 7.3 [RFC5246].

   Bearer Tokens
      Bearer tokens [RFC6750] MAY be used when combined with TLS and a
      token framework such as OAuth 2.0 [RFC6749].  For security

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      considerations regarding the use of bearer tokens in SET delivery
      see Section 4.4.1.

   Basic Authentication
      Usage of basic authentication should be avoided due to its use of
      a single factor that is based upon a relatively static, symmetric
      secret.  Implementers SHOULD combine the use of basic
      authentication with other factors.  The security considerations of
      HTTP BASIC, are well documented in [RFC7617] and SHOULD be
      considered along with using signed SETs (see SET Payload
      Authentication below).

   SET Payload Authentication
      In scenarios where SETs are signed and the delivery method is HTTP
      POST (see Section 2.2), Event Receivers MAY elect to use Basic
      Authentication or not to use HTTP or TLS based authentication at
      all.  See Section 4.1 for considerations.

   As per Section 4.1 of [RFC7235], a SET delivery endpoint SHALL
   indicate supported HTTP authentication schemes via the "WWW-
   Authenticate" header.

   Because SET Delivery describes a simple function, authorization for
   the ability to pick-up or deliver SETs can be derived by considering
   the identity of the SET issuer, or via an authentication method
   above.  This specification considers authentication as a feature to
   prevent denial-of-service attacks.  Because SETs are not commands
   (see ), Event Receivers are free to ignore SETs that are not of

   For illustrative purposes only, SET delivery examples show an OAuth2
   bearer token value [RFC6750] in the authorization header.  This is
   not intended to imply that bearer tokens are preferred.  However, the
   use of bearer tokens in the specification does reflect common

3.1.  Use of Tokens as Authorizations

   When using bearer tokens or proof-of-possession tokens that represent
   an authorization grant such as issued by OAuth (see [RFC6749]),
   implementers SHOULD consider the type of authorization granted, any
   authorized scopes (see Section 3.3 of [RFC6749]), and the security
   subject(s) that SHOULD be mapped from the authorization when
   considering local access control rules.  Section 6 of the OAuth
   Assertions draft [RFC7521], documents common scenarios for
   authorization including:

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   o  Clients using an assertion to authenticate and/or act on behalf of

   o  Clients acting on behalf of a user; and,

   o  A Client acting on behalf of an anonymous user (e.g., see next

   When using OAuth authorization tokens, implementers MUST take into
   account the threats and countermeasures documented in the security
   considerations for the use of client authorizations (see Section 8 of
   [RFC7521]).  When using other token formats or frameworks,
   implementers MUST take into account similar threats and
   countermeasures, especially those documented by the relevant

4.  Security Considerations

4.1.  Authentication Using Signed SETs

   In scenarios where HTTP authorization or TLS mutual authentication
   are not used or are considered weak, JWS signed SETs SHOULD be used
   (see [RFC7515] and Security Considerations
   [I-D.ietf-secevent-token]).  This enables the Event Receiver to
   validate that the SET issuer is authorized to deliver SETs.

4.2.  HTTP Considerations

   SET delivery depends on the use of Hypertext Transfer Protocol and
   thus subject to the security considerations of HTTP Section 9
   [RFC7230] and its related specifications.

   As stated in Section 2.7.1 [RFC7230], an HTTP requestor MUST NOT
   generate the "userinfo" (i.e., username and password) component (and
   its "@" delimiter) when an "http" URI reference is generated with a
   message as they are now disallowed in HTTP.

4.3.  TLS Support Considerations

   SETs contain sensitive information that is considered PII (e.g.
   subject claims).  Therefore, Event Transmitters and Event Receivers
   MUST require the use of a transport-layer security mechanism.  Event
   delivery endpoints MUST support TLS 1.2 [RFC5246] and MAY support
   additional transport-layer mechanisms meeting its security
   requirements.  When using TLS, the client MUST perform a TLS/SSL
   server certificate check, per [RFC6125].  Implementation security
   considerations for TLS can be found in "Recommendations for Secure
   Use of TLS and DTLS" [RFC7525].

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4.4.  Authorization Token Considerations

   When using authorization tokens such as those issued by OAuth 2.0
   [RFC6749], implementers MUST take into account threats and
   countermeasures documented in Section 8 of [RFC7521].

4.4.1.  Bearer Token Considerations

   Due to the possibility of interception, Bearer tokens MUST be
   exchanged using TLS.

   Bearer tokens MUST have a limited lifetime that can be determined
   directly or indirectly (e.g., by checking with a validation service)
   by the service provider.  By expiring tokens, clients are forced to
   obtain a new token (which usually involves re-authentication) for
   continued authorized access.  For example, in OAuth2, a client MAY
   use OAuth token refresh to obtain a new bearer token after
   authenticating to an authorization server.  See Section 6 of

   Implementations supporting OAuth bearer tokens need to factor in
   security considerations of this authorization method [RFC7521].
   Since security is only as good as the weakest link, implementers also
   need to consider authentication choices coupled with OAuth bearer
   tokens.  The security considerations of the default authentication
   method for OAuth bearer tokens, HTTP BASIC, are well documented in
   [RFC7617], therefore implementers are encouraged to prefer stronger
   authentication methods.  Designating the specific methods of
   authentication and authorization are out-of-scope for the delivery of
   SET tokens, however this information is provided as a resource to

5.  Privacy Considerations

   If a SET needs to be retained for audit purposes, JWS MAY be used to
   provide verification of its authenticity.

   Event Transmitters SHOULD attempt to specialize Event Streams so that
   the content is targeted to the specific business and protocol needs
   of subscribers.

   When sharing personally identifiable information or information that
   is otherwise considered confidential to affected users, Event
   Transmitters and Receivers MUST have the appropriate legal agreements
   and user consent or terms of service in place.

   The propagation of subject identifiers can be perceived as personally
   identifiable information.  Where possible, Event Transmitters and

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   Receivers SHOULD devise approaches that prevent propagation -- for
   example, the passing of a hash value that requires the subscriber to
   already know the subject.

6.  IANA Considerations

   There are no IANA considerations.

7.  References

7.1.  Normative References

              Hunt, P., Denniss, W., Ansari, M., and M. Jones, "Security
              Event Token (SET)", draft-ietf-secevent-token-00 (work in
              progress), January 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,

   [RFC5988]  Nottingham, M., "Web Linking", RFC 5988,
              DOI 10.17487/RFC5988, October 2010,

   [RFC6125]  Saint-Andre, P. and J. Hodges, "Representation and
              Verification of Domain-Based Application Service Identity
              within Internet Public Key Infrastructure Using X.509
              (PKIX) Certificates in the Context of Transport Layer
              Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
              2011, <>.

   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <>.

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   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,

   [RFC7517]  Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,

   [RFC7525]  Sheffer, Y., Holz, R., and P. Saint-Andre,
              "Recommendations for Secure Use of Transport Layer
              Security (TLS) and Datagram Transport Layer Security
              (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
              2015, <>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <>.

7.2.  Informative References

              NRI, "OpenID Connect Core 1.0", Nov 2014.

   [POSIX.1]  Institute of Electrical and Electronics Engineers, "The
              Open Group Base Specifications Issue 7", IEEE Std 1003.1,
              2013 Edition, 2013.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,

   [RFC6750]  Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
              Framework: Bearer Token Usage", RFC 6750,
              DOI 10.17487/RFC6750, October 2012,

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   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,

   [RFC7235]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Authentication", RFC 7235,
              DOI 10.17487/RFC7235, June 2014,

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <>.

   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,

   [RFC7521]  Campbell, B., Mortimore, C., Jones, M., and Y. Goland,
              "Assertion Framework for OAuth 2.0 Client Authentication
              and Authorization Grants", RFC 7521, DOI 10.17487/RFC7521,
              May 2015, <>.

   [RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
              RFC 7617, DOI 10.17487/RFC7617, September 2015,

              Internet2, "Assertions and Protocols for the OASIS
              Security Assertion Markup Language (SAML) V2.0", March

Appendix A.  Other Streaming Specifications

   [[EDITORS NOTE: This section to be removed prior to publication]]

   The following pub/sub, queuing, streaming systems were reviewed as
   possible solutions or as input to the current draft:

   XMPP Events

   The WG considered the XMPP events ands its ability to provide a
   single messaging solution without the need for both polling and push
   modes.  The feeling was the size and methodology of XMPP was to far
   apart from the current capabilities of the SECEVENTs community which
   focuses in on HTTP based service delivery and authorization.

   Amazon Simple Notification Service

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   Simple Notification Service, is a pub/sub messaging product from AWS.
   SNS supports a variety of subscriber types: HTTP/HTTPS endpoints, AWS
   Lambda functions, email addresses (as JSON or plain text), phone
   numbers (via SMS), and AWS SQS standard queues.  It doesn't directly
   support pull, but subscribers can get the pull model by creating an
   SQS queue and subscribing it to the topic.  Note that this puts the
   cost of pull support back onto the subscriber, just as it is in the
   push model.  It is not clear that one way is strictly better than the
   other; larger, sophisticated developers may be happy to own message
   persistence so they can have their own internal delivery guarantees.
   The long tail of OIDC clients may not care about that, or may fail to
   get it right.  Regardless, I think we can learn something from the
   Delivery Policies supported by SNS, as well as the delivery controls
   that SQS offers (e.g.  Visibility Timeout, Dead-Letter Queues).  I'm
   not suggesting that we need all of these things in the spec, but they
   give an idea of what features people have found useful.

   Other information:

   o  API Reference:

   o  Visibility Timeouts:

   Apache Kafka

   Apache Kafka is an Apache open source project based upon TCP for
   distributed streaming.  It prescribes some interesting general
   purpose features that seem to extend far beyond the simpler streaming
   model SECEVENTs is after.  A comment from MS has been that Kafka does
   an acknowledge with poll combination event which seems to be a
   performance advantage.  See:

   Google Pub/Sub

   Google Pub Sub system favours a model whereby polling and
   acknowledgement of events is done as separate endpoints as separate


   o  Cloud Overview -

   o  Subscriber Overview -

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   o  Subscriber Pull(poll) -

Appendix B.  Acknowledgments

   The editors would like to thanks the members of the SCIM WG which
   began discussions of provisioning events starting with: draft-hunt-
   scim-notify-00 in 2015.

   The editors would like to thank the authors of draft-ietf-secevent-
   delivery-02, on which this draft is based.

   The editor would like to thank the participants in the the SECEVENTS
   working group for their support of this specification.

Appendix C.  Change Log

   Draft 00 - AB - Based on draft-ietf-secevent-delivery-02 with the
   following changes:

   o  Renamed to "Push-Based SET Token Delivery Using HTTP"

   o  Removed references to the HTTP Polling delivery method.

   o  Removed informative reference to RFC6202.

Authors' Addresses

   Annabelle Backman (editor)


   Michael B. Jones (editor)


   Phil Hunt (editor)
   Oracle Corporation


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   Marius Scurtescu


   Morteza Ansari


   Anthony Nadalin


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