RFC 8322

Resource-Oriented Lightweight Information Exchange (ROLIE)

📅 published February 2018, from ietf

RFC 8322: Resource-Oriented Lightweight Information Exchange (ROLIE) ✨

Okay bestie, this one's from the IETF, published in February 2018 as a Standards Track document (ISSN 2070-1721) 🌈. The authors are J. Field from Pivotal, and S. Banghart and D. Waltermire from NIST 💜. The title block doesn't list anything it obsoletes or updates 🫶.

Abstract ✨

Okay so this doc is all about a resource-oriented way to publish, find, and share security automation info 🔐. Producers may publish, share, and exchange representations of software descriptors, security incidents, attack indicators, software vulnerabilities, configuration checklists, and other security automation information as web-addressable resources 🌸. Consumers and other stakeholders may access and search this security info whenever they need it, which sets up a rapid, on-demand info exchange network for restricted internal use or public access repositories 🚀. This spec extends the Atom Publishing Protocol and Atom Syndication Format so they can carry and share these security automation resource representations 💅.

Status of This Memo 📜

This is an Internet Standards Track document 🎀.

It's a product of the Internet Engineering Task Force (IETF) and represents the consensus of the IETF community 🫶. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG) ✅. For more on Internet Standards, check out Section 2 of RFC 7841 🦋.

Info about the current status of this doc, any errata, and how to give feedback is at https://www.rfc-editor.org/info/rfc8322 💌.

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

This doc is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication. Please review these carefully, because they describe your rights and restrictions for 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 they're provided without warranty as described in the Simplified BSD License 🍓.

Table of Contents 📋

1. Introduction ....................................................3
2. Terminology .....................................................4
3. XML-Related Conventions .........................................5
   3.1. XML Namespaces .............................................5
   3.2. RELAX NG Compact Schema ....................................5
4. Background and Motivation .......................................5
5. ROLIE Requirements for the Atom Publishing Protocol .............7
   5.1. AtomPub Service Documents ..................................7
        5.1.1. Use of the "app:workspace" Element ..................8
        5.1.2. Use of the "app:collection" Element .................8
        5.1.3. Service Document Discovery ..........................9
   5.2. Category Documents .........................................9
   5.3. Transport Layer Security ..................................10
   5.4. User Authentication and Authorization .....................10
   5.5. "/" (Forward Slash) Resource URL ..........................11
   5.6. HTTP Methods ..............................................11
6. ROLIE Requirements for the Atom Syndication Format .............11
   6.1. Use of the "atom:feed" Element ............................11
        6.1.1. Use of the "atom:category" Element .................13
        6.1.2. Use of the "atom:link" Element .....................14
        6.1.3. Use of the "atom:updated" Element ..................15
   6.2. Use of the "atom:entry" Element ...........................16
        6.2.1. Use of the "atom:content" Element ..................17
        6.2.2. Use of the "atom:link" Element .....................17
        6.2.3. Use of the "rolie:format" Element ..................18
        6.2.4. Use of the "rolie:property" Element ................19
        6.2.5. Requirements for a Standalone Entry ................20

7. Available Extension Points Provided by ROLIE ...................21
   7.1. The Category Extension Point ..............................21
        7.1.1. General Use of the "atom:category" Element .........22
        7.1.2. Identification of Security Automation
               Information Types ..................................22
   7.2. The "rolie:format" Extension Point ........................24
   7.3. The Link Relation Extension Point .........................24
   7.4. The "rolie:property" Extension Point ......................24
8. IANA Considerations ............................................26
   8.1. XML Namespaces and Schema URNs ............................26
   8.2. ROLIE URN Sub-namespace ...................................26
   8.3. ROLIE URN Parameters ......................................27
   8.4. ROLIE Information Types Registry ..........................29
9. Security Considerations ........................................29
10. Privacy Considerations ........................................31
11. References ....................................................32
   11.1. Normative References .....................................32
   11.2. Informative References ...................................34
Appendix A. RELAX NG Compact Schema for ROLIE .....................37
Appendix B. Examples of Use .......................................37
  B.1. Service Discovery ..........................................37
  B.2. Feed Retrieval .............................................40
  B.3. Entry Retrieval ............................................42
Acknowledgements ..................................................43
Authors' Addresses ................................................43

1. Introduction 🎀

Okay, this doc defines a resource-oriented approach to security automation info sharing that follows the Representational State Transfer (REST) architectural style [REST] 🌷. In this approach, computer security resources live in web-accessible repositories structured as Atom Syndication Format [RFC4287] Feeds 📚. Inside a given Feed, which the consumer can request, representations of specific types of security automation info are organized, categorized, and described 🗂️. All the collections available to a given user are discoverable too, so the consumer can search everything they're authorized to view and then locate and request the info resources they want 🔎. With granular authentication and access controls, only authorized consumers may be permitted to read or write to a given Feed 🔒.

The goal here is to boost communication and sharing of security info between providers and consumers, so it can be used to automate security processes (for example, incident reports, vulnerability assessments, configuration checklists, and other security automation info) 🤖. Sharing like this lets human operators and computer systems use one standardized communication system to gather info that supports automating security processes 💫.

As new types of security automation info show up over time, this spec defines a bunch of extension points that can be used either privately or globally 🧩. The global extensions are IANA-registered by Resource-Oriented Lightweight Information Exchange (ROLIE) extension specifications, and they give you better interoperability for new use cases and domains 🌍. Sections 5 and 6 of this doc define the requirements for XML representations of ROLIE, and other equivalent representations (e.g. JSON) may be described by other documents 📝. You can find an overview of the extension system in Section 7 🗺️. If you want to support specific security automation info types, check the specification for that domain, as listed in the IANA registry in Section 8.4 💅.

2. Terminology 💅

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "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 🔥.

These key words only define the requirements for implementations of this spec. They're not used for recommendations or requirements for how you use ROLIE 🙌. (In other words, a programmer of a ROLIE server MUST implement a given feature, but a user of that ROLIE server needn't use that feature 💖.)

Some common computer-security terminology used in this doc is defined in Section 2 of [RFC7970] 📖.

This spec has one term that's unique to it 🦋:

Information Type: A class of security automation information having one or more associated data models. Often, this security automation info is used in automating a security process. See Section 7.1.2 for more information ✨.

3.1. XML Namespaces 🌸

This spec uses XML namespaces [W3C.REC-xml-names-20091208] to uniquely identify XML element names 🏷️. It uses these namespace prefix mappings for the namespace URIs listed:

3.2. RELAX NG Compact Schema 🦋

Some sections of this spec are illustrated with fragments of a non-normative RELAX NG Compact Schema [RELAX-NG] 🎨. The text of this spec provides the definition of conformance 📜. Schema for the "https://www.w3.org/2007/app" and "https://www.w3.org/2005/Atom" namespaces appears in Appendix B of [RFC5023] and Appendix B of [RFC4287], respectively 💜.

A complete informative RELAX NG Compact Schema for the new elements introduced by ROLIE is provided in Appendix A of this document 🌈.

4. Background and Motivation ✨

okay so bestie, to automate security stuff, tools need solid sources of structured security info they can actually use to drive the process 🧠 security info sharing is literally the core of automation. vulnerabilities, configurations, software identification, security incidents, and patch data are just a few of the types of info being shared today to keep things secure at scale 🔐 and as defenses get bigger and networks get more complicated, and there's just way too much info for humans to keep up with, the need for automation and machine-to-machine communication gets more and more critical 💀

ROLIE is here to fix this 💅 it gives us four major info-sharing benefits:

  • Extensible information type categories and format agnosticism: ROLIE isn't tied to any one data format or category of information 🌈 instead, the categories are extensible, and Entries declare the format of the referenced data. when there are several formats or serializations available, ROLIE can use link relations to communicate how a consumer can access them. for example, clients may request that a given resource representation be returned as XML, JSON, or some other format or serialization. this lets the provider support multiple isomorphic formats, so the consumer can pick the most suitable version 🎀
  • Open and distributed information sharing: using the Atom Publishing Protocol (AtomPub), ROLIE Feeds can easily aggregate Feeds and accept info posted to them from other sources 🦋 webs of communicating ROLIE servers form ad hoc sharing communities, which means more data is available and linked data can be correlated across sources for participating consumers 🫶 ROLIE servers don't have to be distributed though, since large ROLIE repositories can work as a central collection or federated collections ✨
  • Stateless communication model: ROLIE is RESTful, so it's stateless 🧚 the server doesn't keep track of client sessions and instead uses link relations for state transitions. in practice, any consumer can find and share info at any organizational level and at any time without needing to run a long series of requests 🙈
  • Information discovery and navigation: ROLIE gives clients a bunch of ways to programmatically discover and navigate collections of info so they can dynamically find new or revised content 👑 extensible information types and other categories are one way to figure out which content is desirable. Link elements, each with a target URI and an established relationship type, let ROLIE providers link other info that's relevant to the current Entry or Feed 💜

these benefits add up to an info-sharing protocol that is lightweight, interactive, open, and, most importantly, machine readable 🍓

the requirements in this spec are split into two major sections: extensions to AtomPub [RFC5023] and extensions to the Atom Syndication Format [RFC4287]. all normative requirements in AtomPub and Atom Syndication are inherited from their respective specs and apply here, unless a requirement is explicitly overridden in this document 📚 so this document may upgrade a requirement (e.g., make a "SHOULD" a "MUST") but will never downgrade a given requirement (e.g., make a "MUST" a "SHOULD") 🔒 no backsliding, periodt 💅

5. ROLIE Requirements for the Atom Publishing Protocol 🌸

this section describes a bunch of restrictions on, and extensions to, AtomPub [RFC5023] that define how AtomPub gets used in a ROLIE-based solution 🦋 the normative requirements here are mostly aimed at client and server implementations. understanding the AtomPub specification [RFC5023] helps a lot with the requirements in this section, so go read it first, bestie 🤓

5.1. AtomPub Service Documents

as described in Section 8 of [RFC5023], a Service Document is an XML-based document format that lets a client dynamically discover the Collections a publisher provides 💖 a Service Document is made of one or more app:workspace elements, each of which may contain a bunch of app:collection elements ✨

the general structure of a Service Document goes like this (from Section 4.2 of [RFC5023]):

     Service
        o- Workspace
        |    |
        |    o- Collection
        |    |     |
        |    |     o- URI, categories, media types
        |    |
        |    o- ...
        |
        o- Workspace
        |     |
        |     o- Collection
        |     |     |
        |     |     o- URI, categories, media types
        |     |
        |     o- ...
        |
        o- ...

note that the Internationalized Resource Identifiers (IRIs) in the original diagram have been replaced with URIs 🧩

5.1.1. Use of the app:workspace Element

in AtomPub, a workspace, represented by the app:workspace element, describes a group of one or more Collections 🗂️ building on that concept, a workspace in ROLIE represents an aggregation of Collections about security automation info resources 🔐 this spec doesn't restrict how many workspaces can be in a Service Document, or which Collections go in a given workspace 🌈

a ROLIE implementation can host Collections with both public and private information Entries 🙈 it is suggested that implementations segregate Collections into different app:workspace elements by their client access requirements. with proper workspace naming, a human user has to do way less trial and error to find the Collections they can access 💅

5.1.2. Use of the app:collection Element

in AtomPub, a Collection in a Service Document, represented by the app:collection element, gives metadata that can point to a specific Atom Feed holding info Entries a client might be into 💜 the link between a Collection and a Feed is provided by the href attribute of the app:collection element 🦋 building on that, in ROLIE a Collection is a pointer to a group of security automation info resources about one particular type of security automation info ✨ Collections are represented as Atom Feeds as per RFC 5023, and the requirements specific to Atom Feeds are defined in Section 6.1 🫶

ROLIE defines specialized data requirements for Collections, Feeds, and Entries that contain security automation data 🛡️ you can tell a ROLIE Collection apart from a non-ROLIE Collection defined in a Service Document like this:

  • ROLIE Collection: an app:collection counts as a ROLIE Collection when it contains an app:categories element that contains only one atom:category element with a scheme attribute value of urn:ietf:params:rolie:category:information-type. on top of that, this category needs an appropriate term attribute value, as defined in Section 7.1.1 💖 this makes sure a given Collection matches one specific type of security automation info 👑
  • Non-ROLIE Collection: an app:collection counts as a non-ROLIE Collection when it does not contain an atom:category element with a scheme attribute value of urn:ietf:params:rolie:category:information-type 🌸

because of this split, implementations that support ROLIE can host security automation Collections right alongside Collections of other non-ROLIE info, all inside the same AtomPub instance 🎀

the following are additional requirements for using the app:collection element on a ROLIE Collection:

  • the child atom:category elements inside the app:categories element MUST be the same set of atom:category elements used in the Atom Feed resource that the app:collection element's href attribute value points to 🧚 this way, the category metadata for the Collection and the associated Feed is discoverable in both places 💅
  • the app:categories element in an app:collection MAY include additional atom:category elements using a scheme other than urn:ietf:params:rolie:category:information-type 🌈 this lets other category metadata ride along too ✨

5.1.3. Service Document Discovery

the Service Document is the "head" of a given ROLIE repository: from the Service Document, all the other repository content can be discovered 👑 a client needs to figure out the URL of this Service Document to find the Collections the repository provides 🔍 the client might get the URL from a web page, from out-of-band communication, or through a "service" link relation in a Feed or Entry Document the client has already retrieved. that last one is a super typical scenario if the client heard about a specific Feed or Entry through an out-of-band mechanism and now wants more info from the repository 🫶

this document doesn't provide a fully automated discovery mechanism 🙈 a mechanism may be defined in the future that lets automated clients discover the URL they need to retrieve a ROLIE Service Document representing the head of the ROLIE repository 🔮

5.2. Category Documents

as described in Section 7 of [RFC5023], a Category Document is an XML-based document format that lets a client dynamically discover the categories used within AtomPub Service Documents, Atom Syndication Feeds, and Entry Documents a publisher provides 🦋 a Category Document has one app:categories element that contains a number of inline atom:category elements, or a URI referencing a Category Document 🎀

5.3. Transport Layer Security

ROLIE is intended to be handled with Transport Layer Security (TLS) 🔐 TLS version 1.2 MUST be supported 🚨 TLS 1.2 SHOULD be implemented according to all recommendations and best practices presented in [RFC7525] 💖

it is RECOMMENDED that the most recent published version of TLS be supported 🌈 if that version is TLS 1.3 [TLS-1.3], it is suggested that 0-RTT (Zero Round-Trip Time Resumption) not be used, in order to prevent replay attacks 😭 replay attacks on PUT, POST, or DELETE requests can wreck repository operations by changing data unexpectedly 💀

for example, an automated ROLIE repository that updates super frequently might get a PUT request against a given resource a few times an hour (or more) 🍓 an attacker could store an early PUT request and, at the end of the resumption window, replay it, reverting the resource to an old version 😱 not only could an attacker keep doing this replay to cause havoc on the server, but the client would be completely unaware the attack is happening 🥺

given how potentially sensitive the data handled by ROLIE can be, all appropriate precautions should be taken at the transport layer to protect forward secrecy and user privacy 🔒

the server MUST implement certificate-based client authentication 🪪 this MAY be enabled on a workspace-by-workspace basis ✨

5.4. User Authentication and Authorization 🔐

Okay bestie, so Implementations MUST support user authentication. 💅 But a given implementation MAY let you turn user authentication off on a Feed-by-Feed or workspace-by-workspace basis, so it's flexible. ✨

It is recommended that servers in an information-sharing consortium, which support interactive user logins by consortium members, support client authentication via a federated identity scheme. 🫶

This document does not mandate any specific user authorization mechanisms. 🙈 However, service implementers SHOULD support appropriate authorization checking for all resource accesses, including individual Atom Entries, Atom Feeds, and Atom Service Documents. Lowkey the most important part of this whole section, so don't skip it, periodt. 🔥

5.5. "/" (Forward Slash) Resource URL 🎀

The "/" resource MAY be supported for compatibility with existing deployments that are using [RFC6546] ("Transport of Real-time Inter-network Defense (RID) Messages over HTTP/TLS"). 🦋 The following requirements only apply to implementations that support both RFC 6546 and the "/" resource as described above, so if that's not you, you can chill. 🌸

  • Consistent with Erratum ID 3267 [Err3267] for [RFC6546], a client requesting a GET on the "/" resource SHOULD receive an HTTP status code 405 ("Method Not Allowed"). 🙅‍♀️
  • An implementation MAY provide full support for [RFC6546] such that a POST to the "/" resource containing a recognized RID message is handled correctly as a RID request. Alternatively, a client requesting a POST to "/" MAY receive an HTTP status code 307 ("Temporary Redirect"). In this case, the location header in the HTTP response will provide the URL of the appropriate RID endpoint, and the client may repeat the POST method at the indicated location. 🧚

If RFC 6546 is unsupported, then a request for the "/" resource may be handled as deemed appropriate by the server. 🌈

5.6. HTTP Methods 🍓

Servers MAY accept request methods beyond those specified in this document. Ooh, extra credit for the servers that go above and beyond. ⭐

Clients MUST be capable of recognizing and processing any standard HTTP status code, as defined in Section 5 of [RFC5023]. No skipping the weird status codes, bestie, you gotta handle them all. 💀

6. ROLIE Requirements for the Atom Syndication Format ✨

This section describes a number of restrictions of, and extensions to, the Atom Syndication Format [RFC4287] that define the valid use of the format in the context of a ROLIE implementation. 👑 An understanding of the Atom Syndication Format specification [RFC4287] is helpful to understand the requirements in this section, so go read that first, no cap. 📚

6.1. Use of the "atom:feed" Element 🌸

As described in Section 4.1.1 of [RFC4287], an Atom Feed is an XML-based document format that describes a list of related information items. The Atom Feeds provided by a ROLIE service are listed in the service's Service Document through one or more "app:collection" elements. Each Feed Document, represented using the "atom:feed" element, contains a listing of zero or more Entries. 💖

When applied to the problem domain of security automation information sharing, an Atom Feed may be used to represent any meaningful collection of security automation information resources. Each Entry in a Feed represents an individual resource (e.g., a specific checklist, a software vulnerability record). Additional Feeds can be used to represent other collections of security automation resources. It's giving organized closet energy. 🧚

As discussed in Section 5.1.2, ROLIE defines specialized data requirements for Feeds containing data related to security automation. The difference between a ROLIE Feed and a non-ROLIE Feed can be determined as follows:

ROLIE Feed: For an "atom:feed" to be considered a ROLIE Feed, the "atom:feed" MUST contain only one child "atom:category" element with a "scheme" attribute value of "urn:ietf:params:rolie:category:information-type". This category MUST have an appropriate "term" attribute value as defined in Section 7.1.1. This ensures that a given Feed corresponds to a specific type of security automation information. 🔥

Non-ROLIE Feed: For an "atom:feed" to be considered a non-ROLIE Feed, the "atom:feed" MUST NOT contain an "atom:category" element with a "scheme" attribute value of "urn:ietf:params:rolie:category:information-type". 🙅‍♀️

By distinguishing between ROLIE and non-ROLIE Feeds in this way, implementations supporting ROLIE can host Feeds pertaining to security automation information alongside Feeds of other non-ROLIE information within the same AtomPub instance. This is parallel to the handling of Collections as discussed earlier in this specification (Section 5.1.2). Iconic. 🦋

The following Atom Feed definition represents a stricter definition of the "atom:feed" element defined in [RFC4287] when used as a ROLIE Feed. Any element not specified here inherits its definition and requirements from [RFC4287]. 🎀

   atomFeed =
      element atom:feed {
         atomCommonAttributes,
         (atomAuthor*
          & atomCategory+
          & atomContributor*
          & atomGenerator?
          & atomIcon?
          & atomId
          & atomLink+
          & atomLogo?
          & atomRights?
          & atomSubtitle?
          & atomTitle
          & atomUpdated
          & extensionElement*),
         atomEntry*
      }

The following subsections contain requirements for a ROLIE Feed. 💅

6.1.1. Use of the "atom:category" Element 🌈

An "atom:feed" can contain one or more "atom:category" elements. In Atom, the naming scheme and the semantic meaning of the terms used to identify an Atom category are application defined. So it's totally up to the app, no drama. 🌸

The following are additional requirements on the use of the "atom:category" element when used in a ROLIE Feed:

  • All member Entries in the Feed MUST represent security automation information records of the provided information type category. 🔐
  • The "atom:feed" MAY include additional "atom:category" elements using a scheme other than "urn:ietf:params:rolie:category:information-type". This allows other category metadata to be included. ✨

Link relations defined by the "atom:link" element are used to represent state transitions using a stateless approach. In Atom, a type of link relationship can be defined using the "rel" attribute. 🦋

A ROLIE Feed MUST contain one or more "atom:link" elements with rel="service" and an "href" attribute whose value is a URI that points to an Atom Service Document associated with the Feed. If a client accesses a Feed without first accessing the service's Service Document, a link with the "service" relationship provides a means to discover additional security automation information. The "service" link relationship is defined in the IANA "Link Relations" registry at <https://www.iana.org/assignments/link-relations/>. 🧚

A Feed can contain an arbitrary number of Entries. In some cases, a complete Feed may consist of a large number of Entries. Additionally, as new and updated Entries are ordered at the beginning of a Feed, a client may only be interested in retrieving the first N Entries in a Feed to process only the Entries that have changed since the last retrieval of the Feed. As a practical matter, a large set of Entries will likely need to be divided into more manageable portions, or pages. Based on Section 3 of [RFC5005], link elements SHOULD be included in all Feeds to support paging using the following link relation types: 📄

  • "first" - Indicates that the "href" attribute value of the link identifies a resource URI for the furthest preceding page of the Feed.
  • "last" - Indicates that the "href" attribute value of the link identifies a resource URI for the furthest following page of the Feed.
  • "previous" - Indicates that the "href" attribute value of the link identifies a resource URI for the immediately preceding page of the Feed.
  • "next" - Indicates that the "href" attribute value of the link identifies a resource URI for the immediately following page of the Feed.

For example:

  <?xml version="1.0" encoding="UTF-8"?>
  <feed xmlns="https://www.w3.org/2005/Atom">
      <id>b7f65304-b63b-4246-88e2-c104049c5fd7</id>
      <title>Paged Feed</title>
      <link rel="self" href="https://example.org/feedA?page=5"/>
      <link rel="first" href="https://example.org/feedA?page=1"/>
      <link rel="prev" href="https://example.org/feedA?page=4"/>
      <link rel="next" href="https://example.org/feedA?page=6"/>
      <link rel="last" href="https://example.org/feedA?page=10"/>
      <updated>2012-05-04T18:13:51.0Z</updated>

      <!-- remainder of the Feed's elements -->
  </feed>

Example Paged Feed 🥰

A reference to a historical Feed may need to be stable, and/or a Feed may need to be divided into a series of defined epochs. Implementations SHOULD support the mechanisms described in Section 4 of [RFC5005] to provide link-based state transitions for maintaining the archiving of Feeds. Archive goals, bestie. 🗄️✨

A Feed MAY include additional link relationships not specified in this document. If a client encounters an unknown link relationship type, the client MUST ignore the unrecognized link and continue processing as if the unrecognized link element did not appear. The definition of new link relations that provide additional state transition extensions is discussed in Section 7.3. Unknown links? Just scroll past them, no big deal. 💜

6.1.3. Use of the "atom:updated" Element ⏰

The "atom:updated" element identifies the date and time that a Feed was last updated.

The "atom:updated" element MUST be populated with the current time at the instant the Feed was last updated by adding, updating, or deleting an Entry, or by changing any metadata for the Feed. Timestamps are everything, fr fr. 🕰️

6.2. Use of the "atom:entry" Element 📝

Each Entry in an Atom Feed, represented by the "atom:entry" element, describes a single referenced information record, along with descriptive information about its format, media type, and other publication metadata. The following "atom:entry" schema definition represents a stricter representation of the "atom:entry" element defined in [RFC4287] for use in a ROLIE-based Atom Feed as defined in Section 6.1.1. 🎀

  atomEntry =
    element atom:entry {
      atomCommonAttributes,
      (atomAuthor*
      & atomCategory*
      & atomContent
      & atomContributor*
      & atomId
      & atomLink*
      & atomPublished?
      & atomRights?
      & atomSource?
      & atomSummary?
      & atomTitle
      & atomUpdated
      & rolieFormat?
      & rolieProperty*
      & extensionElement*)
    }

The notable changes from [RFC4287] are the addition of "rolieFormat" and "rolieProperty" elements. Also, the "atomContent" element is restricted to the atomOutOfLineContent formulation and is now REQUIRED. Big glow-up energy for Entries. 🌟

The following subsections contain requirements for Entries in a ROLIE Feed. 🦋

6.2.1. Use of the "atom:content" Element

An "atom:content" element associates its containing Entry with a content resource identified by the "src" attribute.

There MUST be exactly one "atom:content" element in the Entry. The "atom:content" element MUST adhere to this definition, which is a stricter representation of the "atom:content" element defined in [RFC4287]:

atomContent = element atom:content { atomCommonAttributes, attribute type { atomMediaType }, attribute src { atomUri }, empty }

This restricts atomContent in ROLIE to the atomOutOfLineContent formulation presented in [RFC4287].

The "type" attribute MUST identify the serialization type of the content -- for example, "application/xml" or "application/json". A prefixed media type MAY be used to reflect a specific model used with a given serialization approach (e.g., "application/rdf+xml"). The "src" attribute MUST be a URI that can be dereferenced to retrieve the related content data.

6.2.2. Use of the "atom:link" Element

Link relations can be included in an Entry to represent state transitions to and from the Entry, as well as to provide links to related information.

If there is a need to provide the same information in different data models and/or serialization formats, separate Entry instances can be included in the same Feed or a different Feed. Such an alternate content representation can be indicated using an "atom:link" having a "rel" attribute with the value "alternate".

A Feed MAY include additional link relationships not specified in this document. If a client encounters an unknown link relationship type, the client MUST ignore the unrecognized link and continue processing as if the unrecognized link element did not appear. The definition of new link relations that provide additional state transition extensions is discussed in Section 7.3.

6.2.3. Use of the "rolie:format" Element

As mentioned in Sections 1 and 4, a key goal of this specification is to allow a consumer to review a set of published security automation information resources and then identify and retrieve any resources of interest. The format of the data is a key criteria to consider when deciding what information to retrieve. For a given type of security automation information, it is expected that a number of different formats may be used to represent this information. To support this use case, both the serialization format and the specific data model expressed in that format must be known by the consumer.

In the Atom Syndication Format, a media type can be defined using the "type" attribute of the "atom:content" element of an "atom:entry". The media type can be fully descriptive of the format of the linked document, such as "application/atom+xml". In some cases, however, a format-specific media type may not be defined. An example might be when "application/xml" is used because there is no defined specific media type for the content. In such a case, the exact data model of the content cannot be known without first retrieving the content.

In cases where a specific media type does not exist, the "rolie:format" element is used to describe the data model used to express the information referenced in the "atom:content" element. The "rolie:format" element also allows a schema to be identified that can be used when parsing the content to verify or better understand the structure of the content.

When it appears, the "rolie:format" element MUST adhere to this definition:

rolieFormat = element rolie:format { atomCommonAttributes, attribute ns { atomUri }, attribute version { text } ?, attribute schema-location { atomUri } ?, attribute schema-type { atomMediaType } ?, empty }

The "rolie:format" element MUST provide a "ns" attribute that identifies the data model of the resource referenced by the "atom:content" element. For example, the namespace used may be an XML namespace URI or an identifier that represents a serialized JSON model. The URI used for the "ns" attribute MUST be absolute. The resource identified by the URI need not be resolvable.

The "rolie:format" element MAY provide a "version" attribute that identifies the version of the format used for the related "atom:content" element.

The "rolie:format" element MAY provide a "schema-location" attribute, which is a URI that identifies a schema resource that can be used to validate the related "atom:content" element.

The "rolie:format" element MAY provide a "schema-type" attribute, which is a media type (as described in [RFC2045]) identifying the format of the schema resource identified by the "schema-location" attribute.

The following nominal example shows how these attributes describe the format of the content:

<rolie:format ns="urn:ietf:params:xml:ns:iodef-2.0" version="2.0" schema-location= "https://www.iana.org/assignments/xml-registry/schema/iodef-2.0.xsd" schema-type="text/xml"/>

The previous element provides an indication that the content of the given Entry is using the Incident Object Description Exchange Format (IODEF) v2 format.

6.2.4. Use of the "rolie:property" Element

An "atom:category" element provides a way to associate a name/value pair of categorical information using the "scheme" and "term" attributes to represent the name and using the "label" attribute to represent the value. When used in this way, an "atom:category" allows a specific label to be selected from a finite set of possible label values that can be used to further classify a given Entry or Feed. Within ROLIE, there may be a need to associate additional metadata with an Entry. In such a case, the use of an "atom:category" is not practical to represent name/value data for which the allowed values are unbounded. Instead, ROLIE introduces a new "rolie:property" element that can represent non-categorical metadata as name/value pairs. Examples include content-specific identifiers, naming data, and other properties that allow for unbounded values.

There MAY be zero or more "rolie:property" elements in an "atom:entry".

The element MUST adhere to this definition:

rolieProperty = element rolie:property { atomCommonAttributes, attribute name { atomUri }, attribute value { text }, empty }

The "name" attribute provides a URI that identifies the namespace and name of the property as a URI.

The "value" attribute is text that provides a value for the property identified by the "name" attribute.

For example, the nominal element <rolie:property name="urn:ietf:params:rolie:property:content-id" value="12345"/> would expose an IODEF ID value contained in a given Entry's content. The name used in the example also demonstrates the use of a registered ROLIE property extension, which is described in Section 7.4.

Implementations MAY use locally defined and namespaced elements in an Entry in order to provide additional information. Clients that do not recognize a property with an unregistered "name" attribute MUST ignore the "rolie:property" element; that is, the client MUST NOT fail parsing content that contains an unrecognized property.

6.2.5. Requirements for a Standalone Entry

If an Entry is ever shared as a standalone resource, separate from its containing Feed, then the following additional requirements apply:

o The Entry MUST have an "atom:link" element with rel="collection" and href="[URI of the containing Collection]". This allows the Feed or Feeds of which the Entry is a member to be discovered, along with the related information the Feed may contain. In the case where the Entry has multiple containing Feeds, the Entry MUST have one "atom:link" for each related Feed.

o The Entry MUST declare the information type of the content resource referenced by the Entry (see Section 7.1.2).

  1. Available Extension Points Provided by ROLIE

This specification does not require particular information types or data formats; rather, ROLIE is intended to be extended by additional specifications that define the use of new categories and link relations. The primary point of extension is through the definition of new information type category terms. Additional specifications can register new information type category terms with IANA that serve as the main characterizing feature of a ROLIE Collection/Feed or resource/Entry. These additional specifications defining new information type terms can describe additional requirements for including specific categories and link relations, as well as the use of specific data formats supporting a given information type term.

7.1. The Category Extension Point

The "atom:category" element, defined in Section 4.2.2 of [RFC4287], provides a mechanism to provide additional categorization information for a content resource in ROLIE. The ability to define new categories is one of the core extension points provided by Atom. A Category Document, defined in Section 7 of [RFC5023], provides a mechanism for an Atom implementation to make discoverable the "atom:category" terms and associated allowed values.

ROLIE further defines the use of the existing Atom extension category mechanism by allowing ROLIE-specific category extensions to be registered with IANA. The "urn:ietf:params:rolie:category:information-type" category scheme, which has special meaning for implementations of ROLIE, has been assigned (see Section 8.3). This allows category scheme namespaces to be managed in a more consistent way, allowing for greater interoperability between content producers and consumers.

Any "atom:category" element whose "scheme" attribute uses an unregistered scheme MUST be considered "Private Use" as defined in [RFC8126]. Implementations encountering such a category MUST parse the content without error but MAY otherwise ignore the element.

The use of the "atom:category" element is discussed in the following subsections.

7.1.1. General Use of the "atom:category" Element

The "atom:category" element can be used for characterizing a ROLIE resource. An "atom:category" element has a "term" attribute that indicates the assigned category value and a "scheme" attribute that provides an identifier for the category type. The "scheme" provides a means to describe how a set of category terms should be used and provides a namespace that can be used to differentiate terms that are provided by multiple organizations and that have different semantic meaning.

To further differentiate category types used in ROLIE, an IANA subregistry has been established for ROLIE protocol parameters to support the registration of new category "scheme" attribute values by ROLIE extension specifications. The use of this extension point is discussed in Section 8.3, using the "name" field with a type parameter of "category" to indicate a category extension.

7.1.2. Identification of Security Automation Information Types ✨

Okay bestie, ROLIE has a special extension point hiding in the atom:category element 🎀. You use the scheme attribute with the value urn:ietf:params:rolie:category:information-type, and that value is a Uniform Resource Name (URN) [RFC8141] that gets registered with IANA as described in Section 8.3. When you use it as the scheme like this, the term attribute is expected to be a registered value from Section 8.4. So with this one mechanism, a security automation information type can do three jobs 💅:

  1. identify that an app:collection element in a Service Document points to an Atom Feed full of Entries about one specific type of security automation information (see Section 5.1.2),
  2. identify that an atom:feed element in an Atom Feed holds Entries about one specific type of security automation information (see Section 6.1.1), or
  3. identify the information type of a standalone resource (see Section 6.2.5).

For example, the notional security automation information type "incident" would be tagged like this 🦋:

<atom:category
    scheme="urn:ietf:params:rolie:category:information-type"
    term="incident"/>

A security automation information type is basically a class of information that shares the same or similar information model [RFC3444]. Also, this document doesn't register any information types. It just throws out some examples of potential ones 🌸:

  • indicator: Computing device- or network-related "observable features and phenomenon that aid in the forensic or proactive detection of malicious activity and associated metadata" (from [RFC7970]).
  • incident: Information pertaining to or derived from security incidents.
  • vulnerability reports: Information identifying and describing a vulnerability in hardware or software.
  • configuration checklists: Content that can be used to assess the configuration settings related to installed software.
  • software tags: Metadata used to identify and characterize installable software.

This is just a short list to inspire new engineering of information type extensions that support the automation of security processes ✨.

This document doesn't specify any information types itself. Instead, information types in ROLIE are supposed to get registered in extension documents that describe one or more new information types. That's what lets the information types used by ROLIE implementations grow over time for new security automation use cases 🚀. These extension documents can also level up ROLIE Service, Category, Feed, and Entry Documents by defining link relations, other categories, and Format data model extensions for the representational needs of those specific information types. New information types get added to ROLIE through registrations in the IANA "ROLIE Information Types" registry defined in Section 8.4 💜.

7.2. The "rolie:format" Extension Point

Security automation data for a given information type can be expressed in a bunch of supported formats 🧚. Like we covered in Section 6.2.3, the rolie:format element describes the specific data model used to represent the resource referenced by a given atom:entry. That structure gives you a way to extend the atom:entry model. ROLIE extensions MAY further restrict which data models are allowed for a given information type.

Declaring the data model for a resource is lowkey so useful, because a consumer can choose to download the resource, ignore it, or go looking for alternate formats 🫶. That saves the consumer from downloading and parsing resources they don't care about, or resources in formats they can't even support 🙈.

This document uses several link relations from the IANA "Link Relation Types" registry at <https://www.iana.org/assignments/link-relations/> 🌈. More link relations can be registered in that registry so new relationships can be represented in ROLIE, following Section 4.2.7.2 of [RFC4287]. And based on that reference, if a link relation is too specific or limited in its intended use, you can use an absolute URI instead of registering a new simple name with IANA 💅.

7.4. The "rolie:property" Extension Point

Like we talked about in Section 6.2.3, lots of formats have unique identifying and characterizing properties that are vital for sharing information 💖. To give these properties a global reference, this document sets up an IANA registry. It lets ROLIE extensions register named properties by using the name field with a type parameter of property to indicate a property extension (see Section 8.3). Implementations SHOULD prefer registered properties over implementation-specific ones when they can 👑.

ROLIE extensions are expected to register new properties and use existing ones to give valuable identifying and characterizing info for a given information type and/or format ✨.

Any rolie:property element whose name attribute has urn:ietf:params:rolie:property:local as a prefix MUST be considered "Private Use" as defined in [RFC8126]. Implementations that run into one of these MUST parse the content without error, but they MAY otherwise ignore the element 🙈.

This document also registers a bunch of general-use properties that can expose content info in any ROLIE use case. Here's how to use each one 🍓:

urn:ietf:params:rolie:property:content-author-name The value attribute of this property is a text representation indicating the individual or organization that authored the content referenced by the src attribute of the Entry's atom:content element. This author may differ from the atom:author element when the author of the content and the author of the Entry are different people or entities.

urn:ietf:params:rolie:property:content-id The value attribute of this property is a text representation of an identifier pertaining to or extracted from the content referenced by the src attribute of the Entry's atom:content element. For example, if the atom:entry's atom:content element links to an IODEF document, the content-id value would be an identifier of that IODEF document.

urn:ietf:params:rolie:property:content-published-date The value attribute of this property is a text representation indicating the original publication date of the content referenced by the src attribute of the Entry's atom:content element. This date may differ from the published date of the ROLIE Entry because publishing the content and publishing the ROLIE Entry are different events. The date MUST be formatted as specified in [RFC3339].

urn:ietf:params:rolie:property:content-updated-date The value attribute of this property is a text representation indicating the date that the content, referenced by the src attribute of the Entry's atom:content element, was last updated. This date may differ from the updated date of the ROLIE Entry because updates to the content and updates to the ROLIE Entry are different events. The date MUST be formatted as specified in [RFC3339].

8. IANA Considerations 🌸

This document has a number of IANA considerations, which are covered in the subsections below 💅.

8.1. XML Namespaces and Schema URNs

This document uses URNs to describe XML namespaces and XML schemas that follow the registry mechanism described in [RFC3688] 🎀.

  • ROLIE XML Namespace: The ROLIE namespace (rolie-1.0) has been registered in the "ns" registry.

URI: urn:ietf:params:xml:ns:rolie-1.0

Registrant Contact: IESG

XML: None. Namespace URIs do not represent an XML specification.

  • ROLIE XML Schema: The ROLIE schema (rolie-1.0) has been registered in the "schema" registry.

URI: urn:ietf:params:xml:schema:rolie-1.0

Registrant Contact: IESG

XML: See Appendix A of this document.

8.2. ROLIE URN Sub-namespace

IANA has added an entry to the "IETF URN Sub-namespace for Registered Protocol Parameter Identifiers" registry, located at <https://www.iana.org/assignments/params/>, as per [RFC3553] 🦋. The entry looks like this:

Registered Parameter Identifier: rolie

Specification: This document

Repository: ROLIE URN Parameters.  See Section 8.3.

Index value: See Section 8.4.

8.3. ROLIE URN Parameters 🎀

okay so a brand new top-level registry got created, and it's called "Resource-Oriented Lightweight Information Exchange (ROLIE) URN Parameters" 🌸

Registration in the "ROLIE URN Parameters" subregistry goes through the Specification Required policy [RFC8126]. Requests have to be sent to both the MILE Working Group mailing list (mile@ietf.org) and IANA. IANA then forwards them to the Designated Expert 💌

Every entry in this subregistry must record these fields:

  • Name: A URN segment that follows the pattern {type}:{label}. The breakdown is:
    • {type}: The parameter type. The allowed values are "category" or "property". "category" means a category extension, as covered in Section 7.1. "property" means a property extension, as covered in Section 7.4.
    • {label}: A required US-ASCII string that follows the URN syntax rules (see [RFC8141]). This string must be unique within the namespace defined by the {type} keyword. The "local" label for both the "category" and "property" types has been reserved for private use 🔒
  • Extension URI: The identifier you use inside ROLIE, which is the full URN in the form urn:ietf:params:rolie:{name}, where {name} is the "name" field of this registration.
  • Reference: A static link to the specification and the section where the parameter is defined.
  • Subregistry: An optional field that points to an IANA subregistry for this parameter. If the {type} is "category", the subregistry must contain a "name" field whose registered values MUST be US-ASCII. The names in that list are the allowed values of the "term" attribute in the "atom:category" element (see Section 7.1.2). The list is giving organized 📋

This repository starts off with these initial values, and they're lowkey iconic ✨

+--------------+------------------------+-------------+-------------+
| Name         | Extension URI          | Reference   | Subregistry |
|              |                        | (This       |             |
|              |                        | Document)   |             |
+--------------+------------------------+-------------+-------------+
| category:    | urn:ietf:params:rolie: | Section 8.4 | See         |
| information- | category:              |             | Section 8.4 |
| type         | information-type       |             |             |
|              |                        |             |             |
|              |                        |             |             |
|              |                        |             |             |
| property:    | urn:ietf:params:rolie: | Section 7.4 | None        |
| content-     | property:content-      |             |             |
| author-name  | author-name            |             |             |
|              |                        |             |             |
| property:    | urn:ietf:params:rolie: | Section 7.4 | None        |
| content-id   | property:content-id    |             |             |
|              |                        |             |             |
| property:    | urn:ietf:params:rolie: | Section 7.4 | None        |
| content-     | property:content-      |             |             |
| published-   | published-date         |             |             |
| date         |                        |             |             |
|              |                        |             |             |
| property:    | urn:ietf:params:rolie: | Section 7.4 | None        |
| content-     | property:content-      |             |             |
| updated-date | updated-date           |             |             |
+--------------+------------------------+-------------+-------------+

8.4. ROLIE Information Types Registry 🦋

okay this is where we make a whole new subregistry just to store ROLIE information type values 💖

  • Name of Registry: "ROLIE Information Types"
  • Location of Registry: <https://www.iana.org/assignments/rolie/>
  • Fields to record in the registry:
    • Name: The full name of the security resource information type, written as a string from the printable ASCII character set [RFC20], with individual embedded spaces allowed. This value must be unique in the context of this table. The ABNF [RFC5234] syntax for this field is:
1*VCHAR *(SP 1*VCHAR)
  • Index: An IANA-assigned positive integer that identifies the registration. The first entry added to this registry uses the value 1, and the value goes up by one for each entry added after that 🔢
  • Reference: A list of one or more URIs [RFC3986] where the registered specification can be obtained. The registered specification MUST be readily and publicly available from that URI. The URI SHOULD be a stable reference 🔗
  • Allocation Policy: Specification Required, as per [RFC8126]

9. Security Considerations 🔐💀

this section is SERIOUS bestie, so read it carefully 😭

This document defines a resource-oriented approach to lightweight information exchange using HTTP over TLS, the Atom Syndication Format, and AtomPub. That means implementers must understand the security considerations described in those specifications. Everything that follows is guidance only; instructions that are more specific are out of scope for this document 🫶

To protect the confidentiality of a given resource provided by a ROLIE implementation, requests for retrieval of that resource need to be authenticated so unauthorized users can't get in (see Section 5.4). It can also be useful to log and audit access to sensitive resources, so you can verify that proper access controls are still in place over time 👀

Access control for information published using ROLIE should use mechanisms that match the sensitivity of the information. Primitive authentication mechanisms like HTTP Basic Authentication [RFC7617] are rarely appropriate for sensitive information. A number of authentication schemes are defined in the "HTTP Authentication Schemes" registry at <https://www.iana.org/assignments/http-authschemes/>. Of these, HTTP Origin-Bound Authentication (HOBA) [RFC7486] and SCRAM-SHA-256 [RFC7804] ("SCRAM" stands for "Salted Challenge Response Authentication Mechanism") provide improved security properties over HTTP Basic [RFC7617] and Digest [RFC7616] authentication schemes. However, sharing communities that are engaged in sensitive collaborative analysis and/or operational response for indicators and incidents targeting high-value information systems should adopt a suitably stronger user authentication solution, such as a risk-based or multi-factor approach 🚨

Sensitive sharing communities, listen up: for high-value systems, basic-level auth is NOT enough. Go for a stronger solution like risk-based or multi-factor.

Collaborating consortiums may benefit from a federated identity solution, such as one based on OAuth [RFC6749] with the JSON Web Token (JWT) [RFC7797], or SAML-core [SAML-core] ("SAML" stands for "Security Assertion Markup Language"), SAML-bind [SAML-bind], and SAML-prof [SAML-prof] for web-based authentication and cross-organizational single sign-on. Depending on a trusted third-party identity provider means you have to take real care to secure that identity provider. Any attack on the federated identity system would be a risk to the consortium, as a relying party. Potential mitigations include deploying a federation-aware identity provider that is under the control of the information-sharing consortium, with suitably stringent technical and management controls 🛡️

Authorization of resource representations is the responsibility of the source system, meaning it's based on the authenticated user identity associated with an HTTP(S) request. The required authorization policies that get enforced must therefore be managed by the security administrators of the source system 🧑‍💻 Various authorization architectures would be suitable for this, such as Role-Based Access Control (RBAC) <https://csrc.nist.gov/projects/role-based-access-control> and/or Attribute-Based Access Control (ABAC), as embodied in the eXtensible Access Control Markup Language (XACML) [XACML]. In particular, implementers adopting XACML may benefit from being able to represent their authorization policies in a standardized, interoperable format 💅 Note that implementers are free to choose any suitable authorization mechanism that can fulfill the policy enforcement requirements relevant to their consortium and/or organization.

Additional security requirements, such as enforcing message-level security at the destination system, could supplement the security enforcements performed at the source system. However, these destination-provided policy enforcements are out of scope for this specification. Implementers who need this capability should consider leveraging, for example, the <RIDPolicy> element in the RID schema. Refer to Section 9 of [RFC6545] for more information. Also, the underlying serialization approach used in the representation (e.g., XML, JSON) can offer encryption and message authentication capabilities. For example, XML Digital Signatures (XMLDSIG) [RFC3275] for XML, as well as JSON Web Encryption [RFC7516] and JSON Web Signature [RFC7515] for JSON, can provide such mechanisms 🔏

When security policies relevant to the source system are enforced at both the source and destination systems, implementers must take care to avoid unintended interactions between the separately enforced policies. Potential risks include unintended denial of service and/or unintended information leakage. These problems may be mitigated by avoiding any dependence on enforcements performed at the destination system. When distributed enforcement is unavoidable, using a standard language (e.g., XACML) to express authorization policies will let the source and destination systems better coordinate and align their respective policy expressions ⚠️

A service discovery mechanism is not explicitly specified in this document, but there are several approaches available for implementers. When selecting one, implementations need to make sure their choice provides a means for authenticating the server. DNS SRV records [RFC2782] are a possible solution to the discovery problem described in Section 5.1.3 ✨

10. Privacy Considerations 🔐✨

okay bestie, privacy is such a vibe and we need to talk about it 🫶

The optional author field can be a privacy problem if somebody fills it in without the author's consent 😭. That info could go public if the Entry is posted to a public Feed. So when you're aggregating or sharing Entries from other Feeds, or generating ROLIE Entries from some data source, you have to be extra careful that the author's personal info doesn't get shared without their okay 🙈.

When you use AtomPub to POST Entries to a Feed, attackers may use correlating techniques to profile the user 👀. They can compare the request time with the generated updated field of the Entry and piece together info about a given user. You can shut this down by not using HTTP requests to POST Entries when profiling is a risk, and instead using backend control of the Feeds 🛡️.

Okay, this next part is a lot 💀. Using the information-sharing approach in this document makes it easier for users to correlate data across separate, and possibly unrelated, cybersecurity information providers. A client might end up assembling a data set that wouldn't have been allowed under the authorization policies of either provider on its own. So providers may face the risk of an attacker getting access that counts as an undetected separation of duties (SOD) violation 😱. This risk isn't unique to this specification, though. Any other cybersecurity information-sharing protocol has a similar potential for abuse. The thing is, tools for HTTP clients and Atom Feed handling are so widely available that the resources and technical skills needed for a successful exploit may be lower than they used to be. The best way to handle this is careful vetting of the client when the account is provisioned ✅. Any increase in this type of abuse risk should also be balanced by the matching boost in effectiveness this specification gives to the defenders 💪.

Overall, privacy concerns in ROLIE can be handled by following the security considerations and by being careful about using the optional personally identifying elements (like author) that Atom Syndication and ROLIE provide 🎀.

11. References 📚

11.1. Normative References

These are the must-read sources 🤓:

[RELAX-NG] Clark, J., Ed., "RELAX NG Compact Syntax", November 2002,
           <https://www.oasis-open.org/committees/relax-ng/
           compact-20021121.html>.

[RFC20]    Cerf, V., "ASCII format for network interchange", STD 80,
           RFC 20, DOI 10.17487/RFC0020, October 1969,
           <https://www.rfc-editor.org/info/rfc20>.

[RFC2045]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
           Extensions (MIME) Part One: Format of Internet Message
           Bodies", RFC 2045, DOI 10.17487/RFC2045, November 1996,
           <https://www.rfc-editor.org/info/rfc2045>.

[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>.

[RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
           Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
           <https://www.rfc-editor.org/info/rfc3339>.

[RFC3553]  Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
           IETF URN Sub-namespace for Registered Protocol
           Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553,
           June 2003, <https://www.rfc-editor.org/info/rfc3553>.

[RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
           DOI 10.17487/RFC3688, January 2004,
           <https://www.rfc-editor.org/info/rfc3688>.

[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,
           <https://www.rfc-editor.org/info/rfc3986>.

[RFC4287]  Nottingham, M., Ed., and R. Sayre, Ed., "The Atom
           Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
           December 2005, <https://www.rfc-editor.org/info/rfc4287>.

[RFC5005]  Nottingham, M., "Feed Paging and Archiving", RFC 5005,
           DOI 10.17487/RFC5005, September 2007,
           <https://www.rfc-editor.org/info/rfc5005>.

[RFC5023]  Gregorio, J., Ed., and B. de hOra, Ed., "The Atom
           Publishing Protocol", RFC 5023, DOI 10.17487/RFC5023,
           October 2007, <https://www.rfc-editor.org/info/rfc5023>.

[RFC5234]  Crocker, D., Ed., and P. Overell, "Augmented BNF for
           Syntax Specifications: ABNF", STD 68, RFC 5234,
           DOI 10.17487/RFC5234, January 2008,
           <https://www.rfc-editor.org/info/rfc5234>.

[RFC6546]  Trammell, B., "Transport of Real-time Inter-network
           Defense (RID) Messages over HTTP/TLS", RFC 6546,
           DOI 10.17487/RFC6546, April 2012,
           <https://www.rfc-editor.org/info/rfc6546>.

[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, <https://www.rfc-editor.org/info/rfc7525>.

[RFC7970]  Danyliw, R., "The Incident Object Description Exchange
           Format Version 2", RFC 7970, DOI 10.17487/RFC7970,
           November 2016, <https://www.rfc-editor.org/info/rfc7970>.

[RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
           Writing an IANA Considerations Section in RFCs", BCP 26,
           RFC 8126, DOI 10.17487/RFC8126, June 2017,
           <https://www.rfc-editor.org/info/rfc8126>.

[RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in
           RFC 2119 Key Words", BCP 14, RFC 8174,
           DOI 10.17487/RFC8174, May 2017,
           <https://www.rfc-editor.org/info/rfc8174>.

[W3C.REC-xml-names-20091208]
           Bray, T., Hollander, D., Layman, A., Tobin, R., and H.
           Thompson, "Namespaces in XML 1.0 (Third Edition)", World
           Wide Web Consortium Recommendation REC-xml-names-20091208,
           December 2009, <https://www.w3.org/TR/2009/
           REC-xml-names-20091208>.

11.2. Informative References

These ones are the extra background reading 🧠🌸:

[Err3267]  RFC Errata, Erratum ID 3267, RFC 6546,
           <https://www.rfc-editor.org/errata/eid3267>.

[REST]     Fielding, R., "Architectural Styles and the Design of
           Network-based Software Architectures", 2000,
           <http://www.ics.uci.edu/~fielding/pubs/
           dissertation/top.htm>.

[RFC2782]  Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
           specifying the location of services (DNS SRV)", RFC 2782,
           DOI 10.17487/RFC2782, February 2000,
           <https://www.rfc-editor.org/info/rfc2782>.

[RFC3275]  Eastlake 3rd, D., Reagle, J., and D. Solo, "(Extensible
           Markup Language) XML-Signature Syntax and Processing",
           RFC 3275, DOI 10.17487/RFC3275, March 2002,
           <https://www.rfc-editor.org/info/rfc3275>.

[RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
           Information Models and Data Models", RFC 3444,
           DOI 10.17487/RFC3444, January 2003,
           <https://www.rfc-editor.org/info/rfc3444>.

[RFC6545]  Moriarty, K., "Real-time Inter-network Defense (RID)",
           RFC 6545, DOI 10.17487/RFC6545, April 2012,
           <https://www.rfc-editor.org/info/rfc6545>.

[RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
           RFC 6749, DOI 10.17487/RFC6749, October 2012,
           <https://www.rfc-editor.org/info/rfc6749>.

[RFC7486]  Farrell, S., Hoffman, P., and M. Thomas, "HTTP
           Origin-Bound Authentication (HOBA)", RFC 7486,
           DOI 10.17487/RFC7486, March 2015,
           <https://www.rfc-editor.org/info/rfc7486>.

[RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
           Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515,
           May 2015, <https://www.rfc-editor.org/info/rfc7515>.

[RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
           RFC 7516, DOI 10.17487/RFC7516, May 2015,
           <https://www.rfc-editor.org/info/rfc7516>.

[RFC7616]  Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
           Digest Access Authentication", RFC 7616,
           DOI 10.17487/RFC7616, September 2015,
           <https://www.rfc-editor.org/info/rfc7616>.

[RFC7617]  Reschke, J., "The 'Basic' HTTP Authentication Scheme",
           RFC 7617, DOI 10.17487/RFC7617, September 2015,
           <https://www.rfc-editor.org/info/rfc7617>.

[RFC7797]  Jones, M., "JSON Web Signature (JWS) Unencoded Payload
           Option", RFC 7797, DOI 10.17487/RFC7797, February 2016,
           <https://www.rfc-editor.org/info/rfc7797>.

[RFC7804]  Melnikov, A., "Salted Challenge Response HTTP
           Authentication Mechanism", RFC 7804, DOI 10.17487/RFC7804,
           March 2016, <https://www.rfc-editor.org/info/rfc7804>.

[RFC8141]  Saint-Andre, P. and J. Klensin, "Uniform Resource Names
           (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
           <https://www.rfc-editor.org/info/rfc8141>.

[SAML-bind]
           Cantor, S., Hirsch, F., Kemp, J., Philpott, R., and E.
           Maler, "Bindings for the OASIS Security Assertion Markup
           Language (SAML) V2.0", OASIS Standard saml-bindings-
           2.0-os, March 2005, <http://docs.oasis-open.org/
           security/saml/v2.0/saml-bindings-2.0-os.pdf>.

[SAML-core]
           Cantor, S., Kemp, J., Philpott, R., and E. Maler,
           "Assertions and Protocols for the OASIS Security Assertion
           Markup Language (SAML) V2.0", OASIS Standard saml-core-
           2.0-os, March 2005, <http://docs.oasis-open.org/
           security/saml/v2.0/saml-core-2.0-os.pdf>.

[SAML-prof]
           Hughes, J., Cantor, S., Hodges, J., Hirsch, F., Mishra,
           P., Philpott, R., and E. Maler, "Profiles for the OASIS
           Security Assertion Markup Language (SAML) V2.0", OASIS
           Standard saml-profiles-2.0-os, March 2005,
           <http://docs.oasis-open.org/security/saml/v2.0/
           saml-profiles-2.0-os.pdf>.

[TLS-1.3]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
           Version 1.3", Work in Progress, draft-ietf-tls-tls13-23,
           January 2018.

[XACML]    Rissanen, E., "eXtensible Access Control Markup Language
           (XACML) Version 3.0 Plus Errata 01", July 2017,
           <http://docs.oasis-open.org/xacml/3.0/
           xacml-3.0-core-spec-en.pdf>.

Appendix A. RELAX NG Compact Schema for ROLIE ✨

This appendix is informative 🧚

okay so this bit is the RELAX NG Compact schema, and it defines the rolie:format element 💅 It's giving grammar, and it's the blueprint for how that element is shaped. Here it is:

# -*- rnc -*-
# RELAX NG Compact Syntax Grammar for the rolie ns

namespace rolie = "urn:ietf:params:xml:ns:rolie-1.0"

# import the ATOM Syndication RELAX NG Compact Syntax Grammar
include "atomsynd.rnc"

# rolie:format
rolieFormat =
  element rolie:format {
    atomCommonAttributes,
    attribute ns { atomUri },
    attribute version { text } ?,
    attribute schema-location { atomUri } ?,
    attribute schema-type { atomMediaType } ?,
    empty
  }

# rolie:property

rolieProperty =
  element rolie:property {
    atomCommonAttributes,
    attribute name { atomUri },
    attribute value { text },
    empty
  }

and that's the whole schema bestie 🎀 it even includes the rolie:property pattern too, so you get both pieces in one place 🫶

Appendix B. Examples of Use 🦋

This appendix is full of non-normative examples, so think of them as vibes and walkthroughs rather than rules 🌸

B.1. Service Discovery

This appendix provides a non-normative example of a client doing service discovery.

okay so an Atom Service Document is how a client figures out what Feeds a publisher actually has 👑 basically the provider uses one so authorized clients can see what info they're sharing with the community. it should be easy to find too, like a link straight from the producer's home page 🏡

a client can send an HTTP GET request to grab the Service Document from that location:

  GET /rolie/servicedocument
  Host: www.example.org
  Accept: application/atomsvc+xml

notice the Accept: request header there 👀 it's telling the server it wants the MIME type for Atom service discovery. the response is an XML document listing all the Collections on offer 💖

example HTTP GET response:

 HTTP/1.1 200 OK
 Date: Fri, 24 Aug 2016 17:09:11 GMT
 Content-Length: 570
 Content-Type: application/atomsvc+xml;charset="utf-8"

 <?xml version="1.0" encoding="UTF-8"?>
 <service xmlns="https://www.w3.org/2007/app"
     xmlns:atom="https://www.w3.org/2005/Atom">
   <workspace>
     <atom:title type="text">Vulnerabilities</atom:title>
     <collection href="https://example.org/provider/vulns">
       <atom:title type="text">Vulnerabilities Feed</atom:title>
       <categories fixed="yes">
         <atom:category
             scheme="urn:ietf:params:rolie:category:information-type"
             term="vulnerability"/>
       </categories>
     </collection>
   </workspace>
 </service>

this one is simple, one workspace called "Vulnerabilities" with one Collection inside it ✨

a server can also offer a bunch of Collections, each with its own kind of security automation info. in this next one, every Collection gets its own category and authorization scope, which helps clients pick the ones that actually fit their needs 🍓

 HTTP/1.1 200 OK
 Date: Fri, 24 Aug 2016 17:10:11 GMT
 Content-Length: 1912
 Content-Type: application/atomsvc+xml;charset="utf-8"

 <?xml version="1.0" encoding='utf-8'?>
 <service xmlns="https://www.w3.org/2007/app"
     xmlns:atom="https://www.w3.org/2005/Atom">
   <workspace>
     <atom:title>Public Security Information Sharing</atom:title>
     <collection
         href="https://example.org/provider/public/vulns">
       <atom:title>Public Vulnerabilities</atom:title>
       <atom:link rel="service"
         href="https://example.org/rolie/servicedocument"/>
       <categories fixed="yes">
         <atom:category
             scheme="urn:ietf:params:rolie:category:information-type"
             term="vulnerability"/>
       </categories>
     </collection>
   </workspace>
   <workspace>
     <atom:title>Private Consortium Sharing</atom:title>
     <collection
         href="https://example.org/provider/private/incidents">
       <atom:title>Incidents</atom:title>
       <atom:link rel="service"
         href="https://example.org/rolie/servicedocument"/>
       <categories fixed="yes">
         <atom:category
             scheme="urn:ietf:params:rolie:category:information-type"
             term="incident"/>
       </categories>
     </collection>
   </workspace>
 </service>

so in this one the provider has two Collections split across two workspaces 🎀 the first is public software vulnerabilities, and the second is an incident Collection for a private sharing consortium 🔒 a properly authenticated and authorized client can then make HTTP requests for these. the public vulnerability info might be reachable with or without authentication, but people going into the consortium-only Collection are expected to authenticate before they get in 🫶

B.2. Feed Retrieval

This appendix provides a non-normative example of a client retrieving a vulnerability Feed.

once a client has found the Collections, a member of the general public who wants the public vulnerabilities (written as Common Vulnerabilities and Exposures, or CVEs) can grab that Feed with an HTTP GET on the URL in the Collection's href attribute 💜

example HTTP GET request for a Feed:

  GET /provider/public/vulns
  Host: www.example.org
  Accept: application/atom+xml

the response is an XML document with the vulnerability Feed in it:

Example HTTP GET response for a Feed:

  HTTP/1.1 200 OK
  Date: Fri, 24 Aug 2016 17:20:11 GMT
  Content-Length: 2882
  Content-Type: application/atom+xml;charset="utf-8"

  <?xml version="1.0" encoding="UTF-8"?>
  <feed xmlns="https://www.w3.org/2005/Atom"
      xmlns:rolie="urn:ietf:params:xml:ns:rolie-1.0"
      xml:lang="en-US">
    <id>2a7e265a-39bc-43f2-b711-b8fd9264b5c9</id>
    <title type="text">
        Atom-formatted representation of
        a Feed of XML vulnerability documents
    </title>
    <category
        scheme="urn:ietf:params:rolie:category:information-type"
        term="vulnerability"/>
    <updated>2016-05-04T18:13:51.0Z</updated>
    <link rel="self"
        href="https://example.org/provider/public/vulns"/>
    <link rel="service"
        href="https://example.org/rolie/servicedocument"/>
    <entry>
      <rolie:format ns="urn:ietf:params:xml:ns:exampleformat"/>
      <id>dd786dba-88e6-440b-9158-b8fae67ef67c</id>
      <title>Sample Vulnerability</title>
      <published>2015-08-04T18:13:51.0Z</published>
      <updated>2015-08-05T18:13:51.0Z</updated>
      <summary>A vulnerability issue identified by CVE-...</summary>
      <content type="application/xml"
          src="https://example.org/provider/vulns/123456/data"/>
    </entry>
    <entry>
        <!-- ...another entry... -->
    </entry>
  </feed>

this Feed Document has two Atom Entries, and one of them got elided (the <!-- ...another entry... --> bit is the placeholder for it) 🙈 the first Entry is an atom:entry element that gives a quick summary of one vulnerability. if the summary and category info look good, the client can do an HTTP GET on the content src attribute to pull all the full details 🧚

B.3. Entry Retrieval

This appendix provides a non-normative example of a client retrieving a vulnerability as an Atom Entry.

after getting the Feed, the client can look at the description and/or category info and decide that one of the Entries is worth a closer look 👀 to get that vulnerability Entry, it does an HTTP GET on the URL in the src attribute of the atom:content element 🌈

example HTTP GET request for an Entry:

  GET /provider/public/vulns/123456
  Host: www.example.org
  Accept: application/atom+xml;type=entry

the response is an XML document with the Atom Entry for that vulnerability record:

Example HTTP GET response for an Entry:

  HTTP/1.1 200 OK
  Date: Fri, 24 Aug 2016 17:30:11 GMT
  Content-Length: 713
  Content-Type: application/atom+xml;type=entry;charset="utf-8"

  <?xml version="1.0" encoding="UTF-8"?>
  <entry xmlns="https://www.w3.org/2005/Atom"
      xmlns:rolie="urn:ietf:params:xml:ns:rolie-1.0"
      xml:lang="en-US">
    <id>f63aafa9-4082-48a3-9ce6-97a2d69d4a9b</id>
    <title>Sample Vulnerability</title>
    <published>2015-08-04T18:13:51.0Z</published>
    <updated>2015-08-05T18:13:51.0Z</updated>
    <category
        scheme="urn:ietf:params:rolie:category:information-type"
        term="vulnerability"/>
    <summary>A vulnerability issue identified by CVE-...</summary>
    <rolie:format ns="urn:ietf:params:xml:ns:exampleformat"/>
    <content type="application/xml"
        src="https://example.org/provider/vulns/123456/data">
    </content>
  </entry>

so the response here is an XML document, and the src attribute on atom:content points at it. the client can fetch the document using that URL, and that's the whole flow 💖

Acknowledgements 🫶

okay the authors want to shout out Tom Maguire, Kathleen Moriarty, and Vijayanand Bharadwaj 📣 they gave super detailed review comments on earlier drafts, and their suggestions made the doc so much better ✨

they also thank the MILE Working Group, the SACM Working Group, and everyone else from inside and outside the IETF community who reviewed and put in the effort to build this 💅🌸

Authors' Addresses 🎀

here are the authors and how to reach them 💌

John P. Field
Pivotal Software, Inc.
625 Avenue of the Americas
New York, New York  10011
United States of America

Phone: (646)792-5770
Email: jfield@pivotal.io


Stephen A. Banghart
National Institute of Standards and Technology
100 Bureau Drive
Gaithersburg, Maryland  20877
United States of America

Phone: (301)975-4288
Email: stephen.banghart@nist.gov


David Waltermire
National Institute of Standards and Technology
100 Bureau Drive
Gaithersburg, Maryland  20877
United States of America

Email: david.waltermire@nist.gov

and that's a wrap on RFC 8322 bestie 🌈🧚💖 the whole thing is done, you did so amazing for reading it all!

📦 where this page comes from