Network Working Group L. Garshol Internet-Draft Bouvet ASA Intended status: Informational November 24, 2009 Expires: May 28, 2010 application/xtm+xmlMedia Type Registration draft-garshol-applicationxtmxml-00 Abstract This document describes a media type (application/xtm+xml) for serialization of Topic Maps into Extensible Markup Language (XML). Topic Maps is a technology for encoding knowledge and connecting this encoded knowledge to relevant information resources. Topic maps are organized around topics, which represent subjects of discourse; associations, representing relationships between the subjects; and occurrences, which connect the subjects to pertinent information resources. Topic Maps is an ISO standard (ISO 13250). Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on May 28, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. Garshol Expires May 28, 2010 [Page 1] Internet-Draft application/xtm+xml November 2009 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) 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 BSD License. Garshol Expires May 28, 2010 [Page 2] Internet-Draft application/xtm+xml November 2009 1. Introduction Topic Maps is a technology for encoding knowledge and connecting this encoded knowledge to relevant information resources. Topic Maps has a common structure defined by [ISO13250-2] that can be used for interoperable data interchange. Many formats exist for the interchange of Topic Maps, but ISO has defined the XTM syntax [ISO13250-3] as the main interchange syntax, in order to allow topic map to be serialized in an XML format. The application/xtm+xml media type allows consumers of Topic Maps information to identify XTM documents so they can be processed properly. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119]. Garshol Expires May 28, 2010 [Page 3] Internet-Draft application/xtm+xml November 2009 2. application/xtm+xml Registration This is a media type registration as defined in RFC 4288, "Media Type Specifications and Registration Procedures" [RFC4288]. *MIME media type name:* application *MIME subtype name:* xtm+xml *Required parameters:* none *Optional parameters:* charset Same as charset parameter of application/xml, defined in RFC 3023 [RFC3023]. *Encoding considerations:* Same as encoding considerations of application/xml, defined in RFC 3023 [RFC3023]. *Security considerations:* See Section 5. *Interoperability considerations:* It is RECOMMENDED that XTM documents use the new XTM 2.0 syntax [ISO13250-3] as opposed to the older XTM 1.0 syntax [XTM1.0]. In general use of features of XML which XML processors may choose not to support should be avoided. ISO SC34 is currently developing XTM 2.1, which is backwards compatible with XTM 2.0. When XTM 2.1 becomes a standard it is RECOMMENDED to use XTM 2.1 instead of XTM 2.0, despite 2.0 being a subset, as 2.1 is better suited to the interchange of fragments over the internet. *Published specification:* See the Topic Maps Data Model [ISO13250-2] and the XTM specification [ISO13250-3]. *Applications which use this media type:* Any tool which can process or produce data according to the Topic Maps Data Model [ISO13250-2]. This has included in the past generic Topic Maps tools, web portals, product configuration tools, e-learning systems, and a variety of web services and web service clients. *Magic number(s):* none Although no byte sequences can be counted on to consistently identify XTM, XTM documents will have the sequence "http://www.topicmaps.org/xtm/" to identify the XTM namespace. This will usually be near the top of the document. Garshol Expires May 28, 2010 [Page 4] Internet-Draft application/xtm+xml November 2009 *File extensions(s):* .xtm *Macintosh File Type Code(s):* "xtm " *Person & email address to contact for further information:For further information:* Lars Marius Garshol *Intended usage:* COMMON *Author:* Lars Marius Garshol *Change controller:* The IESG. Garshol Expires May 28, 2010 [Page 5] Internet-Draft application/xtm+xml November 2009 3. Fragment Identifiers The id attribute can be used to define fragments in an XTM document. So given an XTM document with the URL someurl the URL reference someurl#frag is taken to refer to the topic element in the XTM document whose id attribute value is "frag". Such URLs commonly occur in XTM documents to refer to topics defined either in the same XTM document or a different XTM document. Garshol Expires May 28, 2010 [Page 6] Internet-Draft application/xtm+xml November 2009 4. IANA Considerations This document calls for registration of a new MIME media type, according to the registration in Section 2. Garshol Expires May 28, 2010 [Page 7] Internet-Draft application/xtm+xml November 2009 5. Security Considerations XTM is a generic format for exchanging application information, but application designers must not assume that it provides generic protection against security threats. RFC 3023 [RFC3023], section 10, discusses security concerns for generic XML, which are also applicable to XTM. XTM documents can be secured for integrity, authenticity and confidentiality using any of the mechanisms available for MIME and XML data, including XML signature, XML encryption, S/MIME, OpenPGP or transport or session level security (e.g., see [RFC3631], especially sections 3.4, 3.5, 3.10, [RFC2818], [RFC3275], [xmlenc-core]). XTM is intended to be used to combine information from disparate sources into a coherent whole, but it is entirely possible for sources outside the control of the receiver to provide information that is false, misleading, unclear, or inappropriately structured. The use of Topic Maps schemas may guard against inappropriate structure, but as far as the other concerns go, caution and careful engineering are required. XTM documents may contain references to other XTM documents via the mergeMap element, and XTM processors are required to dereference and process these references. This can be a source of insecurity, by means either subtle or obvious, such denial of service attacks by automatically generated never-ending chains of mergeMap references or infinitely sized documents. Garshol Expires May 28, 2010 [Page 8] Internet-Draft application/xtm+xml November 2009 6. References [ISO13250-2] Garshol, L. and G. Moore, "ISO 13250-2:2006 - Topic Maps - Data Model", August 2006. The International Organization for Standardization. Prepared by ISO/SC 34. [ISO13250-3] Garshol, L. and G. Moore, "ISO 13250-3:2007 - Topic Maps - XML Syntax", March 2007. The International Organization for Standardization. Prepared by ISO/SC 34. [RFC2119] Bradner, R., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. [RFC3023] Murata, M., St.Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [RFC3275] Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup Language) XML-Signature Syntax and Processing", RFC 3275, March 2002. [RFC3631] Bellovin, S., Schiller, J., and C. Kaufman, "Security Mechanisms for the Internet", RFC 3631, December 2003. [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005. [xmlenc-core] Eastlake, D. and J. Reagle, "XML Encryption Syntax and Processing", December 2002. W3C xmlenc-core [XTM1.0] Pepper, S. and G. Moore, "XML Topic Maps (XTM) 1.0", August 2001. Garshol Expires May 28, 2010 [Page 9] Internet-Draft application/xtm+xml November 2009 TopicMaps.org Specification. Garshol Expires May 28, 2010 [Page 10] Internet-Draft application/xtm+xml November 2009 Author's Address Lars Marius Garshol Bouvet ASA Email: larsga@garshol.priv.no URI: http://www.garshol.priv.no Garshol Expires May 28, 2010 [Page 11]