Network Working Group B. Hoehrmann
Internet-Draft October 28, 2006
Intended status: Standards Track
Expires: May 1, 2007
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Copyright (C) The Internet Society (2006).
identifier scheme for applications that need to specify script code
in contexts where resource identifiers are expected.
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code in a resource identifier in a way similar to the 'data' scheme,
but with extended semantics. This document defines the scheme and
two operations that describe how existing implementations handle it.
The first operation, content retrieval, defines which script code a
fully defined in this document and some applications, such as
implementations of the Virtual Reality Modeling Language, will only
take advantage of this operation.
The second operation, in-context evaluation, is often implemented by
web browser applications, and provides a means to run custom script
code when the resource identifier is dereferenced. As an example,
consider a HTML document containing a hyperlink like:
In typical implementations, when the user activates the hyperlink,
the web browser will pass control to the doSomething() function, and
if the function returns something, render the result in place of the
Some semantics of this operation are out of scope of this document.
As an example, in the example above, if the doSomething() function
returns a string object, the implementation would lack clues, like an
Internet media type, how to process it, it could interprete it as
script, style sheet, HTML document, resource identifier, or any other
type of media as appropriate for the context.
In order not to limit the applicability of this scheme for certain
applications, this document just describes this operation in terms of
an abstract model; it is expected that, where needed, other
specifications define the semantics in more detail using this model.
2. Terminology and Conformance
Resource identifiers, including percent-encoding and requirements for
IRIs, are defined in STD 66, [RFC3986] and [RFC3987]. Source text is
the 'data' scheme in [RFC2397], and UTF-8, including the term byte
order mark, in STD 63, [RFC3629].
An application that generates resource identifiers conforms to this
Hoehrmann Expires May 1, 2007 [Page 2]
conform to this specification.
conforms to this specification if and only if it implements the
content retrieval operation as defined in this specification.
A resource identifier conforms to this specification if and only if
it is a valid IRI and application of the content retrieval operation
error. Use of a byte order mark and literal use of the character "/"
should be avoided.
A resource identifier is said to have one or more encoding errors
when applying the content retrieval operation to it results in one or
more errors. Resource identifiers with encoding errors do not
conform to this specification.
For resource identifiers with encoding errors the considerations for
The algorithms defined in this document are considered equivalent to
any and all algorithms that map the same input to the same results.
This section defines two operations that can be applied to resource
identifiers that conform to this specification. Other operations may
be defined in other specifications.
3.1. Content retrieval
This operation retrieves the source text that is included in the
1. Represent the scheme-specific part as sequence of octets in
the UTF-8 character encoding.
2. Replace any percent-encoded octet by its corresponding octet.
3. If the sequence starts with the sequence 0xEF 0xBB 0xBF,
discard this sequence.
4. Decode the octet sequence using the UTF-8 character encoding
and transform the result into source text.
Hoehrmann Expires May 1, 2007 [Page 3]
3.2. In-context evaluation
This operation defines a model under which applications may evaluate
1. Retrieve the source text using the content retrieval
2. Determine a dereference context for further processing.
3. Evaluate the source text in this context and memorize the
result as dereference by-product.
4. Process the dereference by-product as appropriate for the
4. Interoperability Considerations
of fragment identifiers as in <_scrollto>, and
some applications might have to recover from such errors. Designers
of protocol elements that accept resource identifiers as defined in
this document should consider this case and, where compatibility is a
concern, define a pre-processing step that percent-encodes all '#'
characters before the content of the protocol element is processed as
5. Security Considerations
For applications that rely only on the content retrieval operation as
defined in this document, the security considerations are equivalent
as defined in their respective specifications. In-context evaluation
may introduce additional security issues, but these depend on the
dereference context and how the dereference by-product is processed
and are thus considered out of scope of this document.
6. Internationalization Considerations
None beyond those inherent to resource identifiers and entities of
Hoehrmann Expires May 1, 2007 [Page 4]
7. IANA Considerations
in the IANA Uniform Resource Identifier scheme registry [RFC4395].
8.1. Normative References
[ECMA] European Computer Manufacturers Association, "ECMAScript
Language Specification 3rd Edition", December 1999,
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, January 2005.
[RFC4329] Hoehrmann, B., "Scripting Media Types", RFC 4329,
8.2. Informative References
[RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397,
[RFC4395] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
Registration Procedures for New URI Schemes", BCP 115,
RFC 4395, February 2006.
Weinheimer Strasse 22
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