Foundation of the Project
The ITU-T Study Group 17 ASN.1 Project assist users of ASN.1 (Rec. ITU-T X.680, X.690 and X.890 series) within and outside of ITU-T, and promotes the usage of ASN.1 across a wide range of industries and standards bodies.
Scope of the project
It is the continuation of a part of the common ASN.1 and OID Project established in February 2001 by ITU-T Study Group 7 (now Study Group 17).
Management of the Project
- Provide assistance to users of ASN.1 (Rec. ITU-T X.680, X.690 and X.890 series) within and outside the ITU-T.
- Promote the usage of ASN.1 in new protocols.
- Help the TSB in responding to requests they receive about ASN.1 usage.
- Help the TSB in the maintenance of an up-to-date database of error-free ASN.1 modules. This database contains the modules of more than 200 ITU-T Recommendations and the modules of other SDOs referenced by them.
Paul Thorpe (United States) has been appointed as Project Leader. The Project Leader in consultation with the SG17 Chairman and TSB manages decisions related to the operation of the ITU-T Project including the use of its name and resources. All such decisions are reported to each Plenary session of SG17.
Background on ASN.1
The Project Leader establishes a close working relationship with the SG17 management team and with the Promotion, Edition and Production Department and other parts of the TSB.
ASN.1 is a well-established
technology that is widely used both within ITU-T and outside of it.
The notation is supported by a number of software
ASN.1 module database
The Encoding Control Notation,
ITU-T X.692), makes it possible for ASN.1 to be used for all
existing telecom/computer protocols. This extends the use of ASN.1 into
new areas, and increases the need for coordination of the activity.
The XML Encoding Rules,
XER (Rec. ITU-T X.693), allows
the encoding of ASN.1 values in XML markup format for the purpose of
transmission. A canonical XML encoding is also specified in this
document. ASN.1 can now be used as a schema for XML, in the same way as
XSD and RELAX NG are used.
The mapping from W3C
XML Schemas into ASN.1 modules (Rec.
ITU-T X.694) takes as input a
schema written in XML Schema and produces an ASN.1 module containing a set of type
definitions (and, optionally, an XER encoding instruction section to
keep the same XML encoding, if needed), in such a way that there is a
one-to-one correspondence between ASN.1 abstract values and valid XML
instances. This technique can be applied to any given XML application
language. ASN.1 standardized encoding
such as DER (a canonical encoding that allows digital signatures and
encryption, for example) or PER (to very efficiently transmit data over
a radio channel, for example) can then be used as well as associated ASN.1 tools, or even specific encoding
rules that are described in ECN.
Fast Infoset (Rec.
ITU-T X.891) specifies a representation of an instance of the W3C XML
Information Set using ASN.1 binary encodings. This representation
generally provides smaller encoding sizes and faster processing than a
W3C XML representation. It provides the capability to encode XML
content that is not described by a schema.
Fast Web Services
(Rec. ITU-T X.892) is the term applied to the use of ASN.1 to provide
message exchanges based on a SOAP envelope and WSDL specification of
services that can have a higher transaction-processing rate and less
bandwidth requirements than use of a character-based XML
Rec. ITU-T X.893 "Generic Applications of ASN.1 - Fast Infoset and Fast Web Services Security" specifies the application of standard security methods to the Fast Infoset and Fast Web Services specifications.
The ASN.1 module database
was initiated by France Telecom and donated to the ITU-T in November
2002. The database currently
contains over 733 ASN.1 modules corresponding to more than 200 ITU-T
Recommendations. The maintenance of the database is handled by the Promotion, Edition and Production Department of the ITU TSB.
Implementations of the
associated ITU-T Recommendations require an electronic format (using
ASCII encoding) in order to directly process the formal definitions in
current tools. Obtaining an
ASCII encoding from a printed or a post-script document involves
re-typing, hinders speedy implementation and can introduce errors. Having all ASN.1 modules (in ASCII
format) in one place greatly eases implementation of the corresponding
The TSB validation process is as follows: firstly, the module is
extracted from the Recommendation; a syntax and semantics check is then
performed and, if errors are found, a communication process is
established with the Editor and Rapporteur of the Recommendation to solve
these errors. The modules are
checked as soon as possible after Consent is given. This allows errors to be corrected
during the publication phase and ensures that the published
Recommendations are error-free.
Three validation tools were donated to the TSB: France Telecom donated
Asnp, a syntax checker and HTML pretty-printer; OSS Nokalva donated
their ASN.1 compiler; Opening Technologies donated their ASN.1/GDMO
An agreement was reached with ISO, IETF, ITU-R and UPU in order to
include any of their ASN.1 modules referenced by ITU-T Recommendations.
In cooperation with the Promotion, Edition and Production Department of the ITU TSB, the ASN.1 Project has established a database that contains a machine-processable copy of the current version of all ASN.1 modules that are included in ITU-T Recommendations (see previous section).
TSB extended the module database with
formal descriptions used in ITU-T Recommendations, such as
documents, GDMO definitions, and
SNMP MIB modules.