The following are some frequently asked questions and
answers about the ASN1C compiler:
|
| Q. |
What types of ASN.1
specifications has your product been used on? |
| A. |
Our ASN.1 compilers have been used in a
wide variety of projects involving both custom and standardized ASN.1
specifications. Some of the standard specifications are the following:
- Universal Mobile Telecommunication System (UMTS)
3rd Generation Partnership Project (3GPP) Applications (RANAP, RRC, NBAP,
RNSAP)
- Security Related Specifications (X.509, PKCS,
PKIX, X9 standards, XCBF Biometrics)
- Computer Supported Telephony Applications
(CSTA)
- TAP3 (Transferred Account Procedure)
- Telecom Protocols (GPRS, MAP, CAP, CAMEL)
- Aeronautical Telecommunictions Network (ATN)
- Manufacturing Message Specification (MMS)
- H.323 VoiP related protocols (H.225, H.235,
H.245)
- T.38 Real-Time Fax over IP
- Association Control Service Element (ACSE) and
Remote Operation Support Element (ROSE)
|
|
| Q. |
How does ASN1C handle
Information Objects and Parameterized Types? |
| A. |
The ASN1C compiler gets at the main
type definitions contained within these definitions and generates accurate
C/C++ and/or Java encoders/decoders for these types. This sometimes involves
linking back through layers of parameterized definitions and classes to get to
the base types. The compiler is also capable of pulling embedded type and value
definitions from information objects and generating code for them.
Please download our white-paper
ASN1C Support for Information
Objects and Parameterized Types for further details. |
|
| Q. |
Does ASN1C support
table constraints as specified in X.682? |
| A. |
Version 5.4 and higher of ASN1C
provides the capability to parse and generate code for 'table constraints'.
These are constraints on multi-part message types that contrains the fields
that can appear in certain parts of a message to values in tables defined
within a specification. ASN1C can generate code to make use of these tables
that allow these types of messages to be encoded or decoded in a single
step. |
|
| Q. |
Is the source-code
generated by ASN1C portable? |
| A. |
Yes, generated C and C++ code is
compliant with the American National Standards Institute (ANSI) standards. In
the C++ version, the use of non-portable constructs such as templates, I/O
stream operators, and exceptions is avoided to ensure maximum portability. A
version of the run-time libraries is available that includes source code and it
too is ANSI-standard making it possible to port the ASN1C code to a
wide-variety of platforms. |
|
| Q. |
Can the code be used
in real-time, embedded system applications? |
| A. |
We can provide C/C++ binary libraries
for certain embedded targets as well as J2ME
libraries for Java or C# compact edition libraries for C#. Source code can be
provided for platforms for which we don't have binaries. This code can be
edited to include only what is absolutely necessary to accomplish a specific
encoding or decoding task (you can do this yourself or we can create a custom
package for you). This will allow you to create code with the small footprint
you need to fit into even the most space-constrained systems. |
|
| Q. |
Does ASN1C support all
syntax specified in the ASN.1 standards? |
| A. |
We can parse all syntax as defined in
the 1990 through 2002 standards. Equivalent C, C++, C#, or Java code is
generated for most items. Please see our latest release notes for information on items currently
not supported. |
|
| Q. |
Is the the code
considered to be Open Source? |
| A. |
It depends on your definition of 'Open
Source'. It is not in the GNU sense in which it is available for free download.
But versions of the product are available that include the run-time C and C++
source-code to allow the end-user to port their applications to a wide variety
of platforms. |
|
| Q. |
Does ASN1C support the
old Remote Operation Support Element (ROSE) MACRO notation (OPERATION, ERROR,
etc..)? |
| A. |
The ASN1C compiler has a '-1990' switch
that supports this notation. These keywords are not built into the standard
ASN1C compiler because they are not part of the ASN.1 standard and their use
might clash with other uses of the keywords. A paper describing ROSE MACRO
support is available here. |
|
| Q. |
Does ASN1C support the
X.694 standard to allow ASN.1 to be generated from XML schema to produce
efficient binary encodings of XML data? |
| A. |
ASN1C v5.8 contains a utility program
(xsd2asn1) for converting XML schema (XSD) files to equivalent ASN.1 as per the
X.694 standard. This ASN.1 specification can then be compiled with the ASN1C
compiler to produce encoders/decoders that support the binary ASN.1 encoding
rules. Support is planned for full integrated support of XSD in ASN1C 6.0. |
|
| Q. |
It does not appear
that types/classes and encoders/decoders are generated for many of the ASN.1
type definitions in the CAMEL Application Part (CAP) specification. These have
the following general form:
AccessPointName
{PARAMETERS-BOUND: bound} ::= OCTET STRING (SIZE(
bound.&minAccessPointNameLength ..
bound.&maxAccessPointNameLength))
Why is this? |
| A. |
These are parameterized types and code
is only generated for them when a concrete instantiation is done using a
supplied parameter. Unfortunately, in CAP, these instantiations are done in
information objects several levels removed from where they are needed. In order
to provide a way to create concrete representations of the types at the level
they are defined, the -param command-line argument was added to ASN1C. For CAP,
adding "-param bound=CAP-classes.cAPSpecificBoundSet" to the ASN1C command-line
will provide concrete instances of all of these types. |
|
| Q. |
When code is generated
for many ASN.1 specifications, the names of some of the items are very long. Is
there a way to make them shorter? |
| A. |
By default, ASN1C creates names for
additional types that it generates by concatanating all of the intermediate
nested names of the items. In specifications with heavily nested constructs,
this can lead to very long names. The -shortnames qualifier can be used in
these situations to generate shorter names. |
