Assigning a Built-in ASN.1 Schema to a Message

Built-in ASN.1 schemas are groups of ASN.1 schema files that make up well-known standards. Components (or modules) that make make up the complete schema for a particular standard may be spread across multiple domains. Built-in schemas consolidate this information into a single named item - typically a directory on the system containing the base schema files and a special configuration file describing how imports within those schemas should be resolved.

A built-in ASN.1 schema may be assigned (associated) with a BER, DER, or CER ASN.1 message by using this command. ASN.1 built-in schema are assigned to PER messages when they are created or opened because they are required to understand the content of the message. Assigning an ASN.1 schema will provide symbolic element names and type information for the content items within the message. It will also enable the editing of fields within the message.

1. Click the Assign option from the main menu toolbar.

2. Select the Built-in ASN.1 Schema(s) option to open the built-in ASN.1 schemas dialog.

3. The built-in ASN.1 schema dialog box will be displayed allowing the selection of a built-in schema.

4. After successful compilation of the ASN.1 file(s):

If a single matching PDU type is found in the schema that matches the current message being displayed, then ASN1VE will decode the message using the matched PDU type and the view will be switched to element view completing this operation.

5. If multiple matching PDU types are found, then ASN1VE will prompt the user to select a PDU type using the Select PDU type dialog:

Display Possible PDU Types and Display All Types radio boxes will be displayed with the list of module names in the selected ASN.1 specifications. Each module will contain a list of type names in that module.

The Display Possible PDU Types button selection will show only those types that are most likely to be used for a new message. This is defined to be all types in the module that are not referenced by any other types and which match the initial tag on the message. If no types meet this criteria, then no types will be displayed in this list.

The Display All Types selection will display all of the types for each module.

6. If the user selects a type and presses OK, ASN1VE will try to decode the message with the user-selected PDU type and the view will be switched to element view if decoding is successful. The user may also press the Cancel button at this point to cancel the operation.