Apparc Recognizer for CAF

Overview

Apparc supplies the filename and a buffer containing bytes read from the start of the file. If a file is recognized, the recognizer must return the MIME type and the degree of confidence in recognizing the file — a TInt ranging from KMinInt (Not Recognized) to KMaxInt (Certain).

The implementation of DRM has a problem when determining the MIME type. A DRM file stores one or more content objects. For example, an OMA file with MIME type application/vnd.oma.drm.content may store an image file with MIME type image/jpeg. Apparc expects only one MIME type to be returned, not two.

The CAF recognizer RECCAF.DLL determines whether a file is recognized by CAF and if so, retrieves these two MIME types.

The mapping of these two MIME types returned by CAF to a single MIME type is based on the following rules:

The following is the rationale for the above mapping:

• The x-caf- prefix to the content type shows that the file that can be opened by CAF to read that content type.

• A file that needs to be passed through the supplier interface before it can be used is recognized as the file MIME type; the content type is irrelevant before the supply operation.

• A file containing many content objects must just be recognized as application/x-caf as the packaging of the archive is irrelevant (CAF abstracts the packaging).

The following diagram illustrates the recognition of an OMA file with JPEG content.

Figure 1. Apparc Recognizer for CAF

Application registration files

To use CAF content, applications must update their registration resource files (for example AppName_reg.rss) to include the new CAF MIME types. For example, an image viewer may have only included image/jpeg in the list of MIME types it could open. If the application is updated to use CAF, it must support image/jpeg and x-caf-image/jpeg in order to support unprotected and protected content respectively. See the following example registration file.

All file operations must be conducted through the CAF framework.

Registration file that does not use CAF

...

datatype_list = 
    {
    DATATYPE { priority= EDataTypePriorityHigh ; type="image/jpeg";}, 
    }

...

Registration file that use CAF

...

datatype_list = 
    {       
    DATATYPE { priority= EDataTypePriorityHigh ; type="image/jpeg"; }, 
    
    DATATYPE { priority= EDataTypePriorityHigh ; type="x-caf-image/jpeg"; }, 
    }

...