6  Document History Protocol
  (translated by Benjamin Gandon)

The Document History Protocol allows you to manage a global list of
recently used file (like in the Call menu of Texel for instance). It
also allows you to make a quick launch menu bar (like the one of
Start-Me-Up).

So, let's present briefly with C notation the involved structure:


#define DHST_ADD 0xdadd
#define DHST_ACK 0xdade

typedef struct
{
   char *appname,
        *apppath,
        *docname,
        *docpath;
} DHSTINFO;


Every time the user opens a file, the application looks for the 'DHST'
Cookie. If found, the lower word (two bytes) contains the AED ID value
of the DHST server to witch the DHST_ADD message is to be sent. The
application allocates a DHSTINFO structure in global memory and fills
it with these values:


 appname:     Application name
              (z.B. "Texel")

 apppath:     Absolute path of the application program file
              (z.B. "c:\program\texel.app")

 docname:     Document name
              (z.B. "balmer.txl")

 docpath:     Absolute path of the document file
              (z.B. "d:\daten\balmer.txl")

Then the application sends the following message to the DHST server:


 msg[0]    DHST_ADD

 msg[1]    ap_id

 msg[2]    0

 msg[3]    and

 msg[4]    Pointer to the filled DHSTINFO structure

 msg[5]    0

 msg[6]    0

 msg[7]    0


The application receives the following Message answer. After receiving
this answer, with the allocated memory for the DHSTINFO structure may
be freed.


 msg[0]    DHST_ACK

 msg[1]    ap_id

 msg[2]    0

 msg[3]    and

 msg[4]    Pointer to the DHSTINFO structure (the one send with DHST_ADD)

 msg[5]    0

 msg[6]    0

 msg[7]    0 means that an error occured, any other value means: OK