Re: CA V4 Protocol Specification

[Marty Kraimer <mrk@aps.anl.gov>]

Benjamin Franksen wrote:

> On Wednesday 26 October 2005 00:33, Jeff Hill wrote:
>  
>
> > Attached is a rough cut at the EPICS V4 CA protocol specification.
> >    
>
> Hi Jeff,
>
> Just one little thought about STRING data type:
>
> UINTN			the number of UTF-8 tokens
> OCTET sequence	UTF-8 encoded character string sequence
>
> I take it that 'number of UTF-8 tokens' means 'number of octets', right? 
> Maybe it would be worthwhile to consider adding a 'number 
> of /characters/' count in addition to the byte count. This could 
> improve performance, particularly when converting to other encodings on 
> the client side. Of course any gain must be offset against the 
> increased protocol overhead.
>
> The same applies of course to any library string representations.
>
> Ben
>  

Java 5 uses 16 bits for char, which is not sufficient to encode all 
uni-code character sets.
It uses 2 consecutive chars to hold a unicode character that does not 
fit in 16 bits.

At least some C/C++ implementations use 32 bits for wchar which is 
sufficient for all unicode characters.
But what if an implementation uses 16 bits?

Thus how will the number of characters in a UTF-8 string be used?

Better to just let final sender/receiver of the character string handle it.

Marty