Internationalization and Distributed Networks

This section of the book covers the exchange of information between applications on different hosts. The transfer of data has to consider several parameters:

• The sender's and receiver's codeset

• Whether the protocol is 7-bit or 8-bit

• The type of interchange encoding allowed by the protocol

If the remote host uses the same codeset as the local host, and if the protocol allows 8-bit data, no conversion is needed. If the protocol allows only 7-bit data, the 8-bit code points must be mapped onto 7-bit ASCII values. There are various strategies for conversion.

If the remote host's codeset is different from that of the local host, the following two cases may apply. The conversion depends on the specific protocol. If the protocol allows 8-bit data, the protocol will need to specify which side does the conversion. If the protocol allows only 7-bit data, a 7-bit interchange encoding is needed along with an identifying character repertoire.

Mail Interchange

With the increased use of the Internet and the ease of communicating with people around the world, an email message can be viewed on many platforms and dozens of locales. Standards for email interchange, however, are restricted by desktop machines for which the default email standard is Simple Mail Transfer Protocol (SMTP), which supports only 7-bit transmission channels.

The sending agent converts the body of the message into a standard format and labels it as body. The receiving agent looks at the body and, if it supports the character encoding, converts the body into the local character set.

Due to the fact that dtmail now uses the Language Conversion Library (LCL), dtmail has the capacity to support multibyte characters in both the subject line, the mail body, and in attachments. There is also the ability for dtmail to have characters of different encodings within the same mail, for example, SJIS and EUC encodings for the Japanese (ja) locale.