Programmer Studio uses network protocols to transfer files to and from the PC to provide identical functionality when editing files regardless of their location. Typically this involves using the FTP protocol, although Programmer Studio includes our WTRSH server software specifically for HPe3000 platforms.
FTP, or File Transfer Protocol, is the main Internet protocol for managing and transferring files on a remote machine. Using FTP, Programmer Studio is able to view remote directory listings and transfer files without requiring any additional interaction from the user.
Although FTP is a relatively simple protocol, there is one area where both new and experienced users may become confused. When transferring files, FTP supports a mode option which is used by the server to determine how to format each file transmitted. Programmer Studio supports two FTP modes, ASCII and binary.
The ASCII transfer mode instructs the server to transfer a file, line-by-line, terminating each line sent with a carriage return and line feed. Although the actual format of the file on the server remains unknown, this transfer mode is ideal as the format of a file can be assured.
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Each server profile provides an option to set ASCII as the default transfer mode. It is recommended that this option is enabled for all non-UNIX systems except HPe3000. |
The binary transfer mode, in contrast, instructs the server to transfer a file as a stream of bytes. This mode offers the greatest benefit for users as Programmer Studio can automatically determine which editor (hex or code) should be used to view the file. Currently this mode only works reliably when transferring files from UNIX platforms.
For HPe3000 users using FTP, Programmer Studio provides an automatic transfer mode. Before the transfer of each file begins, Programmer Studio queries the build parameters of each file. Using the MPE file mode, the transfer mode is then switched between ASCII and binary as required.
Perhaps the most important consideration for users should be that FTP is not really suited to the record-based file system employed by the HPe3000. Taking a very simplistic approach to the HPe3000 file system, each file can be described as containing one or more records which may, or may not, be of the same length. This presents a problem when using FTP as the protocol does not provide a mode in which a file may be sent including the length of each record. Without knowing the length of each record, the file cannot therefore be saved.
While this makes it impossible to create or save binary files, ASCII mode files (with either fixed or variable record lengths) may be edited as the FTP server on the HPe3000 terminates each record with a carriage return and line feed.
While FTP provides all the features necessary to navigate and transfer files on most platforms, the HPe3000 (a mini-computer from Hewlett-Packard) employs a very unique file system which is not adequately supported by FTP. WTRSH provides a solution to this problem by implementing a proprietary protocol which allows all HPe3000 file types to be opened, save or created.
In addition to simply supporting the various MPE file modes, variable, fixed, ASCII, binary and byte-stream files, WTRSH also supports SPOOL files, transparent COPYLIBs and even access to Qedit« files.
For more information on WTRSH, where to get the software see WTRSH.
One final consideration when editing files is the character set represented by the server on which the file exists. As the ASCII character set is standardized for the first 128 characters (of a maximum of 256) only, the remaining characters can be interpreted very differently between the PC and the remote server.
For example, the UK currency symbol æúÆ appears at position 163 in the Windows (ISO-Latin-1) ASCII character set. In contrast, the same symbol appears at position 187 in the HP-Roman-8 ASCII character set (used by both HPe3000 and HP-UX servers).
To allow files to be edited correctly, each server profile must specify the ASCII character set supported. This allows Programmer Studio to æmapÆ characters between the host and Windows ASCII character sets while a file is open. In those situations where a character cannot be converted when either loading or saving, Programmer Studio displays a warning to the user.