Inter-site Data Interchange

This information is saved for historical reasons only and does not describe a feature ever implemented in FANG, or one intended to be implemented. It it solely a description of a proposed design done in the past.

*                                                               *
*       Note:  the code described in this chapter is currently  *
*  under development and is not operable in the released level  *
*  of FANG.   This  section is included to document the forth-  *
*  coming capability, and to elicit suggestions regarding this  *
*  implementation effort. Users having an application for this  *
*  feature should contact Marinchip Systems directly.           *
*                                                               *

The inter-site data interchange facility of FANG provides an easy-to-use means of program interchange between 1100 series sites with communications hardware. Both sites must permit real-time in their systems, and both must have compatible synchronous or asynchronous ports available (same at each end).

To transmit data, runs on each end must enter FANG, and execute the CONNECT command upon the desired port. The CONNECT command will dial the connection if dial hardware is available, otherwise the connection must be made manually.

If FANG is being run from demand on both ends, the MESSAGE command will permit users at either end to converse. They may continue to converse while data transmission is in progress.

The INTERCHANGE statement initiates data transmission. Each site must execute an INTERCHANGE statement, specifying the source file and the line id on the transmitting end, and the line id and the receiving file on the receiving end. If the PROTECT command is in effect on the line id, data will be enciphered before transmission, and deciphered by a PROTECT command at the other end.

Validity of transmitted data is insured by the use of a cyclic redundancy check and alternation bit in transmitted buffers, and a checksum on each data block. Erroneous data will be retransmitted until correct. The communications line discipline prevents data loss or duplication.

The line may be released by the DISCONNECT statement. A dial-up line will be hung up.

Data Interchange Commands

The data interchange commands are compatible with all other FANG commands, and follow the same parameter conventions and scheduling rules. When the first CONNECT command is executed, FANG will go real-time. FANG will remain in the real-time state until the DISCONNECT statement releases the last active line. Because the system is unable to dynamically acquire memory for real-time programs, it is recommended that only one line be CONNECTed at once.


                  CONNECT  <line>,(aaa) eee-nnnn

The CONNECT statement establishes FANG in the communications mode, activates the communications line, and optionally dials the connection. <line> is the name to which the communications line to be used has been assigned. If the line is dial-up, and the second parameter is supplied, FANG will dial the connection to the other site. The phone number is in the format '(aaa) eee-nnnn' where 'aaa' is the area code, 'eee' is the exchange (alphabetic or numeric) and 'nnnn' is the number. If the call is local, the area code may be omitted. On the receiving end, of course, the phone number should not be supplied.


                  DISCONNECT  <line>,<line>,...

The DISCONNECT command will release the named communications lines. When the last active communications line has been disconnected, FANG will return to non real-time status. If a line is dial-up, DISCONNECT will hang up the line.


                  INTERCHANGE  <file>,<line>
or:               INTERCHANGE  <line>,<file>

Once the connection is made, the INTERCHANGE statement initiates communication of data from site to site. Once the communications link has been established, data may be sent in either direction. The transmitting site should execute the INTERCHANGE command with the file as the first parameter and the line as the second. The receiving site should specify the line as the first parameter and the destination file as the second. If one file is mass storage and the other is tape, the action will be equivalent to the COPY,Q command. The order of execution of the INTERCHANGE commands at the two sites is irrelevant.


                  MESSAGE  <line>,<string>

The MESSAGE command will display the string in the print file at the other end of the named communications line, previously attached with the CONNECT command. The MESSAGE statement may be used at any time between the execution of a CONNECT and a DISCONNECT for a line, including when an INTERCHANGE command is in progress.