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Network Information ServicesBy Brian A. Lantz/KO4KSTPALAN - Tampa Local Area NetworkThis is a reprint of a paper printed in the Proceedings of the 12th ARRL Digital Communications Conference, September 10-11, 1993, with some information updated
INTRODUCTION:TNOS NETWORK INFORMATION SERVER:NECESSARY COMPONENTS:FILE NAME:TITLE LINE:If the title line starts with a tilde ('~'), it expects a line of this format: ~subdir description Table 1 lists the many filenames in a sample Information Server directory and their title lines. Figure 1 shows how the user sees this information. TNOS SCRIPTING LANGUAGE - TSCRIPT:The design goals of Tscript were:
ANATOMY OF A TSCRIPT FILE:The Tilde character ('~') is treated special at all times. All lines that do NOT begin with the tilde ('~') character are simply sent to the user after a few simple substitutions. All substitutions begin with the tilde character and serve as shortcuts for variable data fields. The special control sequences in text lines are listed in Table 2. The first four sequences allow you to place the caller's callsign, host computer name, or the current date or time into the text data sent to the user. The next 10 sequences allow you to place a string variable into the text flow. There are 10 variable strings given for the script writer's usage. Datafile text, user's responses, and other data can be stored in variable strings and displayed with the "~0" through "~9" control sequences. The next 10 sequences allow you to output a numeric variable. As with string variables, the script writer has 10 integer variables at his/her disposal, named "~i0" through "~i9". The next two allow you to place a bell character or a tilde character into the data stream. The following two sequences allow you to imbed a carriage return into a string, or mark a line to ignore its own carriage return at the end of the text line. The last three sequences allow you to display the current Error variable string, the elapsed time of this script, or the file position of the current data file. CONTROL LINES:The Basic Control Lines are shown in Table 3. The "~<space>" control line allows you to imbed non-displayable, no operation lines that can be used to help document the script file. The "~b" control lines allow you to place a fixed number of blank lines into the data flow. When the "~~" control line is used, the "~~" is simply treated as ordinary characters at the beginning of an ordinary text line, which are interpreted as the "~~" control sequence, and substituted by a single "~". The more control line ("~m") asks the user if he/she wants more, and if so continues. If a negative response is given, the script will do an implicit goto ("~g") the label named "exit". If the label "exit" doesn't exist, the script is complete. You can also exit the script at any time with "~x". You can easily take a regular text file, using these few control commands, and make a decent Service File. You should pace the display so that there is a user interaction or a "more" command for every screenful of data. The Query and Flow Control Lines are shown in Table 4. You can use labels very much like they are used in the C programming language and assembly language. A label is any text name that makes sense to you. Spaces are not allowed in a label name. A label is defined with a "~l" control line. You can go to any label in a script file with the goto ("~g") control line. The label can precede or follow the goto line in the script file. Simple querying can be done with the query ("~q") control line. This command puts out a prompt string, asks for a yes or no reply, and sets the script's query variable to either 'y' or 'n'. The query variable is used for conditional gotos in the "~y" and "~n" control lines. These lines will go to the label given if the query variable matches ('y' for the "~y" command, 'n' for the "~n" command). A different query variation exists with the "~v" (variable query) control line. The prompt is sent to the user, and their response is placed in the string variable that matches "num". The Assignment and Comparison Control Lines are shown in Table 5. You can assign an escape sequence or a literal string into a numbered string variable with the "~a" control line. You can append one string variable onto another with the "~ap" control line. You can place a sub-string of one numbered string variable into a second numbered string variable with the "~p" control line. The "~t" control line allows you to truncate (clip off) a string variable at a certain point. There are two control lines that can be used to compare string variables, "~c" and "~j". The first, "~c", compares the entire string of each, while the "~j" command compares only the first part of the two strings. You can get the length of a string variable's data with the "~z" control line. The "~i" control line handles four different functions with integer variables. The character after the 'i' (0 though 9) indicates which numbered integer variable to use. The next character is the character that determines the function. The '=' assigns a value. The '+' adds to the current value of a variable. The '-' subtracts from the current value. The '?' compares the variable to a set value and sets the query variable accordingly. The "~h" control line is like the "~c" and "~j" commands, but allows searching for a substring within another string, and returns the offset in the string that the substring was found. The "~^" control line can convert a string variable to all lower or upper case. The Data File Control Lines are shown in Table 6. An I/O datafile can be opened with either the "~f" or the "~o" control lines. Both commands close any previously open I/O file, and open the desired file. If no filename is given, these commands simply close any previously opened file. They differ in that the "~f" creates a NEW file and sets the query variable to 'n' if the file couldn't be created or already existed. The "~o" command opens a old file and sets the query variable to 'n' if the file couldn't be opened or didn't already exist. You can seek to the beginning ("~s") or end ("~se") of the data file. The "~sp" control line is used to see to a specific position within a data file. You can check for the end of file with the "~e" control line. The query variable gets set to 'y' if at the end of the file. If a label is given on the control line and it IS the end of file, then a "goto" is executed, moving to the label line. You write to an open data file with the "~w" control line. The rest of the line is treated the same as regular text lines, with imbedded control sequences allowed. You read from an open data file with the "~r" control lines. The next line in the data file is placed into the numbered variable string. The File Utilities Control Lines are shown in Table 7. You can upload a separate text file with the "~u" control line. There is NO special processing of an uploaded file, so normal Information Server escape sequences are not examined, substituted, or acted upon. You can use the "kill" command ("~k") to delete files on the host system's disk. FOR THIS REASON, you should limit only those that you can TRUST to be permitted to add Information Server files on your system. You can send the contents of a file in a mail message to a user with the "~d" control line. The "~dr" control line does this also, but allows you to specify a 'Reply-To:' address to be used in the mail message. Information about a user can be examined and set using the "~?" and "~!" control lines. You can use these to check the user's desire to use color. If the user came through the TNOS BBS and has ANSI color graphics mode on in the BBS, the color option will be on. Others will be initially set to off. The username of the user is ONLY valid on starting a script if the connect was an AX25 connect, NOT a TCP/IP connect. You can find out if the user connected with IP using the "~? I" control line. If this is found to be an IP connect, you may wish to ask the user for a username and also ask them if they would like an ANSI color display (if your script uses these features). The ANSI Color File Control Lines are shown in Table 8. The Information Server allows you to give users (that desire it) a more colorful display. You can change the text colorset, imbed ANSI control sequences in the text flow or add pre-saved ANSI color files at a particular spot in a Service File. The "~*" control line is used to mark the beginning and end of an imbedded ANSI sequence. The Information Server will remove KNOWN sequences from the data flow if the user has not selected ANSI graphics, but this is NOT without flaws. It is suggested that you use conditional looping based on the user's color setting (using a "~? C" control line). A pre-saved color file is inserted into the data stream with the "~%" control line, but ONLY is displayed if the user has color set to ON. Otherwise, the file will be skipped. The current text colorset is changed with the "~@" control line. The "colorcode" is a two digit, hexadecimal value that determines the colorset desired. The first digit determines the background color and the blink attribute. The second digit determines the foreground color and the high intensity attribute. These Color Codes are listed in Table 9. CALLING SCRIPTS AND MAKING CONNECTIONS:The Script and Connection Control Lines are shown in Table 10. The "~$" control line allows you to execute another TScript file from within the present one, waiting for it to complete before continuing with this script, while the "~$$" control line executes the TScript file in the background. The "~(" control line is used to bring up an ax25 or telnet connection, which can receive or send data. Up to 9 different simultaneous connections can be maintained. The "~)" control line disconnects an ax25 or telnet connection opened with the "~(" control line. The "~#" control line allows you to change which connection you use for I/O. Stream 0 is the NORMAL interactive stream, opened with the script begins. The "~=" control line checks the requested connection to see if it is still valid and available to send/receive data. IMPLEMENTATION:SAMPLE SCRIPT:First Test Tutorial ~l loop This is the first test at '~h'. Now we will test the MORE function.... ~b 3 ~m ~b 3 It's time to test the QUERY function.... ~b 2 ~q Loop back ~y loop ~b 3 Tired of looping, huh! One more test of the QUERY function.... ~b 2 ~q Loop back ~n noloop ~g loop ~l noloop ~b 3 Really tired of looping, huh! Time to test variables.... ~b 3 ~v 1 Enter variable #1 (at least 5 characters) The variable entered was ~1! ~i9=4 ~p 6 1 0 ~i9 The first four characters were '~6'. ~u ~z 1 4 The length of the string was ~i4. ~t 1 4 The truncated first four characters are '~1'. Your call sign is ~c. ~a 4 This is variable #4 ~~Variable number 4 is '~4'. ~v 2 Enter your call sign ~v 3 Enter your call sign again ~b 2 ~c 2 3 equal They were NOT equal~b ~g next ~l equal They were equal and they were '~2'.~b ~l next ~j 2 3 2 nowokay Even the first two characters didn't match! ~g skipit ~l nowokay The first two characters matched! ~l skipit ~m ~f /newtest ~w Call sign is '~c' - Variable 4 is '~4'.~n Writing the following to disk: 'Call sign is '~c' - Variable 4 is '~4'.'~n ~f ~o /newtest ~r 5 Variable 5 is '~5'. Rewinding...... ~s ~r 6 Variable 6 is '~6'. ~f ~k /newtest ~n xx1 Deleted temp file ~g xx2 ~l xx1 Couldn't delete temp file~b ~l xx2 ~b2 The date is ~d.~nThe time is ~t. ~m ~ now for the index counters test ~b 2 Here is the equivalent code for "for (k=1; k < 10; k++)" ~i1= ~l indexloop The current value of index1 is ~i1. ~i1?10 ~i1+ ~n indexloop ~i2=~i1 The copied index from index1 to index2 is ~i2. ~m ~b2 And here is the equivalent code for "for (k=10; k; k--)" ~i1=10 ~l indexloop2 The current value of index1 is ~i1. ~i1?1 ~i1- ~n indexloop2 ~l lasttest ~b2 ~v 9 Enter in a number from 1 to 4 It was ~u ~i9=~9 ~i9?1 was1 ~i9?2 was2 ~i9?3 was3 ~i9?4 was4 ~l invalid not one of the numbers asked for! Your answer was~u ~i9?0 ~n badone either zero~nor started with a non-digit! ~u ~g reloop ~l badone ~i9! ~u ~l reloop Try again~b ~g lasttest ~ ~ ~l was1 One! ~g through ~l was2 Two! ~g through ~l was3 Three! ~g through ~l was4 Four! ~l through ~m Your current CONFIG.SYS file is.... ~u /config.sys ~m I'll now send CONFIG.SYS to you in a mail message ~dr nerfman@super.com ~c /config.sys ~n lastoops Sent successfully! ~g lastout ~l lastoops Couldn't send it! ~l lastout ~b 2 ~q Ready to exit ~n loop ~b 3 ~l exit Goodbye, come back and see us!~b Last updated: (none) |