NOTE: if you have not yet installed these OSAXen, then do it before starting this lesson. The script will not compile without them. Go back to the Requirements section to download the OSAXen if you need them.
property crlf : (ASCII character 13) & (ASCII character 10)
property http_10_header : "HTTP/1.0 200 OK" & crlf & "Server: MacHTTP" & crlf & Ā
"MIME-Version: 1.0" & crlf & "Content-type: text/html" & crlf & crlf
property idletime : 300
property datestamp : 0
set datestamp to current date
on «event WWW½sdoc» path_args ¬
given «class kfor»:http_search_args, ¬
«class post»:post_args, «class meth»:method, ¬
«class addr»:client_address, «class user»:username, ¬
«class pass»:password, «class frmu»:from_user, ¬
«class svnm»:server_name, «class svpt»:server_port, ¬
«class scnm»:script_name, «class ctyp»:content_type
try
set datestamp to current date
set return_page to http_10_header ¬
& "<HTML><HEAD><TITLE>Parsed Results</TITLE></HEAD>" ¬
& "<BODY><H1>Parsed Results</H1>" & return
set return_page to return_page & "<H4>post_args</H4><PRE>" & return
set postarglist to tokenize post_args with delimiters {"&"}
set postargtext to ""
repeat with curritem in postarglist
set postargtext to postargtext & ¬
(Decode URL (DePlus (last text item of currpostarg))) & return & return
end repeat
set return_page to return_page & postargtext & "</PRE>" & return
set return_page to return_page ¬
& "<HR><I>Results generated at: " & (current date) ¬
& "</I>" & "</BODY></HTML>"
return return_page
on error errMsg number errNum
set return_page to http_10_header ¬
& "<HTML><HEAD><TITLE>Error Page</TITLE></HEAD>" ¬
& "<BODY><H1>Error Encountered!</H1>" & return ¬
& "An error was encountered while trying to run this script." & return
set return_page to return_page ¬
& "<H3>Error Message</H3>" & return & errMsg & return ¬
& "<H3>Error Number</H3>" & return & errNum & return ¬
& "<H3>Date</H3>" & return & (current date) & return
set return_page to return_page ¬
& "<HR>Please notify Jon Wiederspan at " ¬
& "<A HREF=\"mailto:jonwd@tjp.washington.edu\">jonwd@tjp.washington.edu</A>" ¬
& " of this error." & "</BODY></HTML>"
return return_page
end try
end «event WWW½sdoc»
on idle
if (current date) > (datestamp + idletime) then
quit
end if
return 5
end idle
on quit
continue quit
end quit
We will use two new OSAXen to do the decoding. The first, DecodeURL, was written by Chuck Shotton (yes, that Chuck Shotton). The second, DePlus, was written by myself using tons of Chuck's original code. Both are free products and major time- and code-savers. Here is the section of code that does the decoding:
set postargtext to ""
repeat with curritem in postarglist
set postargtext to postargtext & ¬
(Decode URL (DePlus (last text item of currpostarg))) & return & return
end repeat
I have used several commands on a single line, feeding the output of one to the input of
the next, because it saves some typing and one variable. You could also use the following
to do exactly the same thing:
set postargtext to ""
repeat with curritem in postarglist
set temp to last text item of currpostarg
set temp to DePlus temp
set temp to Decode URL temp
set postargtext to postargtext & temp & return & return
end repeat
Looking at it this way you can see more clearly what we were doing. First, we grab
the piece of text we're interested in (the data portion, delimited by a "=" character).
Then we convert all +'s to spaces. Next, we scan the entire piece of text,
converting hexadecimal encodings ("%XX") to their ASCII equivalents. Finally, we
add this decoded text onto the end of postargtext and add two carriage
returns before looping for the next item. NOTE: it is very important
that DePlus be run before Decode URL. If you ran Decode URL first, you would convert
all of the encoded + characters to real + characters. The DePlus would convert them
to spaces. Doing things in the order in the script protects the real + characters
from being misinterpreted.
Now for you anal retentive types, yes, you could do this same processing in AppleScript without using the OSAX. However, unlike in the last lesson, this time we're talking some serious bulk in your script. Here is some sample code that would perform some of the same function as DecodeURL, except it only decodes occurences of "%20" to spaces:
on decodeSpaces(inText)
set outText to ""
set spacePos to offset of "%20" in inText
repeat while spacePos > 0
if spacePos != 1 then -- if the space is not the first character in the text
set outText to (text from character 1 to character (spacePos - 1) of inText ¬
& space & (text from character (spacePos + 3) to character (length of inText) of inText)
else
set outText to (text from character (spacePos + 3) to character (length of inText) of inText)
end if
end repeat
return (outText)
end decodeSpaces
Even more lines would be required to make it handle all possible encodings, not to mention
converting "+" characters. I have better things to do than figure out how to do things
more slowly. Of course, if you don't believe me, feel free to write the code yourself.
You should be able to time the difference on your wristwatch (or a good hourglass) if
you're dealing with large arguments (like >10K of text). On the other hand, maybe
you'll just want to take my word for it. That should leave you enough spare time to watch
this week's Superman episode.
This looks like a good place to bring up another performance issue. If you remember from the first lesson, there are a number of variables passed to your CGI from MacHTTP. With the exception of post_args and http_search_args, all of the information in these variables is put there by MacHTTP. That means there is no reason to decode the information in these variables, since it is the client that does the encoding. In general, the data in post_args is the only thing that will take a lot of processing in your scripts. If you are using the http_search_args to hold information as well, then you will need to decode that information also.
Jon Wiederspan
Last Edited: December 11, 1994