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DigHT 310
LiveCode Server-side Scripting

HTML was created as a static content markup language. But the true power of the Web today lies in the ability to dynamically modify web page content on demand. This has normally required learning server-side scripting languages with steep learning curves like Perl or PHP. In mid-2009 RunRev released the first version of its server-side LiveCode scripting module, known officially as LiveCode Server. What this means is that LiveCode, formerly confined to scripting in the LiveCode stack environment, can be used to create powerful, dynamic web pages.

One way to get access to LiveCode server-side scripting is to purchase subscription to the On-rev web hosting service, a full-featured service that includes many standard hosting features, and includes a fully-integrated LiveCode Server capability. You can also download the free Community Edition of LiveCode Server from the LiveCode Download site. Once downloaded, LiveCode Server must be installed on your web serer.

For this class, LiveCode Server has been set up on the hummac server, the same server that hosts the class file server and the MySQL server we have been using. You must be a registered student in the course to log in; the login information was given in class or sent to you separately.

First LiveCode Server Script

First we will look at the basics of server-side LiveCode scripting. I will describe the way we did it in the classroom, but the same could be done using any plain text editor and FTP client. BBedit is convenient because it has a built-in FTP client that allows us to work in a single environment.

  1. the BBedit FTP browser login formLaunch BBedit and make a connection to the FTP server.
    File menu > New > FTP/SFTP Browser.
    Your should see a login form like the one at right.
    Enter the login information given you earlier. A browser window should appear with a list of files and folders on the on-rev server. Find your folder and open it.

  2. Create a new document.
    Click the New... button at the bottom of the browser window.
    Name the document something like "firstScript.lc".
    Note that the .lc extension is required for the server to recognize it as a page that may contain LiveCode code.

  3. Enter some LiveCode code.
    Rule #1: Anytime you want to execute LiveCode code you need to enclose it in special lc tags, like this:
      <?lc LiveCode code here ?>
    

    The opening and closing tags can be on different lines, but all LiveCode statements must be enclosed by these tags.

    Type a simple LiveCode statement between the rev tags:

      <?lc
      put "Hello world."
      ?>
    

    Save your document.

  4. Check your document in your web browser.
    Assuming your folder name is george, the URL should look like this:
      http://dight310.byu.edu/students/george/firstScript.lc
    

What do we learn from this very simple example?

One more important concept: LC script documents are simply specialized HTML documents. They can contain any proper HTML code, interspersed with any number of <?lc ?> tags. Indeed, many LC script documents have lots of HTML code in them.

Assignment: Look at some simple examples on the on-rev web site before the next class period. Look at the first five topics: Introduction, Basics, URL Get, Form, and Database. You should understand and try out most of these scripts.

Continuing with LC Server Scripting

Clearly, the simple example we used above is boring and doesn't give any advantage over plain HTML. Let's look at some ways in which embedded LiveCode scripting can be useful.

Date and time. A common desire is to display the current date on the web page. This is easily done with LiveCode. (Keep in mind that since LC scripts are run on the server, the date and time reported will be the settings on the server, not the client. In the case of the on-rev service, the server is located in Texas, USA.)

  <p>Today's date is <?lc put the date ?>. </p>

Dynamic lists. Since you can use any LiveCode structure in LC script files, you can use, for example, repeat loops to create dynamic lists or tables. Note that we also build the HTML "framework" for the LiveCode output at the same time.

<?lc
   put the short date into tDate
   set the itemDelimiter to "/"
   put item 1 of tDate into tMonth
   put "<p>Months elapsed this year:</p>"
   put "<p>"
   repeat with x = 1 to tMonth
    put line x of the monthNames 
    if x = tMonth then
      put " (current month)<br />"
    else
      put "<br />"
    end if
   end repeat
   put "</p>"
?>
	

Sample Output

Defining custom handlers in LC scripting files; Dynamic table creation. By creatively interspersing HTML tags with LiveCode <?lc .. ?> segments we can create sophisticated dynamic page elements. Here is the calendar example that we did in class. It was adapted slightly from the HTML Coding Exercise we did earlier.

<?lc
function q pString
  return quote & pString & quote
end q

function makeCalendar pMonth,pStartDay,pEndDate
  put 1 into tDate
  put "<p><strong>" & pMonth & "</strong></p>" & return into tCal
  put "<table border=" & q("1") & ">" & return after tCal
  repeat with tRow = 1 to 6
    if tRow = 6 and tDate > pEndDate then
      # don't make a sixth row if no dates left in month
      exit repeat	
    end if

    put "<tr align=" & q("right") & ">" & return after tCal
    repeat with tCol = 1 to 7
      if (tRow = 1 and tCol < pStartDay) OR (tDate > pEndDate) then
         put " " into tContents
      else
         put tDate into tContents
         add 1 to tDate
      end if
      put "<td>" & tContents & "</td>" after tCal
    end repeat
    put return & "</tr>" after tCal
  end repeat
  put return & "</table>" after tCal
  return tCal
end makeCalendar

put the long date into tDate
put "<p>Today's date is " & tDate & ".</p>"

put word 1 of item 2 of tDate into tMonth
convert tDate to dateitems
subtract (item 3 of tDate - 1) from item 3 of tDate
convert tDate to dateitems
put item 7 of tDate into tStartDay
add 1 to item 2 of tDate
convert tDate to dateitems
subtract 1 from item 3 of tDate
convert tDate to dateitems
put makeCalendar(tMonth,tStartDay,item 3 of tDate)
?>

You can see the output of this file at http://chum.dev.on-rev.com/teacher/beginning.irev.


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