* Demonstrates the use of Cookies to preserve session information *

Begin

       %rc is Float
       %sp is Float
       %fp is Float
       %dt is Float
       %i  is Float

       %Checked  is String len 10
       %s        is String len 50
       %FPref    is String len 50

       %rc = $Web_Sub('@@')
       %rc = $Web_Type('TEXT/HTML')

* Create a list of options to be shown to the user later.
* ($ListNew and $ListAdd are Sirius "list" functions that create
* easily maniplated data structures as an alternative to %arrays.)

       %sp = $ListNew
       %rc = $ListAdd( %sp, 'Aisle')
       %rc = $ListAdd( %sp, 'Window')
       %rc = $ListAdd( %sp, 'Below overstuffed overhead bin')
       %rc = $ListAdd( %sp, 'Next to turbine intake')
       %rc = $ListAdd( %sp, 'Near distressed infant')

       %FP = $ListNew
       %rc = $ListAdd( %FP, 'Superheated Starch Globules')
       %rc = $ListAdd( %FP, 'Mystery Meat Amalgam (Considered flight insurance?)')
       %rc = $ListAdd( %FP, 'Heavily salted snack')
       %rc = $ListAdd( %FP, 'Petrified omelette')

       In JANWEB Include WEB/TEMPLATE_TOP

       Print '<H2>Strand Travel Customer Preference Form</H2>'

* Web form processing typically calls for execution of two passes
* through the program processing the form. The first is to display the
* form and await input. After putting up the form, the program terminates
* and awaits being called again as a result of the user filling in and
* submitting the form. The second pass processes the form input and
* formats and presents the data in response to the user's request.

* How to know which process is intended in a given call to the program?
* A standard http "header" value is passed from the browser to the
* program with the name "method" and the value is either "post" or "get".
* Think of GET as "get the form", so that pass would present the form.
* Think of POST as "post the results", so that pass would process it.

* Test which pass this is. If form processing, jump to there.

       If $Web_Hdr_Parm('METHOD') eq 'POST' Then
          Jump to ProcessForm
       End If

* Begin building the page to be presented to the user to request input.

* Note, however, that this is a program for handling cookies. This means
* that the user may have previously executed the program (both get and
* post portions) and as a result may have had some cookie data stored
* in their browser's cookie file to hold their preferences.
* If so, we will welcome them back and show their preferences, otherwise
* we'll present the form as if they are a first time visitor.

* When the cookie is stored (as will be described later) it will be setup
* so that whenever this program is called again, the cookie will be
* passed to the program for inspection and/or processing.
* We can quickly tell if a cookie has been stored (and is being passed
* to the program) by way of WEB_NUM_COOKIE which tells us the number of
* cookies being passed to the program.

       If $Web_Num_Cookie ne 0 Then
          Print 'Welcome back. Your preferences are noted below.<p>'
       Else
          Print 'Welcome to Strand Travel. Please indicate your preferences below.<p>'
       End If

* The <Form> tag sets up a form with an action that tells it to
* execute this program again on the user's pressing of Submit.

       Html
       <p>Enter your seating preference:</p>
       <form name="PREFS" method="POST"
        action="{$Web_Hdr_Parm('URL')}">
       <ul>
       End Html

* Next we'll create the choices to be shown on the form. We'll do that
* by going through the list of preferences stored at program startup.
* Note, again, though that we must anticipate that the program is being
* run after cookies have been stored previously to indicate preferences.
* Therefore, we need to examine the cookies and if we find a preference
* stored, indicate that on the form.

* The seating preference in this application is setup as a radio button,
* so only one of the available values can be selected.
* When the form is processed (later), the chosen preference will be
* returned in a form parameter. We will store a number representing
* the value's place on the list above in the cookie named "seatpref".
* (It helps to think of cookies as being in field, value pairs.)

       For %i from 1 to $ListCnt( %sp )

*  As we process the list of preferences to be put on the form, if the
*  seatpref cookie's been set to the number representing that preference
*  in the list, we'll indicate that the
*  preference should be "checked" as we prepare the radio button
*  for display. Otherwise, the preference will simply be listed as an
*  available option.

       If %i eq $Web_Cookie_Parm('SEATPREF') Then
          %Checked = 'CHECKED '
       Else
          %Checked = ''
       End If

*  Note that for the value of each option displayed, we're indicating
*  as the "value" the number representing the place on the list of the
*  option being presented. The user will see the full name, but all that
*  will be returned for form processing will be the number. This is also
*  what we'll store in the cookie. It's just one way of doing such things

          Print '<li> <input ' with %Checked with -
                'type="radio" name="SEATPREF" value="' with %i with '">' with -
                $ListInf( %sp, %I )
       End For

       Print '</ul>'

       Print '<p>Enter your food preference:</p>'
       Print '<ul>'

*  Whereas the seating preference was indicated as a radio button, the
*  food preference is a check box. The user could select multiple values.
*  When the form is processed later, we will store numbers representing
*  the selected values
*  as comma-separated values in the "foodpref" cookie. Therefore, we
*  must now parse the cookie passed to us (if any) as a comma-separated
*  string.

       %FPref = $Web_Cookie_Parm('FOODPREF')

*  To make life easier, we'll append a comma to help find the end of the
*  string later.

       If %FPref ne '' Then
          %FPref = %FPref with ','
       End If

* Go through the list of choices stored at startup, and put them out on
* the display. Again, if one of the values is in the cookie, we'll
* indicate it on the form as being checked.

       For %i from 1 to $ListCnt( %fp )
          If $Windex( %FPref, %i, ',') ne 0 Then
             %Checked = 'CHECKED '
          Else
             %Checked = ''
          End If
          Print '<li> <input ' with %Checked with -
                'type="checkbox" name="FOODPREF" value="' with %i with '">' with -
                $ListInf( %fp, %i )
       End For

       Print '</UL>'

* The following line creates the Submit button, a standard part of forms.

       Print '<input type="submit" value="Submit">'

* Now we want to decide what sort of info to present to the user,
* depending on whether this execution of the "form display" part of the
* program is after a cookie is set or not.

* If not, they're a first time user and we want to explain what the
* whole demo is about.

* If they've been through once and have had a cookie set, we want to
* present them information that talks about the results of having set
* the cookie.

       If $Web_Num_Cookie eq 0 Then
          Html
          <p>This form demonstrates the use of HTTP Cookies.</p>
          <p>Cookies are an extension to the HTTP protocol that allow HTTP servers
          to store a client's preferences and selections on the client machine.</p>
          <p>If this is your first visit to this page today, none of the preferences
          are checked. Click an entry in the seat preferences, then check a box or
          two in the food preferences.
          <p>Now submit the form.</p>
          <p>The server processes the the form, and sends your preferences
          back to your browser as HTTP Cookies.
          <p>The next time you request this form, your earlier preferences will
          be sent back to the server in a "cookie". The server application uses
          the cookies to fill in the form with your earlier choices.</p>
       Else
          <p>This time, the data you entered has been retrieved from the
          cookie which was stored when you submitted your preferences.
          <p>You may change your preferences again if you like, and
          repeat the process.</p>
          End Html
       End If

         Html
         <p>You can
         <a href="/plaintext/DEMO_COOKIE">see the User Language code</a>'
         that does all this.</p>
         End Html

* We're done. End the program which will cause the form to be displayed.

         Jump to FormDone

PROCESSFORM:

* Begin processing the form input. We jump to here if the top of the
* program has determined that we are to process form input (method=post).

* First, we should prepare for setting the 2 cookies which will hold
* the selected preferences (one for seating, one for food). Note that
* when setting cookies, we provide need to provide a name for the cookie,
* a value for it, and an expiration date/time. This date/time tells the
* browser when it can remove the cookie from its cookie file. The
* date/time value must be in a special binary format. Fortunately,
* $WEB_DATE returns the current date in this format. We'll add 24 hours
* to it so that the cookie will expire tomorrow.

       %dt = $Web_Date
       %dt = %dt + (60*60)

* When processing a form, the input that the user selected or entered is
* returned as "form parms". If we know the names of these parms, we can
* simply query what value (if any) has been entered. If a radio button
* was selected, the chosen one is stored as the value of that form parm
* (again, think of them as field,value pairs).

       %s = $Web_Form_Parm('SEATPREF')
       If %s eq '' Then
          Print '<p>Seat preference missing. SEATPREF cookie not stored.</p>'
       Else
          %rc = $Web_Set_Cookie('SEATPREF', %s, %dt)
          If %rc ne 0 Then
             Print '<p><b>Error storing cookie SEATPREF!</b>'
       *  else
       *     Print 'Cookie stored with name=SEATPREF and value=' with %s
          End If
       End If

* The preferences for food were offered in check-box-format. This means
* the user may select multiple values. In this case, multiple occurrences
* of the form parm named "foodpref" may exist, each with the value of the
* preference chosen. We need to loop through those. We'll accumulate them
* in a string of comma separated values and also store them in the cookie
* that way.

       FOR %I FROM 1 TO $WEB_NUM_FORM('FOODPREF')
          %FPREF = %FPREF WITH ',' WITH $WEB_FORM_PARM('FOODPREF', %I )
       END FOR

       %rc = $Web_Set_Cookie('FOODPREF',%FPref,%dt,'/')
       If %rc ne 0 Then
          Print '<p><b>Error storing cookie FOODPREF!</b>'
       *Else
       *  Print '<p>Cookie stored with name=FOODPREF and value=' WITH %FPref
       END IF

* We're done processing the form.

* Note, however, that we did not put the form out on this pass through
* the program. We could have done that, but we instead are putting out
* a "thanks for your input" type display. Since we're explaining to
* programmers how this all works, we offer directions on going back
* and witnessing the results of viewing the "get" pass with cookies
* processed. (The difference will be the different welcome message and
* explanation of what happened, offered above.)

        Html
        <P>Thanks for using Strand Travel</P>
        <P>Your preferences will be stored for 1 day.</P>
        <B>
        <P>Now, return to the previous page (using your browser's) back button.
        <p>Once there, issue your browser's Reload or Refresh
        command to simulate your returning to the web page at a later
        point in time (otherwise, you're just looking at the
        very same screen you just submitted.)
        <p>You'll notice that the welcome message changes, and there
        will now be an explanation of how the cookie worked.</p>
        <table cellpadding="0" cellspacing="0" border="0" width="300" height="300">
          <tr><td>&nbsp;</td></tr>
        </table>
        End Html

FormDone:

       In JANWEB Include WEB/TEMPLATE_BOTTOM

End