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Show a timed message

Another forum question, Another code article!

Demonstration page

For this we have a completely self-contained package. A class for the OOP buffs.

It's all a matter of timing

First off, there is the problem of timing and server locale, because ASP code runs on the server, everything to do with times and dates is taken from the server clock and the server date settings. Not really helpful if the server is located in one time zone and the website users are in another or as in this case you want to show a message to users in the UK between specific times.

Secondly, vBScript, which the majority of ASP code is written in, has no native functions for time zone offsets, BUT fear not, a bit of trickery with ASP in JScript to the rescue in the form of toUTCxxxx methods.
The output and usage of these are exactly the same as they are in client side javascript.

This bit of jscript is used to put the required time data into session variables.

CODE:

Get this Code: Click to download the ASP file.

Do not copy and paste the displayed code. The display function adds line breaks and numbers, so what you see is definitely not you would get. The continuation marker " _ " is used to indicate the break.

01: <%@language="jscript"%>
02: <%
03: var today = new Date();
04: 	Session("UTCDate") = today.toUTCString();
05: 	Session("UTCHour") = today.getUTCHours();
06: 	Session("UTCMin") = today.getUTCMinutes();
07: %>

Save the above file as utc_time.asp.
Take note: If editing the above code, JScript is case sensitive. So "Session" is NOT the same as "session" whereas in case insensitive vBScript it would be.

The Class definition file

Ok a chunk of VbScript OOP code.

CODE:

Get this Code: Click to download the ASP file.


01: <%
02: class  TimedMessage

03: private m_sMessage
04: private m_bShowMessage
05: private m_bHasOverlap
06: private m_bIsDST

07: private m_iStartTime
08: private m_iEndTime
09: private m_sUTCValue
10: private m_sGMTValue
11: private m_iUTCHour
12: private m_iUTCMin
13: private m_iOffset

14: 	private sub class_initialize()
15: 		getTimes()
16: 		m_iOffset = 0
17: 		m_bIsDST = false
18: 	end sub
	
19: 	public property let Offset(ByVal value)
20: 	if value > 12 then value = 12
21: 	if value < -12 then value = -12
22: 		m_iOffset = value
23: 	end property
	
24: 	public property get LocalOffset()
25: 		Offset = m_iOffset
26: 	end property
	
27: 	public property let StartTime(ByVal value)
28: 		m_iStartTime = value
29: 	end property
	
30: 	public property get StartTime()
31: 		StartTime = m_iStartTime
32: 	end property
	
33: 	public property let EndTime(ByVal value)
34: 		m_iEndTime = value
35: 	end property
	
36: 	public property get EndTime()
37: 		EndTime = m_iEndTime
38: 	end property
	
39: 	public property let IsDST(ByVal value)
40: 		m_bIsDST = value
41: 	end property
	
42: 	public property get IsDST()
43: 		IsDST = m_bIsDST
44: 	end property
	
45: 	public property let Message(ByVal value)
46: 		m_sMessage = value
47: 	end property
	
48: 	public property get Message()
49: 		Message = m_sMessage
50: 	end property
	
51: 	public property get GMTDate()
52: 		response.write m_sGMTValue
53: 	end property
	
54: 	public property get UTCDate()
55: 		response.write m_sUTCValue
56: 	end property
	
57: 	public property get GMTHour()
58: 		if m_bIsDST then
59: 			if m_iUTCHour = 23 then
60: 				GMTHour = 0
61: 			else
62: 				GMTHour = m_iUTCHour + 1
63: 			end if
64: 		else
65: 			GMTHour = UTCHour
66: 		end if	
67: 	end property

68: 	public property get OffsetHour()
69: 		OffsetHour = (m_iUTCHour + m_iOffset) & ":" & m_iUTCMin
70: 	end property
	
71: 	public property get OffsetTime()
72: 		OffsetTime = (m_iUTCHour + m_iOffset) & ":" & m_iUTCMin
73: 	end property

74: 	public property get UTCHour()
75: 		UTCHour = m_iUTCHour	
76: 	end property
	
77: 	public property get GMTTime()
78: 		GMTTime = GMTHour & ":" & m_iUTCMin
79: 	end property
	
80: 	public property get UTCTime()
81: 		UTCTime = m_iUTCHour & ":" & m_iUTCMin	
82: 	end property

83: 	public property get ServerTime()
84: 		ServerTime = FormatDateTime(Time(),VBShortTime)
85: 	end property
86: 		
87: 	public function ShowMessage()
88: 		if m_iEndTime < m_iStartTime then
89: 		' show time crosses midnight
90: 			m_bHasOverlap = true
91: 		end if

92: 		if m_bHasOverlap then
93: 			if GMTHour <= m_iStartTime then
94: 				m_bShowMessage = true
95: 			end if
96: 		else
97: 			if GMTHour >= m_iStartTime then
98: 				m_bShowMessage = true
99: 			end if
100: 		end if
101: 		
102: 		if m_bHasOverlap then
103: 			if GMTHour >= m_iEndTime then
104: 				m_bShowMessage = false
105: 			end if
106: 		else
107: 			if m_iEndTime = GMTHour then
108: 				m_bShowMessage = false
109: 			end if
110: 		end if

111: 		if m_bShowMessage then
112: 			ShowMessage = m_sMessage
113: 		end if
114: 	end function
115: ' TODO:	
116: ' logic needs adding for start times after midnight
117: 'with a finish time  that is between midnight and starttime


118: 	private sub getTimes()
119: 		server.execute("utc_time.asp")
120: 		m_sUTCValue = _ 
	replace(session("UTCDate"),"UTC","")
121: 		m_sGMTValue = _ 
	replace(session("GMTDate"),"UTC","")
122: 		m_iUTCHour = cint(session("UTCHour"))
123: 		m_iUTCMin = cint(session("UTCMin"))
124: 	end sub

125: end class
126: %>

Save the above file as cl_message.asp

Code walkthrough

Variable Declarations

CODE:

01: ' declare a class name
02: class  TimedMessage

03: ' declare the local variables
04: ' using a descriptive name makes for ease of maintenance

05: private m_sMessage
06: private m_bShowMessage
07: private m_bHasOverlap
08: ' hasoverlap is a boolean for the time going over midnight

09: private m_bIsDST
10: ' isdst is a boolean for the required time zone using Daylight Saving
11: ' if set will adjust the time +1 hour

12: private m_iStartTime
13: private m_iEndTime
14: private m_sUTCValue
15: private m_sGMTValue
16: private m_iUTCHour
17: private m_iUTCMin
18: private m_iLocalOffset

Declaring and Naming Variables

NB: I use descriptive names for variables so it is pretty self explanatory when returning to the code months or years later it doesn't take long to work out what they are for.
My naming convention is so I know the scope and type of each variable as well from the name. So;
m_ indicates a module wide variable, and l_ would be local to a function or method.
The character following the underscore indicates the type
eg: m_s would be a module wide string and l_b would indicate a local boolean

The rest of the class file is just the property and method declarations used for setting and/or reading the various values used and are pretty self-explanatory.
The ones that should be given a bit more detail with extra commenting are, getTimes() and ShowMessage().

CODE:

01: 	private sub getTimes()
02: 		server.execute("utc_time.asp")
03: 		' call the jscript page and
04: 		'put the values into session variables
05: 		m_sUTCValue = _ 
	replace(session("UTCDate"),"UTC","")
06: 		m_sGMTValue = _ 
	replace(session("GMTDate"),"UTC","")
07: 		m_iUTCHour = cint(session("UTCHour"))
08: 		m_iUTCMin = cint(session("UTCMin"))
09: 		' retrieve the session variables
10: 		'and set them into the variables.
11: 	end sub


12: 	public function ShowMessage()
13: 		if m_iEndTime < m_iStartTime then
14: 		' show time crosses midnight
15: 			m_bHasOverlap = true
16: 		end if
17: 		' check for start and end times crossing midnight
18: 		'and set HasOverlap
19: 		
20: 		if m_bHasOverlap then
21: 			if GMTHour <= m_iStartTime then
22: 				m_bShowMessage = true
23: 			end if
24: 		else
25: 			if GMTHour >= m_iStartTime then
26: 				m_bShowMessage = true
27: 			end if
28: 		end if
29: 		
30: 		if m_bHasOverlap then
31: 			if GMTHour >= m_iEndTime then
32: 				m_bShowMessage = false
33: 			end if
34: 		else
35: 			if m_iEndTime <= GMTHour then
36: 				m_bShowMessage = false
37: 			end if
38: 		end if

39: 		if m_bShowMessage then
40: 			ShowMessage = m_sMessage
41: 		end if
42: 	end function
	
43: ' TODO:	
44: ' logic needs adding for start times after midnight
45: 'with a finish time  that is between midnight and starttime

How to use the class

This is a basic page showing how to set the class, set the message, start and end times, then show the message if required.

CODE:

Get this Code: Click to download the ASP file.

01: <%option explicit%>
02: <!--#include file="cl_message.asp" -->
03: <%
04: ' the file containing the class declaration is included
05: dim m_otm
06: set m_otm = new TimedMessage
07: ' dim variable and instantiate the class object
08: %>

09: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
10: "http://www.w3.org/TR/html4/strict.dtd">
11: <html>
12: <head>
13: <title>GMT / UTC Time</title>
14: <meta http-equiv="Content-Type" content="text/html; _ 
	charset=iso-8859-1">
15: <link rel="stylesheet" href="style.css" _ 
	type="text/css">
16: <style type="text/css">
17: h1 {
18: 	color:blue;
19: 	text-align:center;
}
20: </style>

21: <script type="text/javascript">
22: 	function checkEnd(hour){

23: 	}
24: 	function checkStart(hour){

25: 	}
26: </script>
27: </head>
28: <%
29: m_otm.isdst = false
30: ' set DST OFF
31: m_otm.message = "<h1> It's that time _ 
	already</h1>"
32: ' Define the message to be shown
33: if request.form("set") <> "" then
34: 	m_otm.starttime = cint(request.form("start"))
35: 	m_otm.endtime = cint(request.form("end"))
36: else
37: 	m_otm.starttime = 09
38: 	m_otm.endtime = 12
39: end if
40: ' set the start time and end time
41: ' uses 24 hour (military) clock
42: %>

43: <body>

44: <h1>UCT Time =
45: <%response.write m_otm.UTCTime()
46: ' display the UTC time
47: %></h1>

48: <%

49: response.write m_otm.showmessage
50: ' call the method to display the message
51: %>

52: <%

53: %>
54: <br>
55: <%

56: with response
57: 	.write "GMT Hour: " & m_otm.GMThour & ":00"
58: 	.write "<br>"
59: 	.write "Start Time: " & m_otm.starttime & ":00"
60: 	.write "<br>"
61: 	.write "End Time: " & m_otm.endtime & ":00"
62: end with
63: ' show some of the properties
64: %>
65: <form method="post" action="" _ 
	name="settime">
66: Start Time:-
67: 	<select name="start" _ 
	onchange="checkEnd(this.value)">
68: <%
69: 	const l_sSelect = "selected"
70: 	dim l_ix
71: 	for l_ix = 0 to 23
72: %>
73: 	<option value="<%=l_ix%>"
74: <%	if m_otm.starttime = l_ix then
75: 	with response
76: 		.write l_sSelect
77: 		.write "="
78: 		.write chr(34)
79: 		.write l_sSelect
80: 		.write chr(34)
81: 	end with
82: 	end if
83: %>
84: 	>
85: <%=l_ix%>
86: <% next %>
87: 	</select>
88: 	End time:-
89: 	<select name="end" _ 
	onchange="checkStart(this.value)">
90: <%
91: 	for l_ix = 0 to 23
92: %>
93: 	<option value="<%=l_ix%>"
94: <%	if m_otm.endtime = l_ix then
95: 	with response
96: 		.write l_sSelect
97: 		.write "="
98: 		.write chr(34)
99: 		.write l_sSelect
100: 		.write chr(34)
101: 	end with
102: 	end if
103: %>
104: 	>
105: <%=l_ix%>
106: <% next %>
107: 	</select>
108: 	<br>
109: 	<input type="submit" name="set" _ 
	value="Set Time">
110: </form>
111: <p>
112: Select start and end times around the current time to display or hide _ 
	the message.
113: </body>
114: </html>
115: <% set m_otm = Nothing
116: ' release and destroy the class object
117: %>