HOW TO: Create GUIDs by Using Active Server Pages in IIS

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Summary

This step-by-step article describes how to create several example pages by using various forms of GUIDs for Active Server Pages (ASP) pages to use. These values can be used to create unique data entries in a database, or anywhere else where a unique data field is required.

NOTE: Because these examples do not use session variables, these examples also work on Web servers that have session state disabled.


Create a Simple Time-Based GUID

This example creates a simple 14-character time-based GUID by using the current year, month, day, hour, minute, and seconds. This permits you to sort data based on the GUID.
  1. Click Start, point to Programs, click Accessories, and then click Notepad to open Notepad.
  2. Type or paste the following ASP code in Notepad:
    <%@LANGUAGE="VBSCRIPT"%>
    <HTML>
    <BODY>
    <%

    Response.Write "GUID = " & CreateGUID()

    Function CreateGUID()
    Dim tmpTemp
    tmpTemp = Right(String(4,48) & Year(Now()),4)
    tmpTemp = tmpTemp & Right(String(4,48) & Month(Now()),2)
    tmpTemp = tmpTemp & Right(String(4,48) & Day(Now()),2)
    tmpTemp = tmpTemp & Right(String(4,48) & Hour(Now()),2)
    tmpTemp = tmpTemp & Right(String(4,48) & Minute(Now()),2)
    tmpTemp = tmpTemp & Right(String(4,48) & Second(Now()),2)
    CreateGUID = tmpTemp
    End Function
    %>
    </BODY>
    </HTML>
  3. Save the page:
    1. On the File menu, click Save.
    2. Locate the root folder for your Web site, which is typically the C:\InetPub\Wwwroot folder for the default Web site.
    3. Name the file GuidTest0.asp.
    4. Click Save.
    5. On the File menu, click Exit.
  4. Locate the page with Microsoft Internet Explorer. You see a GUID. As you refresh the page, you see the GUID increment.

Create a Simple Time-Offset GUID

This example creates a 20-character time-based GUID by using the offset in seconds from 12:00 midnight on January 1, 2000. This permits you to sort data based on the GUID, and can be updated to use any other date as the base.
  1. Click Start, point to Programs, click Accessories, and then click Notepad to open Notepad.
  2. Type or paste the following ASP code in Notepad:
    <%@LANGUAGE="VBSCRIPT"%>
    <HTML>
    <BODY>
    <%

    Response.Write "GUID = " & CreateGUID()

    Function CreateGUID()
    Dim tmpTemp1,tmpTemp2
    tmpTemp1 = Right(String(15,48) & CStr(CLng(DateDiff("s","1/1/2000",Date()))), 15)
    tmpTemp2 = Right(String(5,48) & CStr(CLng(DateDiff("s","12:00:00 AM",Time()))), 5)
    CreateGUID = tmpTemp1 & tmpTemp2
    End Function
    %>
    </BODY>
    </HTML>
  3. Save the page:
    1. On the File menu, click Save.
    2. Locate the root folder for your Web site, which is typically the C:\InetPub\Wwwroot folder for the default Web site.
    3. Name the file GuidTest1.asp.
    4. Click Save.
    5. On the File menu, click Exit.
  4. Locate the page with Internet Explorer. You see a GUID. As you refresh the page, you see the GUID increment.
NOTE: This example permits uniqueness only when the function is not called two times in the same second. Any two calls to the function at the same second cause a collision. This may not cause a problem depending on how your code is using the function, but you can use the Create a More Unique Time-Offset GUID example to allow unique values that occur in the same second.


Create a More Unique Time-Offset GUID

This example, like the Create a Simple Time-Offset GUID example, creates a time-based GUID, but it is 25 characters long. This example creates a 20-character value from the offset in seconds from 12:00 midnight on January 1, 2000, and appends an additional five random numbers to the end of that. This permits you to sort data based on the GUID, but permits much greater uniqueness. This can be updated to use any other date as the base.
  1. Click Start, point to Programs, click Accessories, and then click Notepad to open Notepad.
  2. Type or paste the following ASP code in Notepad:
    <%@LANGUAGE="VBSCRIPT"%>
    <HTML>
    <BODY>
    <%

    Response.Write "GUID = " & CreateGUID()

    Function CreateGUID()
    Randomize Timer
    Dim tmpTemp1,tmpTemp2,tmpTemp3
    tmpTemp1 = Right(String(15,48) & CStr(CLng(DateDiff("s","1/1/2000",Date()))), 15)
    tmpTemp2 = Right(String(5,48) & CStr(CLng(DateDiff("s","12:00:00 AM",Time()))), 5)
    tmpTemp3 = Right(String(5,48) & CStr(Int(Rnd(1) * 100000)),5)
    CreateGUID = tmpTemp1 & tmpTemp2 & tmpTemp3
    End Function
    %>
    </BODY>
    </HTML>
  3. Save the page:
    1. On the File menu, click Save.
    2. Locate the root folder for your Web site, which is typically the C:\InetPub\Wwwroot folder for the default Web site.
    3. Name the file GuidTest2.asp.
    4. Click Save.
    5. On the File menu, click Exit.
  4. Locate the page with Internet Explorer. You see a GUID. As you refresh the page, you see the first 20 characters of the GUID increment, and the last five characters are random.
NOTE: This example and the Create a Simple Time-Offset GUID example are created for time-based serialization of calls to the CreateGUID function. If sorting data based on time is not a requirement, you can use the Create a Simple Random GUID example to create a random GUID.


Create a Simple Random GUID

  1. Click Start, point to Programs, click Accessories, and then click Notepad to open Notepad.
  2. Type or paste the following ASP code in Notepad:
    <%@LANGUAGE="VBSCRIPT"%>
    <HTML>
    <BODY>
    <%

    Response.Write "GUID = " & CreateGUID()

    Function CreateGUID()
    Randomize Timer
    Dim tmpCounter,tmpGUID
    Const strValid = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    For tmpCounter = 1 To 20
    tmpGUID = tmpGUID & Mid(strValid, Int(Rnd(1) * Len(strValid)) + 1, 1)
    Next
    CreateGUID = tmpGUID
    End Function
    %>
    </BODY>
    </HTML>
  3. Save the page:
    1. On the File menu, click Save.
    2. Locate the root folder for your Web site, which is typically the C:\InetPub\Wwwroot folder for the default Web site.
    3. Name the file GuidTest3.asp.
    4. Click Save.
    5. On the File menu, click Exit.
  4. Locate the page with Internet Explorer. You see a 20-character random GUID. As you refresh the page, you see the value change randomly.
NOTE: This example creates a fixed-length random GUID. To create a variable-length GUID, use the Create a Variable-Length Random GUID example.


Create a Variable-Length Random GUID

  1. Click Start, point to Programs, click Accessories, and then click Notepad to open Notepad.
  2. Type or paste the following ASP code in Notepad:
    <%@LANGUAGE="VBSCRIPT"%>
    <HTML>
    <BODY>
    <%

    Response.Write "<P>GUID = " & CreateGUID(10)
    Response.Write "<P>GUID = " & CreateGUID(25)
    Response.Write "<P>GUID = " & CreateGUID(50)

    Function CreateGUID(tmpLength)
    Randomize Timer
    Dim tmpCounter,tmpGUID
    Const strValid = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    For tmpCounter = 1 To tmpLength
    tmpGUID = tmpGUID & Mid(strValid, Int(Rnd(1) * Len(strValid)) + 1, 1)
    Next
    CreateGUID = tmpGUID
    End Function
    %>
    </BODY>
    </HTML>
  3. Save the page:
    1. On the File menu, click Save.
    2. Locate the root folder for your Web site, which is typically the C:\InetPub\Wwwroot folder for the default Web site.
    3. Name the file GuidTest4.asp.
    4. Click Save.
    5. On the File menu, click Exit.
  4. Locate the page with Internet Explorer. You see a 10-character, 25-character, and 50-character random GUID. As you refresh the page, you see the values change randomly.
NOTE: This example and the Create a Simple Random GUID example both create strings of concatenated random characters. The Create a Windows-Style Random GUID example expands on this functionality to create a GUID that is formatted like a Microsoft Windows GUID.


Create a Windows-Style Random GUID

Windows primarily uses GUIDs when it registers Class IDs for components and other objects, but GUIDs can be used for anything. Windows GUIDs are long strings of formatted hexadecimal characters, meaning that they use the numbers 0 through 9 and the letters A through F. (Microsoft Access also has a built-in Replication ID in the same format.) This example shows how to use code that is similar to the Create a Variable-Length Random GUID example code to create a GUID like a Windows GUID.
  1. Click Start, point to Programs, click Accessories, and then click Notepad to open Notepad.
  2. Type or paste the following ASP code in Notepad:
    <%@LANGUAGE="VBSCRIPT"%>
    <HTML>
    <BODY>
    <%

    Response.Write "<P>GUID = " & CreateWindowsGUID()

    Function CreateWindowsGUID()
    CreateWindowsGUID = CreateGUID(8) & "-" & _
    CreateGUID(4) & "-" & _
    CreateGUID(4) & "-" & _
    CreateGUID(4) & "-" & _
    CreateGUID(12)
    End Function

    Function CreateGUID(tmpLength)
    Randomize Timer
    Dim tmpCounter,tmpGUID
    Const strValid = "0123456789ABCDEF"
    For tmpCounter = 1 To tmpLength
    tmpGUID = tmpGUID & Mid(strValid, Int(Rnd(1) * Len(strValid)) + 1, 1)
    Next
    CreateGUID = tmpGUID
    End Function
    %>
    </BODY>
    </HTML>
  3. Save the page:
    1. On the File menu, click Save.
    2. Locate the root folder for your Web site, which is typically the C:\InetPub\Wwwroot folder for the default Web site.
    3. Name the file GuidTest5.asp.
    4. Click Save.
    5. On the File menu, click Exit.
  4. Locate the page with Internet Explorer. You see a random GUID that is formatted like a Windows GUID. As you refresh the page, you see the value change randomly.

Create a Stronger Windows-Style Random GUID

Because Windows GUIDs use hexadecimal numbers for each character, 16 values are possible per character in the GUID. If you expand the values to include the whole alphabet, 36 values are possible per character in the GUID. This example uses the function from the Create a Variable-Length Random GUID example to create a GUID in the same format as a Windows GUID.
  1. Click Start, point to Programs, click Accessories, and then click Notepad to open Notepad.
  2. Type or paste the following ASP code in Notepad:
    <%@LANGUAGE="VBSCRIPT"%>
    <HTML>
    <BODY>
    <%

    Response.Write "<P>GUID = " & CreateWindowsGUID()

    Function CreateWindowsGUID()
    CreateWindowsGUID = CreateGUID(8) & "-" & _
    CreateGUID(4) & "-" & _
    CreateGUID(4) & "-" & _
    CreateGUID(4) & "-" & _
    CreateGUID(12)
    End Function

    Function CreateGUID(tmpLength)
    Randomize Timer
    Dim tmpCounter,tmpGUID
    Const strValid = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    For tmpCounter = 1 To tmpLength
    tmpGUID = tmpGUID & Mid(strValid, Int(Rnd(1) * Len(strValid)) + 1, 1)
    Next
    CreateGUID = tmpGUID
    End Function
    %>
    </BODY>
    </HTML>
  3. Save the page:
    1. On the File menu, click Save.
    2. Locate the root folder for your Web site, which is typically the C:\InetPub\Wwwroot folder for the default Web site.
    3. Name the file GuidTest6.asp.
    4. Click Save.
    5. On the File menu, click Exit.
  4. Locate the page with Internet Explorer. You see a random GUID that is formatted like a Windows GUID. As you refresh the page, you see the value change randomly.

References

For additional information about programming topics that are related to Windows GUIDs, click the article numbers below to view the articles in the Microsoft Knowledge Base:

183544 HOWTO: Call CLSID And ProgID Related COM APIs in Visual Basic
176790 HOWTO: Use CoCreateGUID API to Generate a GUID with VB
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ID articol: 320375 - Ultima examinare: 30 iul. 2008 - Revizie: 1

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