Classic ASP

Compress and Decompress Hex String

Imagine we have data represented as a hex string. This example demonstrates how to decode, compress, and re-encode to a smaller hex string representing the compressed data. An even better choice is to re-encode to a more compact encoding such as base64.

Note: This example requires Chilkat v9.5.0.66 or greater.

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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

'  This example assumes the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

strHex = "54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A"

set compress = Server.CreateObject("Chilkat.Compression")
compress.Algorithm = "deflate"

set binDat = Server.CreateObject("Chilkat.BinData")
'  Load the hex string into a BinData object.
'  This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
success = binDat.AppendEncoded(strHex,"hex")

'  Compress the BinData.
success = compress.CompressBd(binDat)

'  Get the compressed data in hex format:
compressedHex = binDat.GetEncoded("hex")
Response.Write "<pre>" & Server.HTMLEncode( "compressed hex:") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( compressedHex) & "</pre>"

'  The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

'  Even better, get the compressed data in base64 format:
'  (base64url and modbase64 are other valid choices...)
compressedBase64 = binDat.GetEncoded("base64")
Response.Write "<pre>" & Server.HTMLEncode( "compressed base64:") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( compressedBase64) & "</pre>"

'  The compressed base64 is: C8lIVSgszUzOVkgqyi/PU0jLr1DIKs0tSE1RyC9LLVIoAcrnJFZVKqTkp+vxcoUMYeW8XAA=

'  Now decompress:
success = binDat.Clear()
success = binDat.AppendEncoded(compressedHex,"hex")
success = compress.DecompressBd(binDat)

decompressedHex = binDat.GetEncoded("hex")
Response.Write "<pre>" & Server.HTMLEncode( "decompressed hex:") & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( decompressedHex) & "</pre>"

'  The output is the original hex string:
'  54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A

%>
</body>
</html>