(Classic ASP) Streaming Compression

Compress and decompress using a stream.

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

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

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.FileAccess")
set fac = Server.CreateObject("Chilkat.FileAccess")
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Compression")
set compress = Server.CreateObject("Chilkat.Compression")
compress.Algorithm = "deflate"

' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Stream")
set streamC = Server.CreateObject("Chilkat.Stream")

' This example sets the source and sink of the stream to files.
' A stream can have use other streams as a source or sink,
' or the application can itself be the source/sink by directly
' reading or writing a stream.  (See below for an example of this..)
streamC.SourceFile = "qa_data/hamlet.xml"
streamC.SinkFile = "qa_output/hamlet_compressed.dat"

' Compress from source to sink.
success = compress.CompressStream(streamC)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( compress.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "File-to-file deflate compression successful.") & "</pre>"
' Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
' the size of the file as a string, then convert to an integer value.
Response.Write "<pre>" & Server.HTMLEncode( "Original size = " & fac.FileSize(streamC.SourceFile)) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "Compressed size = " & fac.FileSize(streamC.SinkFile)) & "</pre>"

' Now do file-to-file decompression
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Stream")
set streamD = Server.CreateObject("Chilkat.Stream")
streamD.SourceFile = "qa_output/hamlet_compressed.dat"
streamD.SinkFile = "qa_output/hamlet_restored.xml"

' Decompress from source to sink.
success = compress.DecompressStream(streamD)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( compress.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "File-to-file deflate decompression successful.") & "</pre>"

' Let's double-check to see that the files are equal in size and content:

bFilesEqual = fac.FileContentsEqual(streamC.SourceFile,streamD.SinkFile)
If (bFilesEqual <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( "The output file is not equal to the input file!") & "</pre>"
Else
    Response.Write "<pre>" & Server.HTMLEncode( "The file was successfully compressed and decompressed.") & "</pre>"
End If

' ---------------------------------------------------------------------
' Now let's decompress again, but this time w/ the application reading
' the decompressed data directly from a stream.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Stream")
set streamA = Server.CreateObject("Chilkat.Stream")

streamA.SourceFile = "qa_output/hamlet_compressed.dat"

' Start decompressing in a background thread.
' task is a Chilkat.Task
Set task = compress.DecompressStreamAsync(streamA)
success = task.Run()

' Read decompressed data from streamA:

Do While (streamA.EndOfStream <> 1)
    If (streamA.DataAvailable = 1) Then
        decompressedText = streamA.ReadString()
        Response.Write "<pre>" & Server.HTMLEncode( decompressedText) & "</pre>"
    End If

Loop

' Let's make sure the background task finished and that the decompress was successful.
' It should already be the case that the task is finished.
Do While (task.Finished <> 1)
    task.SleepMs 20
Loop

' The decompressor may have finished, but it is possible that data
' remains to be flushed.  
If (streamA.DataAvailable = 1) Then
    decompressedText = streamA.ReadString()
    Response.Write "<pre>" & Server.HTMLEncode( decompressedText) & "</pre>"
End If

' Did streamA succeed in reading the entire file?
If (task.TaskSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( "async decompress failed:") & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( task.ResultErrorText) & "</pre>"
    success = 0
End If

Response.Write "<pre>" & Server.HTMLEncode( "The async decompress was successful.") & "</pre>"

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