DataFlex

Compressing StringBuilder Data Using CompressSb (Single Call and Chunked)

See more Compression Examples

This example demonstrates how to compress text stored in a StringBuilder using the CompressSb method in two ways:

1. Single-call compression, where the entire input is compressed in one operation.
2. Chunked compression, where the input is split into multiple parts and processed sequentially using the FirstChunk and LastChunk properties.

The example shows how compressed output is appended to a BinData object, and how the result can be verified by decompressing back to the original text. This is useful for both simple use cases and scenarios where data is processed incrementally (such as streaming or large inputs).

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Key Points

• CompressSb converts text to bytes using the Charset property (UTF-8 recommended).
• Compressed data is appended to a BinData object.
• When both FirstChunk and LastChunk are true, compression is done in a single call.
• For chunked processing:
  • First chunk → FirstChunk = true, LastChunk = false
  • Middle chunks → both false
  • Final chunk → LastChunk = true
• Chunked compression is useful when processing data incrementally.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoCompress
    Variant vSb
    Handle hoSb
    Variant vBdCompressed
    Handle hoBdCompressed
    String sCompressedBase64
    Variant vBdChunkedOut
    Handle hoBdChunkedOut
    Variant vSbPart
    Handle hoSbPart
    String sChunkedBase64
    Variant vSbDecompressed
    Handle hoSbDecompressed
    String sTemp1

    Move False To iSuccess

    // This example assumes the Chilkat API has already been unlocked.
    // See Global Unlock Sample for sample code.

    Get Create (RefClass(cComChilkatCompression)) To hoCompress
    If (Not(IsComObjectCreated(hoCompress))) Begin
        Send CreateComObject of hoCompress
    End
    Set ComAlgorithm Of hoCompress To "zlib"

    // ================================================================
    // 1) Single-call compression (entire data in one call)
    // ================================================================

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSb
    If (Not(IsComObjectCreated(hoSb))) Begin
        Send CreateComObject of hoSb
    End
    Get ComAppend Of hoSb "The quick brown fox jumps over the lazy dog. " To iSuccess
    Get ComAppend Of hoSb "This is a simple example using CompressSb." To iSuccess

    Get Create (RefClass(cComChilkatBinData)) To hoBdCompressed
    If (Not(IsComObjectCreated(hoBdCompressed))) Begin
        Send CreateComObject of hoBdCompressed
    End

    // When both FirstChunk and LastChunk are true (the defaults),
    // the entire compression happens in a single call.
    Set ComFirstChunk Of hoCompress To True
    Set ComLastChunk Of hoCompress To True

    Get pvComObject of hoSb to vSb
    Get pvComObject of hoBdCompressed to vBdCompressed
    Get ComCompressSb Of hoCompress vSb vBdCompressed To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetEncoded Of hoBdCompressed "base64" To sCompressedBase64

    Showln "Single-call compressed (base64):"
    Showln sCompressedBase64

    // ================================================================
    // 2) Chunked compression using FirstChunk / LastChunk
    // ================================================================

    Get Create (RefClass(cComChilkatBinData)) To hoBdChunkedOut
    If (Not(IsComObjectCreated(hoBdChunkedOut))) Begin
        Send CreateComObject of hoBdChunkedOut
    End

    // First chunk
    Set ComFirstChunk Of hoCompress To True
    Set ComLastChunk Of hoCompress To False

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbPart
    If (Not(IsComObjectCreated(hoSbPart))) Begin
        Send CreateComObject of hoSbPart
    End
    Get ComAppend Of hoSbPart "The quick brown fox " To iSuccess

    Get pvComObject of hoSbPart to vSbPart
    Get pvComObject of hoBdChunkedOut to vBdChunkedOut
    Get ComCompressSb Of hoCompress vSbPart vBdChunkedOut To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Middle chunk
    Set ComFirstChunk Of hoCompress To False
    Set ComLastChunk Of hoCompress To False

    Send ComClear To hoSbPart
    Get ComAppend Of hoSbPart "jumps over the lazy dog. " To iSuccess

    Get pvComObject of hoSbPart to vSbPart
    Get pvComObject of hoBdChunkedOut to vBdChunkedOut
    Get ComCompressSb Of hoCompress vSbPart vBdChunkedOut To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Final chunk
    Set ComFirstChunk Of hoCompress To False
    Set ComLastChunk Of hoCompress To True

    Send ComClear To hoSbPart
    Get ComAppend Of hoSbPart "This is a chunked CompressSb example." To iSuccess

    Get pvComObject of hoSbPart to vSbPart
    Get pvComObject of hoBdChunkedOut to vBdChunkedOut
    Get ComCompressSb Of hoCompress vSbPart vBdChunkedOut To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetEncoded Of hoBdChunkedOut "base64" To sChunkedBase64

    Showln "Chunked compressed (base64):"
    Showln sChunkedBase64

    // ================================================================
    // 3) Decompress to verify correctness
    // ================================================================

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbDecompressed
    If (Not(IsComObjectCreated(hoSbDecompressed))) Begin
        Send CreateComObject of hoSbDecompressed
    End

    // Decompress in a single call (entire data already assembled)
    Set ComFirstChunk Of hoCompress To True
    Set ComLastChunk Of hoCompress To True

    Get pvComObject of hoBdChunkedOut to vBdChunkedOut
    Get pvComObject of hoSbDecompressed to vSbDecompressed
    Get ComDecompressSb Of hoCompress vBdChunkedOut vSbDecompressed To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoCompress To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Decompressed text:"
    Get ComGetAsString Of hoSbDecompressed To sTemp1
    Showln sTemp1


End_Procedure