(PowerShell) Compressing StringBuilder Data Using CompressSb (Single Call and Chunked)

See more Compression Examples

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).

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.

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

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

$compress = New-Object Chilkat.Compression
$compress.Algorithm = "zlib"

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

$sb = New-Object Chilkat.StringBuilder
$sb.Append("The quick brown fox jumps over the lazy dog. ")
$sb.Append("This is a simple example using CompressSb.")

$bdCompressed = New-Object Chilkat.BinData

# When both FirstChunk and LastChunk are true (the defaults),
# the entire compression happens in a single call.
$compress.FirstChunk = $true
$compress.LastChunk = $true

$success = $compress.CompressSb($sb,$bdCompressed)
if ($success -eq $false) {
    $($compress.LastErrorText)
    exit
}

$compressedBase64 = $bdCompressed.GetEncoded("base64")

$("Single-call compressed (base64):")
$($compressedBase64)

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

$bdChunkedOut = New-Object Chilkat.BinData

# First chunk
$compress.FirstChunk = $true
$compress.LastChunk = $false

$sbPart = New-Object Chilkat.StringBuilder
$sbPart.Append("The quick brown fox ")

$success = $compress.CompressSb($sbPart,$bdChunkedOut)
if ($success -eq $false) {
    $($compress.LastErrorText)
    exit
}

# Middle chunk
$compress.FirstChunk = $false
$compress.LastChunk = $false

$sbPart.Clear()
$sbPart.Append("jumps over the lazy dog. ")

$success = $compress.CompressSb($sbPart,$bdChunkedOut)
if ($success -eq $false) {
    $($compress.LastErrorText)
    exit
}

# Final chunk
$compress.FirstChunk = $false
$compress.LastChunk = $true

$sbPart.Clear()
$sbPart.Append("This is a chunked CompressSb example.")

$success = $compress.CompressSb($sbPart,$bdChunkedOut)
if ($success -eq $false) {
    $($compress.LastErrorText)
    exit
}

$chunkedBase64 = $bdChunkedOut.GetEncoded("base64")

$("Chunked compressed (base64):")
$($chunkedBase64)

# ================================================================
# 3) Decompress to verify correctness
# ================================================================

$sbDecompressed = New-Object Chilkat.StringBuilder

# Decompress in a single call (entire data already assembled)
$compress.FirstChunk = $true
$compress.LastChunk = $true

$success = $compress.DecompressSb($bdChunkedOut,$sbDecompressed)
if ($success -eq $false) {
    $($compress.LastErrorText)
    exit
}

$("Decompressed text:")
$($sbDecompressed.GetAsString())