Bz2 DataFlex Reference Documentation

Bz2

Current Version: 11.5.0

Requires Chilkat Bundle License

Chilkat.Bz2 provides BZip2 compression and decompression for files, memory buffers, and BinData. It can create standard .bz2 file images, decompress .bz2 content back to its original bytes, and support abortable long-running operations.

For an extended overview, see Bz2 Class Overview

Object Creation

// (Dataflex programs use the 32-bit Chilkat ActiveX)
Handle hoBz2
Get Create(RefClass(cComChilkatBz2)) to hoBz2

Properties

AbortCurrent

Function ComAbortCurrent Returns Boolean
Procedure Set ComAbortCurrent Boolean value

Introduced in version 9.5.0.58

Set this property to True to request cancellation of the compression or decompression operation currently executing on this object. Long-running operations check the request periodically; an operation that finishes quickly may complete before the request is observed.

A synchronous call can be cancelled by setting this property from another thread. After cancellation is processed, Chilkat resets the property to False. If no operation is running, a previously set value is cleared when the next method begins.

Cancellation is cooperative: Setting this property requests an abort; it does not guarantee immediate termination. Check the method's return value and LastErrorText to determine the final outcome.

DebugLogFilePath

Function ComDebugLogFilePath Returns String
Procedure Set ComDebugLogFilePath String value

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

A timeout property set to 0, indicating an infinite timeout.
A hang occurring within an event callback in the application code.
An internal bug in the Chilkat code causing the hang.

More Information and Examples

Example showing how to use DebugLogFilePath.

LastBinaryResult

Function ComLastBinaryResult Returns Variant

This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. It is only accessible if Chilkat.Global.KeepBinaryResult is set to True. This feature allows for the retrieval of large varbinary results in an SQL Server environment, which has restrictions on returning large data via method calls, though temp tables can handle binary properties.

LastErrorHtml

Function ComLastErrorHtml Returns String

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastErrorText

Function ComLastErrorText Returns String

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

More Information and Examples

Concept of LastErrorText LastErrorText Standard Information

LastErrorXml

Function ComLastErrorXml Returns String

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

LastMethodSuccess

Function ComLastMethodSuccess Returns Boolean
Procedure Set ComLastMethodSuccess Boolean value

Indicates the success or failure of the most recent method call: True means success, False means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

LastStringResult

Function ComLastStringResult Returns String

In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.

More Information and Examples

Long Strings Returned by ActiveX Methods in SQL Server

LastStringResultLen

Function ComLastStringResultLen Returns Integer

The length, in characters, of the string contained in the LastStringResult property.

VerboseLogging

Function ComVerboseLogging Returns Boolean
Procedure Set ComVerboseLogging Boolean value

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

Version

Function ComVersion Returns String

Version of the component/library, such as "10.1.0"

More Information and Examples

How to get the Chilkat version at runtime.

Methods

CompressBd

Function ComCompressBd cComChilkatBinData bd Returns Boolean

Introduced in version 11.0.0

Compresses the current contents of bd in place. On success, the BinData no longer contains the original bytes; it contains the complete standard BZip2 stream that may be saved with a .bz2 extension.

In-place transformation: Preserve a copy of the original data if it is still needed after this call. A BZip2 stream contains a stream header, one or more compressed blocks with integrity checks, and an end-of-stream marker. It does not contain archive filenames or directory entries.

Returns True for success, False for failure.

CompressBdAsync ⁽¹⁾

Function ComCompressBdAsync cComChilkatBinData bd Returns cComChilkatTask

Introduced in version 11.0.0

Creates an asynchronous task to call the CompressBd method with the arguments provided.

Returns null on failure

CompressFile

Function ComCompressFile String inFilename String toPath Returns Boolean

Reads the file at inFilename and writes its compressed bytes as a standard BZip2 stream to the file at toPath. The output is conventionally given a .bz2 extension.

Both arguments must identify files, not directories. They may be absolute or relative paths, for example data/report.txt and data/report.txt.bz2.

BZip2 is a compressor, not an archive format: A .bz2 file represents one compressed byte stream. It does not store the original filename, directory path, timestamps, permissions, or multiple archive entries. Formats such as .tar.bz2 first combine files in a TAR archive and then compress that TAR stream with BZip2.

Returns True for success, False for failure.

More Information and Examples

bz2 Compress File

CompressFileAsync ⁽¹⁾

Function ComCompressFileAsync String inFilename String toPath Returns cComChilkatTask

Creates an asynchronous task to call the CompressFile method with the arguments provided.

Returns null on failure

CompressFileToMem

Function ComCompressFileToMem String inFilename Returns Variant

Reads the file at inFilename, compresses it with BZip2, and returns the complete .bz2 byte stream in memory.

Returns null on failure

CompressFileToMemAsync ⁽¹⁾

Function ComCompressFileToMemAsync String inFilename Returns cComChilkatTask

Creates an asynchronous task to call the CompressFileToMem method with the arguments provided.

Returns null on failure

CompressMemory

Function ComCompressMemory Variant inData Returns Variant

Compresses the bytes in inData and returns the complete standard BZip2 stream as an in-memory byte array.

Returns null on failure

CompressMemoryAsync ⁽¹⁾

Function ComCompressMemoryAsync Variant inData Returns cComChilkatTask

Creates an asynchronous task to call the CompressMemory method with the arguments provided.

Returns null on failure

CompressMemToFile

Function ComCompressMemToFile Variant inData String toPath Returns Boolean

Compresses the bytes in inData and writes the resulting standard BZip2 stream to the file at toPath.

Returns True for success, False for failure.

CompressMemToFileAsync ⁽¹⁾

Function ComCompressMemToFileAsync Variant inData String toPath Returns cComChilkatTask

Creates an asynchronous task to call the CompressMemToFile method with the arguments provided.

Returns null on failure

LoadTaskCaller

Function ComLoadTaskCaller cComChilkatTask task Returns Boolean

Introduced in version 9.5.0.80

Loads this Bz2 object with the caller state associated with the asynchronous operation represented by task.

Advanced async infrastructure: This method is used to recover the original caller object associated with a completed task. It is not normally needed by application code. Pass a Task created by a compatible Bz2 asynchronous method; an unrelated task cannot be loaded.

Returns True for success, False for failure.

UncompressBd

Function ComUncompressBd cComChilkatBinData bd Returns Boolean

Introduced in version 11.0.0

Decompresses the BZip2 stream currently contained in bd in place. On success, the BinData is replaced with the original uncompressed bytes.

Input requirement: bd must contain a complete, valid BZip2 stream, such as the bytes of a .bz2 file or the output of CompressBd. This method operates on binary data and does not perform character-set conversion.

Returns True for success, False for failure.

UncompressBdAsync ⁽¹⁾

Function ComUncompressBdAsync cComChilkatBinData bd Returns cComChilkatTask

Introduced in version 11.0.0

Creates an asynchronous task to call the UncompressBd method with the arguments provided.

Returns null on failure

UncompressFile

Function ComUncompressFile String inFilename String toPath Returns Boolean

Reads the BZip2 stream from the file at inFilename, decompresses it, and writes the original uncompressed bytes to the file at toPath.

Both arguments must identify files, not directories. Chilkat does not derive the destination name from the .bz2 filename because the BZip2 stream does not contain the original filename.

Terminology: This method decompresses BZip2 data; it does not “unzip” a ZIP archive. A .bz2 file normally contains a single compressed byte stream rather than a collection of named files.

Returns True for success, False for failure.

UncompressFileAsync ⁽¹⁾

Function ComUncompressFileAsync String inFilename String toPath Returns cComChilkatTask

Creates an asynchronous task to call the UncompressFile method with the arguments provided.

Returns null on failure

UncompressFileToMem

Function ComUncompressFileToMem String inFilename Returns Variant

Reads and decompresses the BZip2 stream in the file at inFilename, returning the original uncompressed bytes in memory.

Returns null on failure

UncompressFileToMemAsync ⁽¹⁾

Function ComUncompressFileToMemAsync String inFilename Returns cComChilkatTask

Creates an asynchronous task to call the UncompressFileToMem method with the arguments provided.

Returns null on failure

UncompressMemory

Function ComUncompressMemory Variant inData Returns Variant

Interprets inData as a complete BZip2 stream and returns the decompressed bytes in memory.

Returns null on failure

UncompressMemoryAsync ⁽¹⁾

Function ComUncompressMemoryAsync Variant inData Returns cComChilkatTask

Creates an asynchronous task to call the UncompressMemory method with the arguments provided.

Returns null on failure

UncompressMemToFile

Function ComUncompressMemToFile Variant inData String toPath Returns Boolean

Interprets inData as a complete BZip2 stream, decompresses it, and writes the original bytes to the file at toPath.

Returns True for success, False for failure.

UncompressMemToFileAsync ⁽¹⁾

Function ComUncompressMemToFileAsync Variant inData String toPath Returns cComChilkatTask

Creates an asynchronous task to call the UncompressMemToFile method with the arguments provided.

Returns null on failure