Stream CkPython Reference Documentation
CkStream
Current Version: 10.1.2
Provides a generic class for streaming from a source to a sink. Streams can be connected together where the sink of one feeds to the source of another.
Note: This class was added in Chilkat v9.5.0.56. Initially it will seem somewhat useless, but over time, streaming functionality will be added to existing Chilkat classes and will be prevalent in new Chilkat classes.
Object Creation
obj = chilkat.CkStream()
Properties
AbortCurrent
boolVal = stream.get_AbortCurrent();
stream.put_AbortCurrent(boolVal);
When set to True, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to False when the next method is called. When the abort occurs, this property is reset to False. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)
topCanRead
boolVal = stream.get_CanRead();
True if the stream supports reading. Otherwise False.
Note: A stream that supports reading, which has already reached the end-of-stream, will still have a CanRead value of True. This property indicates the stream's inherent ability, and not whether or not the stream can be read at a particular moment in time.
topCanWrite
boolVal = stream.get_CanWrite();
True if the stream supports writing. Otherwise False.
Note: A stream that supports writing, which has already been closed for write, will still have a CanWrite value of True. This property indicates the stream's inherent ability, and not whether or not the stream can be written at a particular moment in time.
topDataAvailable
boolVal = stream.get_DataAvailable();
True if it is known for sure that data is ready and waiting to be read. False if it is not known for sure (it may be that data is immediately available, but reading the stream with a ReadTimeoutMs of 0, which is to poll the stream, is the way to find out).
topDebugLogFilePath
# ckStr is a CkString
stream.get_DebugLogFilePath(ckStr);
strVal = stream.debugLogFilePath();
stream.put_DebugLogFilePath(strVal);
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.
DefaultChunkSize
intVal = stream.get_DefaultChunkSize();
stream.put_DefaultChunkSize(intVal);
The default internal chunk size for reading or writing. The default value is 65536. If this property is set to 0, it will cause the default chunk size (65536) to be used. Note: The chunk size can have significant performance impact. If performance is an issue, be sure to experiment with different chunk sizes.
topEndOfStream
boolVal = stream.get_EndOfStream();
True if the end-of-stream has already been reached. When the stream has already ended, all calls to Read* methods will return False with the ReadFailReason set to 3 (already at end-of-stream).
topIsWriteClosed
boolVal = stream.get_IsWriteClosed();
True if the stream is closed for writing. Once closed, no more data may be written to the stream.
topLastErrorHtml
# ckStr is a CkString
stream.get_LastErrorHtml(ckStr);
strVal = stream.lastErrorHtml();
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.
topLastErrorText
# ckStr is a CkString
stream.get_LastErrorText(ckStr);
strVal = stream.lastErrorText();
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.
LastErrorXml
# ckStr is a CkString
stream.get_LastErrorXml(ckStr);
strVal = stream.lastErrorXml();
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.
topLastMethodSuccess
boolVal = stream.get_LastMethodSuccess();
stream.put_LastMethodSuccess(boolVal);
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.
topLength
int64Val = stream.get_Length();
stream.put_Length(int64Val);
The length (in bytes) of the stream's source. If unknown, then this property will have a value of -1. This property may be set by the application if it knows in advance the length of the stream.
topLength32
intVal = stream.get_Length32();
stream.put_Length32(intVal);
The length (in bytes) of the stream's source. If unknown, then this property will have a value of -1. This property may be set by the application if it knows in advance the length of the stream.
Setting this property also sets the Length property (which is a 64-bit integer).
topNumReceived
int64Val = stream.get_NumReceived();
The number of bytes received by the stream.
topNumSent
int64Val = stream.get_NumSent();
The number of bytes sent by the stream.
topReadFailReason
intVal = stream.get_ReadFailReason();
This property is automatically set when a Read* method is called. It indicates the reason for failure. Possible values are:
- No failure (success)
- Timeout, or no data is immediately available for a polling read.
- Aborted by an application callback.
- Already at end-of-stream.
- Fatal stream error.
- Out-of-memory error (this is very unlikely).
ReadTimeoutMs
intVal = stream.get_ReadTimeoutMs();
stream.put_ReadTimeoutMs(intVal);
The maximum number of seconds to wait while reading. The default value is 30 seconds (i.e. 30000ms). A value of 0 indicates a poll. (A polling read is to return with a timeout if no data is immediately available.)
Important: For most Chilkat timeout related properties, a value of 0 indicates an infinite timeout. For this property, a value of 0 indicates a poll. If setting a timeout related property (or method argument) to zero, be sure to understand if 0 means "wait forever" or "poll".
The timeout value is not a total timeout. It is the maximum time to wait while no additional data is forthcoming.
topSinkFile
# ckStr is a CkString
stream.get_SinkFile(ckStr);
strVal = stream.sinkFile();
stream.put_SinkFile(strVal);
Sets the sink to the path of a file. The file does not need to exist at the time of setting this property. The sink file will be automatically opened on demand, when the stream is first written.
Note: This property takes priority over other potential sinks. Make sure this property is set to an empty string if the stream's sink is to be something else.
SinkFileAppend
boolVal = stream.get_SinkFileAppend();
stream.put_SinkFileAppend(boolVal);
If True, the stream appends to the SinkFile rather than truncating and re-writing the sink file. The default value is False.
topSourceFile
# ckStr is a CkString
stream.get_SourceFile(ckStr);
strVal = stream.sourceFile();
stream.put_SourceFile(strVal);
Sets the source to the path of a file. The file does not need to exist at the time of setting this property. The source file will be automatically opened on demand, when the stream is first read.
Note: This property takes priority over other potential sources. Make sure this property is set to an empty string if the stream's source is to be something else.
SourceFilePart
intVal = stream.get_SourceFilePart();
stream.put_SourceFilePart(intVal);
If the source is a file, then this property can be used to stream one part of the file. The SourceFilePartSize property defines the size (in bytes) of each part. The SourceFilePart and SourceFilePartSize have default values of 0, which means the entire SourceFile is streamed.
This property is a 0-based index. For example, if the SourceFilePartSize is 1000, then part 0 is for bytes 0 to 999, part 1 is for bytes 1000 to 1999, etc.
SourceFilePartSize
intVal = stream.get_SourceFilePartSize();
stream.put_SourceFilePartSize(intVal);
If the source is a file, then this property, in conjunction with the SourceFilePart property, can be used to stream a single part of the file. This property defines the size (in bytes) of each part. The SourceFilePart and SourceFilePartSize have default values of 0, which means that by default, the entire SourceFile is streamed.
StringBom
boolVal = stream.get_StringBom();
stream.put_StringBom(boolVal);
If True, then include the BOM when creating a string source via SetSourceString where the charset is utf-8, utf-16, etc. (The term "BOM" stands for Byte Order Mark, also known as the preamble.) Also, if True, then include the BOM when writing a string via the WriteString method. The default value of this property is False.
topStringCharset
# ckStr is a CkString
stream.get_StringCharset(ckStr);
strVal = stream.stringCharset();
stream.put_StringCharset(strVal);
Indicates the expected character encoding, such as utf-8, windows-1256, utf-16, etc. for methods that read text such as: ReadString, ReadToCRLF, ReadUntilMatch. Also controls the character encoding when writing strings with the WriteString method. The supported charsets are indicated at the link below.
The default value is "utf-8".
Utf8
boolVal = stream.get_Utf8();
stream.put_Utf8(boolVal);
When set to True, all "const char *" arguments are interpreted as utf-8 strings. If set to False (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to True, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to False, all "const char *" return values are ANSI strings.
topVerboseLogging
boolVal = stream.get_VerboseLogging();
stream.put_VerboseLogging(boolVal);
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.
topVersion
WriteFailReason
intVal = stream.get_WriteFailReason();
This property is automatically set when a Write* method is called. It indicates the reason for failure. Possible values are:
- No failure (success)
- Timeout, or unable to immediately write when the WriteTimeoutMs is 0.
- Aborted by an application callback.
- The stream has already ended.
- Fatal stream error.
- Out-of-memory error (this is very unlikely).
WriteTimeoutMs
intVal = stream.get_WriteTimeoutMs();
stream.put_WriteTimeoutMs(intVal);
The maximum number of seconds to wait while writing. The default value is 30 seconds (i.e. 30000ms). A value of 0 indicates to return immediately if it is not possible to write to the sink immediately.
topMethods
LoadTaskCaller
ReadBd
Read as much data as is immediately available on the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The incoming data is appended to binData.
Returns True for success, False for failure.
ReadBdAsync (1)
Creates an asynchronous task to call the ReadBd method with the arguments provided.
Returns None on failure
ReadBytes
Read as much data as is immediately available on the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive.
Returns True for success, False for failure.
topReadBytesAsync (1)
Creates an asynchronous task to call the ReadBytes method with the arguments provided.
Returns None on failure
topReadBytesENC
# outStr is a CkString (output)
status = stream.ReadBytesENC(encoding, outStr);
retStr = stream.readBytesENC(encoding);
The same as ReadBytes, except returns the received bytes in encoded string form. The encoding argument indicates the encoding, which can be "base64", "hex", or any of the multitude of encodings indicated in the link below.
Returns True for success, False for failure.
ReadBytesENCAsync (1)
Creates an asynchronous task to call the ReadBytesENC method with the arguments provided.
Returns None on failure
topReadNBytes
# outBytes is a CkByteData (output)
status = stream.ReadNBytes(numBytes, outData);
Reads exactly numBytes bytes from the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive.
Returns True for success, False for failure.
topReadNBytesAsync (1)
Creates an asynchronous task to call the ReadNBytes method with the arguments provided.
Returns None on failure
topReadNBytesENC
# encoding is a string
# outStr is a CkString (output)
status = stream.ReadNBytesENC(numBytes, encoding, outStr);
retStr = stream.readNBytesENC(numBytes, encoding);
The same as ReadNBytes, except returns the received bytes in encoded string form. The encoding argument indicates the encoding, which can be "base64", "hex", or any of the multitude of encodings indicated in the link below.
Returns True for success, False for failure.
ReadNBytesENCAsync (1)
# numBytes is an integer
# encoding is a string
ret_task = stream.ReadNBytesENCAsync(numBytes, encoding);
Creates an asynchronous task to call the ReadNBytesENC method with the arguments provided.
Returns None on failure
topReadSb
Read as much data as is immediately available on the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is appended to sb. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to "utf-8" prior to calling ReadSb.
Returns True for success, False for failure.
topReadSbAsync (1)
Creates an asynchronous task to call the ReadSb method with the arguments provided.
Returns None on failure
ReadString
Read as much data as is immediately available on the stream. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is returned as a string. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to "utf-8" prior to calling ReadString.
Returns True for success, False for failure.
topReadStringAsync (1)
Creates an asynchronous task to call the ReadString method with the arguments provided.
Returns None on failure
topReadToCRLF
Reads the stream until a CRLF is received. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is returned as a string. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to "utf-8" prior to calling ReadString.
Note: If the end-of-stream is reached prior to receiving the CRLF, then the remaining data is returned, and the ReadFailReason property will be set to 3 (to indicate end-of-file). This is the only case where as string would be returned that does not end with CRLF.
Returns True for success, False for failure.
topReadToCRLFAsync (1)
Creates an asynchronous task to call the ReadToCRLF method with the arguments provided.
Returns None on failure
topReadUntilMatch
# outStr is a CkString (output)
status = stream.ReadUntilMatch(matchStr, outStr);
retStr = stream.readUntilMatch(matchStr);
Reads the stream until the string indicated by matchStr is received. If no data is immediately available, it waits up to ReadTimeoutMs milliseconds for data to arrive. The data is returned as a string. The incoming bytes are interpreted according to the StringCharset property. For example, if utf-8 bytes are expected, then StringCharset should be set to "utf-8" prior to calling ReadString.
Note: If the end-of-stream is reached prior to receiving the match string, then the remaining data is returned, and the ReadFailReason property will be set to 3 (to indicate end-of-file). This is the only case where as string would be returned that does not end with the desired match string.
Returns True for success, False for failure.
ReadUntilMatchAsync (1)
Creates an asynchronous task to call the ReadUntilMatch method with the arguments provided.
Returns None on failure
topReset
Resets the stream. If a source or sink is open, then it is closed. Properties such as EndOfStream and IsWriteClose are reset to default values.
topSetSourceBytes
Sets the stream's source to the contents of sourceData.
Returns True for success, False for failure.
topSetSourceString
# charset is a string
status = stream.SetSourceString(srcStr, charset);
Sets the stream's source to the contents of srcStr. The charset indicates the character encoding to be used for the byte representation of the srcStr.
Returns True for success, False for failure.
topWriteBd
WriteBdAsync (1)
Creates an asynchronous task to call the WriteBd method with the arguments provided.
Returns None on failure
topWriteByte
status = stream.WriteByte(byteVal);
Writes a single byte to the stream. The byteVal must have a value from 0 to 255.
Returns True for success, False for failure.
topWriteByteAsync (1)
Creates an asynchronous task to call the WriteByte method with the arguments provided.
Returns None on failure
topWriteBytes
WriteBytesAsync (1)
Creates an asynchronous task to call the WriteBytes method with the arguments provided.
Returns None on failure
topWriteBytesENC
# encoding is a string
status = stream.WriteBytesENC(byteData, encoding);
Writes binary bytes to a stream. The byte data is passed in encoded string form, where the encoding can be "base64", "hex", or any of the supported binary encodings listed at the link below.
Returns True for success, False for failure.
WriteBytesENCAsync (1)
# byteData is a string
# encoding is a string
ret_task = stream.WriteBytesENCAsync(byteData, encoding);
Creates an asynchronous task to call the WriteBytesENC method with the arguments provided.
Returns None on failure
topWriteClose
Indicates that no more data will be written to the stream.
Returns True for success, False for failure.
topWriteSb
Writes the contents of sb to the stream. The actual bytes written are the byte representation of the string as indicated by the StringCharset property. For example, to write utf-8 bytes, first set StringCharset equal to "utf-8" and then call WriteSb.
Returns True for success, False for failure.
topWriteSbAsync (1)
Creates an asynchronous task to call the WriteSb method with the arguments provided.
Returns None on failure
topWriteString
status = stream.WriteString(str);
Writes a string to a stream. The actual bytes written are the byte representation of the string as indicated by the StringCharset property. For example, to write utf-8 bytes, first set StringCharset equal to "utf-8" and then call WriteString.
Returns True for success, False for failure.
topWriteStringAsync (1)
Creates an asynchronous task to call the WriteString method with the arguments provided.
Returns None on failure
top