Stream Chilkat2 Perl Reference Documentation
Chilkat2::Stream
Current Version: 11.7.0
Markdown version of this page for AI tools (v 11.7.0) · all AI docs
Chilkat.Stream
Stream from a source file, byte array, string, or selected file part
without manually loading or copying all data first.
Write streamed data to a sink file, append to an existing file, or output
to
Read or write raw bytes, fixed byte counts, encoded byte strings,
individual bytes, or
Read and write strings using
Control read and write wait behavior, poll for immediately available
data, and inspect read or write failure reasons.
Track bytes sent and received, detect end-of-stream or write-closed
state, reset streams, close writing, and abort long-running operations.
Read, write, pipe, monitor, and control byte or text streams.
Chilkat.Stream is a general-purpose streaming object for moving
data between sources and sinks without requiring the entire payload to be
handled at once. A stream can read from files, byte arrays, strings, or other
sources; write to files, memory, BinData,
StringBuilder, or other sinks; handle binary and text data;
apply character-set rules for strings; process file parts; track bytes sent
and received; and support timeouts, polling, aborts, async task integration,
and end-of-stream handling.
File and memory sources
File and object sinks
BinData, StringBuilder, bytes, or strings.
Binary reads and writes
BinData content.
Text streaming
StringCharset, optionally use a
BOM, and read text until CRLF or a matching delimiter.
Timeouts and polling
Progress and lifecycle
BinData, or
StringBuilder. Check EndOfStream,
ReadFailReason, WriteFailReason,
NumReceived, NumSent, and
LastErrorText to understand stream progress and failures.
ReadTimeoutMs, a value of 0 means a polling
read, not an infinite timeout. For WriteTimeoutMs,
0 means return immediately if the stream cannot be written to
right away.
Object Creation
use Chilkat2;
my $stream = Chilkat2::Stream->new;
# or set properties (and RaiseError) at creation:
# my $stream = Chilkat2::Stream->new(VerboseLogging => 1, RaiseError => 1);Creates the object. The optional pairs set writable properties (and RaiseError) in order, as if set one by one; an unknown or read-only name croaks. use Chilkat2; loads every class; the Chilkat2/Stream.pm file holds only this class's documentation (perldoc Chilkat2::Stream).
Perl frees the object when its last reference goes (undef $stream, or the variable going out of scope); there is nothing to close. Objects returned by methods are independent and freed the same way. The class may be subclassed (use parent -norequire, 'Chilkat2::Stream';): an object is a blessed hash reference whose hash is free for the subclass's own fields.
When false (the default), a method that fails returns false (or undef), and the reason is in LastErrorText. When true, it dies with a Chilkat2::Error instead, as DBI does with its RaiseError. Objects returned by a method inherit the value of the object that returned them.
Errors
A Chilkat2::Error stringifies to the failed call's full LastErrorText, and has the methods text, class ('Chilkat2::Stream'), method (the method name) and object. Methods that look something up and find nothing return undef without dying (each such method says so), methods that answer a question (HasMember, IsUnlocked, ...) return a plain boolean, and property reads and writes never fail for Chilkat reasons.
Misuse always croaks, with your file and line, whatever RaiseError is: a wrong number of arguments, a reference or undef where a string or number is expected, an object of the wrong class, an out-of-range integer, a string containing a NUL character, a wide character in a byte string, or a write to a read-only property.
Strings are Perl character strings in both directions (length, regexes and :encoding layers see characters); binary data (BinData) is a byte string. Unlocking: call Chilkat2::Global->new->UnlockBundle('...') once at startup.
Properties
AbortCurrent
my $boolVal = $stream->AbortCurrent;
$stream->AbortCurrent($boolVal);
When set to 1, 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 0 when the next method is called. When the abort occurs, this property is reset to 0. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)
CanRead
my $boolVal = $stream->CanRead;
1 if the stream supports reading. Otherwise 0.
Note: A stream that supports reading, which has already reached the end-of-stream, will still have a CanRead value of 1. This property indicates the stream's inherent ability, and not whether or not the stream can be read at a particular moment in time.
CanWrite
my $boolVal = $stream->CanWrite;
1 if the stream supports writing. Otherwise 0.
Note: A stream that supports writing, which has already been closed for write, will still have a CanWrite value of 1. This property indicates the stream's inherent ability, and not whether or not the stream can be written at a particular moment in time.
DataAvailable
my $boolVal = $stream->DataAvailable;
1 if it is known for sure that data is ready and waiting to be read. 0 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).
DebugLogFilePath
my $strVal = $stream->DebugLogFilePath;
$stream->DebugLogFilePath($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
my $intVal = $stream->DefaultChunkSize;
$stream->DefaultChunkSize($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
my $boolVal = $stream->EndOfStream;
1 if the end-of-stream has already been reached. When the stream has already ended, all calls to Read* methods will return 0 with the ReadFailReason set to 3 (already at end-of-stream).
HeartbeatMs
my $intVal = $stream->HeartbeatMs;
$stream->HeartbeatMs($intVal);
The interval in milliseconds between each AbortCheck event callback, which enables an application to abort certain method calls before they complete. By default, HeartbeatMs is set to 0, meaning no AbortCheck event callbacks will trigger.
IsWriteClosed
my $boolVal = $stream->IsWriteClosed;
1 if the stream is closed for writing. Once closed, no more data may be written to the stream.
LastErrorHtml
my $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
my $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
my $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
my $boolVal = $stream->LastMethodSuccess;
$stream->LastMethodSuccess($boolVal);
Indicates the success or failure of the most recent method call: 1 means success, 0 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.
Length
my $intVal = $stream->Length;
$stream->Length($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.
topLength32
my $intVal = $stream->Length32;
$stream->Length32($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
my $intVal = $stream->NumReceived;
The number of bytes received by the stream.
topNumSent
my $intVal = $stream->NumSent;
The number of bytes sent by the stream.
topReadFailReason
my $intVal = $stream->ReadFailReason;
This property is automatically set when a Read* method is called. It indicates the reason for failure. Possible values are:
- 0>
- 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
my $intVal = $stream->ReadTimeoutMs;
$stream->ReadTimeoutMs($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
my $strVal = $stream->SinkFile;
$stream->SinkFile($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.
topSinkFileAppend
my $boolVal = $stream->SinkFileAppend;
$stream->SinkFileAppend($boolVal);
If 1, the stream appends to the SinkFile rather than truncating and re-writing the sink file. The default value is 0.
SourceFile
my $strVal = $stream->SourceFile;
$stream->SourceFile($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.
topSourceFilePart
my $intVal = $stream->SourceFilePart;
$stream->SourceFilePart($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
my $intVal = $stream->SourceFilePartSize;
$stream->SourceFilePartSize($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
my $boolVal = $stream->StringBom;
$stream->StringBom($boolVal);
If 1, 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 1, then include the BOM when writing a string via the WriteString method. The default value of this property is 0.
StringCharset
my $strVal = $stream->StringCharset;
$stream->StringCharset($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.
VerboseLogging
my $boolVal = $stream->VerboseLogging;
$stream->VerboseLogging($boolVal);
If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
my $strVal = $stream->Version;
WriteFailReason
my $intVal = $stream->WriteFailReason;
This property is automatically set when a Write* method is called. It indicates the reason for failure. Possible values are:
- 0>
- 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
my $intVal = $stream->WriteTimeoutMs;
$stream->WriteTimeoutMs($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
ReadBd
# $success is true or false
my $success = $stream->ReadBd($binData);
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 on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
ReadBytesENC
# $str is a string or undef
my $str = $stream->ReadBytesENC($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 undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
ReadNBytesENC
# $encoding is a string
# $str is a string or undef
my $str = $stream->ReadNBytesENC($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 undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
ReadSb
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 on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
ReadString
my $str = $stream->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 undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
ReadToCRLF
my $str = $stream->ReadToCRLF();
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 undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
ReadUntilMatch
# $str is a string or undef
my $str = $stream->ReadUntilMatch($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 undef on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
Reset
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.
Returns the object, so calls can be chained.
topSetSourceString
# $charset is a string
# $success is true or false
my $success = $stream->SetSourceString($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 on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
WriteBd
# $success is true or false
my $success = $stream->WriteBd($binData);
Writes the contents of $binData to the stream.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
WriteByte
# $success is true or false
my $success = $stream->WriteByte($byteVal);
Writes a single byte to the stream. The $byteVal must have a value from 0 to 255.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
WriteBytesENC
# $encoding is a string
# $success is true or false
my $success = $stream->WriteBytesENC($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 on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
WriteClose
my $success = $stream->WriteClose();
Indicates that no more data will be written to the stream.
Returns true on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
WriteSb
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 on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
WriteString
# $success is true or false
my $success = $stream->WriteString($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 on success, false on failure; LastErrorText says why. With RaiseError on, a failure dies with a Chilkat2::Error instead (it stringifies to the LastErrorText); the object remains usable either way.
Events
All Chilkat methods are synchronous: the call returns when the work is done. During a long-running call, Chilkat2::Stream reports progress to handlers installed with on, which takes Event => CODE pairs (closures, so a handler can use the variables around it):
$stream->on(
PercentDone => sub { my ($pctDone) = @_; print "$pctDone%\n"; return 0 }, # a true return aborts
ProgressInfo => sub { my ($name, $value) = @_; print "$name: $value\n" },
);
$stream->HeartbeatMs(250); # the AbortCheck handler is called 4 times per secondInstalls the handlers given, replacing those installed before for the same events; undef instead of a CODE reference removes one, and $stream->on() with no arguments returns the installed handlers as a list of pairs. The event names are checked: a misspelled one croaks, and nothing is installed.
The AbortCheck handler is called at the interval set by the HeartbeatMs property (0, the default, disables it); PercentDone is called when an operation's completion percentage is known; ProgressInfo delivers named progress values. A true return from the AbortCheck or PercentDone handler aborts the running method, which then fails in the usual way (false or undef, or a Chilkat2::Error under RaiseError).
Handlers run during the method call, on the thread that called it. Inside a handler, other objects may be used, but calling a method of the same object (or its on) croaks. A die in a handler aborts the running method and is re-thrown from the method call; the object remains usable. A handler that uses $stream itself makes a reference cycle: weaken the captured copy (Scalar::Util) or remove the handler when done.
AbortCheck
$stream->on(AbortCheck => sub { ... });
Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.
Example
my $deadline = time() + 30; # give up after 30 seconds
$stream->HeartbeatMs(250); # call the handler 4 times per second
$stream->on(AbortCheck => sub { return time() > $deadline });PercentDone
$stream->on(PercentDone => sub { ... });
This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).
The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.
To abort the operation, set the abort output argument to 1. This will cause the method to terminate and return a failure status or corresponding failure value.
Example
$stream->on(PercentDone => sub {
my ($pctDone) = @_; # 0 to 100
print "Percent done: $pctDone\n";
return 0; # return a true value to abort the method in progress
});ProgressInfo
$stream->on(ProgressInfo => sub { ... });
This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.
Note: Some Chilkat methods don't fire any ProgressInfo events.
Example
$stream->on(ProgressInfo => sub {
my ($name, $value) = @_;
print "$name: $value\n";
});