PipeExec Component

Properties   Methods   Events   Config Settings   Errors  

PipeExec provides an easy way to start and interact with a process over Stdin, Stdout, and Stderr.

Syntax

TiipPipeExec

Remarks

The PipeExec component provides a way to launch a process and then send/receive data to/from the process. To begin set ProcessFileName to the path of the process on disk. Optionally set ProcessArgs and ProcessWorkingDir.

Call StartProcess to start the process. Next set Stdin or call Send to send data to the process. Received data will be provided through the Stdout and Stderr events.

To terminate the process call StopProcess.

Example Code Pipeexec exec = new Pipeexec(); exec.OnStdout += exec_OnStdout; exec.ProcessFileName = @"C:\Windows\system32\cmd.exe"; exec.ProcessArgs = "/Q"; exec.StartProcess(); exec.Stdin = "dir" + System.Environment.NewLine; while (true) //Wait for output exec.DoEvents(); static void exec_OnStdout(object sender, PipeexecStdoutEventArgs e) { Console.WriteLine(e.Text); }

Property List

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The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the component with short descriptions. Click on the links for further details.

AcceptData Property (PipeExec Component)

Enables or disables data reception (the Stdout and Stderr events).

Syntax

property AcceptData: Boolean read get_AcceptData write set_AcceptData;

Default Value

true

Remarks

This property enables or disables data reception (the Stdout and Stderr events). Setting this property to False, temporarily disables data reception. Setting this property to True, re-enables data reception.

This property is not available at design time.

BytesSent Property (PipeExec Component)

The number of bytes actually sent after an assignment to Stdin.

Syntax

property BytesSent: Integer read get_BytesSent;

Default Value

0

Remarks

This property indicates how many bytes were sent after the last assignment to Stdin. Please check the Stdin property for more information.

This property is read-only and not available at design time.

EOL Property (PipeExec Component)

This property is used to break the incoming data stream into chunks separated by EOL .

Syntax

property EOL: String read get_EOL write set_EOL;
property EOLB: TBytes read get_EOLB write set_EOLB;

Default Value

''

Remarks

This property is used to define boundaries in the input stream using the value of the property.

This property is especially useful with ASCII files. Setting it to CRLF ('#13#10') enables the incoming ASCII text stream to split into defined lines. In this case, one event is fired for each line received (as well as in packet boundaries). The CRLF ('#13#10') bytes are discarded.

This property is a binary string. Notably, this means that it can be more than one byte long, and it can contain NULL bytes.

ProcessArgs Property (PipeExec Component)

The arguments to pass to the process.

Syntax

property ProcessArgs: String read get_ProcessArgs write set_ProcessArgs;

Default Value

''

Remarks

This property specifies the arguments that will be passed to the process when it is started.

This property is not available at design time.

ProcessFileName Property (PipeExec Component)

The path to the file on disk to execute.

Syntax

property ProcessFileName: String read get_ProcessFileName write set_ProcessFileName;

Default Value

''

Remarks

This property specifies the path to the file on disk that will be executed. ProcessArgs optionally specifies the arguments that will be passed. ProcessWorkingDir optionally specifies the working directory in which the process will run.

This property is not available at design time.

ProcessRunning Property (PipeExec Component)

Whether the process is running.

Syntax

property ProcessRunning: Boolean read get_ProcessRunning;

Default Value

false

Remarks

This property indicates whether the process specified by ProcessFileName is running.

After calling StartProcess this property returns True. After calling StopProcess this property returns False.

This property is read-only and not available at design time.

ProcessWorkingDir Property (PipeExec Component)

The working directory of the process.

Syntax

property ProcessWorkingDir: String read get_ProcessWorkingDir write set_ProcessWorkingDir;

Default Value

''

Remarks

This property optionally specifies the working directory in which the process will run.

This property is not available at design time.

SingleLineMode Property (PipeExec Component)

This property includes a special mode for line-oriented protocols.

Syntax

property SingleLineMode: Boolean read get_SingleLineMode write set_SingleLineMode;

Default Value

false

Remarks

When this property is set to True, the component treats the incoming data stream as lines separated by carriage return line feed (CRLF), CR, or LF. The EOL property is ignored.

When this property is set to True, AcceptData automatically will be set to False. Please refer to the GetLine method for more information.

This property is not available at design time.

Stdin Property (PipeExec Component)

A string of data to be sent over the connected pipe.

Syntax

property Stdin: String write set_Stdin;
property StdinB: TBytes write set_StdinB;

Default Value

''

Remarks

Assigning a string to this property makes the component send the string to the server over Stdin. The Send method provides similar functionality.

When Timeout is set to 0 the component will behave asynchronously. If you are sending data to the receiving process faster than it can process it, the outgoing queue might fill up. When this happens, the component raises the exception with errorcode 10035 and message '[10035] Operation would block' (WSAEWOULDBLOCK). You can handle this exception, and then try to send the data again. The BytesSent property shows how many bytes were sent (if any). If 0 bytes were sent, then you can wait for the ReadyToSend event before attempting to send data again. (However, please note that ReadyToSend is not fired when part of the data is successfully sent).

This property is write-only and not available at design time.

Timeout Property (PipeExec Component)

A timeout for the component.

Syntax

property Timeout: Integer read get_Timeout write set_Timeout;

Default Value

60

Remarks

If the Timeout property is set to 0, all operations return immediately, potentially failing with a WOULDBLOCK error if data cannot be sent immediately.

If Timeout is set to a positive value, data is sent in a blocking manner and the component will wait for the operation to complete before returning control. The component will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of Timeout seconds.

The component will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not "freeze" and remains responsive.

If Timeout expires, and the operation is not yet complete, the component raises an exception.

Please note that by default, all timeouts are inactivity timeouts, i.e. the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the Timeout property is 60 seconds.

Config Method (PipeExec Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

DoEvents Method (PipeExec Component)

Processes events from the internal message queue.

Syntax

procedure DoEvents();

Remarks

When DoEvents is called, the component processes any available events. If no events are available, it waits for a preset period of time, and then returns.

GetLine Method (PipeExec Component)

This method gets a line of text from the server.

Syntax

function GetLine(): String;

Remarks

This method gets a line of text from the server. This method is an alternative method of receiving data for line-oriented protocols. The component will block if necessary and then will return the received line. AcceptData will be set automatically to True when the method is called, and then will be set to False after a line is received.

Please refer to the SingleLineMode property for more information.

Interrupt Method (PipeExec Component)

This method interrupts the current action.

Syntax

procedure Interrupt();

Remarks

This method interrupts the current action. If you use SendFile to upload a file, the component will run synchronously until the upload is completed. This method will allow you to stop the file from uploading without disconnecting from the host.

Send Method (PipeExec Component)

Sends data over the connected pipe.

Syntax

procedure Send(Text: TBytes);

Remarks

This method sends data to the server. Calling this method is equivalent to setting the Stdin property to Text.

SendFile Method (PipeExec Component)

Sends the file over the connected pipe.

Syntax

procedure SendFile(FileName: String);

Remarks

This method sends the specified file to the server/process over the connected pipe.

Timeout must be set to a positive value so that the component will operate synchronously.

SendLine Method (PipeExec Component)

This method sends a string followed by a newline.

Syntax

procedure SendLine(Text: String);

Remarks

This method sends a string followed by a newline. This method is used to send data with line-oriented protocols. The line is followed by CRLF ('#13#10') .

Please refer to the GetLine method and SingleLineMode property for more information.

SendStdinBytes Method (PipeExec Component)

This method sends binary data over the connected pipe.

Syntax

procedure SendStdinBytes(Data: TBytes);

Remarks

This method sends the specified binary data to the server over Stdin. To send text, use the SendStdinText method instead.

When Timeout is set to 0 the component will behave asynchronously. If you are sending data to the receiving process faster than it can process it, the outgoing queue might fill up. When this happens, the component raises the exception with errorcode 10035 and message '[10035] Operation would block' (WSAEWOULDBLOCK). You can handle this exception, and then try to send the data again. The BytesSent property shows how many bytes were sent (if any). If 0 bytes were sent, then you can wait for the ReadyToSend event before attempting to send data again. (However, please note that ReadyToSend is not fired when part of the data is successfully sent).

SendStdinText Method (PipeExec Component)

This method sends text over the connected pipe.

Syntax

procedure SendStdinText(Text: String);

Remarks

This method sends the specified text to the server over Stdin. To send binary data, use the SendStdinBytes method instead.

When Timeout is set to 0 the component will behave asynchronously. If you are sending data to the receiving process faster than it can process it, the outgoing queue might fill up. When this happens, the component raises the exception with errorcode 10035 and message '[10035] Operation would block' (WSAEWOULDBLOCK). You can handle this exception, and then try to send the data again. The BytesSent property shows how many bytes were sent (if any). If 0 bytes were sent, then you can wait for the ReadyToSend event before attempting to send data again. (However, please note that ReadyToSend is not fired when part of the data is successfully sent).

StartProcess Method (PipeExec Component)

Starts the process.

Syntax

procedure StartProcess();

Remarks

This method starts the process specified by StartProcess. After starting the process data may be sent to the process by calling Send, SendLine, Send or setting Stdin.

Data received from the process will be available from the Stdout and Stderr events.

The following properties are applicable when calling this method:

• ProcessFileName (required)
• ProcessArgs
• ProcessWorkingDir

StopProcess Method (PipeExec Component)

Stops the process.

Syntax

procedure StopProcess();

Remarks

This method stops the process.

Error Event (PipeExec Component)

Information about errors during data delivery.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the component raises an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

ReadyToSend Event (PipeExec Component)

Fired when the component is ready to send data.

Syntax

type TReadyToSendEvent = procedure (
  Sender: TObject
) of Object;

property OnReadyToSend: TReadyToSendEvent read FOnReadyToSend write FOnReadyToSend;

Remarks

The ReadyToSend event indicates that the underlying pipe is ready to accept data again after a failed send. The event is also fired immediately after a connection to the remote host is established.

Stderr Event (PipeExec Component)

Fired when data come in through stderr.

Syntax

type TStderrEvent = procedure (
  Sender: TObject;
  Text: String;
  TextB: TBytes;
  EOL: Boolean
) of Object;

property OnStderr: TStderrEvent read FOnStderr write FOnStderr;

Remarks

The Stderr event is fired every time the process outputs a line in its standard output. The incoming data is provided through the Text parameter.

Stdout Event (PipeExec Component)

Fired when data come in through stdout.

Syntax

type TStdoutEvent = procedure (
  Sender: TObject;
  Text: String;
  TextB: TBytes;
  EOL: Boolean
) of Object;

property OnStdout: TStdoutEvent read FOnStdout write FOnStdout;

Remarks

The Stdout event is fired every time the process outputs a line in its standard output. The incoming data is provided through the Text parameter.

EOL indicates whether or not the EOL string was found at the end of Text. If the EOL string was found, then EOL is True.

If Text is part of a data portion of length larger than MaxLineLength with no EOL strings in it, then EOL is False. Note: This means that one or more DataIn events with EOL set to False can be received during a connection.

If the EOL property is '' (empty string), then EOL can be disregarded (it is always True).

Config Settings (PipeExec Component)

The component accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

PipeExec Config Settings

Base Config Settings

Trappable Errors (PipeExec Component)

PipeExec Errors

	401   Failed to create event.
	402   Failed to create security descriptor.
	403   Error creating named pipe.
	404   Error connecting to named pipe.
	405   Error disconnecting named pipe.
	408   Error sending data.
	410   Invalid MaxLineLength value.
	411   Error reading data.
	412   Error invoking RegisterWaitForSingleObject.
	413   Operation would block.
	414   Named pipe does not exist.
	415   Named pipe is already connected.
	416   Error connecting to named pipe.
	417   Named pipe not connected.
	419   Unsupported operation, see error message for details.
	420   Failed to create named pipe for Stdin/Stdout/Stderr.
	421   Failed to set handle information for Stdin/Stdout/Stderr.
	422   Failed to create process.
	423   Failed to terminate process.