PipeClient Component

Properties   Methods   Events   Config Settings   Errors  

The PipeClient component is a simple client for connecting and communicating over named pipes.

Syntax

TiipPipeClient

Remarks

The PipeClient component is used to connect to an existing pipe server. After connecting the transfer of data is handled very similarly to socket communication.

To begin, first set PipeName to the name of the pipe to which the connection will be made. Call Connect or set Connected to True to establish the connection. The Connected event will fire when the connection is complete.

After connecting set DataToSend, or call Send or SendFile to send data. Incoming data is received through the DataIn event.

To disconnect call Disconnect or set Connected to False.

Synchronous and Asynchronous Operation

If the Timeout property is set to 0, the component will behave asynchronously and all operations return immediately, potentially failing with an error if they can't be completed immediately.

If Timeout is set to a positive value, the component will behave synchronously and wait for the operation to complete before returning control.

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.

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 (PipeClient Component)

This property enables or disables data reception (the DataIn event).

Syntax

property AcceptData: Boolean read get_AcceptData write set_AcceptData;

Default Value

true

Remarks

This property enables or disables data reception (the DataIn event). Setting this property to False, temporarily disables data reception (and the DataIn event). Setting this property to True, reenables data reception.

Note: It is recommended to use the PauseData or ProcessData method instead of setting this property.

This property is not available at design time.

BytesSent Property (PipeClient Component)

This property includes the number of bytes actually sent after an assignment to DataToSend .

Syntax

property BytesSent: Integer read get_BytesSent;

Default Value

0

Remarks

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

Note: that BytesSent will always return 0 when the component is operating in synchronous mode (i.e., the Timeout property is set to a positive value.)

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

Connected Property (PipeClient Component)

Triggers a connection or disconnection.

Syntax

property Connected: Boolean read get_Connected write set_Connected;

Default Value

false

Remarks

This property triggers a connection or disconnection. Setting this property to True makes the component attempt to connect to the host identified by the RemoteHost property. If successful, after the connection is achieved, the value of the property changes to True and the Connected event is fired.

Setting this property to False closes the connection. How and when the connection is closed is controlled by the Linger property.

Note: It is recommended to use the Connect or Disconnect method instead of setting this property.

This property triggers a connection or disconnection. Setting this property to True makes the component attempt to connect to the pipe identified by the PipeName property. If successful, after the connection is achieved the value of the property changes to True and the Connected event is fired.

Setting this property to False closes the connection.

This property is not available at design time.

DataToSend Property (PipeClient Component)

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

Syntax

property DataToSend: String write set_DataToSend;
property DataToSendB: TBytes write set_DataToSendB;

Default Value

''

Remarks

Assigning a string to this property makes the component send the string to the server. 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.

EOL Property (PipeClient 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.

PipeName Property (PipeClient Component)

The name of the pipe.

Syntax

property PipeName: String read get_PipeName write set_PipeName;

Default Value

''

Remarks

This property specifies the name of the pipe.

This may be the name by itself, for instance "MyPipe", or in the format "\\.\pipe\MyPipe".

RecordLength Property (PipeClient Component)

The length of received data records.

Syntax

property RecordLength: Integer read get_RecordLength write set_RecordLength;

Default Value

0

Remarks

If set to a positive value, this property defines the length of data records to be received. The component will accumulate data until RecordLength is reached and only then fire the DataIn event with data of length RecordLength. This allows data to be received as records of known length. This value can be changed at any time, including within the DataIn event.

The default value is 0, meaning this property is not used.

This property is not available at design time.

SingleLineMode Property (PipeClient 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.

Timeout Property (PipeClient 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 (PipeClient 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.

Connect Method (PipeClient Component)

Connects to a named pipe.

Syntax

procedure Connect();

Remarks

This method connects to a named pipe specified by PipeName. Calling this method is equivalent to setting the Connected property to True.

Example (Connecting)

PipeClient.PipeName = "MyPipe"; PipeClient.Connect();

Disconnect Method (PipeClient Component)

Disconnects from the named pipe.

Syntax

procedure Disconnect();

Remarks

This method disconnects from the pipe. Calling this method is equivalent to setting the Connected property to False.

DoEvents Method (PipeClient 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 (PipeClient 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 (PipeClient 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 (PipeClient 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 DataToSend property to Text.

SendBytes Method (PipeClient Component)

This method sends binary data over the connected pipe.

Syntax

procedure SendBytes(Data: TBytes);

Remarks

This method sends the specified binary data to the server. To send text, use the SendText 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).

SendFile Method (PipeClient 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 (PipeClient 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.

SendText Method (PipeClient Component)

This method sends text over the connected pipe.

Syntax

procedure SendText(Text: String);

Remarks

This method sends the specified text to the server. To send binary data, use the SendBytes 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).

Connected Event (PipeClient Component)

Fired immediately after a connection completes.

Syntax

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

property OnConnected: TConnectedEvent read FOnConnected write FOnConnected;

Remarks

When the connection is successfully established this event will fire.

DataIn Event (PipeClient Component)

This event is fired when data (complete lines) come in.

Syntax

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

property OnDataIn: TDataInEvent read FOnDataIn write FOnDataIn;

Remarks

Trapping the DataIn event is your only chance to get the data coming from the other end of the connection. The incoming data are 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).

Note: Events are not re-entrant. Performing time-consuming operations within this event will prevent it from firing again in a timely manner and may affect overall performance.

Disconnected Event (PipeClient Component)

Fired when a connection is closed.

Syntax

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

property OnDisconnected: TDisconnectedEvent read FOnDisconnected write FOnDisconnected;

Remarks

When the connection is closed this event will fire.

Error Event (PipeClient 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 (PipeClient 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.

Config Settings (PipeClient 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.

PipeClient Config Settings

Base Config Settings

Trappable Errors (PipeClient Component)

PipeClient 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.