PipeServer Control

Properties   Methods   Events   Config Settings   Errors  

The PipeServer control is a lightweight server control based on an asynchronous, event-driven architecture. It is designed to balance the load between connections for a fast, powerful server.

Syntax

PipeServer

Remarks

PipeServer is the server complement of PipeClient (which is used to create client applications). They share a common design philosophy and interface. PipeServer is as easy to use as PipeClient.

The client connections are identified by a ConnectionId, an id generated by the component to identify each connection. This id is unique to each connection. PipeServer's events also have ConnectionId as a parameter to identify the connection to which they are related.

Our main goal in designing PipeServer was to make it easy to use without sacrificing performance. The control has a minimum of properties, and events: Connected, DataIn, Disconnected, ReadyToSend, and Error.

PipeServer can start to listen on a pipe by setting PipeName and then setting Listening to True. When a client connects the Connected event fires, a ConnectionId is assigned, and communication can start. From this point on, the operation is very similar to PipeClient.

Property List

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

ConnectionCount Property (PipeServer Control)

The number of records in the arrays.

Syntax

pipeservercontrol.ConnectionCount

Default Value

0

Remarks

This property controls the size of the following arrays:

• AcceptData
• BytesSent
• Connected
• ConnectionId
• EOL
• MaxLineLength
• SingleLineMode
• Timeout

The array indices start at 0 and end at ConnectionCount - 1.

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

Data Type

Integer

AcceptData Property (PipeServer Control)

This property indicates whether data reception is currently enabled.

Syntax

pipeservercontrol.AcceptData(ConnectionId)

Default Value

True

Remarks

This property indicates whether data reception is currently enabled. When , data reception is disabled and the DataIn event will not fire for the connection. Use the PauseData and ProcessData methods to pause and resume data reception.

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

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

Data Type

Boolean

BytesSent Property (PipeServer Control)

This property shows how many bytes were sent after calling Send or SendBytes .

Syntax

pipeservercontrol.BytesSent(ConnectionId)

Default Value

0

Remarks

This property shows how many bytes were sent after calling Send or SendBytes. Please see Send or SendBytes for more information.

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

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

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

Data Type

Integer

Connected Property (PipeServer Control)

This property is used to disconnect individual connections and/or show their status.

Syntax

pipeservercontrol.Connected(ConnectionId)[=boolean]

Default Value

False

Remarks

This property is used to disconnect individual connections and/or show their status.

The Connected property may be set to false to close the connection.

Connected also shows the status of a particular connection (connected/disconnected).

Use the Connect and Disconnect methods to manage the connection.

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

This property is not available at design time.

Data Type

Boolean

ConnectionId Property (PipeServer Control)

This property contains an identifier generated by the control to identify each connection.

Syntax

pipeservercontrol.ConnectionId(ConnectionId)

Default Value

0

Remarks

This property contains an identifier generated by the control to identify each connection. This identifier is unique to this connection.

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

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

Data Type

Integer

EOL Property (PipeServer Control)

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

Syntax

pipeservercontrol.EOL(ConnectionId)[=string]

Default Value

""

Remarks

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

The EOL property is especially useful with ASCII files. By setting it to CRLF (Chr$(13) & Chr$(10)) , the incoming ASCII text stream can be split into lines. In this case, one event is fired for each line received (as well as in packet boundaries). The CRLF (Chr$(13) & Chr$(10)) . bytes are discarded.

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

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .EOLB.

This property is not available at design time.

Data Type

Binary String

MaxLineLength Property (PipeServer Control)

This property is the size of an internal buffer that holds received data while waiting for an EOL string.

Syntax

pipeservercontrol.MaxLineLength(ConnectionId)[=integer]

Default Value

2048

Remarks

This property is the size of an internal buffer that holds received data while waiting for an EOL string.

If an EOL string is found in the input stream before MaxLineLength bytes are received, the DataIn event is fired with the EOL parameter set to True, and the buffer is reset.

If no EOL is found, and MaxLineLength bytes are accumulated in the buffer, the DataIn event is fired with the EOL parameter set to False, and the buffer is reset.

The minimum value for MaxLineLength is 256 bytes. The default value is 2048 bytes.

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

This property is not available at design time.

Data Type

Integer

SingleLineMode Property (PipeServer Control)

This property shows the special mode for line-oriented protocols.

Syntax

pipeservercontrol.SingleLineMode(ConnectionId)[=boolean]

Default Value

False

Remarks

This property shows the special mode for line-oriented protocols. When SingleLineMode is True, the control treats the incoming data stream as lines separated by carriage return (CR), line feed (LF), or CRLF. The EOL property is ignored.

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

This property is not available at design time.

Data Type

Boolean

Timeout Property (PipeServer Control)

This property specifies a timeout for the control.

Syntax

pipeservercontrol.Timeout(ConnectionId)[=integer]

Default Value

0

Remarks

This property specifies a timeout for the control.

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 control will wait for the operation to complete before returning control. The control will handle any potential WOULDBLOCK errors internally and automatically retry the operation for a maximum of Timeout seconds.

The control 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 control fails with an error.

Note: By default, all timeouts are inactivity timeouts, that is, 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 0 (asynchronous operation).

The ConnectionId parameter specifies the index of the item in the array. The size of the array is controlled by the ConnectionCount property.

This property is not available at design time.

Data Type

Integer

DefaultEOL Property (PipeServer Control)

This property includes a default end-of-line (EOL) value to be used by incoming connections.

Syntax

pipeservercontrol.DefaultEOL[=string]

Default Value

""

Remarks

This property contains a default end-of-line (EOL) value to be used by incoming connections. Once the control accepts and establishes an inbound connection, it will set that connection's EOL to the value in this property. By default, this value is empty (""), meaning that data will be fired as it is received.

To read or write binary data to the property, a Variant (Byte Array) version is provided in .DefaultEOLB.

Data Type

Binary String

DefaultMaxLineLength Property (PipeServer Control)

The property includes the default maximum line length value for inbound connections.

Syntax

pipeservercontrol.DefaultMaxLineLength[=integer]

Default Value

2048

Remarks

This property controls the default size of an internal buffer that holds received data while waiting for an end-of-line (EOL) string.

The minimum value for this property is 256 bytes. The default value is 2048 bytes.

Data Type

Integer

DefaultSingleLineMode Property (PipeServer Control)

This property tells the control whether or not to treat new connections as line oriented.

Syntax

pipeservercontrol.DefaultSingleLineMode[=boolean]

Default Value

False

Remarks

This property instructs the component whether or not to treat newly established connections as line-oriented protocols. If this value is True, newly accepted connections will read the incoming data stream as lines separated by a carriage return line feed (CRLF), carriage return (CR), or line feed (LF) and will ignore the end of lines (EOLs).

Data Type

Boolean

DefaultTimeout Property (PipeServer Control)

This property includes an initial timeout value to be used by incoming connections.

Syntax

pipeservercontrol.DefaultTimeout[=integer]

Default Value

0

Remarks

This property is used by the control to set the operational timeout value of all inbound connections once they are established.

By default, the timeout is 0, meaning that all inbound connections will behave asynchronously.

Data Type

Integer

Listening Property (PipeServer Control)

If True, the control accepts incoming connections.

Syntax

pipeservercontrol.Listening[=boolean]

Default Value

False

Remarks

Use this property to make the control 'listen' (accept connections) on the pipe specified by PipeName. Setting this property to False will make the control stop listening. Please note that this does not close any existing connections.

Use the StartListening and StopListening methods to control whether the control is listening.

This property is not available at design time.

Data Type

Boolean

PipeName Property (PipeServer Control)

The name of the pipe.

Syntax

pipeservercontrol.PipeName[=string]

Default Value

""

Remarks

This property specifies the name of the pipe on which to accept connections. Clients must use this name when establishing a connection to PipeServer.

Data Type

String

Config Method (PipeServer Control)

Sets or retrieves a configuration setting.

Syntax

pipeservercontrol.Config ConfigurationString

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the control, 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.

Disconnect Method (PipeServer Control)

This method disconnects the specified client.

Syntax

pipeservercontrol.Disconnect ConnectionId

Remarks

Calling this method will disconnect the client specified by the ConnectionId parameter.

DoEvents Method (PipeServer Control)

This method processes events from the internal message queue.

Syntax

pipeservercontrol.DoEvents 

Remarks

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

Interrupt Method (PipeServer Control)

This method interrupts a synchronous send to the remote host.

Syntax

pipeservercontrol.Interrupt ConnectionId

Remarks

This property is called using the Connection Id if you wish to interrupt a connection and stop a file from uploading without disconnecting the client connected to the control. If you use SendFile to upload a file, the control will run synchronously on that Connection Id until it is completed.

Send Method (PipeServer Control)

This method sends binary data to the specified client.

Syntax

pipeservercontrol.Send ConnectionId, Text

Remarks

This method sends binary data to the client identified by ConnectionId. To send text, use the SendText method instead.

When Timeout is set to 0, the control will behave asynchronously. If you are sending data to the remote host faster than it can process it, or faster than the network's bandwidth allows, the outgoing queue might fill up. When this happens, the operation fails with error 25036: "[10035] Operation would block" (WSAEWOULDBLOCK). You can trap this error, 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.

Note: The ReadyToSend event is not fired when part of the data is sent successfully.

SendBytes Method (PipeServer Control)

This method sends binary data to the specified client.

Syntax

pipeservercontrol.SendBytes ConnectionId, Data

Remarks

This method sends binary data to the client identified by ConnectionId. To send text, use the SendText method instead.

When Timeout is set to 0, the control will behave asynchronously. If you are sending data to the remote host faster than it can process it, or faster than the network's bandwidth allows, the outgoing queue might fill up. When this happens, the operation fails with error 25036: "[10035] Operation would block" (WSAEWOULDBLOCK). You can trap this error, 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.

Note: The ReadyToSend event is not fired when part of the data is sent successfully.

SendFile Method (PipeServer Control)

This method sends the file to the remote host.

Syntax

pipeservercontrol.SendFile ConnectionId, FileName

Remarks

This method sends the file to the client specified by the ConnectionId.

SendLine Method (PipeServer Control)

This method sends a string followed by a new line.

Syntax

pipeservercontrol.SendLine ConnectionId, Text

Remarks

This method is used to send data with line-oriented protocols. The line is followed by CRLF (Chr$(13) & Chr$(10)) .

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

SendText Method (PipeServer Control)

This method sends text to the specified client.

Syntax

pipeservercontrol.SendText ConnectionId, Text

Remarks

This method sends text to the client identified by ConnectionId. To send binary data, use the SendBytes method instead.

When Timeout is set to 0, the control will behave asynchronously. If you are sending data to the remote host faster than it can process it, or faster than the network's bandwidth allows, the outgoing queue might fill up. When this happens, the operation fails with error 25036: "[10035] Operation would block" (WSAEWOULDBLOCK). You can trap this error, 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.

Note: The ReadyToSend event is not fired when part of the data is sent successfully.

Shutdown Method (PipeServer Control)

This method shuts down the server.

Syntax

pipeservercontrol.Shutdown 

Remarks

This method shuts down the server. Calling this method is equivalent to calling StopListening and then breaking every client connection by calling Disconnect.

StartListening Method (PipeServer Control)

This method starts listening for incoming connections.

Syntax

pipeservercontrol.StartListening 

Remarks

This method begins listening for incoming connections on the pipe specified by PipeName.

To stop listening for new connections, call StopListening. To stop listening for new connections and to disconnect all existing clients, call Shutdown.

StopListening Method (PipeServer Control)

This method stops listening for new connections.

Syntax

pipeservercontrol.StopListening 

Remarks

This method stops listening for new connections. After being called, any new connection attempts will be rejected. Calling this method does not disconnect existing connections.

To stop listening and to disconnect all existing clients, call Shutdown instead.

Connected Event (PipeServer Control)

Fired immediately after a connection completes.

Syntax

Sub pipeservercontrol_Connected(ConnectionId As Integer)

Remarks

This event fires immediately after a client connects. The ConnectionId parameter identifies the client connection.

DataIn Event (PipeServer Control)

This event is fired when data come in.

Syntax

Sub pipeservercontrol_DataIn(ConnectionId As Integer, Text As String, EOL As Boolean)

Remarks

Trapping the DataIn event is your only chance to get the data coming from the other end of the connection specified by ConnectionId. 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 the data portion of length larger than either DefaultMaxLineLength or with no EOL strings in it, then EOL is False. Please note that 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 (PipeServer Control)

Fires when a client disconnects.

Syntax

Sub pipeservercontrol_Disconnected(ConnectionId As Integer)

Remarks

This event fires when a client disconnects. The ConnectionId parameters identifies the client that is disconnected.

Error Event (PipeServer Control)

This event fires information about errors during data delivery.

Syntax

Sub pipeservercontrol_Error(ConnectionId As Integer, ErrorCode As Integer, Description As String)

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally, the control fails with an error.

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

ConnectionId indicates the connection for which the error is applicable.

ReadyToSend Event (PipeServer Control)

Fired when the control is ready to send data.

Syntax

Sub pipeservercontrol_ReadyToSend(ConnectionId As Integer)

Remarks

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

Config Settings (PipeServer Control)

The control 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 control, access to these internal properties is provided through the Config method.

PipeServer Config Settings

Base Config Settings

Trappable Errors (PipeServer Control)

PipeServer Errors