TCPClient Component

Properties   Methods   Events   Config Settings   Errors  

The TCPClient Component is a generic Transmission Control Protocol (TCP) stream client based on an asynchronous, event-driven architecture.

Syntax

TipwTCPClient

Remarks

The TCPClient Component supports both plaintext and Secure Sockets Layer/Transport Layer Security (SSL/TLS) connections. When connecting over SSL/TLS the SSLServerAuthentication event allows you to check the server identity and other security attributes. The SSLStatus event provides information about the SSL handshake. Additional SSL related settings are also supported via the Config method.

Our main goal in designing TCPClient was ease of use. The component has a minimum number of properties and five events: Connected, DataIn, Disconnected, ReadyToSend, and Error. The events are relatively self-explanatory.

The connection is attempted by calling the Connect method or setting the Connected property to True, and then waiting for the Connected event. The destination is defined by setting RemoteHost and RemotePort. Data are sent by calling the Send method with Text as a parameter, or by assigning the data string to the DataToSend property.

To disconnect, you just call the Disconnect method or set the Connected property to False. The Linger property controls how the connection is terminated.

The operation of the component is almost completely asynchronous. All of the calls except the ones that deal with domain name resolution operate through asynchronous messages (no blocking calls). The gain in performance is considerable compared with using blocking calls.

Property List

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

Method List

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

Event List

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

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

AcceptData Property (TCPClient Component)

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

Syntax

__property bool AcceptData = { read=FAcceptData, write=FSetAcceptData };

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.

Data Type

Boolean

BytesSent Property (TCPClient Component)

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

Syntax

__property int BytesSent = { read=FBytesSent };

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.

Data Type

Integer

Connected Property (TCPClient Component)

This property triggers a connection or disconnection.

Syntax

__property bool Connected = { read=FConnected, write=FSetConnected };

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 is not available at design time.

Data Type

Boolean

DataToSend Property (TCPClient Component)

This property includes a string of data to be sent to the remote host.

Syntax

__property String DataToSend = { write=FSetDataToSend };
__property DynamicArray<Byte> DataToSendB = { write=FSetDataToSendB };

Default Value

""

Remarks

Assigning a string to this property makes the component send the string to the remote host. The Send method provides similar functionality.

When Timeout is set to 0, the component 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 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.

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

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

Data Type

Byte Array

EOL Property (TCPClient Component)

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

Syntax

__property String EOL = { read=FEOL, write=FSetEOL };
__property DynamicArray<Byte> EOLB = { read=FEOLB, write=FSetEOLB };

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 ("\r\n") 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 ("\r\n") 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.

Data Type

Byte Array

FirewallAutoDetect Property (TCPClient Component)

This property tells the component whether or not to automatically detect and use firewall system settings, if available.

Syntax

__property bool FirewallAutoDetect = { read=FFirewallAutoDetect, write=FSetFirewallAutoDetect };

Default Value

False

Remarks

This property tells the component whether or not to automatically detect and use firewall system settings, if available.

Data Type

Boolean

FirewallType Property (TCPClient Component)

This property determines the type of firewall to connect through.

Syntax

__property TipwTCPClientFirewallTypes FirewallType = { read=FFirewallType, write=FSetFirewallType };

enum TipwTCPClientFirewallTypes {
  fwNone=0,
  fwTunnel=1,
  fwSOCKS4=2,
  fwSOCKS5=3,
  fwSOCKS4A=10
};

Default Value

fwNone

Remarks

This property determines the type of firewall to connect through. The applicable values are as follows:

Data Type

Integer

FirewallHost Property (TCPClient Component)

This property contains the name or IP address of firewall (optional).

Syntax

__property String FirewallHost = { read=FFirewallHost, write=FSetFirewallHost };

Default Value

""

Remarks

This property contains the name or IP address of firewall (optional). If a FirewallHost is given, the requested connections will be authenticated through the specified firewall when connecting.

If this property is set to a Domain Name, a DNS request is initiated. Upon successful termination of the request, this property is set to the corresponding address. If the search is not successful, the component raises an exception.

Data Type

String

FirewallPassword Property (TCPClient Component)

This property contains a password if authentication is to be used when connecting through the firewall.

Syntax

__property String FirewallPassword = { read=FFirewallPassword, write=FSetFirewallPassword };

Default Value

""

Remarks

This property contains a password if authentication is to be used when connecting through the firewall. If FirewallHost is specified, the FirewallUser and FirewallPassword properties are used to connect and authenticate to the given firewall. If the authentication fails, the component raises an exception.

Data Type

String

FirewallPort Property (TCPClient Component)

This property contains the transmission control protocol (TCP) port for the firewall Host .

Syntax

__property int FirewallPort = { read=FFirewallPort, write=FSetFirewallPort };

Default Value

0

Remarks

This property contains the transmission control protocol (TCP) port for the firewall FirewallHost. See the description of the FirewallHost property for details.

Note: This property is set automatically when FirewallType is set to a valid value. See the description of the FirewallType property for details.

Data Type

Integer

FirewallUser Property (TCPClient Component)

This property contains a user name if authentication is to be used connecting through a firewall.

Syntax

__property String FirewallUser = { read=FFirewallUser, write=FSetFirewallUser };

Default Value

""

Remarks

This property contains a user name if authentication is to be used connecting through a firewall. If the FirewallHost is specified, this property and FirewallPassword properties are used to connect and authenticate to the given Firewall. If the authentication fails, the component raises an exception.

Data Type

String

KeepAlive Property (TCPClient Component)

When True, KEEPALIVE packets are enabled (for long connections).

Syntax

__property bool KeepAlive = { read=FKeepAlive, write=FSetKeepAlive };

Default Value

False

Remarks

The KeepAlive enables the SO_KEEPALIVE option on the socket. This option prevents long connections from timing out in case of inactivity.

Note: System Transmission Control Protocol (TCP)/IP stack implementations are not required to support SO_KEEPALIVE.

Data Type

Boolean

Linger Property (TCPClient Component)

When set to True, this property ensures that connections are terminated gracefully.

Syntax

__property bool Linger = { read=FLinger, write=FSetLinger };

Default Value

True

Remarks

This property controls how a connection is closed. The default is True.

In the case that Linger is True (default), two scenarios determine how long the connection will linger. In the first, if LingerTime is 0 (default), the system will attempt to send pending data for a connection until the default IP timeout expires.

In the second scenario, if LingerTime is a positive value, the system will attempt to send pending data until the specified LingerTime is reached. If this attempt fails, then the system will reset the connection.

The default behavior (which is also the default mode for stream sockets) might result in a long delay in closing the connection. Although the component returns control immediately, the system could hold system resources until all pending data are sent (even after your application closes).

Setting this property to False forces an immediate disconnection. If you know that the other side has received all the data you sent (e.g., by a client acknowledgment), setting this property to False might be the appropriate course of action.

Data Type

Boolean

LocalHost Property (TCPClient Component)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

__property String LocalHost = { read=FLocalHost, write=FSetLocalHost };

Default Value

""

Remarks

The LocalHost property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multi-homed hosts (machines with more than one IP interface) setting LocalHost to the value of an interface will make the component initiate connections (or accept in the case of server components) only through that interface.

If the component is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multi-homed hosts (machines with more than one IP interface).

NOTE: LocalHost is not persistent. You must always set it in code, and never in the property window.

Data Type

String

LocalPort Property (TCPClient Component)

The TCP port in the local host where the component binds.

Syntax

__property int LocalPort = { read=FLocalPort, write=FSetLocalPort };

Default Value

0

Remarks

This property must be set before a connection is attempted. It instructs the component to bind to a specific port (or communication endpoint) in the local machine.

Setting this property to 0 (default) enables the system to choose an open port at random. The chosen port will be returned by the LocalPort property after the connection is established.

LocalPort cannot be changed once a connection is made. Any attempt to set this property when a connection is active will generate an error.

This property is useful when trying to connect to services that require a trusted port in the client side.

Data Type

Integer

ReadyToSend Property (TCPClient Component)

This property indicates whether the component is ready to send data.

Syntax

__property bool ReadyToSend = { read=FReadyToSend };

Default Value

false

Remarks

This property indicates that the underlying Transmission Control Protocol (TCP)/IP subsystem is ready to accept data. This is True after connecting to the remote host and will become False after a failed DataToSend.

After a failed DataToSend, the ReadyToSend event will fire and this property will be True when data can be sent again.

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

Data Type

Boolean

RecordLength Property (TCPClient Component)

This property includes the length of received data records.

Syntax

__property int RecordLength = { read=FRecordLength, write=FSetRecordLength };

Default Value

0

Remarks

If set to a positive value, this setting 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 the 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.

A value of 0 (default) means this setting is not used.

Note: It is recommended to use the ChangeRecordLength method instead of setting this property.

This property is not available at design time.

Data Type

Integer

RemoteHost Property (TCPClient Component)

This property includes the address of the remote host. Domain names are resolved to IP addresses.

Syntax

__property String RemoteHost = { read=FRemoteHost, write=FSetRemoteHost };

Default Value

""

Remarks

This property specifies the IP address (IP number in dotted internet format) or the domain name of the remote host. It is set before a connection is attempted and cannot be changed once a connection is established.

If this property is set to a domain name, a DNS request is initiated, and upon successful termination of the request, this property is set to the corresponding address. If the search is not successful, an error is returned.

If the component is configured to use a SOCKS firewall, the value assigned to this property may be preceded with an "*". If this is the case, the host name is passed to the firewall unresolved and the firewall performs the DNS resolution.

Example. Connecting:

TCPClientControl.RemoteHost = "MyHostNameOrIP" TCPClientControl.RemotePort = 777 TCPClientControl.Connected = true

Data Type

String

RemotePort Property (TCPClient Component)

This property includes the Transmission Control Protocol (TCP) port in the remote host.

Syntax

__property int RemotePort = { read=FRemotePort, write=FSetRemotePort };

Default Value

0

Remarks

This property specifies a service port on the remote host to connect to.

A valid port number (a value between 1 and 65535) is required for the connection to take place. The property must be set before a connection is attempted and cannot be changed once a connection is established. Any attempt to change this property while connected will fail with an error.

Data Type

Integer

SingleLineMode Property (TCPClient Component)

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

Syntax

__property bool SingleLineMode = { read=FSingleLineMode, write=FSetSingleLineMode };

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.

Data Type

Boolean

SSLAcceptServerCertEncoded Property (TCPClient Component)

This is the certificate (PEM/Base64 encoded).

Syntax

__property String SSLAcceptServerCertEncoded = { read=FSSLAcceptServerCertEncoded, write=FSetSSLAcceptServerCertEncoded };
__property DynamicArray<Byte> SSLAcceptServerCertEncodedB = { read=FSSLAcceptServerCertEncodedB, write=FSetSSLAcceptServerCertEncodedB };

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLAcceptServerCertStore and SSLAcceptServerCertSubject properties also may be used to specify a certificate.

When SSLAcceptServerCertEncoded is set, a search is initiated in the current SSLAcceptServerCertStore for the private key of the certificate. If the key is found, SSLAcceptServerCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLAcceptServerCertSubject is set to an empty string.

This property is not available at design time.

Data Type

Byte Array

SSLCertEncoded Property (TCPClient Component)

This is the certificate (PEM/Base64 encoded).

Syntax

__property String SSLCertEncoded = { read=FSSLCertEncoded, write=FSetSSLCertEncoded };
__property DynamicArray<Byte> SSLCertEncodedB = { read=FSSLCertEncodedB, write=FSetSSLCertEncodedB };

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLCertStore and SSLCertSubject properties also may be used to specify a certificate.

When SSLCertEncoded is set, a search is initiated in the current SSLCertStore for the private key of the certificate. If the key is found, SSLCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLCertSubject is set to an empty string.

This property is not available at design time.

Data Type

Byte Array

SSLCertStore Property (TCPClient Component)

This is the name of the certificate store for the client certificate.

Syntax

__property String SSLCertStore = { read=FSSLCertStore, write=FSetSSLCertStore };
__property DynamicArray<Byte> SSLCertStoreB = { read=FSSLCertStoreB, write=FSetSSLCertStoreB };

Default Value

"MY"

Remarks

This is the name of the certificate store for the client certificate.

The SSLCertStoreType property denotes the type of the certificate store specified by SSLCertStore. If the store is password protected, specify the password in SSLCertStorePassword.

SSLCertStore is used in conjunction with the SSLCertSubject property to specify client certificates. If SSLCertStore has a value, and SSLCertSubject or SSLCertEncoded is set, a search for a certificate is initiated. Please see the SSLCertSubject property for details.

Designations of certificate stores are platform dependent.

The following designations are the most common User and Machine certificate stores in Windows:

When the certificate store type is PFXFile, this property must be set to the name of the file. When the type is PFXBlob, the property must be set to the binary contents of a PFX file (i.e., PKCS#12 certificate store).

Data Type

Byte Array

SSLCertStorePassword Property (TCPClient Component)

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Syntax

__property String SSLCertStorePassword = { read=FSSLCertStorePassword, write=FSetSSLCertStorePassword };

Default Value

""

Remarks

If the type of certificate store requires a password, this property is used to specify the password needed to open the certificate store.

Data Type

String

SSLCertStoreType Property (TCPClient Component)

This is the type of certificate store for this certificate.

Syntax

__property TipwTCPClientSSLCertStoreTypes SSLCertStoreType = { read=FSSLCertStoreType, write=FSetSSLCertStoreType };

enum TipwTCPClientSSLCertStoreTypes {
  cstUser=0,
  cstMachine=1,
  cstPFXFile=2,
  cstPFXBlob=3,
  cstJKSFile=4,
  cstJKSBlob=5,
  cstPEMKeyFile=6,
  cstPEMKeyBlob=7,
  cstPublicKeyFile=8,
  cstPublicKeyBlob=9,
  cstSSHPublicKeyBlob=10,
  cstP7BFile=11,
  cstP7BBlob=12,
  cstSSHPublicKeyFile=13,
  cstPPKFile=14,
  cstPPKBlob=15,
  cstXMLFile=16,
  cstXMLBlob=17,
  cstJWKFile=18,
  cstJWKBlob=19,
  cstSecurityKey=20,
  cstBCFKSFile=21,
  cstBCFKSBlob=22,
  cstPKCS11=23,
  cstAuto=99
};

Default Value

cstUser

Remarks

This is the type of certificate store for this certificate.

The component supports both public and private keys in a variety of formats. When the cstAuto value is used, the component will automatically determine the type. This property can take one of the following values:

Data Type

Integer

SSLCertSubject Property (TCPClient Component)

This is the subject of the certificate used for client authentication.

Syntax

__property String SSLCertSubject = { read=FSSLCertSubject, write=FSetSSLCertSubject };

Default Value

""

Remarks

This is the subject of the certificate used for client authentication.

This property must be set after all other certificate properties are set. When this property is set, a search is performed in the current certificate store to locate a certificate with a matching subject.

If a matching certificate is found, the property is set to the full subject of the matching certificate.

If an exact match is not found, the store is searched for subjects containing the value of the property.

If a match is still not found, the property is set to an empty string, and no certificate is selected.

The special value "*" picks a random certificate in the certificate store.

The certificate subject is a comma-separated list of distinguished name fields and values. For instance, "CN=www.server.com, OU=test, C=US, E=support@nsoftware.com". Common fields and their meanings are as follows:

If a field value contains a comma, it must be quoted.

Data Type

String

SSLEnabled Property (TCPClient Component)

Whether TLS/SSL is enabled.

Syntax

__property bool SSLEnabled = { read=FSSLEnabled, write=FSetSSLEnabled };

Default Value

False

Remarks

This setting specifies whether TLS/SSL is enabled in the component. When False (default) the component operates in plaintext mode. When True TLS/SSL is enabled.

TLS/SSL may also be enabled by setting SSLStartMode. Setting SSLStartMode will automatically update this property value.

This property is not available at design time.

Data Type

Boolean

SSLProvider Property (TCPClient Component)

This specifies the SSL/TLS implementation to use.

Syntax

__property TipwTCPClientSSLProviders SSLProvider = { read=FSSLProvider, write=FSetSSLProvider };

enum TipwTCPClientSSLProviders {
  sslpAutomatic=0,
  sslpPlatform=1,
  sslpInternal=2
};

Default Value

sslpAutomatic

Remarks

This property specifies the SSL/TLS implementation to use. In most cases the default value of 0 (Automatic) is recommended and should not be changed. When set to 0 (Automatic) the component will select whether to use the platform implementation or the internal implementation depending on the operating system as well as the TLS version being used.

Possible values are:

In most cases using the default value (Automatic) is recommended. The component will select a provider depending on the current platform.

When Automatic is selected the platform implementation is used by default. When TLS 1.3 is enabled via SSLEnabledProtocols the internal implementation is used.

Data Type

Integer

SSLServerCertEncoded Property (TCPClient Component)

This is the certificate (PEM/Base64 encoded).

Syntax

__property String SSLServerCertEncoded = { read=FSSLServerCertEncoded };
__property DynamicArray<Byte> SSLServerCertEncodedB = { read=FSSLServerCertEncodedB };

Default Value

""

Remarks

This is the certificate (PEM/Base64 encoded). This property is used to assign a specific certificate. The SSLServerCertStore and SSLServerCertSubject properties also may be used to specify a certificate.

When SSLServerCertEncoded is set, a search is initiated in the current SSLServerCertStore for the private key of the certificate. If the key is found, SSLServerCertSubject is updated to reflect the full subject of the selected certificate; otherwise, SSLServerCertSubject is set to an empty string.

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

Data Type

Byte Array

SSLStartMode Property (TCPClient Component)

Determines how the component starts the SSL negotiation.

Syntax

__property TipwTCPClientSSLStartModes SSLStartMode = { read=FSSLStartMode, write=FSetSSLStartMode };

enum TipwTCPClientSSLStartModes {
  sslAutomatic=0,
  sslImplicit=1,
  sslExplicit=2,
  sslNone=3
};

Default Value

sslNone

Remarks

The SSLStartMode property may have one of the following values:

Data Type

Integer

Timeout Property (TCPClient Component)

A timeout for the component.

Syntax

__property int Timeout = { read=FTimeout, write=FSetTimeout };

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.

Data Type

Integer

ChangeRecordLength Method (TCPClient Component)

This method changes the length of received data records.

Syntax

void __fastcall ChangeRecordLength(int RecordLength);

Remarks

This method defines the length of data records to be received (in bytes).

If RecordLength is set to a positive value, the component will accumulate data until RecordLength bytes of data are received and only then will it fire the DataIn event with data of length RecordLength. This allows data to be received as records of known length. This method can be called at any time to change the record length, including within the DataIn event.

A value of 0 (default) means this functionality is not used.

Config Method (TCPClient Component)

Sets or retrieves a configuration setting.

Syntax

String __fastcall Config(String ConfigurationString);

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 (TCPClient Component)

This method connects to a remote host.

Syntax

void __fastcall Connect();

Remarks

This method connects to the remote host specified by RemoteHost and RemotePort. For instance: component.RemoteHost = "MyHostNameOrIP"; component.RemotePort = 7777; component.Connect();

ConnectTo Method (TCPClient Component)

This method connects to a remote host.

Syntax

void __fastcall ConnectTo(String Host, int Port);

Remarks

This method connects to the remote host specified by the Host and Port parameters. For instance: component.ConnectTo("MyHostNameOrIP", 777)

Disconnect Method (TCPClient Component)

This method disconnects from the remote host.

Syntax

void __fastcall Disconnect();

Remarks

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

DoEvents Method (TCPClient Component)

Processes events from the internal message queue.

Syntax

void __fastcall 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 (TCPClient Component)

This method gets a line of text from the server.

Syntax

String __fastcall GetLine();

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 (TCPClient Component)

This method interrupts the current action.

Syntax

void __fastcall 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.

PauseData Method (TCPClient Component)

This method pauses data reception.

Syntax

void __fastcall PauseData();

Remarks

This method pauses data reception when called. While data reception is paused, the DataIn event will not fire. Call ProcessData to reenable data reception.

ProcessData Method (TCPClient Component)

This method reenables data reception after a call to PauseData .

Syntax

void __fastcall ProcessData();

Remarks

This method reenables data reception after a previous call to PauseData. When PauseData is called, the DataIn event will not fire. To reenable data reception and allow DataIn to fire, call this method.

Note: This method is used only after previously calling PauseData. It does not need to be called to process incoming data by default.

Reset Method (TCPClient Component)

Reset the component.

Syntax

void __fastcall Reset();

Remarks

This method will reset the component's properties to their default values.

Send Method (TCPClient Component)

This method sends binary data to the remote host.

Syntax

void __fastcall Send(DynamicArray<Byte> Text);

Remarks

This method sends the specified binary data to the remote host. 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 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 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.

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

SendBytes Method (TCPClient Component)

This method sends binary data to the remote host.

Syntax

void __fastcall SendBytes(DynamicArray<Byte> Data);

Remarks

This method sends the specified binary data to the remote host. 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 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 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.

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

SendFile Method (TCPClient Component)

This method sends a file to the remote host.

Syntax

void __fastcall SendFile(String FileName);

Remarks

This method sends the specified file to the remote host.

This method requires Timeout be set to a positive value. This allows the component to ensure that the file is transferred completely without a WOULDBLOCK error. See Timeout for details.

SendLine Method (TCPClient Component)

This method sends a string followed by a newline.

Syntax

void __fastcall SendLine(String Text);

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 ("\r\n") .

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

SendText Method (TCPClient Component)

This method sends text to the remote host.

Syntax

void __fastcall SendText(String Text);

Remarks

This method sends the specified text to the remote host. 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 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 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.

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

StartSSL Method (TCPClient Component)

This method starts Secure Sockets Layer (SSL) negotiation on a plaintext connection.

Syntax

void __fastcall StartSSL();

Remarks

This method is used to start SSL negotiation on a plaintext connection. Please refer to the SSLStartMode property for more information.

Note: The Connected event will fire again after SSL negotiation is complete.

Connected Event (TCPClient Component)

This event is fired immediately after a connection completes (or fails).

Syntax

typedef struct {
  int StatusCode;
  String Description;
} TipwTCPClientConnectedEventParams;
typedef void __fastcall (__closure *TipwTCPClientConnectedEvent)(System::TObject* Sender, TipwTCPClientConnectedEventParams *e);
__property TipwTCPClientConnectedEvent OnConnected = { read=FOnConnected, write=FOnConnected };

Remarks

If the connection is made normally, StatusCode is 0 and Description is "OK".

If the connection fails, StatusCode has the error code returned by the Transmission Control Protocol (TCP)/IP stack. Description contains a description of this code. The value of StatusCode is equal to the value of the error.

Please refer to the Error Codes section for more information.

ConnectionStatus Event (TCPClient Component)

This event is fired to indicate changes in the connection state.

Syntax

typedef struct {
  String ConnectionEvent;
  int StatusCode;
  String Description;
} TipwTCPClientConnectionStatusEventParams;
typedef void __fastcall (__closure *TipwTCPClientConnectionStatusEvent)(System::TObject* Sender, TipwTCPClientConnectionStatusEventParams *e);
__property TipwTCPClientConnectionStatusEvent OnConnectionStatus = { read=FOnConnectionStatus, write=FOnConnectionStatus };

Remarks

The ConnectionStatus event is fired when the connection state changes: for example, completion of a firewall or proxy connection or completion of a security handshake.

The ConnectionEvent parameter indicates the type of connection event. Values may include the following:

DataIn Event (TCPClient Component)

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

Syntax

typedef struct {
  String Text;
  DynamicArray<Byte> TextB;
  bool EOL;
} TipwTCPClientDataInEventParams;
typedef void __fastcall (__closure *TipwTCPClientDataInEvent)(System::TObject* Sender, TipwTCPClientDataInEventParams *e);
__property TipwTCPClientDataInEvent OnDataIn = { 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 (TCPClient Component)

This event is fired when a connection is closed.

Syntax

typedef struct {
  int StatusCode;
  String Description;
} TipwTCPClientDisconnectedEventParams;
typedef void __fastcall (__closure *TipwTCPClientDisconnectedEvent)(System::TObject* Sender, TipwTCPClientDisconnectedEventParams *e);
__property TipwTCPClientDisconnectedEvent OnDisconnected = { read=FOnDisconnected, write=FOnDisconnected };

Remarks

If the connection is broken normally, StatusCode is 0 and Description is "OK".

If the connection is broken for any other reason, StatusCode has the error code returned by the Transmission Control Protocol (TCP/IP) subsystem. Description contains a description of this code. The value of StatusCode is equal to the value of the TCP/IP error.

Please refer to the Error Codes section for more information.

Error Event (TCPClient Component)

Fired when information is available about errors during data delivery.

Syntax

typedef struct {
  int ErrorCode;
  String Description;
} TipwTCPClientErrorEventParams;
typedef void __fastcall (__closure *TipwTCPClientErrorEvent)(System::TObject* Sender, TipwTCPClientErrorEventParams *e);
__property TipwTCPClientErrorEvent OnError = { 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 (TCPClient Component)

This event is fired when the component is ready to send data.

Syntax

typedef struct {
} TipwTCPClientReadyToSendEventParams;
typedef void __fastcall (__closure *TipwTCPClientReadyToSendEvent)(System::TObject* Sender, TipwTCPClientReadyToSendEventParams *e);
__property TipwTCPClientReadyToSendEvent OnReadyToSend = { read=FOnReadyToSend, write=FOnReadyToSend };

Remarks

The ReadyToSend event indicates that the underlying Transmission Control Protocol (TCP)/IP subsystem is ready to accept data after a failed DataToSend. This event also is fired immediately after a connection to the remote host is established.

SSLServerAuthentication Event (TCPClient Component)

Fired after the server presents its certificate to the client.

Syntax

typedef struct {
  String CertEncoded;
  DynamicArray<Byte> CertEncodedB;
  String CertSubject;
  String CertIssuer;
  String Status;
  bool Accept;
} TipwTCPClientSSLServerAuthenticationEventParams;
typedef void __fastcall (__closure *TipwTCPClientSSLServerAuthenticationEvent)(System::TObject* Sender, TipwTCPClientSSLServerAuthenticationEventParams *e);
__property TipwTCPClientSSLServerAuthenticationEvent OnSSLServerAuthentication = { read=FOnSSLServerAuthentication, write=FOnSSLServerAuthentication };

Remarks

During this event, the client can decide whether or not to continue with the connection process. The Accept parameter is a recommendation on whether to continue or close the connection. This is just a suggestion: application software must use its own logic to determine whether or not to continue.

When Accept is False, Status shows why the verification failed (otherwise, Status contains the string OK). If it is decided to continue, you can override and accept the certificate by setting the Accept parameter to True.

SSLStatus Event (TCPClient Component)

Fired when secure connection progress messages are available.

Syntax

typedef struct {
  String Message;
} TipwTCPClientSSLStatusEventParams;
typedef void __fastcall (__closure *TipwTCPClientSSLStatusEvent)(System::TObject* Sender, TipwTCPClientSSLStatusEventParams *e);
__property TipwTCPClientSSLStatusEvent OnSSLStatus = { read=FOnSSLStatus, write=FOnSSLStatus };

Remarks

The event is fired for informational and logging purposes only. This event tracks the progress of the connection.

Config Settings (TCPClient Component)

TCPClient Config Settings

SSL Config Settings

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
..
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----
MIIEKzCCAxOgAwIBAgIRANTET4LIkxdH6P+CFIiHvTowDQYJKoZIhvcNAQELBQAw
...
eWHV5OW1K53o/atv59sOiW5K3crjFhsBOd5Q+cJJnU+SWinPKtANXMht+EDvYY2w
F0I1XhM+pKj7FjDr+XNj
-----END CERTIFICATE-----
\r \n
-----BEGIN CERTIFICATE-----
MIIEFjCCAv6gAwIBAgIQetu1SMxpnENAnnOz1P+PtTANBgkqhkiG9w0BAQUFADBp
..
d8q23djXZbVYiIfE9ebr4g3152BlVCHZ2GyPdjhIuLeH21VbT/dyEHHA
-----END CERTIFICATE-----

Socket Config Settings

Base Config Settings

Trappable Errors (TCPClient Component)

TCPClient Errors

SSL Errors

TCP/IP Errors