TCPServer Class

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The TCPServer Class is a generic Transmission Control Protocol (TCP) server class based on an asynchronous, event-driven architecture. It is designed to balance the load between connections for a fast, powerful server.

Syntax

class ipworks.TCPServer

Remarks

The TCPServer Class supports both plaintext and Secure Sockets Layer/Transport Layer Security (SSL/TLS) connections. When connecting over SSL/TLS the on_ssl_server_authentication event allows you to check the server identity and other security attributes. The on_ssl_status event provides information about the SSL handshake. Additional SSL related settings are also supported via the config method. The SSLCert properties are used to select a certificate for the server. Note: A valid certificate MUST be selected before the server can function.

TCPServer is the server complement of TCPClient, which is used to create client applications. They share a common design philosophy and interface. We expect you will find TCPServer as easy to use as TCPClient.

By default, each instance of TCPServer can handle up to 1,000 simultaneous incoming connections. This number may be increased up to 100,000 or decreased to a lower value by using the MaxConnections configuration setting.

The connections are identified by a ConnectionId, an Id generated by the component to identify each connection. This Id is unique to each connection. TCPServer's events also have ConnectionId as a parameter to identify the connection they relate to.

Our main goal in designing TCPServer was to make it easy to use without sacrificing performance. The class has a minimum of properties, and six events: on_connection_request, on_connected, on_data_in, on_disconnected, on_ready_to_send, and on_error.

TCPServer can start to listen on a port by setting the listening property to True. When a remote host asks for a connection, the on_connection_request event is fired. At that point, the connection can either be accepted or rejected. If the connection is accepted, a ConnectionId is assigned, and communication can start. From this point on, the operation is very similar to TCPClient. Data are sent by assigning the data string to the data_to_send property. The address and port of the incoming connection can be found by querying the remote_host and remote_port properties.

Note: Server components are designed to process events as they occur. To ensure that events are processed in a timely manner, do_events should be called in a loop after the server is started.

Property List

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

Method List

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

Event List

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

Config Settings

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

connection_backlog Property

This property includes the maximum number of pending connections maintained by the Transmission Control Protocol (TCP)/IP subsystem.

Syntax

def get_connection_backlog() -> int: ...
def set_connection_backlog(value: int) -> None: ...

connection_backlog = property(get_connection_backlog, set_connection_backlog)

Default Value

5

Remarks

This property contains the maximum number of pending connections maintained by the TCP/IP subsystem. This value reflects the SOMAXCONN option for the main listening socket. The default value for most systems is 5. You may set this property to a larger value if the server is expected to receive a large number of connections, and queuing them is desirable.

connection_count Property

The number of records in the arrays.

Syntax

def get_connection_count() -> int: ...

connection_count = property(get_connection_count, None)

Default Value

0

Remarks

This property controls the size of the following arrays:

• accept_data
• bytes_sent
• connected
• connection_id
• data_to_send
• eol
• idle_timeout
• local_address
• ready_to_send
• record_length
• remote_host
• remote_port
• single_line_mode
• ssl_cert_encoded
• ssl_cert_store
• ssl_cert_store_password
• ssl_cert_store_type
• ssl_cert_subject
• timeout
• user_data

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

This property is read-only.

accept_data Property

Setting this property to false temporarily disables data reception (and the DataIn event) for the connection.

Syntax

def get_accept_data(connection_id: int) -> bool: ...
def set_accept_data(connection_id: int, value: bool) -> None: ...

Default Value

TRUE

Remarks

Setting this property to false temporarily disables data reception (and the ondatain event) for the connection. Setting this to true re-enables data reception.

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

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

bytes_sent Property

This property shows how many bytes were sent after the last assignment to DataToSend .

Syntax

def get_bytes_sent(connection_id: int) -> int: ...

Default Value

0

Remarks

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

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

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

This property is read-only.

connected Property

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

Syntax

def get_connected(connection_id: int) -> bool: ...
def set_connected(connection_id: int, value: bool) -> None: ...

Default Value

FALSE

Remarks

This property is used to disconnect individual connections or to 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).

How and when the connection is closed is controlled by the linger property. Please refer to its description for more information.

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

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

connection_id Property

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

Syntax

def get_connection_id(connection_id: int) -> str: ...

Default Value

""

Remarks

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

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

This property is read-only.

data_to_send Property

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

Syntax

def set_data_to_send(connection_id: int, value: bytes) -> None: ...

Default Value

""

Remarks

This property contains a string of data to be sent to the remote host. It is a write-only property.

Assigning a string to the datatosend makes the class send the string to the remote host. The send method provides similar functionality.

When timeout is set to 0, the class 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 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check 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 onreadytosend event before attempting to send data again.

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

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

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

This property is write-only.

eol Property

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

Syntax

def get_eol(connection_id: int) -> bytes: ...
def set_eol(connection_id: int, value: bytes) -> None: ...

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

When reading the value of the property, if ConnectionId does not belong to a valid connection, then NULL will be returned, and the lasterror property will contain a corresponding error message. If no error is encountered, then lasterror will contain NULL.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

idle_timeout Property

This property contains the idle timeout for this connection.

Syntax

def get_idle_timeout(connection_id: int) -> int: ...
def set_idle_timeout(connection_id: int, value: int) -> None: ...

Default Value

0

Remarks

This property contains the idle timeout for this connection. This property is similar to defaultidletimeout but may be set on a per-connection basis to override defaultidletimeout. This property specifies the idle timeout (in seconds) for the connected client. When set to a positive value, the class will disconnect idle clients after the specified timeout.

This applies only to clients that have not sent to received data within the specified number of seconds.

If set to 0 (default), no idle timeout is applied.

Note: doevents must be called for the class to check existing connections.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

local_address Property

This property shows the IP address of the interface through which the connection is passing.

Syntax

def get_local_address(connection_id: int) -> str: ...

Default Value

""

Remarks

This property shows the IP address of the interface through which the connection is passing.

localaddress is important for multihomed hosts so that it can be used to find the particular network interface through which an individual connection is going.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

This property is read-only.

ready_to_send Property

This indicates whether the class is ready to send data.

Syntax

def get_ready_to_send(connection_id: int) -> bool: ...

Default Value

FALSE

Remarks

This indicates whether the class is ready to send data.

This property indicates that the underlying TCP/IP subsystem is ready to accept data. This is True after a client connects but will become False after a failed datatosend.

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

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

This property is read-only.

record_length Property

If set to a positive value, this setting defines the length of the data records to be received.

Syntax

def get_record_length(connection_id: int) -> int: ...
def set_record_length(connection_id: int, value: int) -> None: ...

Default Value

0

Remarks

If set to a positive value, this setting defines the length of the data records to be received. The class will accumulate data until RecordLength is reached and only then will fire the ondatain 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 ondatain 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.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

remote_host Property

This property shows the IP address of the remote host through which the connection is coming.

Syntax

def get_remote_host(connection_id: int) -> str: ...

Default Value

""

Remarks

This property shows the IP address of the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

If the class 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.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

This property is read-only.

remote_port Property

This property shows the Transmission Control Protocol (TCP) port on the remote host through which the connection is coming.

Syntax

def get_remote_port(connection_id: int) -> int: ...

Default Value

0

Remarks

This property shows the Transmission Control Protocol (TCP) port on the remote host through which the connection is coming.

The connection must be valid or an error will be fired.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

This property is read-only.

single_line_mode Property

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

Syntax

def get_single_line_mode(connection_id: int) -> bool: ...
def set_single_line_mode(connection_id: int, value: bool) -> None: ...

Default Value

FALSE

Remarks

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

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

timeout Property

This property specifies a timeout for the class.

Syntax

def get_timeout(connection_id: int) -> int: ...
def set_timeout(connection_id: int, value: int) -> None: ...

Default Value

0

Remarks

This property specifies a timeout for the class.

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

The class 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 class fails with an error.

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 0 (asynchronous operation).

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

user_data Property

The UserData property holds connection-specific user-specified data.

Syntax

def get_user_data(connection_id: int) -> bytes: ...
def set_user_data(connection_id: int, value: bytes) -> None: ...

Default Value

""

Remarks

The userdata property holds connection-specific user-specified data.

User-specified data may be set or retrieved at any point while the connection is valid. This provides a simple way to associate arbitrary data with a specific connection.

The connection_id parameter specifies the index of the item in the array. The size of the array is controlled by the connection_count property.

default_eol Property

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

Syntax

def get_default_eol() -> bytes: ...
def set_default_eol(value: bytes) -> None: ...

default_eol = property(get_default_eol, set_default_eol)

Default Value

""

Remarks

This property contains a default end-of-line (EOL) value to be used by incoming connections. Once the class 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.

default_idle_timeout Property

This property includes the default idle timeout for inactive clients.

Syntax

def get_default_idle_timeout() -> int: ...
def set_default_idle_timeout(value: int) -> None: ...

default_idle_timeout = property(get_default_idle_timeout, set_default_idle_timeout)

Default Value

0

Remarks

This property specifies the idle timeout (in seconds) for clients. When set to a positive value, the class will disconnect idle clients after the specified timeout.

This applies only to clients that have not sent or received data within default_idle_timeout seconds.

If set to 0 (default), no idle timeout is applied.

Note: do_events must be called for the class to check existing connections.

default_max_line_length Property

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

Syntax

def get_default_max_line_length() -> int: ...
def set_default_max_line_length(value: int) -> None: ...

default_max_line_length = property(get_default_max_line_length, set_default_max_line_length)

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.

default_single_line_mode Property

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

Syntax

def get_default_single_line_mode() -> bool: ...
def set_default_single_line_mode(value: bool) -> None: ...

default_single_line_mode = property(get_default_single_line_mode, set_default_single_line_mode)

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).

default_timeout Property

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

Syntax

def get_default_timeout() -> int: ...
def set_default_timeout(value: int) -> None: ...

default_timeout = property(get_default_timeout, set_default_timeout)

Default Value

0

Remarks

This property is used by the class 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.

keep_alive Property

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

Syntax

def get_keep_alive() -> bool: ...
def set_keep_alive(value: bool) -> None: ...

keep_alive = property(get_keep_alive, set_keep_alive)

Default Value

FALSE

Remarks

This property enables the SO_KEEPALIVE option on the incoming connections. 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.

This property is shared among incoming connections. When the property is set, the corresponding value is set for incoming connections as they are accepted. Existing connections are not modified.

linger Property

When set to True, connections are terminated gracefully.

Syntax

def get_linger() -> bool: ...
def set_linger(value: bool) -> None: ...

linger = property(get_linger, set_linger)

Default Value

TRUE

Remarks

This property controls how a connection is closed. The default is True. In this case, the connection is closed only after all the data are sent. Setting it to False forces an abrupt (hard) disconnection. Any data that were in the sending queue may be lost.

The default behavior (which is also the default mode for stream sockets) might result in an indefinite delay in closing the connection. Although the class returns control immediately, the system might indefinitely hold system resources until all pending data are sent (even after your application closes). This means that valuable system resources might be wasted.

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

This property is shared among incoming connections. When the property is set, the corresponding value is set for incoming connections as they are accepted. Existing connections are not modified.

listening Property

If set to True, the class accepts incoming connections on LocalPort.

Syntax

def get_listening() -> bool: ...
def set_listening(value: bool) -> None: ...

listening = property(get_listening, set_listening)

Default Value

FALSE

Remarks

This property indicates whether the class is listening for connections on the port specified by the local_port property.

Note: Use the start_listening and stop_listening methods to control whether the class is listening.

local_host Property

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

Syntax

def get_local_host() -> str: ...
def set_local_host(value: str) -> None: ...

local_host = property(get_local_host, set_local_host)

Default Value

""

Remarks

The local_host 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 class initiate connections (or accept in the case of server classs) only through that interface.

If the class is connected, the local_host 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: local_host is not persistent. You must always set it in code, and never in the property window.

local_port Property

This property includes the Transmission Control Protocol (TCP) port in the local host where the class listens.

Syntax

def get_local_port() -> int: ...
def set_local_port(value: int) -> None: ...

local_port = property(get_local_port, set_local_port)

Default Value

0

Remarks

This property must be set before the class can start listening. If its value is 0, then the TCP/IP subsystem picks a port number at random. The port number can be found by checking the value of this property after the class is listening (i.e., after successfully assigning True to the listening property).

The service port is not shared among servers so two classs cannot be listening on the same port at the same time.

ssl_authenticate_clients Property

If set to True, the server asks the client(s) for a certificate.

Syntax

def get_ssl_authenticate_clients() -> bool: ...
def set_ssl_authenticate_clients(value: bool) -> None: ...

ssl_authenticate_clients = property(get_ssl_authenticate_clients, set_ssl_authenticate_clients)

Default Value

FALSE

Remarks

This property is used in conjunction with the on_ssl_client_authentication event. Please refer to the documentation of the on_ssl_client_authentication event for details.

ssl_cert_encoded Property

This is the certificate (PEM/Base64 encoded).

Syntax

def get_ssl_cert_encoded() -> bytes: ...
def set_ssl_cert_encoded(value: bytes) -> None: ...

ssl_cert_encoded = property(get_ssl_cert_encoded, set_ssl_cert_encoded)

Default Value

""

Remarks

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

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

ssl_cert_store Property

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

Syntax

def get_ssl_cert_store() -> bytes: ...
def set_ssl_cert_store(value: bytes) -> None: ...

ssl_cert_store = property(get_ssl_cert_store, set_ssl_cert_store)

Default Value

"MY"

Remarks

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

The ssl_cert_store_type property denotes the type of the certificate store specified by ssl_cert_store. If the store is password protected, specify the password in ssl_cert_store_password.

ssl_cert_store is used in conjunction with the ssl_cert_subject property to specify client certificates. If ssl_cert_store has a value, and ssl_cert_subject or ssl_cert_encoded is set, a search for a certificate is initiated. Please see the ssl_cert_subject 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).

ssl_cert_store_password Property

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

Syntax

def get_ssl_cert_store_password() -> str: ...
def set_ssl_cert_store_password(value: str) -> None: ...

ssl_cert_store_password = property(get_ssl_cert_store_password, set_ssl_cert_store_password)

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.

ssl_cert_store_type Property

This is the type of certificate store for this certificate.

Syntax

def get_ssl_cert_store_type() -> int: ...
def set_ssl_cert_store_type(value: int) -> None: ...

ssl_cert_store_type = property(get_ssl_cert_store_type, set_ssl_cert_store_type)

Default Value

0

Remarks

This is the type of certificate store for this certificate.

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

ssl_cert_subject Property

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

Syntax

def get_ssl_cert_subject() -> str: ...
def set_ssl_cert_subject(value: str) -> None: ...

ssl_cert_subject = property(get_ssl_cert_subject, set_ssl_cert_subject)

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.

ssl_enabled Property

Whether TLS/SSL is enabled.

Syntax

def get_ssl_enabled() -> bool: ...
def set_ssl_enabled(value: bool) -> None: ...

ssl_enabled = property(get_ssl_enabled, set_ssl_enabled)

Default Value

FALSE

Remarks

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

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

ssl_provider Property

This specifies the SSL/TLS implementation to use.

Syntax

def get_ssl_provider() -> int: ...
def set_ssl_provider(value: int) -> None: ...

ssl_provider = property(get_ssl_provider, set_ssl_provider)

Default Value

0

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 class 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 class will select a provider depending on the current platform.

When Automatic is selected, on Windows the class will use the platform implementation. On Linux/macOS the class will use the internal implementation. When TLS 1.3 is enabled via SSLEnabledProtocols the internal implementation is used on all platforms.

ssl_start_mode Property

Determines how the class starts the SSL negotiation.

Syntax

def get_ssl_start_mode() -> int: ...
def set_ssl_start_mode(value: int) -> None: ...

ssl_start_mode = property(get_ssl_start_mode, set_ssl_start_mode)

Default Value

3

Remarks

The ssl_start_mode property may have one of the following values:

change_record_length Method

This method changes the length of received data records.

Syntax

def change_record_length(connection_id: int, record_length: int) -> None: ...

Remarks

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

If RecordLength is set to a positive value, the class will accumulate data until RecordLength bytes of data are received and only then will fire the on_data_in event with data of the specified 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 on_data_in event.

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

config Method

Sets or retrieves a configuration setting.

Syntax

def config(configuration_string: str) -> str: ...

Remarks

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

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

This method disconnects the specified client.

Syntax

def disconnect(connection_id: int) -> None: ...

Remarks

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

do_events Method

Processes events from the internal message queue.

Syntax

def do_events() -> None: ...

Remarks

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

interrupt Method

This method interrupts a synchronous send to the remote host.

Syntax

def interrupt(connection_id: int) -> None: ...

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 class. If you use send_file to upload a file, the class will run synchronously on that Connection Id until it is completed.

pause_data Method

This method pauses data reception.

Syntax

def pause_data(connection_id: int) -> None: ...

Remarks

This method pauses data reception for the connection identified by ConnectionId when called. While data reception is paused, the on_data_in event will not fire for the specified connection. Call process_data to reenable data reception.

process_data Method

This method reenables data reception after a call to PauseData .

Syntax

def process_data(connection_id: int) -> None: ...

Remarks

This method reenables data reception for the connection identified by ConnectionId after a previous call to pause_data. When pause_data is called, the on_data_in event will not fire for the specified connection. To reenable data reception and allow on_data_in to fire, call this method.

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

reset Method

Reset the class.

Syntax

def reset() -> None: ...

Remarks

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

send Method

This method sends binary data to the specified client.

Syntax

def send(connection_id: int, text: bytes) -> None: ...

Remarks

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

When ws_connection_timeout is set to 0, the class 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 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check this error, and then try to send the data again. . The bytes_sent property shows how many bytes were sent (if any). If 0 bytes were sent, then you can wait for the on_ready_to_send event before attempting to send data again.

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

send_bytes Method

This method sends binary data to the specified client.

Syntax

def send_bytes(connection_id: int, data: bytes) -> None: ...

Remarks

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

When ws_connection_timeout is set to 0, the class 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 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check this error, and then try to send the data again. . The bytes_sent property shows how many bytes were sent (if any). If 0 bytes were sent, then you can wait for the on_ready_to_send event before attempting to send data again.

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

send_file Method

This method sends the file to the remote host.

Syntax

def send_file(connection_id: int, file_name: str) -> None: ...

Remarks

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

send_line Method

This method sends a string followed by a new line.

Syntax

def send_line(connection_id: int, text: str) -> None: ...

Remarks

This method is used to send data with line-oriented protocols. The line is followed by CRLF ("\r\n") .

Please refer to the get_line method and single_line_mode property for more information.

send_text Method

This method sends text to the specified client.

Syntax

def send_text(connection_id: int, text: str) -> None: ...

Remarks

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

When ws_connection_timeout is set to 0, the class 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 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check this error, and then try to send the data again. . The bytes_sent property shows how many bytes were sent (if any). If 0 bytes were sent, then you can wait for the on_ready_to_send event before attempting to send data again.

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

shutdown Method

This method shuts down the server.

Syntax

def shutdown() -> None: ...

Remarks

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

start_listening Method

This method starts listening for incoming connections.

Syntax

def start_listening() -> None: ...

Remarks

This method begins listening for incoming connections on the port specified by local_port. Once listening, events will fire as new clients connect and data are transferred.

To stop listening for new connections, call stop_listening. To stop listening for new connections and to disconnect all existing clients, call shutdown.

start_ssl Method

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

Syntax

def start_ssl(connection_id: int) -> None: ...

Remarks

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

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

stop_listening Method

This method stops listening for new connections.

Syntax

def stop_listening() -> None: ...

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.

on_connected Event

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

Syntax

class TCPServerConnectedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def status_code() -> int: ...

  @property
  def description() -> str: ...

# In class TCPServer:
@property
def on_connected() -> Callable[[TCPServerConnectedEventParams], None]: ...
@on_connected.setter
def on_connected(event_hook: Callable[[TCPServerConnectedEventParams], None]) -> None: ...

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 system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

on_connection_request Event

This event is fired when a request for connection comes from a remote host.

Syntax

class TCPServerConnectionRequestEventParams(object):
  @property
  def address() -> str: ...

  @property
  def port() -> int: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

# In class TCPServer:
@property
def on_connection_request() -> Callable[[TCPServerConnectionRequestEventParams], None]: ...
@on_connection_request.setter
def on_connection_request(event_hook: Callable[[TCPServerConnectionRequestEventParams], None]) -> None: ...

Remarks

This event indicates an incoming connection. The connection is accepted by default. Address and Port will contain information about the remote host requesting the inbound connection. If you want to refuse it, you can set the Accept parameter to False.

on_data_in Event

This event is fired when data come in.

Syntax

class TCPServerDataInEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def text() -> bytes: ...

  @property
  def eol() -> bool: ...

# In class TCPServer:
@property
def on_data_in() -> Callable[[TCPServerDataInEventParams], None]: ...
@on_data_in.setter
def on_data_in(event_hook: Callable[[TCPServerDataInEventParams], None]) -> None: ...

Remarks

Trapping the on_data_in 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 default_max_line_length or with no eol strings in it, then EOL is False. Please note that this means that one or more on_data_in 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.

on_disconnected Event

This event is fired when a connection is closed.

Syntax

class TCPServerDisconnectedEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def status_code() -> int: ...

  @property
  def description() -> str: ...

# In class TCPServer:
@property
def on_disconnected() -> Callable[[TCPServerDisconnectedEventParams], None]: ...
@on_disconnected.setter
def on_disconnected(event_hook: Callable[[TCPServerDisconnectedEventParams], None]) -> None: ...

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 system. Description contains a description of this code. The value of StatusCode is equal to the value of the system error.

Please refer to the Error Codes section for more information.

on_error Event

This event fires information about errors during data delivery.

Syntax

class TCPServerErrorEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def error_code() -> int: ...

  @property
  def description() -> str: ...

# In class TCPServer:
@property
def on_error() -> Callable[[TCPServerErrorEventParams], None]: ...
@on_error.setter
def on_error(event_hook: Callable[[TCPServerErrorEventParams], None]) -> None: ...

Remarks

The on_error event is fired in case of exceptional conditions during message processing. Normally, the class 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.

on_ready_to_send Event

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

Syntax

class TCPServerReadyToSendEventParams(object):
  @property
  def connection_id() -> int: ...

# In class TCPServer:
@property
def on_ready_to_send() -> Callable[[TCPServerReadyToSendEventParams], None]: ...
@on_ready_to_send.setter
def on_ready_to_send(event_hook: Callable[[TCPServerReadyToSendEventParams], None]) -> None: ...

Remarks

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

on_ssl_client_authentication Event

This event is fired when the client presents its credentials to the server.

Syntax

class TCPServerSSLClientAuthenticationEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def cert_encoded() -> bytes: ...

  @property
  def cert_subject() -> str: ...

  @property
  def cert_issuer() -> str: ...

  @property
  def status() -> str: ...

  @property
  def accept() -> bool: ...
  @accept.setter
  def accept(value) -> None: ...

# In class TCPServer:
@property
def on_ssl_client_authentication() -> Callable[[TCPServerSSLClientAuthenticationEventParams], None]: ...
@on_ssl_client_authentication.setter
def on_ssl_client_authentication(event_hook: Callable[[TCPServerSSLClientAuthenticationEventParams], None]) -> None: ...

Remarks

This event enables the server to decide whether or not to continue. The Accept parameter is a recommendation on whether to continue or to 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").

on_ssl_connection_request Event

This event fires when a Secure Sockets Layer (SSL) connection is requested.

Syntax

class TCPServerSSLConnectionRequestEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def supported_cipher_suites() -> str: ...

  @property
  def supported_signature_algs() -> str: ...

  @property
  def cert_store_type() -> int: ...
  @cert_store_type.setter
  def cert_store_type(value) -> None: ...

  @property
  def cert_store() -> str: ...
  @cert_store.setter
  def cert_store(value) -> None: ...

  @property
  def cert_password() -> str: ...
  @cert_password.setter
  def cert_password(value) -> None: ...

  @property
  def cert_subject() -> str: ...
  @cert_subject.setter
  def cert_subject(value) -> None: ...

# In class TCPServer:
@property
def on_ssl_connection_request() -> Callable[[TCPServerSSLConnectionRequestEventParams], None]: ...
@on_ssl_connection_request.setter
def on_ssl_connection_request(event_hook: Callable[[TCPServerSSLConnectionRequestEventParams], None]) -> None: ...

Remarks

This event fires when an SSL connection is requested and ssl_provider is set to Internal. This event provides an opportunity to select an alternative certificate to the connecting client. This event does not fire when ssl_provider is set to Platform.

This event allows the class to be configured to use both RSA and ECDSA certificates depending on the connecting client's capabilities.

ConnectionId is the connection Id of the client requesting the connection.

SupportedCipherSuites is a comma-separated list of cipher suites that the client supports.

SupportedSignatureAlgs is a comma-separated list of certificate signature algorithms that the client supports.

CertStoreType is the store type of the alternate certificate to use for this connection. The class supports both public and private keys in a variety of formats. When the cstAuto value is used, the class will automatically determine the type. This property can take one of the following values:

CertStore is the store name or location of the alternate certificate to use for this connection.

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).

CertPassword is the password of the certificate store containing the alternate certificate to use for this connection.

CertSubject is the subject of the alternate certificate to use for this connection.

The special value * matches any subject and will select the first certificate in the 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.

on_ssl_status Event

This event is fired to show the progress of the secure connection.

Syntax

class TCPServerSSLStatusEventParams(object):
  @property
  def connection_id() -> int: ...

  @property
  def message() -> str: ...

# In class TCPServer:
@property
def on_ssl_status() -> Callable[[TCPServerSSLStatusEventParams], None]: ...
@on_ssl_status.setter
def on_ssl_status(event_hook: Callable[[TCPServerSSLStatusEventParams], None]) -> None: ...

Remarks

The event is fired for informational and logging purposes only. It is used to track the progress of the connection.

TCPServer Config Settings

TCPServer 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-----

Base Config Settings

TCPServer Errors

TCPServer Errors

SSL Errors

TCP/IP Errors