UDP Class

Properties   Methods   Events   Config Settings   Errors  

The UDP class is used to facilitate UDP (datagram) communications. It can act both as a client and a server and communicate with any number of hosts simultaneously, as well as generate and receive broadcast packets.

Syntax

class ipworks.UDP

Remarks

The interface of the class is similar to the interface of TCPClient, only much simpler. The class is activated/deactivated through the active property. This property enables or disables sends or receives. The data can be sent in the same way as TCPClient, using the send method and specifying the text to send. This is identical to assigning data to the data_to_send property. The destination is specified using the remote_host and remote_port properties. Inbound data is received through the on_data_in event.

If the UseConnection config setting is set to True, then a local association is created with the remote host. Otherwise, the class can receive datagrams (packets) from any host, and send datagrams to any host. Packets can be broadcast on the local net by setting the destination (remote_host) to 255.255.255.255.

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

Property List

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

Method List

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

Event List

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

Config Settings

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

accept_data Property

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

Syntax

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

accept_data = property(get_accept_data, set_accept_data)

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 on_data_in event). Setting this property to True, reenables data reception.

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

active Property

Indicates whether the class is active.

Syntax

def get_active() -> bool: ...
def set_active(value: bool) -> None: ...

active = property(get_active, set_active)

Default Value

FALSE

Remarks

This property indicates whether the class is currently active and can send or receive data.

If UseConnection is set to True, then a local association (connection) to the remote host and port is also created.

Note: Use the activate or deactivate method to control whether the class is active.

data_to_send Property

A string of data to be sent to the remote host. Write-only property.

Syntax

def set_data_to_send(value: bytes) -> None: ...

data_to_send = property(None, set_data_to_send)

Default Value

""

Remarks

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

Attempts to send the string assigned to data_to_send as a complete message. If system buffers are full, or the message cannot be delivered for any other reason, an error is fired, and no portion of the message is sent. This is different from TCP where portions of the messages can be sent. UDP sends either a complete message or nothing at all.

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, data_to_send fails with error 10035: "[10035] Operation would block" (WSAEWOULDBLOCK). You can check this error, and then try to send the data again.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.DataToSend = "Hello!"

This property is write-only.

dont_route Property

If this property is set to True, it forces the socket to send data directly to the interface (no routing).

Syntax

def get_dont_route() -> bool: ...
def set_dont_route(value: bool) -> None: ...

dont_route = property(get_dont_route, set_dont_route)

Default Value

FALSE

Remarks

If this property is set to True, it forces the socket to send data directly to the interface (no routing). Normally, IP sockets send packets of data through routers and gateways until they reach the final destination. If this property is set to True, then data will be delivered on the local subnet only.

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

The UDP port in the local host where UDP binds.

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

The local_port property must be set before UDP is activated (active is set to True). It instructs the class to bind to a specific port (or communication endpoint) in the local machine.

Setting it to 0 (default) enables the TCP/IP stack to choose a port at random. The chosen port will be shown by the local_port property after the connection is established.

local_port cannot be changed once the class is active. Any attempt to set the local_port property when the class is active will generate an error.

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

remote_host Property

The address of the remote host. Domain names are resolved to IP addresses.

Syntax

def get_remote_host() -> str: ...
def set_remote_host(value: str) -> None: ...

remote_host = property(get_remote_host, set_remote_host)

Default Value

""

Remarks

The remote_host property specifies the IP address (IP number in dotted internet format) or Domain Name of the remote host.

If remote_host is set to 255.255.255.255, the class broadcasts data on the local subnet.

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

If UseConnection is set to True, the remote_host must be set before the class is activated (active is set to True).

remote_port Property

The UDP port in the remote host.

Syntax

def get_remote_port() -> int: ...
def set_remote_port(value: int) -> None: ...

remote_port = property(get_remote_port, set_remote_port)

Default Value

0

Remarks

The remote_port is the UDP port on the remote_host to send UDP datagrams to.

A valid port number (a value between 1 and 65535) is required.

If UseConnection is set to True, the remote_port must be set before the class is activated (active is set to True).

time_to_live Property

The maximum number of subnets that a datagram can traverse.

Syntax

def get_time_to_live() -> int: ...
def set_time_to_live(value: int) -> None: ...

time_to_live = property(get_time_to_live, set_time_to_live)

Default Value

0

Remarks

The default value for this property is 0, which tells the class to use the default TTL value of the underlying TCP/IP subsystem. Depending on the application, you can specify a value between 1 and 255.

activate Method

Enables sending and receiving of data.

Syntax

def activate() -> None: ...

Remarks

This method enables sending and receiving of data. When called the class will create a communication endpoint (socket) which can be used for sending and receiving UDP messages. This method must be called before using the class to send and receive data.

If the UseConnection configuration setting is set to True, then a local association (connection) to the remote host is also created.

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.

deactivate Method

Disables sending and receive of data.

Syntax

def deactivate() -> None: ...

Remarks

This method disables sending and receiving of data. When called the class will destroy the existing socket and disable data communications.

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.

pause_data Method

This method pauses data reception.

Syntax

def pause_data() -> None: ...

Remarks

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

process_data Method

This method reenables data reception after a call to PauseData .

Syntax

def process_data() -> None: ...

Remarks

This method reenables data reception after a previous call to pause_data. When pause_data is called, the on_data_in event will not fire. 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.

resolve_remote_host Method

Resolves the hostname in RemoteHost to an IP address.

Syntax

def resolve_remote_host() -> None: ...

Remarks

This method resolves the hostname specified by remote_host to an IP address. The resolved value is available in the remote_host property after this method returns.

In most cases calling this method is not necessary, the class will resolve the hostname automatically when necessary. If DelayHostResolution is True this method may be called to manually resolve remote_host if desired.

send Method

Send data to the remote host.

Syntax

def send(text: bytes) -> None: ...

Remarks

Calling this method is equivalent to setting the data_to_send property to Text.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.Send("Hello!")

send_bytes Method

Send data to the remote host.

Syntax

def send_bytes(data: bytes) -> None: ...

Remarks

Calling this method is equivalent to call send_bytes/send_text method.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.Send("Hello!")

send_text Method

Send data to the remote host.

Syntax

def send_text(text: str) -> None: ...

Remarks

Calling this method is equivalent to call send_bytes/send_text method.

Example (Send Data)

UDPControl.LocalPort = 8765 UDPControl.RemotePort = 8765 UDPControl.RemoteHost = "HostNameOrIPAddress" UDPControl.Active = True UDPControl.Send("Hello!")

on_data_in Event

Fired when data is received.

Syntax

class UDPDataInEventParams(object):
  @property
  def datagram() -> bytes: ...

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

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

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

Remarks

The on_data_in event is fired every time a new datagram is received.

Datagram contains the packet as sent by the remote host.

SourceAddress contains the IP number (Internet address) of the remote host, and SourcePort contains the port from which the packet originated.

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_error Event

Information about errors during data delivery.

Syntax

class UDPErrorEventParams(object):
  @property
  def error_code() -> int: ...

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

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

on_ready_to_send Event

Fired when the class is ready to send data.

Syntax

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

Remarks

The on_ready_to_send event indicates that the underlying TCP/IP subsystem is ready to accept data after a failed data_to_send.

UDP Config Settings

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

UDP Config Settings

Socket Config Settings

Base Config Settings

UDP Errors

UDP Errors

	104   UDP is already active.
	106   You cannot change the local_port while the class is active.
	107   You cannot change the local_host at this time. A connection is in progress.
	109   The class must be active for this operation.
	112   Cannot change MaxPacketSize while the class is active.
	113   Cannot change ShareLocalPort option while the class is active.
	114   Cannot change remote_host when UseConnection is set and the class active.
	115   Cannot change remote_port when UseConnection is set and the class is active.
	116   remote_port can't be zero when UseConnection is set. Please specify a valid service port number.
	117   Cannot change UseConnection while the class is active.
	118   Message can't be longer than MaxPacketSize.
	119   Message too short.
	434   Unable to convert string to selected CodePage

SSL Errors

	270   Cannot load specified security library.
	271   Cannot open certificate store.
	272   Cannot find specified certificate.
	273   Cannot acquire security credentials.
	274   Cannot find certificate chain.
	275   Cannot verify certificate chain.
	276   Error during handshake.
	280   Error verifying certificate.
	281   Could not find client certificate.
	282   Could not find server certificate.
	283   Error encrypting data.
	284   Error decrypting data.

TCP/IP Errors

	10004   [10004] Interrupted system call.
	10009   [10009] Bad file number.
	10013   [10013] Access denied.
	10014   [10014] Bad address.
	10022   [10022] Invalid argument.
	10024   [10024] Too many open files.
	10035   [10035] Operation would block.
	10036   [10036] Operation now in progress.
	10037   [10037] Operation already in progress.
	10038   [10038] Socket operation on non-socket.
	10039   [10039] Destination address required.
	10040   [10040] Message too long.
	10041   [10041] Protocol wrong type for socket.
	10042   [10042] Bad protocol option.
	10043   [10043] Protocol not supported.
	10044   [10044] Socket type not supported.
	10045   [10045] Operation not supported on socket.
	10046   [10046] Protocol family not supported.
	10047   [10047] Address family not supported by protocol family.
	10048   [10048] Address already in use.
	10049   [10049] Can't assign requested address.
	10050   [10050] Network is down.
	10051   [10051] Network is unreachable.
	10052   [10052] Net dropped connection or reset.
	10053   [10053] Software caused connection abort.
	10054   [10054] Connection reset by peer.
	10055   [10055] No buffer space available.
	10056   [10056] Socket is already connected.
	10057   [10057] Socket is not connected.
	10058   [10058] Can't send after socket shutdown.
	10059   [10059] Too many references, can't splice.
	10060   [10060] Connection timed out.
	10061   [10061] Connection refused.
	10062   [10062] Too many levels of symbolic links.
	10063   [10063] File name too long.
	10064   [10064] Host is down.
	10065   [10065] No route to host.
	10066   [10066] Directory not empty
	10067   [10067] Too many processes.
	10068   [10068] Too many users.
	10069   [10069] Disc Quota Exceeded.
	10070   [10070] Stale NFS file handle.
	10071   [10071] Too many levels of remote in path.
	10091   [10091] Network subsystem is unavailable.
	10092   [10092] WINSOCK DLL Version out of range.
	10093   [10093] Winsock not loaded yet.
	11001   [11001] Host not found.
	11002   [11002] Non-authoritative 'Host not found' (try again or check DNS setup).
	11003   [11003] Non-recoverable errors: FORMERR, REFUSED, NOTIMP.
	11004   [11004] Valid name, no data record (check DNS setup).