open_socket_acceptT_open_socket_acceptOpenSocketAcceptOpenSocketAccept (Operator)


open_socket_acceptT_open_socket_acceptOpenSocketAcceptOpenSocketAccept — Open a socket that accepts connection requests.


open_socket_accept( : : Port, GenParamName, GenParamValue : AcceptingSocket)

Herror T_open_socket_accept(const Htuple Port, const Htuple GenParamName, const Htuple GenParamValue, Htuple* AcceptingSocket)

void OpenSocketAccept(const HTuple& Port, const HTuple& GenParamName, const HTuple& GenParamValue, HTuple* AcceptingSocket)

void HSocket::HSocket(Hlong Port, const HTuple& GenParamName, const HTuple& GenParamValue)

void HSocket::HSocket(Hlong Port, const HString& GenParamName, const HString& GenParamValue)

void HSocket::HSocket(Hlong Port, const char* GenParamName, const char* GenParamValue)

void HSocket::HSocket(Hlong Port, const wchar_t* GenParamName, const wchar_t* GenParamValue)   (Windows only)

void HSocket::OpenSocketAccept(Hlong Port, const HTuple& GenParamName, const HTuple& GenParamValue)

void HSocket::OpenSocketAccept(Hlong Port, const HString& GenParamName, const HString& GenParamValue)

void HSocket::OpenSocketAccept(Hlong Port, const char* GenParamName, const char* GenParamValue)

void HSocket::OpenSocketAccept(Hlong Port, const wchar_t* GenParamName, const wchar_t* GenParamValue)   (Windows only)

static void HOperatorSet.OpenSocketAccept(HTuple port, HTuple genParamName, HTuple genParamValue, out HTuple acceptingSocket)

public HSocket(int port, HTuple genParamName, HTuple genParamValue)

public HSocket(int port, string genParamName, string genParamValue)

void HSocket.OpenSocketAccept(int port, HTuple genParamName, HTuple genParamValue)

void HSocket.OpenSocketAccept(int port, string genParamName, string genParamValue)


open_socket_acceptopen_socket_acceptOpenSocketAcceptOpenSocketAcceptOpenSocketAccept opens a socket that will accept incoming connection requests. This operator is the necessary first step in the establishment of a communication channel between two HALCON processes. The socket listens for incoming connection requests on the port number given by PortPortPortPortport.

It is possible to specify a PortPortPortPortport of 0, triggering implementation-defined behaviour. On most operating systems, using a port number of 0 instructs the operating system to choose a free port randomly.

The generic parameter 'protocol'"protocol""protocol""protocol""protocol" may be used to specify the protocol to be used. The default is the 'HALCON'"HALCON""HALCON""HALCON""HALCON" protocol without specific address family. Therefore, IPv4 or IPv6 will be used automatically depending on the network configuration of the computer. To use a specific address family a '4' or '6' (for IPv4 or IPv6, respectively) must be appended to the name of the protocol. For example, 'HALCON4'"HALCON4""HALCON4""HALCON4""HALCON4" designates a HALCON connection over IPv4. Possible values for a generic socket communication are 'UDP'"UDP""UDP""UDP""UDP" and 'TCP'"TCP""TCP""TCP""TCP" which also support appended '4' and '6'. Both communication partners must use the same protocol. To exchange data using generic sockets use send_datasend_dataSendDataSendDataSendData and receive_datareceive_dataReceiveDataReceiveDataReceiveData only.

The generic parameter 'address'"address""address""address""address" can be used to instruct the socket to accept only connection requests addressed to a specific address. This address is specified as either an IPv4 or IPv6 address in numerical form, or a hostname. For example, 'localhost'"localhost""localhost""localhost""localhost" would instruct the socket to accept only connections addressed to the address 'localhost'"localhost""localhost""localhost""localhost", which normally maps to the local loopback network interface ''"""""""".

The generic parameter 'timeout'"timeout""timeout""timeout""timeout" can be used to set a timeout for this socket. The timeout is given in seconds or as the string 'infinite'"infinite""infinite""infinite""infinite". It is used especially as timeout and waiting mode in a following socket_accept_connectsocket_accept_connectSocketAcceptConnectSocketAcceptConnectSocketAcceptConnect call with the parameter Wait set to 'auto'"auto""auto""auto""auto".

The generic parameter 'string_encoding'"string_encoding""string_encoding""string_encoding""string_encoding" can be used to set the string encoding that is expected when sending and receiving strings with this socket. It is used for send_tuplesend_tupleSendTupleSendTupleSendTuple and receive_tuplereceive_tupleReceiveTupleReceiveTupleReceiveTuple as well as send_datasend_dataSendDataSendDataSendData and receive_datareceive_dataReceiveDataReceiveDataReceiveData. When the protocol 'HALCON'"HALCON""HALCON""HALCON""HALCON" is used, the setting only has effect on connections to HALCON versions prior to 18.11. If the connection partner is detected to have HALCON version 18.11 or newer, UTF-8 is used to encode tuples.

The generic parameter 'reuseaddr'"reuseaddr""reuseaddr""reuseaddr""reuseaddr" can be used to control the setting of the socket option SO_REUSEADDR. The default value is 'true'"true""true""true""true". When 'reuseaddr'"reuseaddr""reuseaddr""reuseaddr""reuseaddr" is set to 'false'"false""false""false""false", SO_REUSEADDR will not be set. On Windows Systems, conflicting access on a single port will only be detected, when 'reuseaddr'"reuseaddr""reuseaddr""reuseaddr""reuseaddr" is set to 'false'"false""false""false""false".

The accepting socket is returned in AcceptingSocketAcceptingSocketAcceptingSocketAcceptingSocketacceptingSocket. open_socket_acceptopen_socket_acceptOpenSocketAcceptOpenSocketAcceptOpenSocketAccept returns immediately without waiting for a request from another process, which must be initiated by calling open_socket_connectopen_socket_connectOpenSocketConnectOpenSocketConnectOpenSocketConnect. This allows multiple other processes to connect to the particular HALCON process that calls open_socket_acceptopen_socket_acceptOpenSocketAcceptOpenSocketAcceptOpenSocketAccept. To accept an incoming 'HALCON'"HALCON""HALCON""HALCON""HALCON" or 'TCP'"TCP""TCP""TCP""TCP" connection request, socket_accept_connectsocket_accept_connectSocketAcceptConnectSocketAcceptConnectSocketAcceptConnect must be called to obtain a socket for the final communication.

Execution Information

This operator returns a handle. Note that the state of an instance of this handle type may be changed by specific operators even though the handle is used as an input parameter by those operators.


PortPortPortPortport (input_control)  number HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Port number.

Default value: 3000

Suggested values: 3000, 4570

Typical range of values: 1024 ≤ Port Port Port Port port ≤ 65535

Minimum increment: 1

Recommended increment: 1

GenParamNameGenParamNameGenParamNameGenParamNamegenParamName (input_control) HTupleHTupleHtuple (string) (string) (HString) (char*)

Names of the generic parameters that can be adjusted for the socket.

Default value: []

List of values: 'address'"address""address""address""address", 'protocol'"protocol""protocol""protocol""protocol", 'string_encoding'"string_encoding""string_encoding""string_encoding""string_encoding", 'timeout'"timeout""timeout""timeout""timeout"

GenParamValueGenParamValueGenParamValueGenParamValuegenParamValue (input_control)  attribute.value(-array) HTupleHTupleHtuple (string / real / integer) (string / double / int / long) (HString / double / Hlong) (char* / double / Hlong)

Values of the generic parameters that can be adjusted for the socket.

Default value: []

Suggested values: 0, 3.0, 'infinite'"infinite""infinite""infinite""infinite", 'HALCON'"HALCON""HALCON""HALCON""HALCON", 'UDP'"UDP""UDP""UDP""UDP", 'TCP'"TCP""TCP""TCP""TCP", 'HALCON4'"HALCON4""HALCON4""HALCON4""HALCON4", 'UDP4'"UDP4""UDP4""UDP4""UDP4", 'TCP4'"TCP4""TCP4""TCP4""TCP4", 'HALCON6'"HALCON6""HALCON6""HALCON6""HALCON6", 'UDP6'"UDP6""UDP6""UDP6""UDP6", 'TCP6'"TCP6""TCP6""TCP6""TCP6", 'utf8'"utf8""utf8""utf8""utf8", 'locale'"locale""locale""locale""locale", 'ignore'"ignore""ignore""ignore""ignore"

AcceptingSocketAcceptingSocketAcceptingSocketAcceptingSocketacceptingSocket (output_control)  socket HSocket, HTupleHTupleHtuple (handle) (IntPtr) (HHandle) (handle)

Socket number.

Example (HDevelop)

* Process 1
dev_set_colored (12)
open_socket_accept (3000, [], [], AcceptingSocket)
* Busy wait for an incoming connection
dev_error_var (Error, 1)
dev_set_check ('~give_error')
OpenStatus := 5
while (OpenStatus != 2)
    socket_accept_connect (AcceptingSocket, 'false', Socket)
    OpenStatus := Error
    wait_seconds (0.2)
dev_set_check ('give_error')
* Connection established
receive_image (Image, Socket)
threshold (Image, Region, 0, 63)
send_region (Region, Socket)
receive_region (ConnectedRegions, Socket)
area_center (ConnectedRegions, Area, Row, Column)
send_tuple (Socket, Area)
send_tuple (Socket, Row)
send_tuple (Socket, Column)
close_socket (Socket)
close_socket (AcceptingSocket)

* Process 2
dev_set_colored (12)
open_socket_connect ('localhost', 3000, [], [], Socket)
read_image (Image, 'fabrik')
send_image (Image, Socket)
receive_region (Region, Socket)
connection (Region, ConnectedRegions)
send_region (ConnectedRegions, Socket)
receive_tuple (Socket, Area)
receive_tuple (Socket, Row)
receive_tuple (Socket, Column)
close_socket (Socket)

Possible Successors


See also

open_socket_connectopen_socket_connectOpenSocketConnectOpenSocketConnectOpenSocketConnect, close_socketclose_socketCloseSocketCloseSocketCloseSocket, get_socket_paramget_socket_paramGetSocketParamGetSocketParamGetSocketParam, set_socket_paramset_socket_paramSetSocketParamSetSocketParamSetSocketParam, send_imagesend_imageSendImageSendImageSendImage, receive_imagereceive_imageReceiveImageReceiveImageReceiveImage, send_regionsend_regionSendRegionSendRegionSendRegion, receive_regionreceive_regionReceiveRegionReceiveRegionReceiveRegion, send_tuplesend_tupleSendTupleSendTupleSendTuple, receive_tuplereceive_tupleReceiveTupleReceiveTupleReceiveTuple, send_datasend_dataSendDataSendDataSendData, receive_datareceive_dataReceiveDataReceiveDataReceiveData