Operator Reference
open_socket_accept (Operator)
open_socket_accept — Open a socket that accepts connection requests.
Signature
open_socket_accept( : : Port, GenParamName, GenParamValue : AcceptingSocket)
Description
open_socket_accept 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 Port.
It is possible to specify a Port of 0, triggering
implementation-defined behavior.
On most operating systems, using a port number of 0 instructs the
operating system to choose a free port randomly.
The following parameters can be set for GenParamName.
- 'protocol':
-
Specifies the protocol to be used. The 'HALCON' protocol without a specific address family, will use IPv4 or IPv6 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' designates a HALCON connection over IPv4. Possible values for a generic socket communication are 'UDP' and 'TCP' which also support appended '4' and '6'. Both communication partners must use the same protocol. To exchange data using generic sockets use
send_dataandreceive_dataonly.Default: 'HALCON'
- 'address':
-
Instructs 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' would instruct the socket to accept only connections addressed to the address 'localhost', which normally maps to the local loopback network interface '127.0.0.1'.
- 'timeout':
-
Sets a timeout for this socket. The timeout is given in seconds or as the string 'infinite'. It is used especially as timeout and waiting mode in a following
socket_accept_connectcall with the parameterWaitset to 'auto'. - 'string_encoding':
-
Sets the string encoding that is expected when sending and receiving strings with this socket. It is used for
send_tupleandreceive_tupleas well assend_dataandreceive_data. When the protocol '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. - 'reuseaddr':
-
Controls the setting of the socket option
SO_REUSEADDR. When 'reuseaddr' is set to 'false',SO_REUSEADDRwill not be set. On Windows Systems, conflicting access on a single port will only be detected, when 'reuseaddr' is set to 'false'.Default: 'true'
- 'tls_enable':
-
Controls the use of Transport Layer Security (TLS) for the new Socket. When 'tls_enable' is set to 'true', the created socket will accept TLS secured connections only. Furthermore, both generic parameters 'tls_private_key' and 'tls_certificate' must be set, each with a path to the private certificate key and the path to the public server certificate. Private key and server certificate must be provided in PEM-format.
Default: 'false'
The accepting socket is returned in AcceptingSocket.
open_socket_accept returns immediately without waiting for a request
from another process, which must be initiated by calling
open_socket_connect. This allows multiple other processes to connect
to the particular HALCON process that calls open_socket_accept. To
accept an incoming 'HALCON' or 'TCP' connection request,
socket_accept_connect must be called to obtain a socket for the final
communication.
Execution Information
- Multithreading type: reentrant (runs in parallel with non-exclusive operators).
- Multithreading scope: global (may be called from any thread).
- Processed without parallelization.
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.
Parameters
Port (input_control) number → (integer)
Port number.
Default: 3000
Suggested values: 3000, 4570
Value range:
1024
≤
Port
≤
65535
Minimum increment: 1
Recommended increment: 1
GenParamName (input_control) attribute.name(-array) → (string)
Names of the generic parameters that can be adjusted for the socket.
Default: []
List of values: 'address', 'protocol', 'string_encoding', 'timeout', 'tls_certificate', 'tls_enable', 'tls_private_key'
GenParamValue (input_control) attribute.value(-array) → (string / real / integer)
Values of the generic parameters that can be adjusted for the socket.
Default: []
Suggested values: 0, 3.0, 'infinite', 'HALCON', 'UDP', 'TCP', 'HALCON4', 'UDP4', 'TCP4', 'HALCON6', 'UDP6', 'TCP6', 'utf8', 'locale', 'ignore', 'true', 'false'
AcceptingSocket (output_control) socket → (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)
endwhile
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_connect,
close_socket,
get_socket_param,
set_socket_param,
send_image,
receive_image,
send_region,
receive_region,
send_tuple,
receive_tuple,
send_data,
receive_data
Module
Foundation