QLocalServer#
The QLocalServer class provides a local socket based server. More…
Synopsis#
Functions#
def
close()def
errorString()def
fullServerName()def
isListening()def
listen(name)def
listen(socketDescriptor)def
listenBacklogSize()def
maxPendingConnections()def
serverError()def
serverName()def
setListenBacklogSize(size)def
setMaxPendingConnections(numConnections)def
setSocketOptions(options)def
socketDescriptor()def
socketOptions()def
waitForNewConnection(msec)
Virtual functions#
def
hasPendingConnections()def
incomingConnection(socketDescriptor)def
nextPendingConnection()
Signals#
def
newConnection()
Static functions#
def
removeServer(name)
Detailed Description#
This class makes it possible to accept incoming local socket connections.
Call listen() to have the server start listening for incoming connections on a specified key. The newConnection() signal is then emitted each time a client connects to the server.
Call nextPendingConnection() to accept the pending connection as a connected QLocalSocket . The function returns a pointer to a QLocalSocket that can be used for communicating with the client.
If an error occurs, serverError() returns the type of error, and errorString() can be called to get a human readable description of what happened.
When listening for connections, the name which the server is listening on is available through serverName() .
Calling close() makes QLocalServer stop listening for incoming connections.
Although QLocalServer is designed for use with an event loop, it’s possible to use it without one. In that case, you must use waitForNewConnection() , which blocks until either a connection is available or a timeout expires.
See also
- class PySide6.QtNetwork.QLocalServer([parent=None])#
- Parameters
parent –
PySide6.QtCore.QObject
Create a new local socket server with the given parent.
See also
- PySide6.QtNetwork.QLocalServer.SocketOption#
(inherits enum.Flag) This enum describes the possible options that can be used to create the socket. This changes the access permissions on platforms (Linux, Windows) that support access permissions on the socket. Both GroupAccess and OtherAccess may vary slightly in meanings depending on the platform. On Linux and Android it is possible to use sockets with abstract addresses; socket permissions have no meaning for such sockets.
Constant
Description
QLocalServer.NoOptions
No access restrictions have been set.
QLocalServer.UserAccessOption
Access is restricted to the same user as the process that created the socket.
QLocalServer.GroupAccessOption
Access is restricted to the same group but not the user that created the socket on Linux. Access is restricted to the primary group of the process on Windows
QLocalServer.OtherAccessOption
Access is available to everyone but the user and group that created the socket on Linux. Access is available to everyone on Windows.
QLocalServer.WorldAccessOption
No access restrictions.
QLocalServer.AbstractNamespaceOption
The listening socket will be created in the abstract namespace. This flag is specific to Linux. In case of other platforms, for the sake of code portability, this flag is equivalent to WorldAccessOption.
See also
- PySide6.QtNetwork.QLocalServer.close()#
Stop listening for incoming connections. Existing connections are not affected, but any new connections will be refused.
See also
- PySide6.QtNetwork.QLocalServer.errorString()#
- Return type
str
Returns the human-readable message appropriate to the current error reported by serverError() . If no suitable string is available, an empty string is returned.
See also
- PySide6.QtNetwork.QLocalServer.fullServerName()#
- Return type
str
Returns the full path that the server is listening on.
Note: This is platform specific
See also
- PySide6.QtNetwork.QLocalServer.hasPendingConnections()#
- Return type
bool
Returns true if the server has a pending connection; otherwise returns false.
- PySide6.QtNetwork.QLocalServer.incomingConnection(socketDescriptor)#
- Parameters
socketDescriptor –
quintptr
This virtual function is called by QLocalServer when a new connection is available. socketDescriptor is the native socket descriptor for the accepted connection.
The base implementation creates a QLocalSocket , sets the socket descriptor and then stores the QLocalSocket in an internal list of pending connections. Finally newConnection() is emitted.
Reimplement this function to alter the server’s behavior when a connection is available.
- PySide6.QtNetwork.QLocalServer.isListening()#
- Return type
bool
Returns true if the server is listening for incoming connections otherwise false.
- PySide6.QtNetwork.QLocalServer.listen(name)#
- Parameters
name – str
- Return type
bool
Tells the server to listen for incoming connections on name. If the server is currently listening then it will return false. Return true on success otherwise false.
name can be a single name and QLocalServer will determine the correct platform specific path. serverName() will return the name that is passed into listen.
Usually you would just pass in a name like “foo”, but on Unix this could also be a path such as “/tmp/foo” and on Windows this could be a pipe path such as “\\.\pipe\foo”
Note
On Unix if the server crashes without closing listen will fail with AddressInUseError. To create a new server the file should be removed. On Windows two local servers can listen to the same pipe at the same time, but any connections will go to one of the server.
See also
- PySide6.QtNetwork.QLocalServer.listen(socketDescriptor)
- Parameters
socketDescriptor –
qintptr- Return type
bool
Instructs the server to listen for incoming connections on socketDescriptor. The property returns false if the server is currently listening. It returns true on success; otherwise, it returns false. The socket must be ready to accept new connections with no extra platform-specific functions called. The socket is set into non-blocking mode.
serverName() , fullServerName() may return a string with a name if this option is supported by the platform; otherwise, they return an empty QString . In particular, the addresses of sockets in the abstract namespace supported by Linux will not yield useful names if they contain unprintable characters.
See also
- PySide6.QtNetwork.QLocalServer.listenBacklogSize()#
- Return type
int
Returns the backlog queue size of to be accepted connections.
See also
- PySide6.QtNetwork.QLocalServer.maxPendingConnections()#
- Return type
int
Returns the maximum number of pending accepted connections. The default is 30.
- PySide6.QtNetwork.QLocalServer.newConnection()#
This signal is emitted every time a new connection is available.
- PySide6.QtNetwork.QLocalServer.nextPendingConnection()#
- Return type
Returns the next pending connection as a connected QLocalSocket object.
The socket is created as a child of the server, which means that it is automatically deleted when the QLocalServer object is destroyed. It is still a good idea to delete the object explicitly when you are done with it, to avoid wasting memory.
None is returned if this function is called when there are no pending connections.
- static PySide6.QtNetwork.QLocalServer.removeServer(name)#
- Parameters
name – str
- Return type
bool
Removes any server instance that might cause a call to listen() to fail and returns true if successful; otherwise returns false. This function is meant to recover from a crash, when the previous server instance has not been cleaned up.
On Windows, this function does nothing; on Unix, it removes the socket file given by name.
Warning
Be careful to avoid removing sockets of running instances.
- PySide6.QtNetwork.QLocalServer.serverError()#
- Return type
Returns the type of error that occurred last or NoError .
See also
- PySide6.QtNetwork.QLocalServer.serverName()#
- Return type
str
Returns the server name if the server is listening for connections; otherwise returns QString()
See also
- PySide6.QtNetwork.QLocalServer.setListenBacklogSize(size)#
- Parameters
size – int
Sets the backlog queue size of to be accepted connections to size. The operating system might reduce or ignore this value. By default, the queue size is 50.
- PySide6.QtNetwork.QLocalServer.setMaxPendingConnections(numConnections)#
- Parameters
numConnections – int
Sets the maximum number of pending accepted connections to numConnections. QLocalServer will accept no more than numConnections incoming connections before nextPendingConnection() is called.
Note: Even though QLocalServer will stop accepting new connections after it has reached its maximum number of pending connections, the operating system may still keep them in queue which will result in clients signaling that it is connected.
- PySide6.QtNetwork.QLocalServer.setSocketOptions(options)#
- Parameters
options –
SocketOptions
This property holds the socket options that control how the socket operates..
For example, the socket may restrict access to what user ids can connect to the socket.
These options must be set before listen() is called.
In some cases, such as with Unix domain sockets on Linux, the access to the socket will be determined by file system permissions, and are created based on the umask. Setting the access flags will override this and will restrict or permit access as specified.
Other Unix-based operating systems, such as macOS, do not honor file permissions for Unix domain sockets and by default have WorldAccess and these permission flags will have no effect.
On Windows, UserAccessOption is sufficient to allow a non elevated process to connect to a local server created by an elevated process run by the same user. GroupAccessOption refers to the primary group of the process (see TokenPrimaryGroup in the Windows documentation). OtherAccessOption refers to the well known “Everyone” group.
On Linux platforms it is possible to create a socket in the abstract namespace, which is independent of the filesystem. Using this kind of socket implies ignoring permission options. On other platforms AbstractNamespaceOption is equivalent to WorldAccessOption .
By default none of the flags are set, access permissions are the platform default.
See also
- PySide6.QtNetwork.QLocalServer.socketDescriptor()#
- Return type
qintptr
Returns the native socket descriptor the server uses to listen for incoming instructions, or -1 if the server is not listening.
The type of the descriptor depends on the platform:
On Windows, the returned value is a Winsock 2 Socket Handle.
On INTEGRITY, the returned value is the
QTcpServersocket descriptor and the type is defined bysocketDescriptor.On all other UNIX-like operating systems, the type is a file descriptor representing a listening socket.
See also
- PySide6.QtNetwork.QLocalServer.socketOptions()#
- Return type
SocketOptions
This property holds the socket options that control how the socket operates..
For example, the socket may restrict access to what user ids can connect to the socket.
These options must be set before listen() is called.
In some cases, such as with Unix domain sockets on Linux, the access to the socket will be determined by file system permissions, and are created based on the umask. Setting the access flags will override this and will restrict or permit access as specified.
Other Unix-based operating systems, such as macOS, do not honor file permissions for Unix domain sockets and by default have WorldAccess and these permission flags will have no effect.
On Windows, UserAccessOption is sufficient to allow a non elevated process to connect to a local server created by an elevated process run by the same user. GroupAccessOption refers to the primary group of the process (see TokenPrimaryGroup in the Windows documentation). OtherAccessOption refers to the well known “Everyone” group.
On Linux platforms it is possible to create a socket in the abstract namespace, which is independent of the filesystem. Using this kind of socket implies ignoring permission options. On other platforms AbstractNamespaceOption is equivalent to WorldAccessOption .
By default none of the flags are set, access permissions are the platform default.
See also
- PySide6.QtNetwork.QLocalServer.waitForNewConnection(msec)#
- Parameters
msec – int
- Return type
(retval, timeOut)
Waits for at most msec milliseconds or until an incoming connection is available. Returns true if a connection is available; otherwise returns false. If the operation timed out and timedOut is not None, *timedOut will be set to true.
This is a blocking function call. Its use is ill-advised in a single-threaded GUI application, since the whole application will stop responding until the function returns. waitForNewConnection() is mostly useful when there is no event loop available.
The non-blocking alternative is to connect to the newConnection() signal.
If msec is -1, this function will not time out.