Connection objects

Connection objects allow the sending and receiving of picklable objects or strings. They can be thought of as message oriented connected sockets.

Connection objects usually created using processing.Pipe() -- see also Listener and Clients.

Connection objects have the following methods:

send(obj)

Send an object to the other end of the connection which should be read using recv().

The object must be picklable.

recv()

Return an object sent from the other end of the connection using send(). Raises EOFError if there is nothing left to receive and the other end was closed.

fileno()

Returns the file descriptor or handle used by the connection.

close()

Close the connection.

This is called automatically when the connection is garbage collected.

poll(timeout=0.0)

Return whether there is any data available to be read within timeout seconds.

If timeout is None then an infinite timeout is used.

Unlike the other blocking methods on Windows this method can be interrupted by Ctrl-C.

sendBytes(buffer)

Send byte data from an object supporting the buffer interface as a complete message.

Can be used to send strings or a view returned by buffer().

recvBytes()

Return a complete message of byte data sent from the other end of the connection as a string. Raises EOFError if there is nothing left to receive and the other end was closed.

recvBytesInto(buffer, offset=0)

Read into buffer at position offset a complete message of byte data sent from the other end of the connection and return the number of bytes in the message. Raises EOFError if there is nothing left to receive and the other end was closed.

buffer must be an object satisfying the writable buffer interface and offset must be non-negative and less than the length of buffer (in bytes).

If the buffer is too short then a BufferTooShort exception is raised and the complete message is available as e.args[0] where e is the exception instance.

For example:

>>> from processing import Pipe
>>> a, b = Pipe()
>>> a.send([1, 'hello', None])
>>> b.recv()
[1, 'hello', None]
>>> b.sendBytes('thank you')
>>> a.recvBytes()
'thank you'
>>> import array
>>> arr1 = array.array('i', range(5))
>>> arr2 = array.array('i', [0] * 10)
>>> a.sendBytes(arr1)
>>> count = b.recvBytesInto(arr2)
>>> assert count == len(arr1) * arr1.itemsize
>>> arr2
array('i', [0, 1, 2, 3, 4, 0, 0, 0, 0, 0])