asynchat.async_chat

class asynchat.async_chat

This class is an abstract subclass of asyncore.dispatcher. To make practical use of the code you must subclass async_chat, providing meaningful collect_incoming_data() and found_terminator() methods. The asyncore.dispatcher methods can be used, although not all make sense in a message/response context.

Like asyncore.dispatcher, async_chat defines a set of events that are generated by an analysis of socket conditions after a select() call. Once the polling loop has been started the async_chat object’s methods are called by the event-processing framework with no action on the part of the programmer.

Two class attributes can be modified, to improve performance, or possibly even to conserve memory.

ac_in_buffer_size

The asynchronous input buffer size (default 4096).

ac_out_buffer_size

The asynchronous output buffer size (default 4096).

Unlike asyncore.dispatcher, async_chat allows you to define a first-in-first-out queue (fifo) of producers. A producer need have only one method, more(), which should return data to be transmitted on the channel. The producer indicates exhaustion (i.e. that it contains no more data) by having its more() method return the empty bytes object. At this point the async_chat object removes the producer from the fifo and starts using the next producer, if any. When the producer fifo is empty the handle_write() method does nothing. You use the channel object’s set_terminator() method to describe how to recognize the end of, or an important breakpoint in, an incoming transmission from the remote endpoint.

To build a functioning async_chat subclass your input methods collect_incoming_data() and found_terminator() must handle the data that the channel receives asynchronously. The methods are described below.