1LSQUIC Documentation
2====================
3
4This is the documentation for LSQUIC_ |release|, last updated |today|.
5
6LiteSpeed QUIC (LSQUIC) Library is an open-source implementation of QUIC
7and HTTP/3 functionality for servers and clients.  LSQUIC is:
8
9- fast;
10
11- flexible; and
12
13- production-ready.
14
15Most of the code in this distribution has been  used in our own products
16-- `LiteSpeed Web Server`_, `LiteSpeed Web ADC`_, and OpenLiteSpeed_ --
17since 2017.
18
19Currently supported QUIC versions are v1, Internet-Draft versions 29, and 27;
20and the older "Google" QUIC versions Q043, Q046, an Q050.
21
22LSQUIC is licensed under the `MIT License`_; see LICENSE in the source
23distribution for details.
24
25Features
26--------
27
28LSQUIC supports nearly all QUIC and HTTP/3 features, including
29
30- DPLPMTUD
31- ECN
32- Spin bits (allowing network observer to calculate a connection's RTT)
33- Path migration
34- NAT rebinding
35- Push promises
36- TLS Key updates
37- Extensions:
38
39 - :ref:`extensible-http-priorities`
40 - :ref:`apiref-datagrams`
41 - Loss bits extension (allowing network observer to locate source of packet loss)
42 - Timestamps extension (allowing for one-way delay calculation, improving performance of some congestion controllers)
43 - Delayed ACKs (this reduces number of ACK frames sent and processed, improving throughput)
44 - QUIC grease bit to reduce ossification opportunities
45
46Architecture
47------------
48
49The LSQUIC library does not use sockets to receive and send packets; that is handled by the user-supplied callbacks.  The library also does not mandate the use of any particular event loop.  Instead, it has functions to help the user schedule events.  (Thus, using an event loop is not even strictly necessary.)  The various callbacks and settings are supplied to the engine constructor.
50LSQUIC keeps QUIC connections in several data structures in order to process them efficiently.  Connections that need processing are kept in two priority queues: one holds connections that are ready to be processed (or "ticked") and the other orders connections by their next timer value.  As a result, no connection is processed needlessly.
51
52.. _LSQUIC: https://github.com/litespeedtech/lsquic
53.. _`MIT License`: http://www.opensource.org/licenses/mit-license.php
54.. _`LiteSpeed Web Server`: https://www.litespeedtech.com/products/litespeed-web-server/
55.. _`LiteSpeed Web ADC`: https://www.litespeedtech.com/products/litespeed-web-adc/
56.. _OpenLiteSpeed: https://openlitespeed.org/
57
58Contents
59--------
60
61.. toctree::
62   :maxdepth: 2
63
64   gettingstarted
65   tutorial
66   apiref
67   devel
68   internals
69   faq
70
71Indices and tables
72==================
73
74* :ref:`genindex`
75* :ref:`search`
76