.. _sec-quakelink-intro:

Introduction
************

QuakeLink was developed to exchange event data and Did-you-feel-it (DYFI)
reports where security, performance and reliability are a primary focus.

The **QuakeLink package is used for:**

- Exchanging event data and Did-you-feel-it (DYFI) reports between 2 or more
  :cite:t:`SeisComP` systems.
- Providing fast and secure access to event data via a web interface to external
  clients.
- Importing event parameters from external or local SeisComP systems, QuakeLink
  server or FDSNWS into a local SeisComP system or a QuakeLink server in real time.

.. figure:: media/quakelink_3systems.png
   :align: center
   :width: 10cm

   Secure parameter exchange between 3 SeisComP systems. The description is
   given in :ref:`quakelink-examples`.


Features
========

QuakeLink includes the following features:

- Exchange of SeisComP objects is triggered by event updates. No messages
  will be exchanged until the exporting SeisComP system has produced an event.
- Complete event parameter exchange including Events, Origins, Amplitudes, Picks
  and FocalMechanisms.
- Secure protocol solves security issues:

  - No access to local SeisComP by system foreigners.
  - User/password authentication including SSL.
  - Fined-grained access control lists including IP addresses, SeisComP object
    subsets and many more.

- Fast event access even to large databases.
- SQLite database for event indexing.
- No events are missed on downtime.
- Reduced bandwidth consumption through server-side filters.
- Fast event exchange in real-time or time window based.
- Full event log (replacement of scevtlog).
- Event archive file structure: :file:`2014/09/09/eventid/eventid.(N).xml.gz`.
- QuakeLink protocol with telnet interface.
- HTTP interface similar to FDSNWS (GET + POST).
- QuakeLink can be configured using :cite:t:`scconfig`.
- QuakeLink provides earthquake parameters to :program:`EQInfo`, an
  Android-based gempa App for customized earthquake information world-wide.
  EQInfo is freely available e.g. from `Google Play`_ or `App Store`_.


.. _quakelink-architecture-intro:

Architecture
============

QuakeLink provides quakelink, a :ref:`server<quakelink>` that collects data from
SeisComP systems using :ref:`QuakeLink plugins<sec-ql-plugins>`.
The data is stored in the database and provided to clients. The clients may be
other SeisComP systems, web browsers or other applications such as EQInfo.
:ref:`Frontend applications<sec-ql-plugins>` allow direct user-interaction with
the server and the database.

.. _fig-intro_architecture:

.. figure:: media/quakelink.png
   :align: center
   :width: 16cm

   QuakeLink architecture.


Downloads
=========

.. target-notes::

.. _`Google Play` : https://play.google.com/store/apps/details?id=de.gempa.android.eqinfo
.. _`App Store` : https://apps.apple.com/us/app/eqinfo/id1617064091