MEREDIAN - Java SeedLink development
Anthony Lomax
Anthony Lomax Scientific Software, Mouans-Sartoux, France
SeedLink is the realtime communications component of the Seismological Communication
Processor (SeisComP).
The recently completed MEREDIAN - Java SeedLink project provides
end-user and development software for interaction with SeedLink servers
over the Internet. The project components are:
- JSeedLink -
Implementation in Java of the existing C library libslink and
the example program slclient.c (in Java: SLClient) to
provide a basic class library for development of Java programs that
interact with SeedLink servers. This development includes most
of the components of libslink and adds SeedLink INFO
packet support with parsing of XML into a Java "InfoPacket" data structure.
- SeisGram2K SeedLink Monitor -
Incorporation of the new Java SeedLink classes into the existing Java
visualisation and analysis program SeisGram2K to allow reading of multiple
stations and channels from one or more SeedLink servers on TCP/IP
(locally or over the Internet) for continuous, monitor-type display of near-real-time data.
- QuakeExplorer SeedLink Support -
Extends the existing QuakeExplorer browser to support connection to a
SeedLink server, viewing of parametric information, and selection and display of near-realtime streams with
SeisGram2K SeedLink Monitor.
The MEREDIAN - Java
SeedLink development was performed by Anthony Lomax of Anthony Lomax Scientific Software.
Further information, documentation and download instructions are
available at: http://alomax.net/projects/seedlink
JSeedLink is a set of Java packages (nl.knmi.orfeus,
nl.knmi.orfeus.seedlink, nl.knmi.orfeus.seedlink.client)
and documentation which simplify the development in Java of applications
that interact with SeedLink servers. These Java packages
reproduce most of the C library libslink and include a Java
version (nl.knmi.orfeus.SLClient) of the utility program slclient.c
from libslink.
JSeedLink also includes classes for SeedLink INFO packet support
through parsing of XML into a Java org.dom4j.Document data
structure (class nl.knmi.orfeus.seedlink.XMLParser).
SeisGram2K is an easy-to-use,
platform-independent, Java program for interactive visualization and
analysis of earthquake seismograms. SeisGram2K runs and reads data files
locally and over the Internet. In the new SeedLink Monitor
mode, SeisGram2K connects to one or more SeedLink
servers, requests one or more data streams, and appends and displays
new data packets as they are received in near-realtime. The
display updates each second to maintain the right edge of the display
at the current real-time. A status panel to the left of each
trace group show the data (Lf) and feed (Lf) latency with configurable
colors for different latency time limits. (Figure 1).
Figure 1. The SeisGram2K SeedLink Monitor displaying
3-component trace sets from 4 stations in near-realtime from SeedLink servers over the Internet.
QuakeExplorer
QuakeExplorer is a
browser for earthquake seismology: it is an interactive tool for easy
and rapid searching, visualisation and analysis of earthquake events
and associated seismic traces over the Internet. For
visualisation, QuakeExplorer launches the Java applications
SeismicityViewer and
SeisGram2K. New extensions to
QuakeExplorer support
a) connection to a SeedLink server to view parametric network, station and
stream information, b) display, sorting and selection of available streams, and c) continuous, near-realtime
display of selected streams with SeisGram2K SeedLink Monitor (Figure 2).
Figure 2. QuakeExplorer displaying parametric information from a SeedLink server (left frame) and a sortable table of
available streams (right). One or more streams can be selected
and displayed in a SeisGram2K SeedLink monitor.
If you are interested in a ready-to-use application for monitoring or analysing near-realtime
seismic streams that are available on a SeedLink server (to which you have connection
permission) and a) if you wish one-time viewing or script controlled startup,
try the SeisGram2K SeedLink Monitor, or b) if you wish interactive examination of
parametric information and streams, and interactive selection of the streams to display, try
QuakeExplorer. If you are interested in
command line recovery of basic parametric information or data streams
from a SeedLink Server, try the SLClient Java utility. If you
are interested in developing Java software for interacting with a SeedLink server, take a
look at the JSeedLink packages and their
documentation.
Further information, documentation and download instructions are
available at: http://alomax.net/projects/seedlink
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