SeedLink

SeedLink is a TCP/IP-based data transmission protocol that allows near-real-time access to data from thousands of geophysical monitoring instruments. See data keywords list and channel id syntax for options.

seedlink!(S, mode, chans, KWs)

seedlink!(S, mode, chans, patts, KWs)

S = seedlink(mode, chans, KWs)

Initiate a SeedLink session in DATA mode to feed data from channels chans with selection patterns patts to SeisData structure S. A handle to a TCP connection is appended to S.c. Data are periodically parsed until the connection is closed. One SeisData object can support multiple connections, provided that each connection’s streams feed unique channels.

mode

SeedLink mode (“DATA”, “FETCH”, or “TIME”; case-sensitive).

chans

Channel specification can use any of the following options:

1. A comma-separated String where each pattern follows the syntax NET.STA.LOC.CHA.DFLAG, e.g. UW.TDH..EHZ.D. Use “?” to match any single character.

2. An Array{String,1} with one pattern per entry, following the above syntax.

3. The name of a configuration text file, with one channel pattern per line; see Channel Configuration File syntax.

patts

Data selection patterns. See official SeedLink documentation; syntax is identical.

Keywords

Shared Keywords

v, w

SeedLink Keywords

kw	def	type	meaning
gap	3600	R	a stream with no data in >gap seconds is considered offline
kai	600	R	keepalive interval (s)
port	18000	I	port number
refresh	20	R	base refresh interval (s) [1]
seq		S	Starting sequence hex value, like “5BE37A”
u	rtserve.iris.washington.edu	S	base SeedLink service URL, no “http://”
x_on_err	true	Bool	exit on error?

Table Footnotes

[1]	This value is a base value; a small amount is added to this number by each new SeedLink session to minimize the risk of congestion

Change these with SeisIO.KW.SL.[key] = value, e.g., SeisIO.KW.SL.refresh = 30.

Special Behavior

1. SeedLink follows unusual rules for wild cards in sta and patts:

   1. * is not a valid SeedLink wild card.
   2. The LOC and CHA fields can be left blank in sta to select all locations and channels.

2. DO NOT feed one data channel from multiple SeedLink connections. This leads to TCP congestion on your computer, which can have severe consequences:

   1. A channel fed by multiple SeedLink connections will have many small segments, all out of order. merge! might fix this if caught quickly, but with hundreds of disjoint segments, expect memory and CPU issues.
   2. Your SeedLink connection will probably reset.
   3. Julia may freeze, requiring kill -9. To the best of our knowledge Julia has no special handling to mitigate TCP congestion.
   4. Your data may be corrupted, including disk writes from w=true.

Special Methods

• close(S.c[i]) ends SeedLink connection i.
• !deleteat(S.c, i) removes a handle to closed SeedLink connection i.

SeedLink Utilities

SL_info(v, url)

Retrieve SeedLink information at verbosity level v from url. Returns XML as a string. Valid strings for L are ID, CAPABILITIES, STATIONS, STREAMS, GAPS, CONNECTIONS, ALL.

has_sta(sta[, u=url, port=n])

SL keywords: gap, port

Other keywords: u specifies the URL without “http://”

Check that streams exist at url for stations sta, formatted NET.STA. Use “?” to match any single character. Returns true for stations that exist. sta can also be the name of a valid config file or a 1d string array.

Returns a BitArray with one value per entry in sta.

has_stream(cha::Union{String, Array{String, 1}}, u::String)

has_stream(sta::Array{String, 1}, sel::Array{String, 1}, u::String, port=N::Int, gap=G::Real)

SL keywords: gap, port

Other keywords: u specifies the URL without “http://”

Check that streams with recent data exist at url u for channel spec cha, formatted NET.STA.LOC.CHA.DFLAG, e.g. “UW.TDH..EHZ.D, CC.HOOD..BH?.E”. Use “?” to match any single character. Returns true for streams with recent data. cha can also be the name of a valid config file.

If two arrays are passed to has_stream, the first should be formatted as SeedLink STATION patterns (SSSSS NN, e.g. [“TDH UW”, “VALT CC”]); the second should be an array of SeedLink selector patterns (LLCCC.D, e.g. [“??EHZ.D”, “??BH?.?”]).