RecordStream

RecordStream interface for SeisComP.

Description

SeisComP applications access waveform data through the RecordStream interface. The following tables lists available implementations:

Name	Service Prefix	Description
SeedLink	slink	Connects to SeedLink server
ArcLink	arclink	Connects to an ArcLink server
FDSNWS	fdsnws	Connects to FDSN Web service
File	file	Reads records from file
SDSArchive	sdsarchive	Reads records from SeisComP archive (SDS)
CAPS	caps, capss	Connects to a gempa CAPS server
Memory	memory	Reads records from memory
Combined	combined	Combines archive and real-time stream
Balanced	balanced	Distributes requests to multiple proxy streams
Decimation	dec	Decimates (resamples) a proxy stream
Resample	resample	Resamples (up or down) a proxy stream to a given sampling rate

Application

The RecordStream parameters considered by an application can be provided like a URI in 2 alternative ways:

• Specification of the URI on the command line. Use the option -I URI

• Configuration of the URI using the global parameters. Adjust either:

  • the URI in recordstream or

  • the URI separated into recordstream.service and recordstream.source.

Implementations

SeedLink

This RecordStream fetches data from a SeedLink server. The source is read as an URL and supports URL encoded parameters. The default host is set to localhost, the default port to 18000. Optional parameters are:

• timeout - connection timeout in seconds, default: 300

• retries - number of connection retry attempts, default: 0

• no-batch - disables BATCH mode to request data, does not take a value

Examples

URI: service://source?options

• slink://

• slink://geofon.gfz-potsdam.de?timeout=60&retries=5

• slink://localhost:18000

ArcLink

This RecordStream fetches data from a ArcLink server. The source is read as an URL and supports URL encoded parameters. The default host is set to localhost, the default port to 18001. Optional parameters are:

• user - user name required on some servers

• pwd - password required on some servers

• dump - optional output file for all records being received

Examples

URI: service://source?options

• arclink://

• arclink://geofon.gfz-potsdam.de?user=foo&pwd=secret

• arclink://localhost:18042

• arclink://localhost?dump=test.mseed

FDSNWS

This RecordStream fetches data from a FDSN Web service. The source is read as an URL.

Examples

URI: service://source?options

• fdsnws://service.iris.edu:80/fdsnws/dataselect/1/query

File

This RecordStream reads data from a file. The source is read as an file path. If the source is set to ‘-‘ the data is read from stdin. By default the record type is set to mseed. If a file name extension is available the record type is set as follows:

Extension	Record Type
*.xml	xml
*.bin	binary
*.mseed	mseed

Examples

URI: service://source

• file://-

• file:///tmp/input.mseed

SDSArchive

This RecordStream reads data from one or more SeisComP (SDS) archives using the File RecordStream. The source is interpreted as a directory path list separated using commas.

Example

URI: service://source

• sdsarchive:///home/sysop/seiscomp/var/lib/archive

• sdsarchive:///SDSA,/SDSB,/SDSC

Different SDS are not merged, but are read sequentially depending on data existence. If a requested file is missing in the current SDS, it is searched for in the archive next in the list. On success it will deliver all the rest of files for the current channel from this SDS archive. On failure the next SDS archive is searched.

This process is repeated for each requested channel individually. It always starts to search data from the first given SDS to the last one, for each data channel.

CAPS

This RecordStream reads data from a gempa CAPS server. The source is an URL. The default host is set to localhost, the default port to 18002 for unencrypted connections and 18022 for SSL connections. Optional parameters are:

• arch - No parameter. Retrieve only archived data. In this mode the connection

  finished when all available data has been sent. It won’t wait for additional real-time data.

• ooo - Allow out-of-order data

• timeout - The socket timeout in seconds

• user - The user name of an authenticated request

• pwd - The password of an authenticated request

• request-file - Use the given file to feed the request

The service can either be caps or capss. The latter establishes an SSL connection.

Example

URI: service://user:password@source?options

• caps://localhost:18002

• capss://localhost:18022

• caps://localhost:18002?arch

• caps://user:mysecret@localhost:18002

Memory

This RecordStream reads data from memory and is only useful for developing applications. For instance a record sequence stored in an internal buffer could be passed to an instance of this RecordStream for reading.

Combined

This RecordStream combines one archive and one real-time RecordStream, e.g. ArcLink and SeedLink. First the archive stream is read up to the size of the real-time buffer. Then the acquisition is switched to the real-time stream. The syntax for the source is similar to an URL:

URI: service://source??options

combined://real-time-stream;archive-stream??parameters

By default the real-time stream is set to SeedLink and the archive-stream is set to ArcLink. Any other streams may be configured. The parameters of the combined stream are separated by 2 question marks (??) in order to distinguish them from the parameters used in the proxy streams:

• slinkMax|rtMax|1stMax - Buffer size in seconds of the first stream (typically the real-time stream), default: 3600

  Time spans can be configured with an additional and optional suffix:

  Suffix	Multiplicator
  s	1
  m	60
  h	3600
  d	86400
  w	86400*7

• splitTime - The absolute time of the separation of both sources. The argument is an ISO time string, e.g. 2018-05-10T12:00:00Z or a year, e.g. 2018, which is the same as 2018-01-01T00:00:00.000Z. splitTime can be used if the waveform archives are spread over several directories or harddisks. See also the examples.

The combined record stream may be nested allowing the configuration of a (theoretically) infinite number of archive streams. The URI syntax for a nested configuration uses parenthesis:

combined://real-time-stream;combined/(archive-stream1;archive-stream2??parameters)??parameters

Examples

URI: service://source?options

URI	Description
combined://localhost:18000;localhost:18001	Seedlink on localhost:18000 combined with Arclink on localhost 18001
combined://slink/localhost:18000;arclink/localhost:18001	Same as above
combined://;	Same as above
combined://:18042;?user=foo&pwd=secret??rtMax=1800	Seedlink on localhost:18042 combined with Arclink on localhost 18001, real-time (SeedLink) buffer size set to 30min
combined://slink/localhost:18000;sdsarchive//home/sysop/seiscomp/var/lib/archive	Seedlink combined with SDS archive
combined://slink/localhost:18000;combined/(arclink/localhost:18001;arclink/localhost:18002??1stMax=30d)??1stMax=1h	Seedlink combined with a combined record stream using two Arclink sources
combined://slink/localhost:18000;combined/(sdsarchive//home/sysop/seiscomp/var/lib/archive;combined/(sdsarchive//home/sysop/seiscomp/var/lib/archive2017;sdsarchive//home/sysop/seiscomp/var/lib/archive2016??splitTime=2017)??splitTime=2018)	Seedlink combined with a combined recordStream providing access to 3 different SDS archives separated by time. The first SDS archive contains the most recent archived data. The other two contain the data from 2016 and 2017.
combined://slink/localhost:18000;combined/(sdsarchive//home/sysop/seiscomp/var/lib/archive;combined/(sdsarchive//home/sysop/seiscomp/var/lib/archive2017;sdsarchive//home/sysop/seiscomp/var/lib/archive2016??splitTime=2017-06-01T00:00:00Z)??splitTime=2018-06-01T00:00:00Z)	Seedlink combined with a combined recordStream providing access to 3 different SDS archives separated by time. The first SDS archive contains the most recent archived data. The other two are separated in mid of 2016.

Balanced

This RecordStream distributes requests quasi-equally (but deterministically) to multiple proxy streams. It can be used for load balancing and to improve failure tolerance. The algorithm to choose a proxy stream (counting from 0) is based on station code and can be expressed in Python as follows:

stationCode = "WLF"
nproxies = 2

x = 0
for c in stationCode:
    x += ord(c)

print("choosing proxy stream", x % nproxies)

Examples

URI: service://source

URI	Description
balanced://slink/server1:18000;slink/server2:18000	Distribute requests to 2 SeedLink RecordStreams
balanced://combined/(server1:18000;server1:18001);combined/(server2:18000;server2:18001)	Distribute requests to 2 Combined RecordStreams

Decimation

This RecordStream decimates (resamples) a proxy stream, e.g. SeedLink. The syntax for the source is similar to an URL:

dec://proxy-stream?parameters/address

Optional parameters are:

• rate - target sampling rate in Hz, default: 1

• fp - default: 0.7

• fs - default: 0.9

• cs - coefficient scale, default: 10

Examples

URI: service://source?options

• dec://slink/localhost:18000

• dec://file?rate=2/-

• dec://combined/;

Resample

This RecordStream resamples (up or down) a proxy stream, e.g. SeedLink, to a given sampling rate. The syntax for the source is similar to an URL:

resample://proxy-stream?parameters/address

Optional parameters are:

• rate - target sampling rate in Hz, default: 1

• fp - default: 0.7

• fs - default: 0.9

• cs - coefficient scale, default: 10

• lw - lanczos kernel width, default: 3

• debug - enables debug output, default: false

Examples

URI: service://source?options

• resample://slink/localhost:18000

• resample://file?rate=2/-

• resample://combined/;