RecordStream

RecordStream interface for SeisComP.

Description

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

Name

URL Scheme(s)

Description

ArcLink

arclink

Connects to an ArcLink server

Balanced

balanced

Distributes requests to multiple proxy streams

CAPS

caps, capss

Connects to a gempa CAPS server

Combined

combined

Combines archive and real-time stream

Decimation

dec

Decimates (downsamples) a proxy stream

FDSNWS

fdsnws, fdsnwss

Connects to FDSN web service

File

file

Reads records from file

Memory

memory

Reads records from memory

Resample

resample

Resamples (up or down) a proxy stream to a given sampling rate

SDSArchive

sdsarchive

Reads records from SeisComP archive (SDS)

SeedLink

slink

Connects to SeedLink server

Application

The RecordStream parameters considered by an application are provided as a URL in 2 alternative ways:

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

  • Configuration of the URL using the global parameter recordstream.

The URL scheme defines the specific RecordStream implementation. If the scheme is omitted, the File implementation is used as default.

Note

Older SeisComP versions used to split the URL into the parameters recordstream.service and recordstream.source. These parameters are deprecated and will be removed in future versions.

Implementations

FDSNWS

This RecordStream fetches data from a FDSN web service.

Definition

URL: fdsnws[s]://host[:port][path]

The host is a mandatory parameter. The default port depends on the URL scheme used:

  • fdsnws: 80 (HTTP)

  • fdsnwss: 443 (HTTPS)

The default path is set to /fdsnws/dataselect/1/query. If a path is specified, it needs to be complete up until the query resource.

Authentication via the queryauth resource is currently not supported.

Examples

  • fdsnws://service.iris.edu

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

  • fdsnwss://geofon.gfz-potsdam.de

File

This RecordStream reads data from a file.

Definition

URL: file://path

The path may be a absolute or relative path to a file. Environment variables are not resolved. If path 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, then the record type is set as follows:

Extension

Record Type

*.xml

xml

*.bin

binary

*.mseed

mseed

Examples

  • file://-

  • file:///tmp/input.mseed

SDSArchive

This RecordStream reads data from one or more SeisComP (SDS) archives using the File RecordStream.

Definition

URL: sdsarchive://[path[,path2[, ...]]]

The default path is set to $SEISCOMP_ROOT/var/lib/archive.

In contrast to a formal URL definition, the URL path is interpreted as a directory path list separated by commas.

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.

Examples

  • sdsarchive://

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

  • sdsarchive:///SDSA,/SDSB,/SDSC

CAPS

This RecordStream reads data from a gempa CAPS server.

Definition

URL: caps[s]://[user:pass@][host[:port]][?parameters]

The default host is set to localhost. The default port depends on the URL scheme used:

  • caps: 18002

  • capss: 18022 (SSL)

Optional URL encoded 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 - Deprecated: The user name of an authenticated request. Please use

    the standard URL userinfo in front of the host instead.

  • pwd - Deprecated: The password of an authenticated request. Please use

    the standard URL userinfo in front of the host instead.

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

Example

  • caps://

  • caps://localhost:18002

  • capss://localhost:18022

  • caps://localhost:18002?arch

  • capss://user:mysecret@localhost

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:

Definition

URL-like: 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 definition of the proxy streams has slightly changed: Scheme and source are only separated by a slash, e.g. slink://localhost needs to be defined as slink/localhost.

The URL 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 hard disks. See also the examples.

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

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

Examples

URL

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)

Definition

URL-like: balanced://proxy-stream[;proxy-stream2[; ...]]

The definition of the proxy streams has slightly changed: Scheme and source are only separated by a slash, e.g. slink://localhost needs to be defined as slink/localhost.

Examples

URL

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 (downsamples) a proxy stream, e.g. SeedLink.

Definition

URL-like: dec://proxy-stream-scheme[?dec-parameters]/[proxy-stream-source]

The definition of the proxy streams has slightly changed: Scheme and source are only separated by a slash, e.g. slink://localhost needs to be defined as slink/localhost. Also optional decimation parameters directly follow the proxy stream scheme.

Optional decimation parameters are:

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

  • fp - default: 0.7

  • fs - default: 0.9

  • cs - coefficient scale, default: 10

Examples

  • 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.

Definition

URL-like: resample://proxy-stream-scheme[?dec-parameters]/[proxy-stream-source]

The definition of the proxy streams has slightly changed: Scheme and source are only separated by a slash, e.g. slink://localhost needs to be defined as slink/localhost. Also optional decimation parameters directly follow the proxy stream scheme.

Optional resample 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

  • resample://slink/localhost:18000

  • resample://file?rate=2/-

  • resample://combined/;