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
Balanced	`balanced`	Distributes requests to multiple proxy streams
Routing	`routing`	Distributes requests to multiple proxy streams according to user defined rules
CAPS	`caps`, `capss`	Connects to a CAPS server [3]
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:

Configuration of the URL using the global parameter recordstream.
Specification of the URL on the command line. Use the option -I URL

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

Note

SeisComP in version < 5.0.0 used to split the URL into the parameters recordstream.service and recordstream.source. These parameters are not supported anymore.

Optional parameters may be given depending on the RecordStream implementation. The parameters are appended to the URL of the implementation by a _?_ except for the combined RecordStream.

Implementations¶

SeedLink¶

This RecordStream fetches data from a SeedLink 3.x server. It is referred to as slink.

Warning

Do not use slink for modules which must not read from real-time sources such as fdsnws.

Definition¶

URL: slink://[host][:port][?parameter]

The default host is set to localhost, the default port to 18000. Optional URL encoded parameters are:

timeout - connection timeout in seconds, default: 300
retries - number of connection retry attempts, default: -1
no-batch - disables BATCH mode to request data, does not take a value

Examples¶

slink://
slink://geofon.gfz.de?timeout=60&retries=5
slink://localhost:18000

SeedLink4¶

This RecordStream fetches data from a SeedLink 4.x server.

Definition¶

URL: slink4[s]://[host][:port][?parameter]

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

slink4: 18000
slink4s: 18500 (TLS)

Optional URL encoded parameters are:

timeout - connection timeout in seconds, default: 300
retries - number of connection retry attempts, default: -1
format - miniSEED format to request (2,3), default: any
fetch - close connection at end of data, default: false

Authentication is currently not supported.

Examples¶

slink4://
slink4://localhost:18000

FDSNWS¶

This RecordStream fetches data from a server offering FDSN web services, such as by the SeisComP fdsnws. See also FDSNWS [8] and FDSN data centers [6].

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.earthscope.org
fdsnws://service.earthscope.org:80/fdsnws/dataselect/1/query
fdsnwss://geofon.gfz.de

File¶

This RecordStream reads data from a file.

Definition¶

URL: file://path

The path may be an absolute or relative path to a file or stdin (-). SeisComP environment variables such as @DATADIR@ are resolved. If path is set to -, the data is read from stdin.

Supported files types are:

miniSEED
SAC
XML
binary

By default the record type is set to mseed. SAC data can be read using the #sac descriptor. If a file name extension is available, then the record type is set as follows:

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

Optional descriptor:

sac - input data are in SAC format.

Examples¶

Read data from miniSEED files

file:///tmp/input.mseed
file://@DATADIR@/input.mseed

Read data from stdin
```
file://-
```
where - refers to input of data from stdin
Read data from a file in SAC format
```
file:///tmp/input.sac#sac
```

Note

When defining the File RecordStream on the command line using the -I, the file name can also be passed without the URL scheme, e.g.

-I -
-I /tmp/input.mseed

Reading from stdin allows passing the data to a processing modules without intermediate storage to file. Example: A combination of scart with scautopick

scart -dsE -l list.txt | scautopick --playback --ep -d localhost -I -

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. SeisComP environment variables such as @ROOTDIR@ are resolved.

Note

When defining multiple directories separated by comma in a configuration file, please enclose the entire definition (including sdsarchive:// with double quotes. Otherwise the configuration parser will interpret it as a list and will only return the first part up to the first comma.

Different SDS archives are not merged, but are read sequentially depending on data existence. If a requested file is missing in the current SDS archive, 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. An alternative to searching the archives sequentially is to organize the different archives by unique time windows and then access them by the combined RecordStream using the splitTime parameter.

Examples¶

sdsarchive://
sdsarchive:///home/sysop/seiscomp/var/lib/archive
sdsarchive://@ROOTDIR@/var/lib/archive
"sdsarchive:///SDSA,/SDSB,/SDSC"
sdsarchive:///SDSA\,/SDSB\,/SDSC

Note

When different archives are configured the entire value must be enclosed by quotes or the comma must be protected by backslash as \,. Otherwise, the the value is interpreted as a list of RecordStreams and not as a single one with multiple archives.

CAPS¶

This RecordStream reads data from a CAPS server [3].

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.

Warning

Use arch for modules which must not read from real-time sources such as fdsnws.
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

Examples¶

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 real-time RecordStream and one archive, e.g. ref:rs-slink and FDSNWS. 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 a URL. Use ?? for parameters of the combined RecordStream instead of ?. In this way parameters my be added, e.g. for the archive RecordStream by ? followed by ?? for combined.

Note

Instead of an real-time RecordStream any other RecordStream can be used.

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 FDSNWS. Any other streams may be configured.

Warning

Do not use slink for modules which must not read from real-time sources such as fdsnws.

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. Optional URL encoded parameters are:

slinkMax, rtMax or 1stMax (all have identical meaning) - Buffer size in seconds of the first stream (typically a real-time stream). Default value: 3600.

Time spans can be configured with an additional and optional suffix (see examples below):

Suffix

Multiplier

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.

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

The combined RecordStream may be nested allowing the configuration of a (theoretically) infinite number of archive streams. Read the examples below. The URL syntax for a nested configuration uses parenthesis. ??parameters defines a parameter for the combined RecordStream:

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

Examples¶

Default: Seedlink on localhost:18000 combined with FDSNWS on standard port 80 (all examples result in identical requests)

combined://slink/localhost:18000;fdsnws/localhost:80
combined://slink/localhost:18000;fdsnws/localhost
combined://slink/localhost;
combined://;

Seedlink on localhost:18000 combined with SDS archive

combined://localhost:18000;sdsarchive/@ROOTDIR@/var/lib/archive

Seedlink on localhost:18000 combined with FDSNWS on default port 8080
```
combined://slink/localhost:18000;fdsnws/localhost:8080
```
Seedlink on localhost:18042 combined with SDS archive, real-time (SeedLink) buffer size set to 1800 seconds instead of the default
```
combined://:18042;sdsarchive/@ROOTDIR@/var/lib/archive??rtMax=1800
```

Seedlink combined with a combined record stream using one SDS and one FDSNWS source

combined://slink/localhost:18000;combined/(sdsarchive/@ROOTDIR@/var/lib/archive;fdsnws/remote-host:80??1stMax=30d)??1stMax=1h

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/@ROOTDIR@/var/lib/archive;combined/(sdsarchive/@ROOTDIR@/var/lib/archive2017;sdsarchive/@ROOTDIR@/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 are separated in mid of 2016.

combined://slink/localhost:18000;combined/(sdsarchive/@ROOTDIR@/var/lib/archive;combined/(sdsarchive/@ROOTDIR@/var/lib/archive2017;sdsarchive/@ROOTDIR@/var/lib/archive2016??splitTime=2017-06-01T00:00:00Z)??splitTime=2018-06-01T00:00:00Z)

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¶

Distribute requests to 2 SeedLink RecordStreams

balanced://slink/server1:18000;slink/server2:18000

Distribute requests to two Combined RecordStreams

balanced://combined/(server1:18000;server1:18001);combined/(server2:18000;server2:18001)

Routing¶

This RecordStream distributes requests to multiple proxy streams according to user supplied routing rules, which allow to route specific network, station, location or channel codes to fixed proxy streams.

Definition¶

URL-like: routing://proxy-stream??match=pattern[;proxy-stream2??match=pattern[; ...]]

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 routing stream are separated by 2 question marks (??) in order to distinguish them from the parameters used in the proxy streams.

pattern defines the rule used to route the request to the proxy stream and it is in NET.STA.LOC.CHA format. The special characters ? * | ( ) are allowed.

Examples¶

Requests for network NET1 and NET2 go to server1, all the rest to server2

routing://slink/server1:18000??match=(NET1|NET2).*.*.*;slink/server2:18000??match=*.*.*.*

Requests for network TMPX go to server1, for network NET go to server 2, all others are not fulfilled
```
routing://slink/server1:18000??match=TMP?.*.*.*;slink/server2:18000??match=NET.*.*.*
```

Requests for channels HH and EH go to server1, all the rest to server2

routing://slink/server1:18000??match=*.*.*.(HH|EH)?;slink/server2:18000??match=*.*.*.*

Split requests to 2 Combined RecordStreams according to the network code STA1 or STA2. Other network codes are not fulfilled

routing://combined/(server1:18000;server1:18001??rtMax=1800)??match=NET1.*.*.*;combined/(server2:18000;server2:18001??rtMax=1800)??match=NET2.*.*.

Requests for special network SP are fulfilled by seedlink special-server and sdsarchive @ROOTDIR@/var/lib/special-archive, all the rest are fulfilled by seedlink default-server and archive @ROOTDIR@/var/lib/default-archive
```
routing://combined/(slink/special-server:18000;sdsarchive/@ROOTDIR@/var/lib/special-archive)??match=SP.*.*.*;combined/(slink/default-server:18000;sdsarchive/@ROOTDIR@/var/lib/default-archive)??match=*.*.*.*
```

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/;

The last example considers defaults for the combined RecordStream.

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]

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/;

The last example considers defaults for the combined RecordStream.