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 |
|---|---|---|
|
Connects to an ArcLink server |
|
|
Distributes requests to multiple proxy streams |
|
|
Connects to a gempa CAPS server |
|
|
Combines archive and real-time stream |
|
|
Decimates (downsamples) a proxy stream |
|
|
Connects to FDSN web service |
|
|
Reads records from file |
|
|
Reads records from memory |
|
|
Resamples (up or down) a proxy stream to a given sampling rate |
|
|
Reads records from SeisComP archive (SDS) |
|
|
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 URLConfiguration 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¶
SeedLink¶
This RecordStream fetches data from a SeedLink server.
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: 0
no-batch - disables BATCH mode to request data, does not take a value
Examples¶
slink://slink://geofon.gfz-potsdam.de?timeout=60&retries=5slink://localhost:18000
ArcLink¶
This RecordStream fetches data from a ArcLink server.
Definition¶
URL: arclink://[host][:port][?parameters]
The default host is set to localhost, the default port to 18001. Optional URL encoded 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¶
arclink://arclink://geofon.gfz-potsdam.de?user=foo&pwd=secretarclink://localhost:18042arclink://localhost?dump=test.mseed
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.edufdsnws://service.iris.edu:80/fdsnws/dataselect/1/queryfdsnwss://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.
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 |
mseed |
Optional descriptor:
sac - input data are in SAC format.
Examples¶
file://-file:///tmp/input.mseedfile:///tmp/input.sac#sac
Note
When defining the File RecordStream on the command line using the option -I, the file name can also be passed without the URL scheme, e.g.
-I -
-I /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/archivesdsarchive:///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:18002capss://localhost:18022caps://localhost:18002?archcapss://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 |
|---|---|
|
Seedlink on localhost:18000 combined with Arclink on localhost 18001 |
|
Same as above |
|
Same as above |
|
Seedlink on localhost:18042 combined with Arclink on localhost 18001, real-time (SeedLink) buffer size set to 30min |
|
Seedlink combined with SDS archive |
|
Seedlink combined with a combined record stream using two Arclink sources |
|
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. |
|
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.
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:18000dec://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:18000resample://file?rate=2/-resample://combined/;
