arclink_fetch

May 2020: Arclink service will soon be shut down at GFZ and elsewhere. Arclink has been removed from SeisComP versions ≥ 4.0.0. Use fdsnws_fetch instead of this client. This page is preserved for historical interest only.

arclink_fetch is a more sophisticated client that can be used to get data with a single command. It performs routing automatically, and can conveniently handle encryption. When you install SeisComp3 it is automatically installed on your computer together with SeisComp3, but it may also be installed as a standalone package for users wishing only to request data from an ArcLink server.

You can get a stand alone version of ArcLink fetch client here. After downloading the package appropriate for your system you can read more about the installation at one of these links:

Please use these instructions carefully, and you use them at your own risk.

License

arclink_fetch is a subpackage of SeisComP released under GNU General Public License. 

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

Contact the authors as described here.

Command line options

--version
Show program’s version number and exit
-h, --help
Show this help message and exit
-l, --longhelp
Show a long help message describing the input file format for the requests and about the password file (-w option). Also presents a short description of the ArcLink protocol.
-v
Increase verbosity level
-q
Decrease verbosity level
-a ADDRESS, --address=ADDRESS
Address of primary ArcLink node (default webdc.eu:18001)
-f REQUEST_FORMAT, --request-format=REQUEST_FORMAT
Request format: breqfast, native (default native)
-k DATA_FORMAT, --data-format=DATA_FORMAT
Data format: mseed, mseed4k, fseed, dseed, inv[entory] (default mseed)
-o OUTPUT_FILE, --output-file=OUTPUT_FILE
Local file where downloaded data is to be written to
-u USER, --user=USER
User’s e-mail address
-n, --no-resp-dict
Avoid using response dictionary (default False)
-g, --rebuild-volume
Rebuild SEED volume (default False)
-p, --proxy
Proxy mode, no routing (default False)
-t TIMEOUT, --timeout=TIMEOUT
Timeout in seconds (default 300)
-x RETRIES, --retries=RETRIES
Download retries (default 5)
-w SSLPASSWORDFILE, --password-file=SSLPASSWORDFILEUSER
The file containing passwords used for decryption of encrypted data (default dcidpasswords.txt).

MiniSeed reblocking

The mseed4k data format (-k mseed4k) enables a client side re-blocking of the received MiniSeed records from the server to a default block size of 4096. This is especially important when you are downloading data from two different networks that were archived with different block sizes and would like to receive a uniform (in terms of block size) MiniSeed file.

Some programs have problems to proper display miniseed packages with different block sizes on the same file. This issue can be avoided by instead of requesting MiniSeed data directly (-k mseed), just request re-blocked MiniSeed (-k mseed4k).

Rebuilding SEED volume

If -g option is used in combination with fseed data format (-k fseed), then instead of full SEED, inventory and Mini-SEED is requested; full SEED volume is created from inventory and Mini-SEED data locally. In this case, waveform data from multiple datacenters can be merged into one SEED volume.

Examples

Example of a request file named “req.txt”: 

2010,02,18,12,00,00 2010,02,18,12,10,00 GE WLF BH*
2010,02,18,12,00,00 2010,02,18,12,10,00 GE VSU BH*

Submit the request in req.txt to the ArcLink server on st55, and download full SEED data to req.mseed. 

> arclink_fetch -a st55:18002 -k fseed -g -u andres@gfz-potsdam.de -o req.mseed -v req.txt
requesting inventory from st55:18002
requesting routing from st55:18002
launching request thread (st55:18002)
st55:18002: request 41 ready
launching request thread (st14:18002)
st14:18002: request 39 ready
the following data requests were sent:
GFTEST55
Request ID: 41, Label: , Type: WAVEFORM, Args: compression=bzip2 format=MSEED
Status: READY, Size: 37137, Info:
  Volume ID: GFTEST, Status: OK, Size: 37137, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE WLF BHN .
    Status: OK, Size: 15360, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE WLF BHE .
    Status: OK, Size: 15360, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE WLF BHZ .
    Status: OK, Size: 15872, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE VSU BHN .
    Status: NODATA, Size: 0, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE VSU BHZ .
    Status: NODATA, Size: 0, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE VSU BHE .
    Status: NODATA, Size: 0, Info:
GFTEST
Request ID: 39, Label: , Type: WAVEFORM, Args: compression=bzip2 format=MSEED
Status: READY, Size: 46269, Info:
  Volume ID: GFTEST, Status: OK, Size: 46269, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE VSU BHN .
    Status: OK, Size: 17408, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE VSU BHZ .
    Status: OK, Size: 16896, Info:
    Request: 2010,2,18,12,0,0 2010,2,18,12,10,0 GE VSU BHE .
    Status: OK, Size: 17408, Info:
rebuilding SEED volume

Note that part of the request was routed to secondary server after the primary server returned NODATA.

You can read more about the req.txt (request) file format here.

Install Notes

Linux

For installing arclink_fetch onto your system please just choose the appropriate file (deb or rpm) for your system, and you should be able to install it without any problems by just double-clicking the file at the file browser on any modern Linux distribution. Note that during installation you could be asked to install additional packages as dependency, just accept.

MacOs

For installing arclink_fetch on your Mac you can decompress the file provided into the /usr/local folder. By default this folder doesn't exist and should be created. For doing that: 

su - #Your admin/root password will be asked
cd /usr
mkdir -p local
cd local
tar xvf <path to>/arclink-fetch.tar
 or (if your browser didn't decompress the file)
tar xvzf <path to>/arclink-fetch.tar.gz

Please also note that for this to work you should have installed Python on your Mac. For checking just type python on the command line and you should get something like: 

mbianchi@sec24c79:~> python
Python 2.7 (r27:82500, Aug 07 2010, 16:54:59) [GCC] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>

We have tested it with MacOs 10.6 and python 2.6 and it worked fine. Also, if you want to be able to decrypt encrypted volumes you should also install the M2Crypto egg file into your python using the following command: 

easy_install M2Crypto-0.21.1-py2.6-macosx-10.6-universal.egg
Windows

To come ...