python-ew 2.1.4

Allow reading from and writing to Earthworm shared memory ring buffers.

python-ew

This is a 2019 updating of the PythonEw Python 2.x compatible modules by OSOP to work with Python 3.x

python-ew is a Python wrapper for accessing a Earthworm shared memory rings, allowing you to extend the Earthworm system with Python code.

Earthworm itself is a set of open source programs, tools and libraries that are used in the development of software for maintaining seismic networks, research and other seismological and geophysical applications.

Supported message types:

• TYPE_HEARTBEAT: python_ew.HeartBeatRing
• TYPE_STATUS: python_ew.StatusRing, python_ew.StatusMessage
• TYPE_TRACEBUF2: python_ew.Tracebuf2Ring, python_ew.Tracebuf2Message

Installation

In order to install python-ew, you need to have first installed Earthworm itself. This module builds successfully on Linux against earthworm-7.9 compiled with EWBITS=64 and with "-m64 -fPIC" added to GLOBALFLAGS in ${EW_HOME}/environment/ew_linux.bash. Your milage may vary for other versions of Earthworm, or on other platforms.

To compile the python-ew C extensions, we need to find the Earthworm .o and .h files. We'll look in the following places:

Libraries:

• ${EW_HOME}/lib
• ${EW_HOME}/earthworm_7.9/lib

Include files:

• ${EW_HOME}/include
• ${EW_HOME}/earthworm_7.9/include

Thus, ensure that the EW_HOME environment variable is set apporpriately.

Then:

pip install python-ew

Example usage

Reading TRACEBUF2 messages

Let's say your ring with TYPE_TRACEBUF2 messages is named WAVE_RING, and you want to get all messages regardless of what module created them:

> python3
>>> from python_ew import Tracebuf2Ring
>>> ring = Tracebuf2Ring('WAVE_RING', 'MOD_WILDCARD')
>>> messages = ring.read()
>>> messages[0]
{'pinno': 0, 'nsamp': 100, 'starttime': 1564770703.968393, 'endtime': 1564770704.958393, 'samprate': 100.0, 'sta': 'FOO', 'net': 'XX', 'chan': 'HNN', 'loc': '--', 'version': '20', 'datatype': 'i4', 'quality': '', 'pad': '', 'samples': [-22129, -22130, -22131, -22132, -22129, -22130, -22128, -22128, -22130, -22128, -22130, -22128, -22128, -22129, -22129, -22129, -22129, -22130, -22127, -22128, -22129, -22128, -22128, -22130, -22131, -22128, -22131, -22131, -22128, -22128, -22132, -22130, -22125, -22128, -22129, -22126, -22128, -22130, -22133, -22132, -22131, -22132, -22130, -22131, -22128, -22129, -22132, -22127, -22129, -22129, -22129, -22132, -22130, -22127, -22129, -22131, -22127, -22128, -22131, -22128, -22128, -22130, -22129, -22130, -22129, -22128, -22133, -22128, -22129, -22133, -22131, -22130, -22128, -22131, -22130, -22128, -22132, -22132, -22129, -22127, -22129, -22132, -22130, -22132, -22133, -22128, -22129, -22130, -22129, -22130, -22128, -22129, -22130, -22131, -22130, -22128, -22129, -22130, -22129, -22129]}