The ET or Event Transfer system is used to transfer "events" (data buffers) between different user processes using shared memory. It's designed for speed and reliability. Remote access to ET system data is possible over TCP sockets as well.
ET is written for use in either C or Java programming environments.
Documentation on GitHub:
Software Library Documentation:
To build C code from this repository:
git clone https://github.com/JeffersonLab/et/
cd et; mkdir build
cmake -S . -B build
cmake --build build --target install --parallel
Note that during the cmake configure step (first of two cmake commands above), one can
toggle the following special flag:
-
MAKE_EXAMPLES: build example/test programs (default-DMAKE_EXAMPLES=0) -
CODA_INSTALL: installs in this base directory. If not used, then the env variable$CODA location is next checked. Otherwise defaults to $ {CMAKE_HOST_SYSTEM_NAME}-${CMAKE_HOST_SYSTEM_PROCESSOR}, typically something like[evio_directory]/Linux-x86_64.
C 11 or higher and cmake. Compilation can be done using clang or gcc (gcc 11 or higher recommended). Java 8 or higher is needed if compiling the library et_jni (used to speed up the Java interface, recommended but not required).
The Java version of et (internally org.jlab.coda.et) can also be used for the same process-to-process copying of data. A "fat" jar file with all dependencies is included in the java/jars folder, the only thing strictly required to run and execute et in Java.
Java 17 is the default version used, however the Java et library should be compatible with all Java versions 8 and higher. If one wants to create a new jar file for any reason (e.g. to modify Java versions), do:
git clone https://github.com/JeffersonLab/evio/
cd evio
mvn clean install
It was written by Carl Timmer of the Data Acquisition group of the Thomas Jefferson National Accelerator Facility.
This software runs on Linux and Mac OSX. VxWorks is no longer supported in this version.
The jni.h and jni_md.h header files supplied with the java JDK have lived in different places over the years. These are needed for compilation. The best way to facilitate that is to set your JAVA_HOME environment variable so that these includes can be found. These days the Oracle Java is placed so that you need to do a:
setenv JAVA_HOME /Library/Java/JavaVirtualMachines/<jdk_dir>/Contents/Home
where <jdk_dir> is the directory in which your specific java distribution lives. This package assumes the header files are found in $JAVA_HOME/include and in $JAVA_HOME/include/darwin.
There is a java-based GUI to monitor ET systems graphically. It can connect to ET processes, whether they were started using C binaries or in Java.
It can be started by executing the script:
scripts/etmonitor
See
For any issues regarding use and copyright, read the license file.