How to write your DAQModule

This page contains a starting point to write a new DAQ Module compatible withe operation of the application framework.

Code

From the C++ point of view, DAQ modules are implementation of a DAQ Module interface. That means that apart from the constructor (that receives a name) only one method has to be implemented: init().
The function has to handle all those configuration items that are not supposed to be reconfigurable during the run. Optionally it can configure all those variables that can be overridden during run time.

The most important thing that init has to do is to call register_command in order to associate functions to each command that the module is expected to support. Each function has to be a set of operations that changes the internal status of the module according to the command that it is implementing. The prototype of each function is in the form

void do_something( const vector<string> & args ) ;

The function can be virtual and the system is able to pick the most downstream specification.

Assuming that the name of the module you are developing is MyNewDAQModule a call to associate the command "start" to a function called do_start will be

register_command("start",  & MyNewDAQModule::do_start);

It is expected that the operations of the DAQ Module are carried on in other threads under the control of the DAQModule itself.

Good practices

Every piece of code that is related to the application framework will be part of a large suite of software that will require long term maintenance and support given the long lifetime of the DUNE experiment. It is important that the style guide is respected.

Compilation

DAQModules need to be created with a factory pattern simply via their name. In the application framework this is dune using CETlib. In order to do that, each implementation (cpp file) needs to have a call to the macro DEFINE_DUNE_DAQ_MODULE(<name_including_namespace>) for example

DEFINE_DUNE_DAQ_MODULE(dunedaq::appfwk::DummyModule)

In order to generate a shared object library that is linkable in runtime from the application framework, the name of the library has to be the in the form <package>_<module_name_no_namespace>_duneDAQModule. This can be achieved simply adding a line in the CMakeLists.txt file of your project in the form add_library(<package>_<module_name_no_namespace>_duneDAQModule path/to/my/file.cpp). For example:

add_library(appfwk_DummyModule_duneDAQModule test/DummyModule.cpp)