The SmartDaqApplication class allows for automatic creation of modules and connections for a known application. The general pattern is that a SDA ingests a set of module configuration objects and connection rules and uses them to create a well-defined application with modules, internal connections, and external connections.

Writing a new SmartDaqApplication

SmartDaqApplications implement the std::vector<const confmodel::DaqModule*> generate_modules(const comnfmodel::Session*) method, which is responsible for generating a set of modules and connection objects. Each SmartDaqApplication has a UID from the configuration.

This section will use the "[DFOApplication](https://github.com/DUNE-DAQ/appmodel/blob/develop/src/DFOApplication.cpp)" SmartDaqApplication as an example.

ConfigObjectFactory

ConfigObjectFactory is an helper class to simplify the creation of appfwk configuration objects in SmartApplication. Once instantiated at the start of generate_modules, it offers a set of methods to facilitate the creation of configurarion objects, queues and network connections.

Creating a module

++
 
 ConfigObjectFactory obj_fac(this):
 
 TLOG_DEBUG(7) << "creating OKS configuration object for DFOModule class ";
 conffwk::ConfigObject dfoObj = obj_fac.create("DFOModule", "DFO-"+UID());
 
 auto dfoConf = get_dfo();
 dfoObj.set_obj("configuration", &dfoConf->config_object());

Here, it is important to understand the DFOApplication schema definition:

<class name="DFOApplication">
 <superclass name="SmartDaqApplication"/>
 <relationship name="dfo" class-type="DFOConf" low-cc="one" high-cc="one" is-composite="no" is-exclusive="no" is-dependent="no"/>
 <method name="generate_modules" description="Generate DaqModule dal objects for streams of the application on the fly">
  <method-implementation language="c++" prototype="std::vector&lt;const dunedaq::confmodel::DaqModule*&gt; generate_modules(const confmodel::Session*) const override" body=""/>
 </method>
</class>

In addition to the fields from SmartDaqApplication, the DFOApplication class has a relationship named "dfo" to a DFOConf object. As an OKS object, it also has a "UID"" field. The code uses this UID (accessed via the `UID()` method) to create the UID for a `DFOModule` object. The object is created in the in-memory database, and its configuration assigned using the "dfo" relationship from the DFOApplication schema. @subsection autotoc_md546 Reading connection rules and creating connections @icode{C} ++ for (auto rule : get_network_rules()) { auto endpoint_class = rule->get_endpoint_class(); auto descriptor = rule->get_descriptor(); conffwk::ConfigObject connObj = obj_fac.create_net_obj(descriptor); if (descriptor->get_data_type() == "TriggerDecision") { tdInObj = connObj; input_conns.push_back(&tdInObj); } else if (descriptor->get_data_type() == "TriggerDecisionToken") { tokenInObj = connObj; input_conns.push_back(&tokenInObj); } else if (descriptor->get_data_type() == "TriggerInhibit") { busyOutObj = connObj; output_conns.push_back(&busyOutObj); } } @endicode The next stage of DFOApplication is to retrieve the network connection rules to assign the inputs and outputs of the <tt>DFOModule</tt> instance. A DFO has two fixed inputs (decisions and tokens), and one fixed output (inhibits). Decisions sent to TRB instances are dynamically instantiated at run-time using information in the token messages. @subsection autotoc_md547 Setting Module Connection relationships @icode{C} ++ dfoObj.set_objs("inputs", input_conns); dfoObj.set_objs("outputs", output_conns);

// Add to our list of modules to return modules.push_back(confdb->get<DFOModule>(dfoUid));

return modules;

Once the fixed connections are retrieved using the network rules, the module's input and output relations are set, and the module is added to the output vector, which is returned.

Summary

These basic steps are repeated in all SmartDaqApplication instances, with differences depending on the specific applciation being implemented. The DFOApplication is one of the simplest applications in the system, but it demonstrates the basic logic followed by all SmartDaqApplications.