ConsumerTask

In this task, we will consume the temperature value produced in the producer task. We will first create a 'Cons' task. For this, execute the following command

DH> python programs/scripts/dune-create-task.py . DuneAuthor Tutorials/TempCons

This will create TempCons task. Go to the TempCons directory and open the Task.cpp using a text editor so that you can make changes to it. To use the temperature value produced by the producer task we need first to bind the message from IMC and write a consume method.

First binding the value from the IMC message, for this include bind<IMC::Temperature>(this); in the constructor.

Task(const std::string& name, Tasks::Context& ctx):
  DUNE::Tasks::Task(name, ctx)
{
  bind<IMC::Temperature>(this);
}

Then create a consumer method before the main loop. The following is the consumer method

void
consume(const IMC::Temperature* msg)
{
  inf("temperature is %f", msg->value);
}

(The function inf prints information to the console.)

Compiling the consumer task

In order to compile the consumer task, follow the instructions of the producer task.

cd DBuild>
DBuild>$ make rebuild_cache
DBuild>$ make

This will compile the consumer task.

Testing the consumer task

Create consumer.ini file in DH>/etc/development folder. In this folder include the contents as given below

[Include ../common/transports.ini]

[Tutorials.TempCons]
Enabled = Always
Entity Label = Consumer

[Transports.Logging]
Enabled = Always
Entity Label = Logger
Transports = Temperature

The first line [Include ..] includes the transports.ini file into the current file. [Tutorials.TempCons] directs the task towards the TempCons directory. Enabled = Always tells that the task is always enabled. Entity Label = Consumer informs that this task is a consumer. For the entity label there is no need provide in the Task.cpp file, rather dune takes care of the entity label.

Then run the command

DBuild>$ ./dune -c ../etc/development/consumer

Upon execution you can see the output as:

[2013/05/31 17:57:10] - MSG [Transports.Logging] >> starting
[2013/05/31 17:57:10] - MSG [Tutorials.TempCons] >> starting
[2013/05/31 17:57:10] - MSG [Transports.Logging] >> log started '20130531/175710_idle'

We can see that the tasks Tutorials.TempCons and Transports.Logging have started.

[Example1 main page] (https://github.com/LSTS/dune/wiki/Example1)
[Next section: Producer and Consumer Task interaction] (https://github.com/LSTS/dune/wiki/Producer-and-Consumer-Task-Interaction)