3.2.1 Creating the Integrator and Function Components

In order to have some exportable or importable functionality in a component we must have some uses and provides ports. Bocca will also create the scaffolding and code for ports. Following the model of the integrator application of Chapter 2, we will create a Function , an Integrator , and a Driver . However before we can do that we will have to create some ports for these components to use and provide .

Let's begin by creating a FunctionPort and an Integration :

$	bocca create port Integration

Updating makefiles (for demo.Integration)...

$	bocca create port FunctionPort

Updating makefiles (for demo.FunctionPort)...

Notice that we are continuing to use the default package demo, though we could specify something different.

Now, create a set of components similar to those that you used in Chapter 2, specifying that they will provide or use the appropriate ports:

$	bocca create component Function --provides=FunctionPort@fun

Babel updating the cxx implementation of component demo.Function ...

$	bocca create component Integrator \ --provides=Integration@integrate \ --uses=FunctionPort@odeRHS

Babel updating the cxx implementation of component demo.Integrator ...

$	bocca create component Driver --go=run \ --uses=Integration@integrate

Babel updating the cxx implementation of component demo.Driver ...

This last bocca create decorates our Driver component with a CCA standard go port, which is not specified as part of this project. Since gov.cca.ports.GoPort is a part of the CCA specification, Bocca takes care of knowing where to find the SIDL definition of this port. The special --go option allows Bocca to generate a default go implementation which prefetches the uses ports so that all the user needs to do for our example is add numerical code. In languages which are not object-oriented, this substantially reduces the errors in handling ports, exceptions, and memory deallocation.

Note It is not necessary to know at component creation time all ports that will be used or provided or other implementation details. Bocca provides various commands for changing project entities, e.g. adding or removing uses and provides ports.

As we have defined a number of new things, this would be a good time to rebuild the project:

$

make

make[1]: Entering directory `/home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo'
# =======================================================================
# No SIDL files in external/sidl, skipping build for external
# =======================================================================
# =======================================================================
# Building in ports/, languages: cxx
# =======================================================================
 ## Building ports... 
   [c] using Babel to generate cxx client code for demo.FunctionPort... 
   [c] creating library: libdemo.FunctionPort-cxx.la... 
   [c] installing demo.FunctionPort.sidl 
   [c] building /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/install/share/cca/demo/demo.FunctionPort_depl.xml ... 11071 
   [c] using Babel to generate cxx client code for demo.Integration... 
   [c] creating library: libdemo.Integration-cxx.la... 
   [c] installing demo.Integration.sidl 
   [c] building /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/install/share/cca/demo/demo.Integration_depl.xml ... 11404 
# =======================================================================
# Building in components/clients/, languages: cxx
# =======================================================================
 ## Building clients... 
# =======================================================================
# Building in components/, languages: cxx
# =======================================================================
   [s] Building class/component demo.Driver: 
   [s] using Babel to generate cxx implementation code from demo.Driver.sidl... 
   [s] compiling sources... 
   [s] creating class/component library: libdemo.Driver.la ... 
   [s] finished libtooling: components/demo.Driver/libdemo.Driver.la ... 
   [s] building /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/install/share/cca/demo/demo.Driver_depl.xml ... 
   [s] creating Ccaffeine test script (components/tests/instantiation.gen.rc)... 
   [s] Building class/component demo.Function: 
   [s] using Babel to generate cxx implementation code from demo.Function.sidl... 
   [s] compiling sources... 
   [s] creating class/component library: libdemo.Function.la ... 
   [s] finished libtooling: components/demo.Function/libdemo.Function.la ... 
   [s] building /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/install/share/cca/demo/demo.Function_depl.xml ... 
   [s] creating Ccaffeine test script (components/tests/instantiation.gen.rc)... 
   [s] Building class/component demo.Integrator: 
   [s] using Babel to generate cxx implementation code from demo.Integrator.sidl... 
   [s] compiling sources... 
   [s] creating class/component library: libdemo.Integrator.la ... 
   [s] finished libtooling: components/demo.Integrator/libdemo.Integrator.la ... 
   [s] building /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/install/share/cca/demo/demo.Integrator_depl.xml ... 
   [s] creating Ccaffeine test script (components/tests/instantiation.gen.rc)... 
   [s] Building class/component demo.emptyComponent: 
doing nothing -- library is up-to-date.
Build summary:
SUCCESS building demo.Driver
SUCCESS building demo.Function
SUCCESS building demo.Integrator
### To test instantiation of successfully built components, run 'make check' ###
################ Finished building everything #################
####### You can run some simple tests with 'make check' #######
make[1]: Leaving directory `/home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo'

Note that this operation can be very time-consuming when your project is managing many ports and components with the fully supported set of Babel language bindings.

Running make check will test whether the components you've created can be instantiated successfully in the Ccaffeine framework:

$	make check

make[1]: Entering directory `/home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo'
make --no-print-directory --no-builtin-rules -C components check
### Test library load and instantiation for the following languages: cxx
Running instantiation tests only
Test script: /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/components/tests/instantiation.gen.rc
Log file: /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/components/tests/instantiation.gen.rc.log
SUCCESS:
==> Instantiation tests passed for all built components (see /home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo/components/tests/instantiation.gen.rc.log).
make --no-print-directory --no-builtin-rules check-user
make[1]: Leaving directory `/home/bernhold/bassi/project/projectdirs/cca/pde-hands-on/doc/scratch/cxx/demo'

So far, with very little work, we have generated what appears to be an application but is really just the componentized shell of an application. If you were to run the GUI (Section 2.1) or do the command-line equivalent in Ccaffeine (Section 2.2), you would find that the components are decorated with the ports you expect, and they can even be connected (an operation of the framework, not of the components or ports). But if you attempted to run an application using these components, nothing would happen because they're only skeletons, providing the component-ness, but not the functionality.

Note Along with everyting else it does, Bocca generates a set of utility scripts which are tailored to the specific Bocca project (i.e. having the right paths, the right sets of components, etc.). In Section 2 you ran Bocca-generated utility scripts in the pre-built tutorial tree (i.e.  $TUTORIAL_SRC/utils/run-gui.sh). When you're working in your own Bocca projects, make sure you use the utility scripts associated with that project, or things won't work properly.