Medical Imaging Interaction Toolkit
2016.11.0
Medical Imaging Interaction Toolkit
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This example creates a module that implements a service. Implementing a service is a two-step process, first we must define the interface of the service and then we must define an implementation of the service interface. In this particular example, we will create a dictionary service that we can use to check if a word exists, which indicates if the word is spelled correctly or not. First, we will start by defining a simple dictionary service interface in a file called dictionaryservice/IDictionaryService.h
:
The service interface is quite simple, with only one method that needs to be implemented. Because we provide an empty out-of-line destructor (defined in the file IDictionaryService.cpp
) we must export the service interface by using the module specific DICTIONARYSERVICE_EXPORT
macro.
In the following source code, the module uses its module context to register the dictionary service. We implement the dictionary service as an inner class of the module activator class, but we could have also put it in a separate file. The source code for our module is as follows in a file called dictionaryservice/Activator.cpp
:
Note that we do not need to unregister the service in the Unload() method, because the C++ Micro Services library will automatically do so for us. The dictionary service that we have implemented is very simple; its dictionary is a set of only five words, so this solution is not optimal and is only intended for educational purposes.
For an introduction how to compile our source code, see Example 1 - Service Event Listener.
After running the usCoreExamplesDriver
program we should make sure that the module from Example 1 is active. We can use the s
shell command to get a list of all modules, their state, and their module identifier number. If the Example 1 module is not active, we should load the module using the load command and the module's identifier number or name that is displayed by the s
command. Now we can load our dictionary service module by typing the l dictionaryservice
command:
CppMicroServices-build> bin/usCoreExamplesDriver > s Id | Name | Status ----------------------------------- - | dictionaryservice | - - | eventlistener | - 1 | CppMicroServices | LOADED > l eventlistener Starting to listen for service events. > l dictionaryservice Ex1: Service of type IDictionaryService/1.0 registered. > s Id | Name | Status ----------------------------------- 1 | CppMicroServices | LOADED 2 | Event Listener | LOADED 3 | Dictionary Service | LOADED >
To unload the module, use the u <id>
command. If the module from Example 1 is still active, then we should see it print out the details of the service event it receives when our new module registers its dictionary service. Using the usCoreExamplesDriver
commands u
and l
we can unload and load it at will, respectively. Each time we load and unload our dictionary service module, we should see the details of the associated service event printed from the module from Example 1. In Example 3, we will create a client for our dictionary service. To exit usCoreExamplesDriver
, we use the q
command.
Next: Example 2b - Alternative Dictionary Service Module
Previous: Example 1 - Service Event Listener