ReferenceApplication Consumer - Data Logger
Working through this tutorial gives you an introductory understanding of the steps required to implement
Consumer role of OOI Reactive Application. DataLogger is a sample implementation of the Consumer part of the ReferenceApplication, which is an example application of Semantic-Data reactive networking based on OPC UA Part 14 Pub/Sub specification.Here are steps undertook to implement the
Consumer role in the application:- 1.
DataManagementSetup: this class has been overridden by theLoggerManagementSetupclass and it initializes the communication and binds data fields recovered form messages to local resources. - 2.
IEncodingFactoryandIMessageHandlerFactory: has been implemented in external common libraries andConsumerdoesn't depend on this implementation - current implementation of the interfaces is localized as services using an instance of theIServiceLocatorinterface. - 3.
IBindingFactory: has been implemented in the classDataConsumerthat is responsible to synchronize the values of the local data repository properties and messages received over the wire. - 4.
IConfigurationFactory: the classConsumerConfigurationFactoryimplements this interface to be used for the configuration file opening.
The
LoggerManagementSetup constructor initializes all properties, which are injection points of all parts composing this role. public sealed class LoggerManagementSetup : DataManagementSetup
{
public LoggerManagementSetup()
{
IServiceLocator _serviceLocator = ServiceLocator.Current;
string _ConsumerConfigurationFileName = _serviceLocator.GetInstance<string>(ConsumerCompositionSettings.ConfigurationFileNameContract);
m_ViewModel = _serviceLocator.GetInstance<ConsumerViewModel>(ConsumerCompositionSettings.ViewModelContract);
ConfigurationFactory = new ConsumerConfigurationFactory(_ConsumerConfigurationFileName);
EncodingFactory = _serviceLocator.GetInstance<IEncodingFactory>();
BindingFactory = new DataConsumer(m_ViewModel);
MessageHandlerFactory = _serviceLocator.GetInstance<IMessageHandlerFactory>();
}
....
}
In this example, it is assumed that
ServiceLocator is implemented to resolve references to any external services.Finally the
DataManagementSetup.Start() method is called to initialize the infrastructure, enable all associations and start pumping the data.Implementation of this interface is a basic step to implement
Consumer functionality. An instance of the IBindingFactory is responsible to create objects implementing IBinding that can be used by the Consumer to save the data received over the wire in the local data repository.The class
DataConsumer is a sample implementation of a data logger functionality recording data over time. It consumes the testing data sent and updates properties in the class ConsumerViewModel implementing ViewModel layer in the Model View ViewModel (on MSDN) (MVVM pattern). The class DataConsumer demonstrates how to create bindings interconnecting the data received over the wire and the properties that are the ultimate destination of the data. The user interface provided by the View layer implemented in the UAOOI.Networking.ReferenceApplication.MainWindow class is dynamically bounded at run time with the ConsumerViewModel. To implement the ViewModel layer in the *MVVM pattern* the helper generic class UAOOI.Networking.SemanticData.DataRepository.ProducerBindingMonitoredValue` is used.Implementation of this interface is straightforward and based entirely on the library
UAOOI.Configuration.Networking. In a typical scenario, this implementation should not be considered for further modification. The only open question is how to provide the name of the file containing the configuration of this role. In proposed solution the name is provided by a service defined by the application entry point part and localized using IServiceLocator in the class LoggerManagementSetup - see code snipped below:
string _ConsumerConfigurationFileName = _serviceLocator.GetInstance<string>(ConsumerCompositionSettings.ConfigurationFileNameContract);
This role uses independent configuration file
ConfigurationDataConsumer.xml attached to the project. This file contains a mirror configuration of the Producer role configuration to log all the generated data.Note; This library is not considered to be published as the NuGet package.