Introduction

This example takes the very simple flow element described in the simple flow element example, and delegates all the logic to a cloud service.

Instead of the data being stored locally and processing being carried out by the flow element directly, as demonstrated in the simple flow element example, this example will call a cloud service to perform the required functionality.

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The source code used in this example is available here:

Dependencies

The aspect engine will need a dependency on the Pipeline engines package, and cloud request engine package

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The dependencies needed for .NET are the FiftyOne.Pipeline.Engines and FiftyOne.Pipeline.CloudRequestEngine NuGet packages.

The only dependency needed for Java is the pipeline.core Maven package from com.51degrees. To include this, add the following to the <dependencies> section of the project's pom.xml:

<groupId>com.51degrees</groupId>

<artifactId>pipeline.cloudrequestengine</artifactId>

</dependency>

<groupId>com.51degrees</groupId>

<artifactId>pipeline.engines</artifactId>

</dependency>

Data

The element data implemented in the previous example can now be upgraded to implement an aspect data.

Select a tab to view language specific aspect data implementation.

Instead of implementing IElementData, the IStarSignData will now implement IAspectData which extends IElementData.

Now the internal implementation of it will implement a 'getter' and add a 'setter' for StarSign in the same way as the previous example.

Instead of implementing ElementData, the StarSignData will now implement AspectData which extends ElementData.

Now the internal implementation of it will implement a 'getter' and add a 'setter' for StarSign in the same way as the previous example.

Note that this concrete implementation of StarSignData sits in the same package as the aspect engine, not the StarSignData interface, as it only needs to be accessible by the aspect engine.

Aspect engine

Now the actual aspect engine needs to be implemented. For this, the class from the previous example will now implement the cloud aspect engine's base class.

Select a tab to view language specific aspect engine implementation.

First let's change the class to extend CloudAspectEngineBase. This has the type arguments of IStarSignData - the interface extending aspect data which will be added to the flow data, and IAspectPropertyMetaData - instead of IElementPropertyMetaData.

The existing constructor needs to change to match the CloudAspectEngineBase class.

The constructor will also take a CloudRequestEngine instance to get the available properties from.

Now the abstract methods can be implemented to create a functional aspect engine.

First let's change the class to extend CloudAspectEngineBase. This has the type arguments of StarSignData - the interface extending aspect data which will be added to the flow data, and AspectPropertyMetaData - instead of ElementPropertyMetaData.

The existing constructor needs to change to match the CloudAspectEngineBase class.

The constructor will also take a CloudRequestEngine instance to get the available properties from.

The loadAspectProperties method in this example will get the aspect properties from the CloudRequestEngine and store them. In this case we know the only property will be 'star sign', but more complex cloud engines can have many properties.

Now the abstract methods can be implemented to create a functional aspect engine.

Builder

Now the aspect engine needs one final thing, an element builder to construct it. This needs to provide the aspect engine with a logger and an aspect data factory as in the previous example. However, it also now needs a cloud request aspect engine.

Select a tab to view language specific element builder implementation.

As this aspect engine is using a data file, the builder can make use of the logic in the CloudAspectEngineBuilderBase.

Usage

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This new aspect engine can now be added to a Pipeline along with a CloudRequestEngine, and used like:

to give an output of:

With a date of birth of 18/12/1992, your star sign is Sagittarius.