Calculator: step by step tutorial

This document describes how to create a simple Calculator microservice with XComponent whose triggered methods are implemented in JavaScript instead of C#.

Overview

XComponent is a platform to create, monitor and share microservices.

In the Calculator sample we are going to create two different pieces of software:

[Calculator microservice] - A XComponent microservice that receives requests to calculate additions;
[Calculator.js worker] - A simple NodeJS application to run triggered methods coded in JavaScript.

Install XComponent Community

The easiest way to install the XComponent Community Edition is to download the latest version from Nuget

Create your first microservice

Create a new XComponent project

Start XCStudio [packages\XComponent.Community\tools\XCStudio\XCStudio.exe]
Create a new project named Calculator:

Create your first component

Create a new component named Calculator:

Create a CalculatorManager and a Calculator state machines

Note : the CalculatorManager create instances of Calculator with two numbers as input, through Calculate transition. The Calculator state machine do operation(s) with the inputs.

You should end up with the following component:

Calculator component

On Entry_Point, Ready, Calculating and Done states triggered methods select Rest Worker so as they wont be generated in C# but will be implemented in any other language able to consume REST services. In the present example we will use JavaScript.

Complete your composition view

Go back to the composition view
Add links between your component and the default api.

You should end up with the following figure:

composition view

Note: In the composition view, on each component, inputs are the left side bullet points and component outputs are the right side bullet points.

Configuration

Open the properties window of your project (see following figure)

open properties

Fill the RabbitMQ settings:

In the Communication section choose a name for the RabbitMQ bus and click on the Add button. You should see your bus with a green indicator as in the following figure:

rabbitmq config

In the Components section change the deployment target from Stand Alone to Server. In the drop down you should see the previously configured RabbitMQ bus.

server mode

Test your microservice

Build your solution (see following figure)

microservices

Start your microservice (Project menu + Run sub menu + Microservices button and then the Start button)
Create a NodeJS application to implement your triggered methods
Add the xcfunctions.js library to your project with the following command:
```
PS npm add xcfunctions
```
Copy/Paste the following code in your index.js

const xcfunctions = require('xcfunctions');

xcfunctions.registerTriggeredMethods('Calculator', 'CalculatorManager', {
    ExecuteOn_EntryPoint: (event, publicMember, internalMember, context, sender) => {
        sender.Init();
    },

    ExecuteOn_Ready_From_Up_Through_Prepare: (event, publicMember, internalMember, context, sender) => {
        sender.Calculate({ Number1: 5, Number2: 3}, true);
        sender.Relaunch();
    }
});

xcfunctions.registerTriggeredMethods('Calculator', 'Calculator', {
    InitializePublicMember: (event, publicMember) => {
        publicMember.Result = 10;
    },

    ExecuteOn_Calculating_From_Ready_Through_Calculate: (event, publicMember, internalMember, context, sender) => {
    const result = event.Number1 * event.Number2;

        if (result >= 0) {
            publicMember.Result = result;
            sender.Finished({ Result: result }, true);
        } else {
            publicMember.ErrorMessage = 'Bad value';
            sender.Finished({ Result: result }, true);
        }
    },

    ExecuteOn_Done_From_Calculating_Through_Finished: (event, publicMember) => {
        publicMember.Result = event.Result;
    }
});

xcfunctions.startEventQueue();

Run your NodeJS application. You should end up with an output similar to that:

JS output

Questions?

If you have any questions about this sample, please create a Github issue for us!

xcomponent

Develop microservices in C# using state machines.