Hello World  Tutorial

Objectives

This guide is to take a new Vantiq user to the minimum set of steps required to create an event-driven application on the Vantiq platform.

Tutorial Overview

In this tutorial, the developer accomplishes two basic tasks:

• Simulate events
• Ingest and process those events

Step 1: Start a New Project

While not strictly necessary, let’s make sure we’re building our application from scratch. If you’re already seeing a popup asking about what kind of project you’ll be making, skip ahead in these instructions to the popup that you’re seeing.

1. From the Projects menu on the Nav Bar, choose New Project. Click the radio button for Add Project in the New Project pop-up, then click Continue.
2. Choose Empty for the Project Wizard popup choice, and click Continue

3. Finally, give your project a name, and click Finish

Step 2: Create a Topic

Topics are a way to send events within the Vantiq platform. We’re going to create a Topic to simulate events that our Service can ingest and process.

1. Choose Add -> Advanced -> Topic in the Nav Bar.

2. Click + New Topic in the New Topic popup

3. Name: /Hello
4. Package: hello.world
5. Ignore the rest for now, and click OK

You’ve now made a Topic, which we’ll use to send events to our Service for processing. Leave this pane up for now.

Step 3: Create a Service

Services in Vantiq work much like classic microservices, but with some special characteristics to make them more event-driven and stateful. We’re going to create our own Service to take in and apply logic to the events sent from our Topic.

1. From the Nav Bar Add menu, choose Service…, then click on + New Service
2. Name: HelloSvc
3. Package: Select hello.world from the drop-down, and click OK

Your workspace in the IDE is now a Topic and a Service side-by-side. These are all we need to make our application.

Step 4: Configure the Service to take Topic Events

1. Click on the Implement tab at the top left of the Service. 

2. Click on the + next to internal Event Handlers, and select the Add New Visual Internal Event Handler option

3. Name: HelloHandler, then click OK 

The first Activity Task to appear in the Visual Event Handler is labeled Initiate and it is an EventStream task to ingest events. Click on it to select it and a menu will slide in from the right side.

4. Next to Configuration, click Click to Edit
5. inboundResource: Select topics from the drop-down
6. inboundResourceId: Select /hello.world/Hello, then Click OK

7. Save the Service to apply the changes

Step 5: Apply Logic to the EventStream

Visual Event Handlers let developers apply application logic requiring little or no code, just by dragging pre-built code blocks called Activity Patterns into the visual event flow. We’re going to add an activity task now.

1. From the Actions submenu, click and drag a LogStream pattern onto the Initiate task.

Upon release, LogStream will appear downstream from Initiate.

2. Click on the LogStream task, and then Click to Edit to configure it
3. Choose the Info log level from the drop-down, then click OK
4. Save the Service

Step 6: Make Log Messages Visible

At the bottom of the IDE is a panel for seeing Errors, Log Messages and Autopsies (for debugging). Click on the drop-down and make sure that Log Messages is toggled on.

Step 7: Run the Hello World Application

We’ve got everything in place: A topic for sending an event, a Service listening for that event, and logic to log the message received. Let’s verify that our application works!

1. In the Publish Message pane in the Topic window, write a JSON-formatted message. Example:

{
    "bread" : "white",
    "loaves" : 7
}

2. Click the Publish button
3. You should see red event badges on the Activity Tasks in the Visual Event Handler in the Service:

And in the Log Messages panel at the bottom of the IDE, you should see the logged message:

Conclusion

Congratulations! You’ve created your first event-driven application on the Vantiq platform, and you didn’t have to write a single line of code! Most of the time, you won’t even need to create a Topic; Vantiq takes in events through integrations with anything that exists on the Internet.

Services take in asynchronous inputs, apply logic to them as the application requires, and outputs the results, sometimes to other Services for further processing.

Application logic can be applied visually, using Activity Patterns that are configured into tasks that are shown as part of the event processing flow. Code can be inserted at any point in the application, using Vantiq’s proprietary language, VAIL.

Where to Learn More

Vantiq provides a suite of Tutorials and Documentation on all different development topics. Just click on the Help button on the Nav Bar and choose Developer Guides.