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How to scaffold Mule flows from a published API spec in Anypoint Code Builder (ACB)


In this post:


In this post, I am going to show you how to scaffold your flows in Anypoint Code Builder from a published API specification.

📚 Related To do this same thing in Anypoint Studio, refer to How to scaffold Mule flows from a published API spec in Anypoint Studio

Why would you want to scaffold Mule flows from an API specification? This way you will be able to get started on your Mule application with a base project that is created upon your specification, instead of starting the Mule project and Mule flows from scratch.

Once you scaffold the Mule project, you will have:

  • Mule flows for each HTTP method in your specification

  • Basic error handling for different HTTP status codes

  • Initial Mule project with some Transform Message components where applicable


  • Anypoint Platform - You should have an Anypoint Platform account. You can create a new free trial account here.

  • API specification - You should already have an API specification published in Anypoint Exchange.

  • Visual Studio Code - To use Anypoint Code Builder, you must first install VS Code. You can download it here.

  • Anypoint Extension Pack - To enable Anypoint Code Builder in your Visual Studio Code, you must install this extension. You can install it from here.

  • GitHub Repo - If you want to follow along with the code I generated, you can check it out here.

📚 Related If this is your first time creating an API specification, refer to How to use MuleSoft's visual API Designer to create a To-Do API specification using clicks, not code

Create a Mule project in ACB

Once you are inside Anypoint Code Builder, select the Implement an API quick action.

Anypoint Code Builder's Quick Actions menu, selecting the Implement an API option

This will open a new menu or window, and it will ask you to sign in to Anypoint Platform to retrieve the API Specification from your account. Click Allow and follow the prompts to sign in.

Once you are signed in, you will be able to search an API Specification from Exchange to implement it. Simply search for your asset's name on the search bar and select it from the list by clicking on Add Asset.

Window to search an API Specification from Exchange to implement it in Anypoint Code Builder

ℹ️ Note If you're having issues searching for your asset, you can use the Show filters toggle to search for more specific assets. For example, using your own organization or the asset's type.

After the API Specification has been selected, click on Create Project. Wait a few seconds for everything to finish processing and you'll have the finalized project after that.

Navigate the generated project

Once the project has been created, you should be able to see the flows in the configuration file located under src/main/mule.

Preview of the XML configuration file with both the graphical and code view

You can click on the Flow List button from the top-left of the graphical view (or the flow canvas) to see a complete list of all the flows that have been implemented in the current XML file.

Flow List button in Anypoint Code Builder to see a complete list of all the flows that have been implemented in the current XML mule configuration file

The Error Handling has been added automatically to the main flow as well. This contains the HTTP status codes for some basic errors like 400 Bad Request or 404 Not Found.

Error Handling that has been automatically added to the main flow in Anypoint Code Builder

Notice how some of the flows already have a Transform Message component for you to see which DataWeave code is needed to retrieve some data like the URI Parameter(s). This, of course, is just in the case that your API Specification contains a URI Parameter.

Preview of the Transform Message component created automatically after scaffolding the project in Anypoint Code Builder

There will also be Transform Message components added for some cases where you have set up an example in the API Specification.

Transform Message component preview showing the JSON example that was set in the API Specification - in Anypoint Code Builder

Pretty cool, right?

Keep posted for some more articles on scaffolding in Anypoint Studio or Anypoint Code Builder!

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💬 Prost! 🍻

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