How to scaffold Mule flows from a published API spec in Anypoint Studio

Q: How do I import the published API into a new Mule project?

First open Anypoint Studio and click `Create a Mule project`, then give it a name. Next click the green plus button under `Import a published API` and select `from Exchange`. Follow the prompts to authenticate by clicking `Add Account` and entering your Username and Password, then search for your API Specification, select it, click `Add >`, and finally click `Finish` to generate the project.

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

Docs

To do this same thing in Anypoint Code Builder, refer to How to scaffold Mule flows from a published API spec in Anypoint Code Builder (ACB)

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

Prerequisites

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.
Anypoint Studio - MuleSoft’s IDE based on Eclipse. You can download it here.
GitHub Repo - If you want to follow along with the code I generated, you can check it out here.

Docs

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 Studio

First of all, let’s open Anypoint Studio and click on Create a Mule project from the options on the left.

Anypoint Studio Package Explorer with the "Create a Mule Project" link among project options

Add any name of your choice in Project Name. Click on the green ➕ button under Import a published API and select from Exchange.

New project dialog: the add API button expanded to "from Exchange" or "from Maven"

Follow the prompts to authenticate to your Anypoint Platform account by clicking Add Account and adding your Username and Password. Once you are signed in, search for your API Specification, select it, and click on Add >. Once you selected it on the right-hand panel, click on Finish.

Add Dependencies dialog with the To-Do API selected from Exchange before clicking Finish

After the API appears under Import a published API, you can click on Finish to close the window and see the generated project.

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.

Generated main flow with an HTTP Listener connected to an APIkit Router

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.

Auto-generated error handling with On Error Propagate scopes for BAD_REQUEST and NOT_FOUND

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.

Generated get-by-id flow whose Transform Message reads attributes.uriParams.'id'

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

Transform Message generated from an API example outputting sample JSON to-do data

Pretty cool, right?

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

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Prost!

FAQs

Frequently asked questions about this post.

Why would I scaffold Mule flows from an API specification instead of starting from scratch?

Scaffolding lets you 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 project you get Mule flows for each HTTP method in your specification, basic error handling for different HTTP status codes, and an initial Mule project with some Transform Message components where applicable.

What do I need before I can scaffold flows from a published API spec in Anypoint Studio?

You need an Anypoint Platform account (a free trial works), an API specification already published in Anypoint Exchange, and Anypoint Studio, which is MuleSoft's Eclipse-based IDE. If this is your first time creating an API specification, the post links to a separate guide on using the visual API Designer to create one.

How do I import the published API into a new Mule project?

First open Anypoint Studio and click Create a Mule project, then give it a name. Next click the green plus button under Import a published API and select from Exchange. Follow the prompts to authenticate by clicking Add Account and entering your Username and Password, then search for your API Specification, select it, click Add >, and finally click Finish to generate the project.

What error handling gets generated automatically in the scaffolded project?

Error Handling is added automatically to the main flow, containing the HTTP status codes for some basic errors like 400 Bad Request or 404 Not Found, implemented with On Error Propagate scopes for cases such as BAD_REQUEST and NOT_FOUND.

Why do some of the generated flows already include a Transform Message component?

Some flows already have a Transform Message component so you can see which DataWeave code is needed to retrieve data like the URI Parameter(s), which only happens if your API Specification contains a URI Parameter. Transform Message components are also added for cases where you have set up an example in the API Specification.

Prerequisites

Create a Mule project in Studio

Navigate the generated project

FAQs

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