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Workflow: Convert an Existing Mule Project to an APIkit Project

If you create a new Studio project and do not specify an API definition file, APIkit generates a skeletal RAML file and XML configuration that includes the following things:

  • HTTP Listener configuration

  • APIkit Router component

  • Error handling flows

The following screenshot shows the Specify API Definition File Location or URL option, which you uncheck to create the backend first:

backend first project

Later, you can add an API specification, and then use API Console to simulate the API.

Adding APIkit to an Existing Design

You add APIkit components to an existing design, for example a legacy project that you want to modernize using RAML and APIkit, by creating the RAML code within Studio as follows:

RAML-based API

  • Define the API definition files.

  • Create a main flow, or use an existing one, that includes an HTTP Listener and APIkit Router.

  • Generate backend flows.

The generated backend flows contain the core logic of the API, error handling flows, API Console. You need to add REST resource-action pairing.

Defining the API Definition Files

If you want a RAML-backed API, you can use Studio to create the file: Studio: File > New > RAML API Definition.

new raml

For example:

  1. Use the RAML specification and dependent JSON example files provided in the Workflow: Generating a Mule Flow from an API Specification.

  2. Right-click the name of the RAML in /src/main/resources/api and select Validate. Proceed if there are no problems with the RAML.

  3. Create any dependent files, or drag and drop them into Studio beside the main RAML. For example, drag the user-example.json to /src/main/resources/api.

    Ignore error messages in the Problems window that pertain to undefined attributes.

Creating a Main Flow

Within the APIkit project, build a flow.

  1. Drag the following components from the Mule palette:

    • An HTTP Listener

    • An APIkit Router

  2. In the properties editor for APIkit Router, in Router Configuration, select api-config.

  3. In the properties editor for HTTP Listener, in Connector Configuration, select api-httpListenerConfig, and set a path. For example, in Path, enter /.

Generating REST Backend Flows

When you create a RAML in Studio, generating backend flows is optional. Error handling is generated for a RAML-based API. You need to reference generated flows from the main flow. This procedure assumes you have already created a main flow.

To generate backend flows: 

  1. In the Package Explorer, right-click the project name.

  2. Select Mule > Generate Flows From REST API.

    The backend flows appear below the main flow.

Mapping RAML Resources to Actions

As part of the backend-first design process, you map RAML resources to actions as shown in the following procedure. This procedure assumes you have generated backend flows.

To map resources to actions:

  1. Click the APIkit Router to open the Properties Editor. In Router configuration, click Add 16x16.

    The Global Element Properties wizard appears.

  2. Enter the relative path to the RAML file you created within Studio, for example: src/main/resources/api/api.raml. If you browse, the file name alone is used and that isn’t sufficient.

  3. In Mappings, click Add 16x16 to create a new mapping.

    The New Mapping dialog appears.

  4. Use the drop-down to map the resources to actions.

    • In the Resource drop-down, select /users.

    • In the Action drop-down, select GET.

    • In the Flow drop-down, select the flow that contains the get users action: get:\users:api-config.

      Click OK.

      apikit-using-ab251
  5. Repeat the previous step for each resource-action pairing in the API.

Now, you are ready to run the new project and simulate calls using API Console.

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