Defining header components

A header component defines a reusable custom header that can be sent in an API request or returned in an API response.

About this task

  • This task relates to configuring an OpenAPI 3.0 API definition. For details on how to configure an OpenAPI 2.0 API definition, see Editing an OpenAPI 2.0 API definition.
  • OpenAPI 3.0 APIs are supported only with the DataPower® API Gateway, not with the DataPower Gateway (v5 compatible).
  • For details of current OpenAPI 3.0 support limitations, see OpenAPI 3.0 support in IBM® API Connect.

You can complete this task either by using the API Designer UI application, or by using the browser based API Manager UI.

To make use of a header component, you must reference it from elsewhere in your API definition.

A header is similar to a parameter, with the following differences:
  • Parameters carry actual data and are available to end users, headers carry meta data associated with a request or response and are hidden from end users.
  • A parameter can have various locations, the location of a header is always set to header.
  • A parameter can have various format styles, the style of a header is always simple.
For more information on parameters, see Creating a parameter.

At any time, you can switch directly to the underlying OpenAPI YAML source that corresponds to the design form in the user interface by clicking the Source icon OpenAPI Source icon. To return to the design form, click the Form icon Form icon.


  1. Open the required API for editing, as described in Editing an OpenAPI 3.0 API definition.
  2. Expand Components then, if there are already one or more header components defined, expand Headers.
  3. You can create a new header component, or edit any existing header component.
    • To create a header component, click the add icon OpenAPI 3.0 API add icon alongside Headers, then refer to Creating a header.
    • To edit an existing header component, click the header component name in the navigation pane, then refer to Editing a header.