Set Header

The Set Header EIP defines or modifies a message header.

Parameters

Parameter Description Default value Type

Name

The name of the message header to be configured.

String

Expression

Defines the value to be set in the header. It is mandatory and can use various supported expression languages such as Simple, XPath, JSONPath.

ExpressionDefinition

Expression

The expression allows dynamically calculating or defining values during message processing in the integration flow. It is a way to configure behaviors that may vary based on the context of the in-transit message.

Expressions are divided into two hierarchical levels, enabling a more extensible and adaptable structure for different contexts:

  • First level: specifies the type of logic to be applied (constant, simple, jsonpath, etc.).

  • Second level: defines the actual value of the expression, that is, the data that will be assigned to the header.

Common types of expressions

  • constant: defines a fixed value. In the example, it will always return "400".

    - setHeader:
        name: my-header-name
        expression:
          constant:
            expression: "400"

  • simple: allows using placeholders and simple logic to access message data. In the example, it returns the value of the operacao header.

- setHeader:
    name: my-header-name
    expression:
      simple:
        expression: "${header.operacao}"

  • jsonpath: extracts information from messages with a JSON body. In the example, it returns the value of the token field within the data object.

- setHeader:
    name: my-header-name
    expression:
      jsonpath:
        expression: "$.data.token"

  • xpath: extracts information from messages with an XML body. In the example, it returns the id attribute of the customer node within order.

- setHeader:
    name: my-header-name
    expression:
      xpath:
        expression: "/order/customer/@id"

  • groovy/javascript/python (or another scripting language): uses custom scripts for complex operations. In the example, the expression checks the length of the message body. If the body contains data, it sets the header to Valid; if it is empty, it sets it to Invalid. It uses Groovy to perform this conditional check.

- setHeader:
    name: my-header-name
    expression:
      groovy:
        expression: "return request.body.length() > 0 ? 'Valid' : 'Invalid'"

Example

  • The following example defines the header name as Content-Type.

  • The expression parameter is set to constant, meaning it will have a fixed value. This value will always be application/json, indicating that the request body will be in JSON format.

- setHeader:
    id: setHeader-4103186938
    description: Set header urlencoded
    expression:
      constant:
        expression: application/json
    name: Content-Type
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