Customize HTTP headers for AS2 messages - Amazon Transfer Family
Template OverviewHow It WorksKey FeaturesImplementation DetailsDeployment and Usage
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Customize HTTP headers for AS2 messages

When sending AS2 messages to trading partners, you may need to customize the HTTP headers to meet specific requirements or enhance compatibility with your partner's AS2 server configuration. This Amazon CloudFormation template creates an infrastructure to enable customized HTTP headers for AS2 messages sent through Amazon Transfer Family. It sets up an Amazon API Gateway and Lambda function to act as a proxy, allowing dynamic modification of headers required by trading partners' AS2 servers.

Use this template to do the following:

  • Add custom HTTP headers to outbound AS2 messages

  • Override default header values with custom values

    Important

    Be careful when overriding default header values, as it can cause send failures: some AS2 headers are required.

  • Ensure compatibility with trading partners that have specific header requirements

Template Overview

The template creates the following main components:

  • A Lambda function that processes and forwards AS2 messages

  • An Amazon API Gateway to expose the Lambda function

  • IAM roles and permissions for the Lambda function

  • Conditional resources for HTTPS support

The template file is available here: Dynamic HTTP headers template.

How It Works

  1. The Amazon API Gateway receives incoming AS2 messages from Amazon Transfer Family.

  2. The request is forwarded to the Lambda function.

  3. The Lambda function processes the request, adding or modifying headers as needed.

  4. The modified request is then forwarded to the partner's AS2 server.

  5. The response from the partner's server is returned through the Lambda and Amazon API Gateway back to Amazon Transfer Family.

Key Features

  • Dynamic Header Modification: Allows customization of the Subject header and addition of other required headers.

  • Protocol Support: Works with both HTTP and HTTPS protocols.

  • Flexible Configuration: Allows specification of partner host, port, and path.

Implementation Details

The template implements the following key components:

Lambda Function

The core of the solution is a Node.js Lambda function that:

  • Receives requests from the Amazon API Gateway

  • Modifies headers based on configuration and incoming request data

  • Forwards the modified request to the partner's AS2 server

  • Handles both HTTP and HTTPS protocols

  • Includes error handling and logging

Amazon API Gateway

An HTTP API is set up to:

  • Receive incoming AS2 messages

  • Route requests to the Lambda function

  • Return responses back to Amazon Transfer Family

Template parameters

Enter information for the template parameters as follows. Note that all of these parameters are strings.

  • Environment: this parameter is used to name the resources that the template creates: whether they are intended for a development or production environment. Valid values are dev and prod.

  • PartnerHost: the IP address or hostname of the AS2 partner server.

  • PartnerPort: the port number for the AS2 partner server. If not specified, defaults to 80 for HTTP and 443 for HTTPS.

  • PartnerPath: the path to the AS2 endpoint on the partner server

  • ProtocolType: the protocol to use for the AS2 communication: valid values are HTTP and HTTPS.

Conditional Resources

For HTTPS support, the template conditionally creates:

  • A Lambda Layer for CA certificates

  • HTTPS-specific configuration in the Lambda function

Deployment and Usage

To customize AS2 HTTP headers using a CloudFormation template

  1. Open the Amazon CloudFormation console at https://console.amazonaws.cn/cloudformation.

  2. In the left navigation pane, choose Stacks.

  3. Choose Create stack, and then choose With new resources (standard).

  4. In the Prerequisite - Prepare template section, choose Choose an existing template.

  5. Copy this link, Dynamic HTTP headers template, and paste it into the Amazon S3 URL field.

  6. Choose Next.

  7. Fill in the parameter details with your information. These are detailed in Template parameters.

  8. Choose Next. On the Configure stack options page, choose Next again.

  9. Review the details for the stack that you're creating, and then choose Create stack.

    Note

    At the bottom of the page, under Capabilities, you must acknowledge that Amazon CloudFormation might create Amazon Identity and Access Management (IAM) resources.

After deploying this Amazon CloudFormation stack:

  1. Note the Amazon API Gateway endpoint URL provided in the stack outputs.

  2. Update your existing Amazon Transfer Family Connector to use this new Amazon API Gateway endpoint.

  3. The solution will now handle AS2 messages, adding or modifying headers as configured.

Warning

Only modify the Subject header or add headers that your partner explicitly expects. Changing other headers may cause transfer failures.