Delay streaming large files over proxy in API Gateway 11.2

Products

• CA API Gateway

Issue/Introduction

API Gateway 11.2.0 users may observe a non-deterministic delay of 2–3 minutes when streaming large files (e.g., 60MB+) using the Route via HTTP(S) assertion through an HTTP proxy. While the routing assertion completes quickly in logs, the client does not receive the full stream for several minutes.

Environment

• CA API Gateway 11.2.0 (Appliance or Software)
• Apache HttpClient 5.4.3 (Introduced in 11.2)
• HTTP Proxy configured in routing assertion

Cause

The new HttpClient in Gateway 11.2 may buffer response streams if the Content-Type header returned by the backend is generic (e.g., text/html) or does not match the binary nature of the payload. This causes the Gateway to wait for buffer saturation or a timeout before transmitting the stream to the client.

Resolution

 To resolve the streaming delay, ensure the backend service provides the correct Content-Type for binary data.

1. Identify the header returned by the backend (e.g., Content-Type: text/html).
2. Update the backend service to return the specific type for the file, such as Content-Type: application/zip.
3. Verify the Configure Message Streaming assertion is enabled for the response.