GH-46315 [C#] Apache Arrow Flight Middleware

[HackPoint]

Enhancement: Apache Arrow Flight Middleware in C#

Overview

This Pull Request enhances middleware support for Apache Arrow Flight using C#, focusing on improved metadata header management and propagation for better observability and extensibility. It also provides handling for HTTP/HTTPS communication.

Rationale for this Change

Effective middleware is critical for managing metadata headers, ensuring accurate request/response handling, and simplifying debugging in distributed systems. By improving middleware capabilities, we enhance reliability and observability, significantly benefiting developers and operational teams managing complex Flight-based applications.

What's Included in this PR?

• Middleware enhancements supporting complete metadata header propagation.
• Middleware lifecycle hooks for better request/response management.
• Comprehensive integration tests validating middleware functionality.
• Documentation updates reflecting middleware improvements.

Key Features

• Complete Header Propagation: Ensures accurate propagation of gRPC metadata headers throughout middleware lifecycle events.
• HTTP/HTTPS Handling: Supports middleware integration and metadata propagation for HTTP and HTTPS communications.
• Middleware Lifecycle Management: Supports reliable middleware hooks (OnBeforeSendingHeaders, OnHeadersReceived, OnCallCompleted).
• Enhanced Testing: Adds comprehensive integration tests to verify correct middleware behavior.

Impact

• Improves middleware reliability and simplifies debugging.
• Enhances transparency in gRPC and HTTP/S communication within Flight-based applications.

Are These Changes Tested?

Testing Overview

Unit Tests:

• Added tests for middleware lifecycle event execution (e.g., OnBeforeSendingHeaders, OnHeadersReceived, OnCallCompleted).
• Verified internal logic for capturing and storing gRPC metadata headers.

Integration Tests:

• Tested end-to-end with a real Flight client and in-memory server setup.
• Validated propagation of custom headers (e.g., x-server-header, Set-Cookie) between client and server.

End-to-End Tests:

• Simulated real-world Flight requests to ensure headers are processed consistently across middleware layers.
• Confirmed correct invocation order and middleware behavior under different server responses.

Example Test Cases:

• Verify that OnHeadersReceived correctly captures server-sent headers.
• Ensure custom client middleware modifies request headers as expected.
• Validate that OnCallCompleted is triggered on both success and error cases.

Checklist

• Implementation completed
• Tests added and passing

• GitHub Issue: [C#] Apache Arrow Flight Middleware #46315

[github-actions]

⚠️ GitHub issue #46315 has been automatically assigned in GitHub to PR creator.