What

Create unified protocol interfaces that all protocol implementations (TCP, UDP, HTTP, WebSocket) will implement. This establishes a common contract for clients and servers across all protocols.

Summary

Define two core interfaces:

• IProtocolClient: Common interface for all protocol clients
• IProtocolServer: Common interface for all protocol servers

Change Type

• Refactor (architectural improvement)

Affected Components

• include/interfaces/ - New interface definitions
• Protocol implementations (TCP, UDP, HTTP, WebSocket) - Will implement these interfaces in subsequent tasks

Why

Problem Solved

Currently, each protocol (TCP, UDP, HTTP, WebSocket) has its own client/server structure with duplicated patterns. This creates:

• Maintenance burden: Changes must be replicated across protocols
• Learning curve: Developers must understand each protocol's unique structure
• Testing complexity: Each protocol requires separate test infrastructure

Related Issues

• Part of [EPIC] refactor: Apply Facade pattern to reduce protocol header complexity #577 (EPIC: Apply Facade pattern to reduce protocol header complexity)
• Blocks subsequent tasks: facade implementation, adapter consolidation

Business Value

• Consistency: Uniform API across all protocols
• Maintainability: Single source of truth for protocol contracts
• Extensibility: New protocols can easily adopt the common interface

When

Urgency

• High Priority - Foundation for EPIC [EPIC] refactor: Apply Facade pattern to reduce protocol header complexity #577

Target Release

Milestone: EPIC #577 completion

Dependencies

• None - This is the first task in the EPIC

Blocks

• Facade class implementation
• Adapter consolidation
• Protocol-specific refactoring

Where

Files to Create

Files to Reference (for API design)

• Existing TCP/UDP/HTTP/WebSocket client/server implementations
• Current protocol patterns

How

Implementation Approach

1. Analyze existing protocols:

   • Review common operations across TCP, UDP, HTTP, WebSocket clients
   • Review common operations across TCP, UDP, HTTP, WebSocket servers
   • Identify common lifecycle methods (connect, send, receive, disconnect)

2. Design IProtocolClient interface:

   class IProtocolClient {
   public:
       virtual ~IProtocolClient() = default;
       
       // Connection management
       virtual bool connect(const std::string& address, uint16_t port) = 0;
       virtual bool disconnect() = 0;
       virtual bool is_connected() const = 0;
       
       // Data transfer
       virtual bool send(const std::vector<uint8_t>& data) = 0;
       virtual std::optional<std::vector<uint8_t>> receive() = 0;
       
       // Configuration
       virtual void set_timeout(std::chrono::milliseconds timeout) = 0;
   };

3. Design IProtocolServer interface:

   class IProtocolServer {
   public:
       virtual ~IProtocolServer() = default;
       
       // Server lifecycle
       virtual bool start(uint16_t port) = 0;
       virtual bool stop() = 0;
       virtual bool is_running() const = 0;
       
       // Connection handling
       virtual void set_connection_handler(
           std::function<void(ConnectionInfo)> handler) = 0;
       virtual void set_data_handler(
           std::function<void(const std::vector<uint8_t>&)> handler) = 0;
   };

4. Documentation:

   • Add detailed Doxygen comments
   • Document design rationale
   • Provide usage examples

Acceptance Criteria

• IProtocolClient interface defined with common client operations
• IProtocolServer interface defined with common server operations
• Interfaces use modern C++ features (smart pointers, std::optional)
• Comprehensive Doxygen documentation
• No breaking changes to existing code (interfaces are additive)
• Code compiles without warnings
• Design reviewed and approved

Testing Plan

• No runtime tests required for interface-only changes
• Verify compilation succeeds
• Verify documentation builds correctly

Breaking Changes

None - This is an additive change. Existing code is not modified.

Checklist

• Code follows project style guidelines
• Self-review completed
• Documentation added
• No breaking changes
• Compiles without warnings