logos-delivery/liblmapi/IMPLEMENTATION_SUMMARY.md

liblmapi - Summary

Overview

Created a new C FFI library liblmapi (Logos Messaging API) that provides a simplified interface to the high-level API functions from waku/api/api.nim.

Files Created

Core Library Files

1. liblmapi/liblmapi.h - C header file

   • Defines C FFI interface
   • Includes function declarations for node lifecycle and messaging
   • Return codes and callback typedef

2. liblmapi/liblmapi.nim - Main library entry point

   • Imports and includes API modules
   • Exports lmapi_destroy function
   • Follows same pattern as library/libwaku.nim

3. liblmapi/declare_lib.nim - Library declaration

   • Uses declareLibrary("lmapi") macro
   • Exports lmapi_set_event_callback function

4. liblmapi/nim.cfg - Nim configuration

   • Sets up compiler flags (gc:refc, threads:on)
   • Configures paths for nim-ffi and project root
   • Library-specific build settings

API Implementation Files

5. liblmapi/lmapi/node_api.nim - Node lifecycle API

   • lmapi_create_node - Creates node from JSON config
   • lmapi_start_node - Starts the node
   • lmapi_stop_node - Stops the node
   • Uses registerReqFFI macro for CreateNodeRequest

6. liblmapi/lmapi/messaging_api.nim - Messaging API

   • lmapi_subscribe - Subscribe to content topic
   • lmapi_unsubscribe - Unsubscribe from content topic
   • lmapi_send - Send message with base64-encoded payload
   • All use {.ffi.} pragma for automatic FFI wrapping

Documentation and Examples

7. liblmapi/README.md - Main documentation

   • API function reference
   • Configuration examples
   • Build instructions
   • Usage patterns
   • Architecture overview

8. liblmapi/examples/liblmapi_example.c - C example program

   • Demonstrates all API functions
   • Shows proper callback handling
   • Complete lifecycle example

9. liblmapi/examples/README.md - Example documentation

   • Build instructions per platform
   • Expected output
   • Usage notes

Build System Integration

10. Modified waku.nims

    • Added liblmapiStatic task
    • Added liblmapiDynamic task
    • Both use buildLibrary helper with chronicle params

11. Modified Makefile

    • Added liblmapi to PHONY targets
    • Added LMAPI_BUILD_COMMAND variable
    • Added liblmapi target that calls nim tasks
    • Respects STATIC flag for static/dynamic build

API Functions

Node Lifecycle

• lmapi_create_node - Create and configure node
• lmapi_start_node - Start node operations
• lmapi_stop_node - Stop node operations
• lmapi_destroy - Clean up and free resources

Messaging

• lmapi_subscribe - Subscribe to content topic
• lmapi_unsubscribe - Unsubscribe from content topic
• lmapi_send - Send message envelope

Events

• lmapi_set_event_callback - Register event callback

Build Commands

# Build dynamic library (default)
make liblmapi

# Build static library
make liblmapi STATIC=1

# Or directly via nim
nim liblmapiDynamic waku.nims liblmapi.so
nim liblmapiStatic waku.nims liblmapi.a

Key Design Decisions

1. Follows libwaku pattern: Same structure and conventions as existing library/libwaku.nim

2. Uses nim-ffi framework: Leverages vendor/nim-ffi for:

   • Thread-safe request processing
   • Async operation management
   • Callback marshaling
   • Memory management between C and Nim

3. Wraps new high-level API: Directly wraps waku/api/api.nim functions:

   • createNode(config: NodeConfig)
   • subscribe(w: Waku, contentTopic: ContentTopic)
   • send(w: Waku, envelope: MessageEnvelope)

4. JSON-based configuration: Uses JSON for:

   • Node configuration (mode, networking, protocols)
   • Message envelopes (contentTopic, payload, ephemeral)
   • Simplifies C interface while maintaining flexibility

5. Base64 payload encoding: Message payloads must be base64-encoded in JSON

   • Avoids binary data issues in JSON
   • Standard encoding for C interop

Integration Points

The library integrates with:

• waku/api/api.nim - Main API functions
• waku/api/api_conf.nim - Configuration types (NodeConfig, NetworkingConfig, etc.)
• waku/api/types.nim - Core types (MessageEnvelope, RequestId, etc.)
• waku/factory/waku.nim - Waku instance type
• vendor/nim-ffi/ - FFI infrastructure

Testing

To test the library:

1. Build it: make liblmapi
2. Build the example: make liblmapi_example or cd liblmapi/examples && gcc -o liblmapi_example liblmapi_example.c -I.. -L../../build -llmapi
3. Run: ./build/liblmapi_example

Next Steps

Potential enhancements:

• Add more examples (async, multi-threaded, etc.)
• Add proper test suite
• Add CI/CD integration
• Add mobile platform support (Android/iOS)
• Add language bindings (Python, Go, etc.)