Performance Tips for Microsoft “Casablanca” (C++ REST SDK)

“Casablanca”“Casablanca” (also known as the C++ REST SDK) is an open-source Microsoft library that simplifies writing modern C++ applications that interact with web services. It provides higher-level abstractions over HTTP, JSON serialization, asynchronous tasks, and more, allowing C++ developers to build RESTful clients and servers with expressive, cross-platform code.

Background and purpose

Microsoft released “Casablanca” to bring modern web-programming idioms to C++, particularly asynchronous programming and HTTP/REST interactions. The project aimed to reduce boilerplate and enable developers to write networked C++ applications more productively, similar to the ease found in higher-level languages like C# or JavaScript.

Key components

• HTTP client and server

  • A fluent HTTP client API for sending requests and receiving responses.
  • A server-side HTTP listener for building lightweight REST services.

• JSON support

  • A JSON library for parsing, constructing, and serializing JSON values (objects, arrays, strings, numbers, booleans, null).

• Asynchronous tasks

  • A task-based asynchronous model inspired by the PPL (Parallel Patterns Library) and continuations, enabling non-blocking I/O and composition of async operations.

• Uri and WebSocket utilities

  • Helper classes for URI parsing/formatting and (in some versions) basic WebSocket support.

Programming model and features

• Modern C++ idioms

  • Uses STL containers and smart pointers; integrates with C++11 and later features.
  • Encourages RAII and exception-safe patterns.

• Fluent APIs

  • Methods often return objects that allow method chaining, improving readability when composing HTTP requests.

• Cross-platform

  • Initially Windows-focused, later versions supported Linux and macOS, making it usable for cross-platform server and client applications.

• Extensibility

  • Modular design allowing integration with other libraries (e.g., Boost, OpenSSL for TLS on non-Windows platforms).

Example: simple HTTP GET client

#include <cpprest/http_client.h> #include <cpprest/filestream.h> using namespace web; using namespace web::http; using namespace web::http::client; int main() {     http_client client(U("http://www.example.com"));     client.request(methods::GET, U("/")).then([](http_response response) {         if (response.status_code() == status_codes::OK) {             return response.extract_string();         }         return pplx::task_from_result(std::wstring());     }).then([](pplx::task<std::wstring> previousTask) {         try {             auto body = previousTask.get();             ucout << body << std::endl;         } catch (...) {             ucout << U("Error retrieving response") << std::endl;         }     }).wait();     return 0; } 

Building and dependencies

• On Windows, Casablanca integrates with Visual Studio and can be built via MSBuild.
• On Linux and macOS, it typically relies on CMake and may require additional libraries like OpenSSL and libcurl/libboost for networking and TLS.
• Recent community forks and package manager ports (vcpkg, Conan) make installation simpler.

Use cases

• Microservices and lightweight REST APIs
• HTTP clients for consuming web APIs
• Prototyping networked C++ applications with JSON payloads
• Cross-platform tools that need to communicate over HTTP/HTTPS

Strengths

• Provides a high-level, expressive API for web programming in C++.
• Encourages asynchronous, non-blocking architecture.
• Cross-platform support broadens deployment choices.

Limitations and considerations

• Some parts of the API feel dated compared to modern C++ library conventions.
• Project activity has varied; check current forks/maintained versions before adopting for long-term projects.
• Dependency management (OpenSSL, platform networking backends) can add complexity on non-Windows platforms.

Migration and alternatives

If Casablanca doesn’t meet your needs, consider:

• Boost.Beast — low-level, highly performant HTTP and WebSocket support.
• cpp-httplib — single-header, lightweight HTTP client/server.
• Pistache — modern C++ REST framework (Linux-focused).
• libcurl with a JSON library (nlohmann::json) for flexible client implementations.

Conclusion

“Casablanca” brought a useful, higher-level approach to web programming in C++, making RESTful client/server development more approachable. For new projects, evaluate current maintenance status and compare with modern alternatives (Boost.Beast, cpp-httplib) to choose the best fit for performance, ease of use, and long-term support.