App

A Crow app defines an interface to allow the developer access to all the different parts of the framework, without having to manually deal with each one.

An app allows access to the HTTP server (for handling connections), router (for handling URLs and requests), Middlewares (for extending Crow), among many others.

Crow has 2 different app types:

SimpleApp

Has no middlewares.

App<m1, m2, ...>

Has middlewares.

Using the app

To use a Crow app, simply define crow::SimpleApp or crow::App<m1, m2 ...> if you're using middlewares.
The methods of an app can be chained. That means that you can configure and run your app in the same code line.

app.bindaddr("192.168.1.2").port(443).ssl_file("certfile.crt","keyfile.key").multithreaded().run();

Or if you like your code neat

app.bindaddr("192.168.1.2")
.port(443)
.ssl_file("certfile.crt","keyfile.key")
.multithreaded()
.run();

Note

The run() method is blocking. To run a Crow app asynchronously run_async() should be used instead.

Warning

When using run_async(), make sure to use a variable to save the function's output (such as auto _a = app.run_async()). Otherwise the app will run synchronously.

TCP socket options

master

Crow lets you control TCP_NODELAY for accepted connections.

• app.tcp_nodelay(true) enables TCP_NODELAY on HTTP server connections.
• app.websocket_tcp_nodelay(true) enables TCP_NODELAY on WebSocket connections.

These settings can be configured independently.

crow::SimpleApp app;

app.tcp_nodelay(true)
   .websocket_tcp_nodelay(true)
   .port(18080)
   .multithreaded()
   .run();

For more info on middlewares, check out this page.

For more info on what functions are available to a Crow app, go here.