RequestContext - Contains vital information about the client requesting a resource, such as request method, request body, IP address, etc. The request object can also be used to pass information from one handler to the next.ResponseContext - Allows you to send headers, write data, and more, to be sent to the client. To prevent a response from being modified by future handlers, call res.end() to prevent further writing.bool: Request handling will end prematurely if you return false, but it will continue if you return true.null: Request handling will continue, unless you closed the response object by calling res.close(). Some response methods, such as res.redirect() or res.serialize() automatically close the response.RequestHandler: the returned handler will be executed.Stream: toList will be called, and then returned.Future: it will be awaited, and then returned.json.encode. However, you can change a response's serialization method by setting res.serializer = foo;. If you want to assign the same serializer to all responses, globally set serializer on your Angel instance. If you are only returning JSON-compatible Dart objects, like Maps or Lists, you might consider injecting JSON.encode as a serializer, to improve runtime performance (this is the default in 2.0).RequestContext and ResponseContext. Consult the dependency injection documentation.Map based on the URI query parameters by calling RequestContext.queryParameters.