Middleware

Middleware

Blackfish is essentially routing and middleware web framework that has minimal functionality of its own: A Blackfish application is essentially a series of middleware function calls.

Middleware functions are functions that have access to the request object (request), the response object (response), and the next middleware function in the application’s request-response cycle. The next middleware function is commonly denoted by a variable named next.

Middleware functions can perform the following tasks:

• Execute any code.
• Make changes to the request and the response objects.
• End the request-response cycle.
• Call the next middleware function in the stack.

If the current middleware function does not end the request-response cycle, it must call next() to pass control to the next middleware function. Otherwise, the request will be left hanging.

A Blackfish application can use the following types of middleware:

• Application-level middleware
• Router-level middleware
• Error-handling middleware (Coming Soon)
• Built-in middleware
• Third-party middleware

You can load application-level and router-level middleware with an optional mount path. You can also load a series of middleware functions together, which creates a sub-stack of the middleware system at a mount point.

Application-level middleware

Bind application-level middleware to an instance of the app object by using the app.use(middleware: ) and app.METHOD() functions, where METHOD is the HTTP method of the request that the middleware function handles (such as GET, PUT, or POST) in lowercase.

This example shows a middleware function with no mount path. The function is executed every time the app receives a request.

import Blackfish

let app = Blackfish()

app.use { request, response, next in
    print("Time: \(NSDate())")
    next()
}