# Generating a Page Dynamically

The goal of this example is to show you how to dynamically generate the contents of a page.

Taking care of some of the necessary imports first, we’ll import `Site`, the `reactor`, and `endpoints` :

    from twisted.internet import reactor, endpoints
    from twisted.web.server import Site

The Site is a factory which associates a listening port with the HTTP protocol implementation. The reactor is the main loop that drives any Twisted application. Endpoints are used to create listening ports.

Next, we’ll import one more thing from Twisted Web: `Resource` . An instance of `Resource` (or a subclass) represents a page (technically, the entity addressed by a URI).

    from twisted.web.resource import Resource

Since we’re going to make the demo resource a clock, we’ll also import the time module:

    import time

With imports taken care of, the next step is to define a `Resource` subclass which has the dynamic rendering behavior we want. Here’s a resource which generates a page giving the time:

    class ClockPage(Resource):
        isLeaf = True
        def render_GET(self, request):
            return (b"<!DOCTYPE html><html><head><meta charset='utf-8'>"
                    b"<title></title></head><body>" + time.ctime().encode('utf-8'))

Setting `isLeaf` to `True` indicates that `ClockPage` resources will never have any children.

The `render_GET` method here will be called whenever the URI we hook this resource up to is requested with the `GET` method. The byte string it returns is what will be sent to the browser. In this case, that byte string is an HTML 5 web page encoded as UTF-8.

With the resource defined, we can create a `Site` from it:

    resource = ClockPage()
    factory = Site(resource)

Just as with the previous static content example, this configuration puts our resource at the very top of the URI hierarchy, ie at `/` . With that `Site` instance, we can tell the reactor to create a TCP server and start servicing requests:

    endpoint = endpoints.TCP4ServerEndpoint(reactor, 8880)
    endpoint.listen(factory)
    reactor.run()

Here’s the code with no interruptions:

    from twisted.internet import reactor, endpoints
    from twisted.web.server import Site
    from twisted.web.resource import Resource
    import time

    class ClockPage(Resource):
        isLeaf = True
        def render_GET(self, request):
            return (b"<!DOCTYPE html><html><head><meta charset='utf-8'>"
                    b"<title></title></head><body>" + time.ctime().encode('utf-8'))

    resource = ClockPage()
    factory = Site(resource)
    endpoint = endpoints.TCP4ServerEndpoint(reactor, 8880)
    endpoint.listen(factory)
    reactor.run()