HTTP Extension - HTTP Server

This notebook demonstrates the HTTP extension which introduces the %server, %server.static and %server.route commands to implement a HTTP server and handle API requests.



In [1]:

    
%extension http

Starting the HTTP Server

The %server command can be used to start a server on a specified port, and it can also be used to stop it. The server is accessible via any process on the local machine.



In [2]:

    
%server start -p 8081

Static Content

Static content can be declared inline within the cell. The name serves as the key for the content, and can be used to update it subsequently. It is also used in creating the URL that serves the content.



In [3]:

    
%%server.static add --name foo --mime text/plain
Hello World!

foo

Static content can also be associated with the current value of a variable previously defined in the notebook. For example, the next cell defines a variable named jsondata to the result of parsing a JSON literal, and the subsequent cell exposes it as static content with the name json



In [4]:

    
%%json --name=jsondata
{
  "abc": 123
}



In [5]:

    
%server.static add --name json --mime application/json --data jsondata









    




json

Routes and Dynamic Content

You can declare request handlers as functions and then expose them as route handlers. The next cell defines a function named helloHandler that is then exposed as the /hello endpoint (by default for the GET HTTP method).

The following cell uses the %request command also provided by the HTTP extension to invoke that endpoint. While the example shows the notebook invoking the endpoint also published by the notebook, in reality some other client application could be the one invoking the endpoint.



In [6]:

    
function helloHandler(req, res) {
  res.send('Hello World!');
  res.end();
}



In [7]:

    
%%server.route add /hello --handler helloHandler



In [8]:

    
%%request
GET http://localhost:8081/hello









    



HTTP 200 

x-powered-by: Express
content-type: text/html; charset=utf-8
content-length: 12
etag: W/"c-1c291ca3"
date: Thu, 28 May 2015 00:33:25 GMT
connection: keep-alive







    





Hello World!

You can also write the script defining the request handler inline when declaring the route. In this case, you do not write the signature of the function. The code you write becomes the body of a generated handler, and the request and response objects exist within scope of the function body.



In [9]:

    
%%server.route add /echo --method POST
response.json(request.body);
response.end();



In [10]:

    
%%request
POST http://localhost:8081/echo
Content-Type: application/json

{
  "xyz": "xyz"
}









    



HTTP 200 

x-powered-by: Express
content-type: application/json; charset=utf-8
content-length: 13
etag: W/"d-7fa24d58"
date: Thu, 28 May 2015 00:33:27 GMT
connection: keep-alive

Routes are dynamic. You can remove existing routes, or replace the implementation of an existing route.



In [11]:

    
%%server.route remove /echo



In [12]:

    
%%request
POST http://localhost:8081/xyz









    



HTTP 404 






    



x-powered-by: Express
x-content-type-options: nosniff
content-type: text/html; charset=utf-8
content-length: 17
date: Thu, 28 May 2015 00:33:29 GMT
connection: keep-alive

Stopping the Server



In [13]:

    
%server stop



In [ ]: