How to perform Tornado requests within a Tornado request

Question

I am using the Tornado Web Server (version 4.1) with Python 2.7 to create a REST web application. One of my request handlers (web.RequestHandler) handles batch requests consisting of multiple HTTP requests combined into one HTTP request using the multipart/mixed content type. I currently have the batch request handler able to receive the POST request and parse the multipart/mixed content into individual requests that look like this:

GET /contacts/3 HTTP/1.1
Accept: application/json

My question is, what would be a good way of converting these inner batched requests into requests that Tornado can service from within my request handler? I would like to collect the responses within my batch request handler and, once these requests are all complete, return a single multipart/mixed response containing all the batched responses.

Using an HTTPClient to execute the batched requests feels like overkill. It seems like I should be able to build a request object and inject it into the web.Application for processing--I'm at a loss as to how to do this however. Thanks!

Answer 1

Tornado doesn't have any direct support for this. Going through an HTTP client is probably going to be the simplest solution. However, if you're really interested in avoiding that route, here's a sketch of a solution, which relies on the interfaces defined in the tornado.httputil module.

1. Define a class that implements the HTTPConnection interface by saving the arguments to write and write_headers into internal buffers.

2. The Application is an HTTPServerConnectionDelegate . Call its start_request method with an instance of your connection class as both arguments (the first argument doesn't really matter, but it should be unique and since we won't be reusing "connections" that object is fine).

3. start_request returns an HTTPMessageDelegate . Call its headers_received , data_received (for POST/PUT), and finish methods to make your request. Once you have called finish , the handler will run and make calls back into your connection object.