12 - On demand streaming

Most video or audio playing software (like VLC) have a way to stream content from an HTTP server using range requests. Let's create a bridge that exposes our application as an HTTP endpoint.

Tips

Make sure the bridge supports the HTTP Range header.

When an HTTP client wants only part of a file being served by the server, it can set the Range header to indicate which bytes it wants to fetch:

Range: bytes=500-999

Use the range-parser module to make this easy.

Here's some files to get started:

• Use the same server as from exercise 11 (solutions/12/server.js)
• We'll modify the client from exercise 11 slightly by exposing it as an API so our HTTP server can use it programatically (solutions/12/client.js)
  • client.getHandshake(callback) - The callback will be called with an optional error object as the first argument and an object as the 2nd: {type: 'handshake', mimeTyoe: '...', hashses: [...], chunkSize: ..., fileSize: ...}
  • client.getData(index, callback) - The index argument is the chunk number. The callback will be called with an optional error object as the first argument and the chunk as the 2nd

Assignment

Create an HTTP server that bridges the p2p application.

Tests

Share a video file using the server and see if you can play it in VLC by connecting to the bridge.

What's next?

If you get this far, here's a few ideas for how to expand your p2p program:

• Make it work in the browser
• Live streaming