Links

NoSQL: Overview

Unlike most of the other projects in this book, NoSQL is not a tool, but an ecosystem composed of several complimentary and competing tools. The tools branded with the NoSQL monicker provide an alternative to SQL-based relational database systems for storing data. To understand NoSQL, we have to understand the space of available tools, and see how the design of each one explores the space of data storage possibilities.

If you are considering using a NoSQL storage system, you should first understand the wide space of options that NoSQL systems span. NoSQL systems do away with many of the traditional comforts of relational database systems, and operations which were typically encapsulated behind the system boundary of a database are now left to application designers. This requires you to take on the hat of a systems architect, which requires a more in-depth understanding of how such systems are built.

Adam Marcus (NoSQL): Adam is a Ph.D. student focused on the intersection of database systems and social computing at MIT's Computer Science and Artificial Intelligence Lab. His recent work ties traditional database systems to social streams such as Twitter and human computation platforms such as Mechanical Turk. He likes to build usable open source systems from his research prototypes, and prefers tracking open source storage systems to long walks on the beach. He blogs at http://blog.marcua.net.

Hummingbird: Site tracking and analytics storage

Hummingbird lets you see how visitors are interacting with your website in real time.

And by “real time” we don’t mean it refreshes every 5 minutes—WebSockets enable Hummingbird to update 20 times per second.

Hummingbird is built on top of Node.js, a new javascript web toolkit that can handle large amounts of traffic and many concurrent users.

Hummingbird is organized into two parts: a node.js-based tracking server that records user activity via a tracking pixel, and a collection of javascript-based widgets that display that activity. The server records all activity in MongoDB and broadcasts it to the clients using WebSockets if possible, and falling back to Flash sockets if necessary.

The Hummingbird.WebSocket object receives websocket events from the server in the form of JSON objects. Individual widgets subscribe to a property in the JSON tree and register handler functions to be called whenever that property is present.