Strata is a fast, streaming web framework for node.js that is patterned after time-honored and battle tested web application design principles pioneered in the Python and Ruby communities (see WSGI and Rack). Using Strata, developers can build highly performant web servers in a powerful, modular style that is easy to maintain and takes full advantage of the streaming capabilities and excellent I/O handling of node.js.
The core Strata distribution consists of three things:
- A specification (see SPEC) for building applications and middleware
- A library (see lib) with many useful utilities and middleware to aid developers in the common tasks of building applications that conform to the specification
- An executable (see bin/strata) for running Strata applications from the command line
Strata was created to provide a stable platform for the development of complex, modular web applications on node.js. At the time it was created, there already existed two major alternatives for building web applications on node.js: Connect/Express and JSGI. This section of this document explains why Strata was written despite the existence of these libraries.
First, it is beneficial to provide a basic overview of how Strata works. The Strata SPEC defines two interfaces: 1) an interface for the HTTP server to communicate the request to the application and 2) an interface for the application to communicate the response back to the server.
application by calling it with two arguments: the environment and a
callback. The environment is an object that has CGI-like properties
pathInfo, etc.), some
Strata-specific properties, and may also include application-specific extension
properties. The callback is a function the application uses to send the response.
The application communicates with the server by calling the callback with three arguments: the response status code, an object containing HTTP headers, and the response body. The body may be a string or a Stream. The server then returns the appropriate response to the client. If the response body is a Stream, it is streamed to the client as data becomes available.
The main advantage that Strata has over the Connect/Express library is that it provides a CGI-like abstraction (the environment) to web applications that gives them a greater degree of power and modularity, and which allows them to operate with other applications and middleware more easily. Nearly every major web server and/or framework in use today employs a similar technique (see Apache, nginx, PHP, Rails, Sinatra, Pylons, etc.) and the various benefits of doing so are outside the scope of this document.
Connect/Express provides no such abstraction and instead gives the user the basic request and response objects as they were received from node's HTTP server and a callback. Thus, Connect/Express does little more for the user than setup a callback chain. While this may be an acceptable approach for building applications with a small amount of logic, the lack of a common server environment does not scale well.
Strata also comes bundled with several modules that are commonly used in modern web applications but are missing in the Connect/Express distribution at the time of this writing. These include a fast, well-tested multipart parser, a gzip middleware for gzip-encoding response bodies, and a mocking module for building test cases. Also, Strata includes a comprehensive test suite and a user manual that contains well-documented examples for many common use cases.
The main difference between Strata and JSGI (which is only a specification, NOT an implementation) is that Strata uses a callback to serve responses asynchronously whereas JSGI uses promises. Since there is no promises module in the node core distribution, this requires any JSGI implementation for node to depend on a separate promises module, of which there are many, each with a slightly different implementation. Also, since promises have failed to gain very wide adoption in the node community many users are not familiar with using promises at all. This dependence on promises and a general lack of familiarity with the promises interface within the node community make JSGI a poor choice for a node-specific web framework that aims to gain wide adoption.
The easiest way to install Strata is by using npm:
$ npm install strata
You are also free to browse or download the source.
The manual is written in such a way that the topics and examples discussed in higher numbered chapters build upon previous ones. Thus, it is recommended to start with lower numbered chapters when getting started with Strata and work your way up to higher ones.
You can read the manual online.
The test directory contains a comprehensive suite of unit tests for all of Strata's core modules. To run the tests, first install vows:
$ npm install -g vows
Run all tests with:
$ vows test/*_test.js
Otherwise, run the tests for a specific module with:
$ vows test/utils_test.js
Copyright 2011 Michael Jackson
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
The software is provided "as is", without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and non-infringement. In no event shall the authors or copyright holders be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or the use or other dealings in the software.
Strata's multipart parser is based on the fast parser in the node-formidable project written by Felix Geisendörfer. It is included in Strata under the terms of the MIT license.
Strata's view module is based on the ejs templating system developed by TJ Holowaychuk. It is included in Strata under the terms of the MIT license.
My sincere thanks to the authors of each of these libraries for the excellent work they've done and graciously shared.