node-multiparse

A simple library to parse multipart messages the right way. The parser is implemented as a WritableStream expecting the body of a multipart message. It supports nested multipart messages out of the box.

Usage

The parser exposes the standard WritableStream interface including the methods write() and end().

var MultiParser = require('multiparse');

// Parse our message with 'boundary' as it's boundary
var parser = new MultiParser('boundary');

parser.write(...);
parser.end();

parser.on('part', function (part) {

});

Architecture

Dependencies are minimal, only the content-type package is used. Parsing headers is done with the native HTTP parser included in node. Searching for boundaries is done using the native Boyer-Moore-Horspool implementation as provided through String.indexOf. A small cache accounts for boundaries splitted over several chunks.

Classes

Class	Description
MultiParser	The MultiParser class is a WritableStream which will parse the provided message and will emit a new ReadableStream for each message part it encounters.
MessagePart	This is the IncomingMessage analog for message parts. It implements the ReadableStream interface.

Reference

MultiParser

The MultiParser constructor accepts one mandatory string argument to be used as the boundary of the message being parsed:

new MultiParser(boundary)

Function	Description
on(event,callback)	Add a listener for a specific event. The event can be any of data, part, trailer and error.
write(chunk)	Write a chunk of data to the parser.
end()	Terminate the multipart message. This method will emit an error if the root message was not properly finished (no closing boundary was found).

MessagePart

A new MessagePart will be constructor each time the MultiParser encounters a message part. The main difference with the interface of an IncomingMessage is the presence of an optional parts property.

Property	Description
headers	Contains all the message headers where the keys correspond to the lowercase header names.
parts	If the message part is also a multipart message, this property will contain an array of MessagePart instances corresponding with the parts.

Function	Description
on(event,callback)	Add a listener for a specific event. The event can be any of data, part, trailer and error.
pipe(stream)	Pipe the stream to a WritableStream.

The MultiParser class emits the same events as the MessagePart and provides a way to listen to events emitted by the root message.