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Libxmljs-mt

Build Status

AppVeyor Build Status

This project is a fork of libxmljs. The current version 0.18.3 is based on libxmljs 0.18.7 and libxml 2.9.4.

Libxmljs was originally designed with single-threaded operations in mind. There are no asynchroneous operations for things like parsing XML documents. But even more importantly, since the embedded libxml was configured only for single-threaded use, no other package could build on this to provide multi-threaded operations using libxml. The issue is discussed at length in upstream issue 296.

This package here adds multi-threading support to libxmljs. It does offer a method to asynchroneously parse an XML file using

libxmljs.fromXmlAsync(buffer, options, function callback(err, doc) {…});

and it can be used by other packages to provide more advanced asynchroneous operations. To do so, the code has to construct a libxmljs::WorkerParent object on the V8 thread and then a libxmljs::WorkerSentinel on the worker thread. Both of these are RAII sentinels, so they do some setup in their constructor and some cleaning up in their destructor. Getting their lifetime right is important. When using nan, it's easiest to make the WorkerParent a member of the class derived from NanAsyncWorker and have a WorkerSentinel variable in the Execute method of that class.

It is to be hoped that this fork is a temporary solution, and that the original libxmljs project will adapt either this solution or a similar one to become usable in a multi-threaded way. But the corresponding bug report has remained open for too long, and even though there was some very valuable discussion going on, there were also long spans with no activity at all. It is hard to tell when this fork will become obsolete, if ever.

Note that this project makes use of a git submodule for the libxml code, so if you are building from a git checkout you might have to perform git submodule update --init before you can do npm install.

Below comes the documentation from the original project, with only slight modifications where appropriate.

Libxmljs

LibXML bindings for node.js

var libxmljs = require("libxmljs-mt");
var xml =  '<?xml version="1.0" encoding="UTF-8"?>' +
           '<root>' +
               '<child foo="bar">' +
                   '<grandchild baz="fizbuzz">grandchild content</grandchild>' +
               '</child>' +
               '<sibling>with content!</sibling>' +
           '</root>';

var xmlDoc = libxmljs.parseXml(xml);

// xpath queries
var gchild = xmlDoc.get('//grandchild');

console.log(gchild.text());  // prints "grandchild content"

var children = xmlDoc.root().childNodes();
var child = children[0];

console.log(child.attr('foo').value()); // prints "bar"

Support

API and Examples

Check out the wiki http://github.com/libxmljs/libxmljs/wiki.

See the examples folder.

Installation via npm

npm install libxmljs-mt

Contribute

Start by checking out the open issues both for the upstream project and the multi-threaded fork. Specifically the desired feature ones.

Requirements

Make sure you have met the requirements for node-gyp. You do not need to manually install node-gyp; it comes bundled with node.