Category Archives: Internet

Toying with node.js

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A commenter rightly complained that despite my claims of “playing around” with node.js, all I could come up was with the example in the man page. I replied saying that I did intend to post something that I wrote from scratch, and as promised, here is my first toy node.js program:

var sys = require('sys');
var http = require('http');
var url = require('url');
var path = require('path');

function search() {
  stdin = process.openStdin();
  stdin.setEncoding('utf8');
  stdin.on('data', function(term) {
    term = term.substring(0, term.length - 1);
    var google = http.createClient(80, 'ajax.googleapis.com');
    var search_url = "/ajax/services/search/web?v=1.0&q=" + term;
    var request = google.request('GET', search_url, {
      'host': 'ajax.googleapis.com',
      'Referer': 'http://floatingsun.net',
      'User-Agent': 'NodeJS HTTP client',
      'Accept': '*/*'});
    request.on('response', function(response) {
      response.setEncoding('utf8');
      var body = ""
      response.on('data', function(chunk) {
        body += chunk;
      });
      response.on('end', function() {
        var searchResults = JSON.parse(body);
        var results = searchResults["responseData"]["results"];
        for (var i = 0; i < results.length; i++) {
          console.log(results[i]["url"]);
        }
      });
    });
    request.end();
  });
}

search();

This program (also available as a gist) reads in search terms on standard input, and does a Google search on those terms, printing the URLs of the search results.

I was quite surprised (and a bit embarrassed) at how long it took me to get this simple program working. For instance, it took me the better part of an hour to realize that when I read something from stdin, it includes the trailing newline (as the user hits ‘Enter’). Earlier, I was using the input as-is for the search term, and that was leading to a 404 error, because the resulting URL was malformed.

Debugging was also harder, as expected. Syntax errors are easily caught by V8, but everything else is still obscure. I’m sure some of the difficulty is because of my lack of expertise with Javascript. But at one point, I got this error:

events:12
        throw arguments[1];
                       ^
Error: Parse Error
    at Client.ondata (http:881:22)
    at IOWatcher.callback (net:517:29)
    at node.js:270:9

I still haven’t figured out exactly where that error was coming from. Nonetheless, it was an interesting exercise. I’m looking forward to writing some non-trivial code with node.js now.

What is node.js?

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The logo of the Node.js Project from the offic...
Image via Wikipedia

If you follow the world of Javascript and/or high-performance networking, you have probably heard of node.js. If you already grok Node, then this post is not for you; move along. If, however, you are a bit confused as to exactly what Node.js is and how it works, then you should read on.

The node.js website doesn’t mince words in describing the software: “Evented I/O for V8 JavaScript.” While that statement is precise and captures the essence of node.js succinctly, at first glance it did not tell me much about node.js. I did what anyone interested in node.js should do: downloaded the source and started playing around with it.

So what exactly is node.js? Well, first and foremost it is a Javascript runtime. Think of your web browser; how does it run Javascript? It implements a Javascript runtime and supports APIs that make sense in the browser such as DOM manipulation etc. Javascript as a language itself is fairly browser agnostic. So node.js is yet another runtime for Javascript, implemented primarily in C++.

Because node.js focuses on networking, it does not support the standard APIs available in a browser. Instead, it provides a different set of APIs (with fantastic documentation). Thus, for instance, HTTP support is built into node.js — it is not an external library.

The other salient feature of node.js is that it is event driven. If you are familiar with event driven programming (ala Python Twisted, Ruby’s Event Machine, the event loop in Qt etc), you know what I’m talking about. The key difference though is that unlike all these systems, you never explicitly invoke a blocking call to start the event loop — node.js automatically enters the event loop as soon as it has finished loaded the program. A corollary is that you can only write event driven programs in node.js, no other programming models are supported. Another consequence of this design choice is that node.js is single-threaded. To exploit CPU parallelism, you need to run multiple node.js instances. Of course, there are several node.js modules and projects already available to address this very issue.

To implement a runtime for Javascript, node.js first needs to parse the input Javascript. node.js leverages Google’s V8 Javascript engine to do this. V8 takes care of interpreting the Javascript so node.js need not worry about syntactical issues; it only need to implement the appropriate hooks and callbacks for V8.

node.js claims to be extremely memory efficient and scalable. This is possible because node.js does not expose any blocking APIs. As a result, the program is completely callback driven. Of course, any kind of I/O (disk or network) will eventually block. node.js does all blocking I/O in an internal thread pool — thus even though the application executes in a single thread, internally there are multiple threads that node.js manages.

Overall, node.js is very refreshing. The community seems great and there is a lot of buzz around the project right now, with some big companies like Yahoo starting to use experiment with node.js. node.js is also driving the “server side Javascript” movement. For instance, Joyent’s Smart platform allows you to write your server code in Javascript, which they can then execute on their hosted platforms.

Finally, no blog post about node.js is complete without an example of node.js code. Here is a simple web server:

Throw away mailing lists

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Have you ever found yourself in a situation where you are on a mailing list and you want to send an email to all but 2 members on that list? A common case here is planning a surprise for someone on that list.

Photo by http://www.anna-om-line.com/

In general, I find myself on (long) email threads containing a different subset of people for different occasions (birthdays, anniversaries etc) several times a year. The email threads quickly become long and unwieldy. People keep adding other people as the thread progresses, and the only way the new adds can figure out whats going on is looking at the content of future emails. There is no way for anyone to go back and read all the discussion so far.

That got me thinking, wouldn’t it be great to have a service that provide throw away mailing lists? Hear me out. Here’s how the service would work:

  • To start a new mailing list, I simply send an email to newlist@mycoolservice.com. In the email, I also include a list of email addresses I want to seed the list with.
  • The service sends me back the address of a newly created throw away list. This could be of the form some-random-number@googlegroups.com.
  • For all practical purposes, this is exactly like any other mailing list (or Google Group). We can add more members, search the messages etc.
  • Start your discussion and let the thoughts flow.
  • …
  • At some point, the purpose behind the list will cease to exist (successful surprise, for instance). Needless to add, further discussions on the topic will also cease.
  • You forget you even created this mailing list. After the mailing list has been idle for some time (say two weeks), the service automatically deletes the mailing list. Any future messages to that address will bounce back saying that the list has been deleted, please contact the administrator.

Does anyone else think this could be useful?

Web based password managers: 3 years later

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Almost three years ago (yes, I was quite surprised myself), I wrote about my requirements from a web based password manager. That post generated a lot of discussion, and we have come a long long way since then. I figured it was a good time to step back and present what I feel are some of the best solutions out there.

First, let us recap some basic requirements:

  • Security: this is a no-brainer. If I’m going to trust my passwords to a software, it better be secure. In particular, the developer/owners of the software should not be able to look at my passwords.
  • Online and offline access: I want access to my password regardless of whether or not I have internet connectivity. I should also be able to get to my passwords from any of my devices from anywhere in the world. This usually translates to a web-based system where passwords are stored at some server(s) in the “cloud”.
  • Export: My password data is mine and mine alone, and I want to be able to export it out of the system (for personal backups, for instance).
  • Desktop, Tools, API: I would prefer an open system, one that provides rich access interfaces. I’d love to have a desktop app, plugins for Do or QuickSilver etc. You get the idea.
  • Simple to use: The password manager should not get in my way. Adding new passwords should be a breeze. Using stored passwords should be equally simple. Ideally, I shouldn’t even notice that I’m using a web-based password manager and not the stored passwords from my browser.

Without further ado, here are the top three web-based password managers.

clipperz

clipperz

If you are really paranoid about security, clipperz might be a good option. clipperz is open-source, so you can audit the code yourself should you so desire. It is also a measure of confidence from clipperz — by revealing their source code, they are basically saying, “Hey, we are clean, you can check us out yourself”. It also signals that clippers does not believe in security by obscurity. Apart from being open source, clipperz has all the other expected goodies: you can export your data, it supports one-click logins, you can download an offline copy etc.

I personally did not end up using clipperz because a variety of small problems: I did not like the interface; when I started using clipperz, the one-click login was barely functional; and overall I found the user experience of PassPack much better (read below).

PassPack

PassPack

PassPack is the first web-based password manager that I used seriously, and so far it has worked out great! The team is very responsive and constantly rolling out new features. I think PassPack did a really good job of promoting and educating the public on “host-proof hosting“, meaning that even the service provider does not have access to your data. This is something that most web-based password managers now support, but at least in my mind, PassPack really led the way in terms of awareness.

Some features that really drew me to PassPack: password tagging; I can mark certain passwords as “favorites” so they are loaded first; the two-level security; the desktop app based on Adobe AIR; the ability to store arbitrary notes (such as routing numbers or PINs). PassPack is particularly well-suited for groups. You can share passwords in a secure manner with people in your group. Recently they even added a feature to allow sending passwords securely via email. Now you no longer need to copy/paste your passwords into chats and emails.

What I always missed in PassPack was browser integration and seamless one-click login. With the PassPack bookmarklet, one-click login is almost seamless, but it never worked very well for me. For some websites it just won’t work. For others I’d have to re-login into my PassPack account. Yet other times there the bookmarklet would work in one browser but not in another. At the end of the day, it was just becoming cumbersome to manage multiple copies of my passwords — one in each of the browsers I used on each of my devices, and one in PassPack.

LastPass

LastPass

I recently discovered LastPass, and right now it is my favorite tool. I found it via its Chrome extension, which is when I realized that they have plugins for Firefox and work with pretty much all the good browsers on all the major platforms. I have to admit though, LastPass is nowhere close to PassPack in terms of the maturity of the UI and the overall user experience. But the killer feature for me was browser integration. With LastPass, adding new websites is exactly like Firefox asking you to store password information for a website. In fact, the FireFox plugin for LastPass allows you to disable and bypass the Firefox password manager altogether. When you come to a website that has already been stored in LastPass, it will fill out your username and password just like your browser would do. No need to click on a bookmarklet or any thing else. Transparent, seamless integration.

Unlike PassPack, LastPass has no group features at this point, which is perfectly fine by me. In the words of Tara Kelly, a co-founder of PassPack:

Passpack is pwd mngr with sharing & workgroups. Lastpass is login tool for individuals. Different strokes 4 different folks.

If there is a better web-based password manager out there that you know of, I’d love to hear about it.

Google (Contacts, Mail, Talk) confusion

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Image representing Google Talk as depicted in ...
Image via CrunchBase

When Gmail first introduced the ability to import Contacts, I prompty exported my addressbook from KAddressbook. And then I mostly forgot about it, until recently. In the meantime, Google happily kept adding “suggested” contacts to my addressbook.

I decided to revisit my Google Contacts after reading some blog posts about new functionality. Sure enough, Contacts now even has its own URL (google.com/contacts). I figured this was a good time to clean out the contact and start from scratch with a clean list not polluted by the automatic suggested contacts. So I went ahead and deleted all the contacts and re-imported them from my desktop address book.

Surprisingly, there are weird interactions between my Google Contacts, and my Google Talk buddy list. A lot of people on my buddy list silently disappeared, without any kind of message or confirmation from either GMail, Talk or Contacts. And since then, my attempts to add back all the deleted buddies has failed miserably. Every time I add someone to my list, they show up just fine, but if I log out and log back in, they are usually not there.

What is even worse, this behavior is non-determinstic. Some additions persist across multiple sessions, while others are more ephemeral. I still don’t know exactly what the interaction between these three properties is, but it is very confusing. Google should clarify this more — what exactly is the impact of modifying my Contacts on things like Google Talk etc?

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