As Atul mentioned in “The Social Constraints of Bettering The Web” [toolness.com], Account Manager will likely not make its way into Firefox 4. He points out one of the biggest bottlenecks as getting approval from Firefox product drivers:

Within Mozilla, I see my coworkers vie for the attention of this tiny handful of gatekeepers. People in charge need convincing; the clever social engineer has a lot of power when it comes to navigating this landscape.

This last step of getting approval comes at the very end of a long line of work. While Dan and I have been busy implementing the core feature and making sure it doesn’t regress performance and tests, a good number of people have been involved both inside and outside of Mozilla to design the user interface, to flesh-out the spec and to integrate the feature into sites or as plug-ins.

Alex Faaborg's mockup of letting users pick different types of accounts

But this approval process affects people outside of Mozilla as well. New developers in the community hear about neat features of the upcoming Firefox and want to help by hacking on patches of related features. For example, the status bar removal in Firefox 4 has a number of side-effects including the removal of the download statusbar. Alex Limi has suggested ways for “Improving download behaviors in web browsers” [limi.net], which would add a new toolbar interface, and while there are initial patches from multiple community members, it seems unlikely to make it to Firefox 4.

I even ran into this same roadblock a couple years ago when I was trying to get the AwesomeBar into Firefox 3. Back then I was a random community member that had a good idea and was able to hack on stuff in my “free” (ha! ;)) time. It was only after a lot of prodding and persistence that got just a bit of what I worked on into Firefox 3, but that was all very stressful as I looked back on “Why I Worked On Firefox.”

But fear not community members! There’s always another release. The product drivers are not approving patches during this beta-crunch time because there’s always some risk involved with changes (especially those “it’s just a one line change” fixes :D). New changes typically are followed up by a number of new issues and patches that then need to be additionally hacked on, tested, reviewed, and approved. So just because it doesn’t get approval now doesn’t mean it won’t be accepted when the tree is more open.

Additionally, patches usually come with a number of dependent fixes that might be able to land first. And in the case of Account Manager, I’ve already gotten in some changes into Firefox 4 that improve the new PopupNotifications (used by Geolocation and Add-ons) and testing infrastructure. Some other useful changes that could land independently of Account Manager are some upgrades to the Password Manager and networking APIs. So while the core feature might not be in yet, the platform is made better and ready for it.

So keep hacking away and perhaps your feature will be ready to land on the open tree after Firefox 4 branches. And then it’ll have many months to bake and get tested by other community members and eventually be seen by millions of Firefox users. 🙂

In designing the Firefox-facing APIs of Account Manager, thunder [sandmill.org] and I decided to make most of the interfaces take a callback/continuation. Two main reasons were 1) to allow add-ons to add extra account types like OpenID and 2) to find out if you’re logged-in to a site over multiple network requests.

For an add-on to provide a new account type, it needs to be able to tell Firefox what saved accounts are available and how to connect to them. These might need to read data from disk and/or network; or perhaps request more information from the user like a 1-time code sent over SMS. For Firefox to support these more-complex interactions, it can’t assume that a method implemented by the add-on can return a value immediately.

Asking for additional information to connect to a banking site

In this particular mockup, the site has told Firefox not to use the basic username-password account type but instead to use an account type that asks for more information. Here, an add-on has already saved the username/password and doesn’t to ask for them, but it can’t immediately connect without asking for more information, so it tells Firefox to show this popup. With the async. API, the add-on can later tell Firefox that it has finished the connect process.

The second reason for going async. overlaps with the first of supporting add-ons; Account Manager and account types need to talk over the network to other machines. These requests can take more than just a few milliseconds, so blocking the rest of Firefox when you click on the “Sign in” button using a synchronous request would be bad. In the case of finding the account status, Firefox might need to make requests for any or all of host-meta, AMCD and the session status.

The Password Manager API in Firefox happens to be synchronous—as are many other interfaces in Firefox. Converting it to be asynchronous for use in the username/password account type was fairly simple, but there’s a couple things to keep in mind: when the work is done and when the result is given.

Implementing the async. interface with the synchronous Password Manager

Here, we’ve made the call to savedAccounts immediately do the work of finding the logins, so this means the caller might have to wait before the asynchronous savedAccounts call returns. We could have just as easily delayed this work to run after the function returns by moving the logic into the async function call, but one needs to be aware that if the arguments are live objects, the contents might change by the time async triggers the callback.

The second point of “when the result is given” is less flexible. The function above could have been written to just call onComplete(accounts) immediately without the async wrapper, but that could break the caller as the implementation is no longer truly asynchronous. The caller would stop working if code is supposed to execute after the call to savedAccounts but before the call to continuation, onComplete.

Trivial example of how non-async. implementations could break

For web developers, implementing async is pretty simple as the global window object has setTimeout. So one implementation could look like function async(callback) setTimeout(callback, 0);

Making the choice of having the APIs be asynchronous does have some drawbacks in terms of code structure. Any function that eventually calls an async. function will be forced to take a callback as well, and if it needs to call multiple async. functions, the logic needs to be broken up into multiple callbacks. If you want to share variables across these callbacks, you’ll end up creating many nested anonymous functions (closures).

Additionally, some simple things like doing Array.reduce (fold), which visits each array item and applies a function to produce a single result, can get pretty complicated if you want to pass in an async. function. In a later post, I’ll describe a way to have asynchronous functions look like they’re synchronous so that you can avoid some of this callback craziness. 😉

Since helping get Firefox Sync and Firefox Panorama into Firefox 4, I’ve been hacking recently on a neat feature called Account Manager. For end users, it makes it easy to connect to sites, and for web developers, it makes it easy to add that functionality. In the process of testing the feature, I added some basic functionality to my website in less than 5 lines of PHP!

(If you already know the details and just want the download, here they are: Windows, OS X and Linux)

An icon shows up in the location bar

If you visit my site using Firefox with Account Manager, you should see something like the picture above. By default, you get a plain image indicating that the site allows you to personalize your experience. Clicking on the icon indicates to Firefox that you want to sign-in.

Firefox asking for information to Sign In (WIP graphics!)

After successfully signing in, Firefox will reload the page. Notice that in addition to the page showing I’m signed-in, Firefox also knows who I’m signed-in as and informs me from the location bar.

Firefox and the website showing my signed-in status

What’s happening is that my site tells Firefox how to sign-in, and Firefox POSTs a request to my connect page, which just does the following:

<?php // connect.php
  $_SESSION["id"] = $_POST["id"];
?>

My site also tells Firefox how to figure out what account I’m signed in as, and my site responds as so:

<?php // status.php
  if ($id = $_SESSION["id"])
    echo "active; authmethod=\"username-password-form\"; id=\"$id\"";
  else
    echo "none";
?>

As a web developer, I didn’t need to write any HTML forms with input boxes and make sure they’re styled nicely. Firefox handles all that and makes it available from any page on my site. This is useful to blend into the look-n-feel of the user’s platform whether it be Windows or OS X or other devices like phones or TVs.

As an end user, I didn’t need to search for the fields to enter my information or find a link on the page that leads to a sign-in box. I know that I can just click in the same spot that I would click to sign in for other sites to sign-in. Additionally, I know at a glance that I’m looking at a personalized site and if I’m connected to the wrong account.

Now, if I were to restart Firefox, it has already remembered that I’ve signed-in to my site before, so signing-in is even easier the second time!

Signing-in to sites you've been to

Instead of the plain image, Firefox shows “Sign in” because it can do that for me. In a single click, Firefox will talk to the site in the background and reload the page. It’s so easy! Just one click. 🙂

Additionally, if I have multiple accounts on the site, perhaps an admin account and a user account, or if multiple people use one Firefox to visit the same web site, clicking “Sign in” will provide a list of those accounts.

No typing necessary to pick an account

You can try out this version of Firefox with Account Manager on Windows (installer), Mac OS X (disk image) and Linux (tarball). This is built on top of Firefox 4 Beta 4, so it includes features like Sync and Panorama and all the HTML5 and speed improvement goodness. 🙂

If you’d like to look into the details of how my site informs Firefox how to connect and get account status, you can take a peek at my Account Management Control Document which is linked from my host-meta. From there, you can start adding support for Account Manager to your own site!