If you looked at OilCan – a Greasemonkey-like browser extension for Android – and Mosembro, you’d quickly realize that they have a lot in common. Both are experimental browser extensions which run on Android, both aim to make websites friendlier, both support installable actions written in JavaScript, and both make it possible for those scripts to modify web pages and launch other applications. And since looking at OilCan’s source code has allowed me to avoid reinventing the wheel at several occasions, some pretty obvious similarities can also be spotted at the source code level.

So, with so many things in common, how are they different at all?

The main difference, I believe, is what causes user scripts to be triggered. A typical OilCan script is triggered by a web page’s URL and is executed only once. Its goal is to change the content or functionality of a very specific document. Mosembro scripts, on the other hand, are triggered by embedded microformats and can be executed dozens of times for each page, while not caring about which page they were executed on.

I could say at this point that OilCan’s approach to invoking scripts could be compared to function calls in programming languages and Mosembro’s approach compared to what is done in aspect oriented programming, with functionality implemented by actions attached to bits of semantic content being cross-cutting concerns, but I’m not sure about it, so I won’t. ;-)

Also, because Mosembro is very narrowly focused on adding functionality to web pages based on semantic data embedded in them it can also provide additional infrastructure, like microformat parsers and action menus, which wouldn’t exactly fit in with a more general purpose framework. And finally, there’s the integrated support for site-level search.

So, there you have it. While it’s true that both apps have a lot in common, it’s their unique features that really matter.

Mosembro, short for “mobile semantic browser”, is a proof-of-concept web browser for the Android mobile platform, which has integrated support for microformats. It was my entry for the Android developer challenge (but was called SmartBrowser back then), and while it wasn’t one of the 50 finalists who made it to the second round, it did finish in the top 25% of all entries, which is pretty good, I suppose.

The goal of this project is very simple: to make a better mobile browser with the help of embedded semantic metadata.

What does it do? It scans any loaded web page for microformats and inserts special links into it, based on any microformats it may have found. These links then enable the user to quickly perform tasks like looking up an address on a map or adding an event to his calendar. While manually performing these tasks is very simple on a computer, it can be pretty tedious on a mobile device without a proper keyboard, mouse, or even without the ability to copy and paste text.

Full feature list, demo videos, downloads and source code are available at the Mosembro project page.