Firefox add-ons for the occasional web developer

I'm not a hardcore web developer but I do some occasional web-based work, and one of the issues I have is that - because web applications exist in an environment which spans both browser and server (and which often seems to hide the workings of its components) - it can be quite difficult to see under the hood when there are problems.

Fortunately there are a number of adds-on for Firefox (my browser of choice) that can help. These are the ones that I like to use:

• Firebug http://getfirebug.com/ is possibly one of the most essential add-ons for web development. I first came across it as a Javascript logger and debugger, but it's far more than that: describing itself as a complete web development tool, its functionality extends to HTML and CSS in additional to script profiling and network analysis capabilities. As an occasional user I've found the Javascript debugging functions invaluable, and the ability to edit CSS in-place and see the results immediately has also been really helpful in debugging style sheets - in fact its biggest downside from my perspective is that it's not immediately obvious how to use many of its functions.

• Live HTTP Headers http://livehttpheaders.mozdev.org/ is a great tool for exposing the interactions between your browser and a server. I found this invaluable when I was debugging some website functionality that I was developing earlier this year, as it enabled me to follow a redirect that I'm sure I couldn't have seen otherwise.

• QuickJava http://quickjavaplugin.blogspot.com/ is a utility that allows support for Java, Javascript, Flash, Silverlight, images and others to be toggled on and off within your browser, enabling you to check how a page behaves when viewed by someone who doesn't have these enabled.
  

• I really like the HTML Validator http://users.skynet.be/mgueury/mozilla/ for ensuring that my HTML markup is actually W3C compliant; the main issue with this is that it's only available for Windows platforms. Provided you have the "Add-on Bar" visible in Firefox (toggle via "Options" in the Firefox main menu, or do ctrl+/), this displays a little icon at the bottom of the screen indicating the goodness or otherwise of your markup.

There are a few other useful add-ons for working with design elements like colours and images:

• Colorzilla http://www.colorzilla.com/ is a tool that allows you (among other things) to pick colours from the current webpage and get the corresponding hex codes or RGB values.

• Measureit http://frayd.us/ creates a ruler that lets you measure the size of page elements in pixels - particularly helpful when sizing images for web display.

• In the past I've found the in-browser screen capture utility Fireshot http://screenshot-program.com/fireshot/ quite handy for taking screenshots of an entire webpage including the off-screen portions. I have to admit I haven't used it for a while though. There's a paid "pro" version which offers a lot of additional functionality.
  

Although I've given URLs, the easiest way to install any of these is via the "Get Add-ons" tab accessed via the "Add-ons" option in Firefox's main menu (I'm using Firefox 8.0 at the time of writing). Once installed the individual add-ons appear in various places, for example by default Firebug's icon can be found at the top-right hand corner. If an add-on's icon doesn't appear automatically (as seems to happen for Measureit) then you might have to add it manually: go to "Options"/"Toolbar layout", locate the item and drag it to the toolbar.

I wouldn't try to argue that this is definitive list, but for an occasional user like as myself these tools work well and (with the exception of Firebug) are easy to remember how to use even after several months away from them. However if these don't meet your needs then I'd recommend checking out the "Web Development" category of Mozilla's add-ons site for many more options.

Creative Commons overview

A while ago I came across an interesting overview of the Creative Commons licence for digital content by Jude Umeh in the BCS "IT Now" newsletter ("Flexible Copyright", also available via the BCS website at http://www.bcs.org/content/conBlogPost/1828 as "Creative Commons: Addressing the perils of re-using digital content"), which I felt gave a very clear and concise introduction to the problem that Creative Commons (CC) is trying to solve, how it works in practice, and some of the limitations.

Essentially, anyone who creates online content - whether a piece of writing (such as this blog), an image (such as a photo in my Flickr stream), or any other kind of media - automatically has "all rights reserved" copyright on that content. This default position means that the only way someone else can (legally) re-use that content is by explicitly seeking and obtaining the copyright owner's permission (i.e. a licence) to do so. As you might imagine this can present a significant barrier to re-using online content.

The aim of the Creative Commons is to enable content creators to easily pre-emptively grant permissions for others to re-use their work, by providing a set of free licences which bridge the gap between the "all rights reserved" position (where the copyright owner retains all rights on their work) and "public domain" (where the copyright owner gives up those rights, and allows anyone to re-use their work in any way and for any purpose).

These licences are intended to be easily understood and provide a graduated scale of permissiveness. According to the article the six most common are:

• BY ("By Attribution"): this is the most permissive, as it grants permission to reuse the original work for any purpose - including making "derived works" - with no restrictions other than that it must attributed to the original author.

• BY-SA ("By Attribution-Share Alike"): the same as BY, with the additional restriction that any derived work must also be licensed as BY-SA.

• BY-ND ("By Attribution-No Derivatives"): the original work can be freely used and shared with attribution, but derivative works are not allowed.

• BY-NC ("By Attribution-Non-Commerical"): as with BY, the original work can be used, shared and used in derived works, provided attribution is made to the original author; however the original work cannot be used for commercial purposes.

• BY-NC-SA ("By Attribution-Non-Commercial-Share Alike"): similar to BY-SA, so any derived work must use the same BY-NC-SA licence, and like BY-NC, in that commercial use of the original work is not permitted.

• BY-NC-ND ("By Attribution-Non-Commercial-No Derivatives"): the most restrictive licence (short of "all rights reserved"), as this only allows re-use of the original work for non-commercial purposes, and doesn't permit derivative works to be made. Umeh states that BY-NC-ND is "often regarded as a 'free advertising' licence".
  

As Umeh points out, "CC is not a silver bullet", and his article cites examples of some of its limitations and potential pitfalls. Elsewhere I've also come across some criticisms of using the non-commercial CC licences in certain contexts: for example, the scientist Peter Murray Rust has blogged about what he sees as the negative impact of CC-NC licensing in science and teaching (see "Suboptimal/missing Open Licences by Wiley and Royal Society" http://blogs.ch.cam.ac.uk/pmr/2011/10/27/suboptimalmissing-open-licences-by-wiley-and-royal-society/ and "Why you and I should avoid NC licences" http://blogs.ch.cam.ac.uk/pmr/2010/12/17/why-i-and-you-should-avoid-nc-licences/).

However it's arguable that these are special cases, and that more generally CC-based licensing has a significant and positive impact on enabling the legal re-use of online material that would otherwise not be possible: indeed, even the posts cited above only criticise its NC aspects, and otherwise see the CC as greatly beneficial. Certainly it's worth investigating if you're interested in allowing others to reuse digital content that you've produced (there's even a page on the CC website to help choose the appropriate CC licence based on answers to plain English questions: http://creativecommons.org/choose/).

As I'm not an expert on CC (or indeed on copyright law or content licensing), I'd recommend Umeh's article as the next step for a more comprehensive and expert overview; and beyond that of course more information can be found at the Creative Commons website http://www.creativecommons.org/ (with the UK-specific version due to become available at http://www.creativecommons.org.uk later this month).