What are practical applications of Queues?

Desktop vs. Web applications

• There is a heavy discussion going about web going to replace web applications. Yet, beyond that discusion my personal observation is that desktop applications have something that web applications do not have, what is that? I belive this thing make people prefer desktop applications over web applications. Let me give you my personal example. I have an many email accounts with different providers. For each of these accounts, I am able to retrieve my emails both using Thunderbrid and a Web mail client. Yet, when I have access to my Thunderbird I always use it and never the web mail client. Worst, when I have problem with Thunderbird (like now) I notice that I check my emails less regularly. Thunderbird is set to retrieve my emails every 2 minutes. With the web mail client I check my emails every 10 minutes. Why? Can you identify the difference and state it consisely? One difference I just noticed (in the course of formulating this question) is that Thunderbird manages all my email accounts (i.e. five of them!). With web mail, I would need to go through each of them, log in, etc. This is more cumbersome. But beside this, is there any difference you can identify and document on the user firendliness of desktop applications over web applications? There is one borrying argument that desktop applications GUIs are richer than web application GUIs. I don't buy this argument; I don't think it is the key point. Help me solve this mystery?:-) Chai, Klausy.

• Answer:

  Hi klaus777-ga, I think it's safe to say that web applications are not going to completely replace desktop applications, just as the car hasn't replaced the bicycle, television hasn't replaced newspapers, recorded music hasn't replaced live music, etc. In every case there is a "certain something" to ensure that the older technology will retain a secure niche. So what defines the niche that will remain for desktop applications? To identify that, it helps to use the web usability factors identified by Chris Loosley of E-Commerce Times: "To satisfy customers, a Web site must fulfill four distinct needs: availability, responsiveness, clarity, and utility. This list presents the four essential qualities in order of their significance..." E-Commerce News: When is your web site fast enough? http://www.ecommercetimes.com/story/46627.html At first glance, it seems like desktop applications have the edge for availability. After all, you can use your desktop applications even when the web server is down (or if you are not connected to the internet at all). But there's more to it than that. You can't use your desktop applications when you are anywhere other than at your desktop. You can't use them at school, at the office, on the road, on the airplane, in another city, etc. Having your "desktop" applications on a "laptop" is a partial solution, but it ties the availability of the application to the physical presence of a particular piece of equipment. A web application is usable anywhere you have a web browser. So the web application wins for availability. What about clarity? I agree with you that the GUI is not the key factor here. There are web apps with rich, clear user interfaces, and there are desktop apps with rich, clear user interfaces. Similarly, there are appaling examples of both. When you think about it, the browser is itself a desktop application. When browsing the web, we are interacting with a desktop application. Of course there are differences in the GUI toolkits available for browser applications and for desktop applications, but each of these toolkits is evolving to include the best of what the other has to offer. So, although a rich, clear interface is vital, it's not the factor that divides desktop applications from web applications. Next, let's consider utility. Does the application do what you need? Interestingly, Chris Loosley puts this last in his order of importance. It's tempting to put it first, yet the most functional application in the world is useless if it's not available, or if it's too confusing to use. So I'm with Chris on this one: utility comes last (but it's still absolutely essential). So is utility the factor that sets desktop applications apart from web applications? It's temping to say "yes", because we don't yet have any web application that does everything that Microsoft Word or Excel can do (although we are certainly getting close). But that's a very one-sided way to look at the issue, when there are web applications that simply cannot be replicated on the desktop. A search engine such as Google cannot be implemented on the desktop. Our individual computers do not have the power to crawl the entire web, index it, and perform complex search queries. Nor can we have collaborative websites such as photo-sharing sites on the desktop. Perhaps, though, you are more interested to compare internet applications accessed through a web browser, versus internet applications access through a desktop application. Here it gets interesting. Consider Google Earth on the desktop: http://earth.google.com/ versus Google Maps on the web browser: ://www.google.com/maphp?hl=en&tab=wl&q= Both can display maps, satellite photography, driving directions, etc, yet the desktop application seems to be more powerful and elegant. Google Earth versus Google Maps is only one data point however. If internet-enabled desktop applications were substantially more functional, we would expect to see more of them than we do. There certainly are banks, collaborative groups, ticketing agencies and recreational sites that use internet-enabled desktop applications, yet there are vastly more that use browser-based applications. Of Chris Loosley's four "needs", this now leaves only "responsiveness" as a possible decider between web applications and desktop applications, and I believe "responsiveness" is indeed the important one. Chris doesn't say much about it though: "Having reached the site, pages that download slowly are likely to drive customers to try an alternate site." http://www.ecommercetimes.com/story/46627.html Is that all one can say about responsiveness? I don't think so. Firstly, it's really important. Microsoft urges developers to steer away from unresponsive pauses in the operation of their applications: "This leads the user to attempt to terminate the application ... or even to reboot the computer. Usability studies conducted by Microsoft show that even periods as short as a few seconds are too long for many users." Make It Reliable http://msdn.microsoft.com/windowsvista/prodinfo/what/reliability/default.aspx Right now, most desktop applications are more responsive than their web equivalents. That's not surprising, considering that the bandwidth between the computer and its hard drive could easily be a hundred times higher than the bandwidth between the computer and the server. Also, desktop applications are likely to be written in an efficient compiled language whereas web applications will be using an interpreted scripting language for user interface operations. So, unless the application has a particularly high computational overhead, the desktop version is likely to be more responsive. Communication speeds are increasing, however, and in the future we can expect the gap between local response times and internet response times to continually narrow. That's not enough though, and here we get to what I believe is the essence of the situation. It's not the absolute response time that is most important; it's how predictable the response time is. Given a choice between an application that always responds in half a second, or one that responds mostly in a tenth of a second but sometimes only after two seconds, users will choose the first application. It's the variation, the unpredictability, in the response time of a web application that makes a desktop application feel smoother to use. To some extent, an unpredictable response time is inevitable with a web application. There are always going to be unknown delays in communication over a complex network; those delays are greater and less predictable than those due to communicating to and from a local hard drive. Also of some relevance to your question is an observation that modern web applications result from a meshing of two technologies - the web as a hypertext information space (as originally conceived), and the web as a link between the client and server of a specific application (as frequently found in web applications). This dichotomy, whilst extremely powerful, can make the web application less than fully satisfactory in terms of access to hyperspace and also in terms of a user interface to a single application. This dichotomy is illustrated by an annotated diagram in this PDF page by Jesse James Garrett: The Elements of User Experience http://www.jjg.net/ia/elements.pdf which is also available as part of a book by the same name: The Elements of User Experience http://jjg.net/elements/ At this point, klaus777-ga, I would like to know whether you find it a satisfying hypothesis that desktop applications gain their usability edge due to the predictability of their responsiveness. If you accept this hypothesis, do you need me to take it any further? If not, please state why it is not acceptable in order to guide my further research. Just let me know by using the "Request for Clarification" feature. In closing, I would like to add two further points. First, you mentioned that you found Thunderbird more functional because it managed all of your email accounts in one place. That's certainly an important factor, but it's not one that's fundamental to a desktop application. For example, you could have five accounts all configured to forward to one Gmail account http://gmail.google.com/ from which you could manage all of your accounts using the Gmail web application. Secondly, I believe that we will see an explosion in hybrid desktop-web applications over the next few years. By that I mean applications that will operate as a desktop application when you are on your own computer. When you are on another computer (or a mobile phone etc) you will be able to access the same (or very similar) functionality as a web application. Your same data files will be used in each case: either the desktop copy or the webserver copy will be considered the "golden" copy, with other copies transparently duplicated, cached and synchronised on demand. As I said above, please let me know if you require clarification or additional research. Regards, eiffel-ga Google Search Strategy: "web applications" "desktop applications" ://www.google.com/search?q=%22web+applications%22+%22desktop+applications%22 responsiveness applications predictable ://www.google.com/search?q=responsiveness+applications+predictable "response time" "more important than" ://www.google.com/search?q=%22response+time%22+%22more+important+than%22 Additional Links: Web Applications: Richar or Poorer? http://www.ecommercetimes.com/story/48889.html Performance Matters: Managing Rich Internet Applications http://performancematters.blogspot.com/2006/03/managing-rich-internet-applications-6.html