Wednesday, 30 May 2007

Smart Phone or Mobile Browser - Part II

In my first post on this topic, I talked about the history of web-based applications, and also quickly took a look at Japan, the land of mobile browsers (as opposed to smartphones).

In this post, I'll dig into specific issues with applications in general, and web-based apps in particular. So let's get stuck in.

In order for applications to be enjoyable to use, there are a number of factors that must meet certain strict requirements. Putting aside prettiness (which is a factor, but is less critical than these three), we all require the following from applications: responsiveness, reliability, and privacy (this last one is increasingly an issue in a thoroughly networked world). Let's look at each in turn.


Responsiveness is a critical usability feature in any modern, GUI-based application. It is critical in GUI applications because we interact at such a fine-grained level with the application, performing little operations one at a time, such as typing a single character, selecting a single item, or choosing a single command.

Responsiveness is even more important in mobile applications, because we are operating these applications in high-demand situations. Situations where we need to achieve our goal in a strictly limited amount of time. Poor responsiveness will obstruct us from achieving our goal, and will force us into using alternative mechanisms (for example, something other than our phone) to achieve our goals.

There are two forms of responsiveness that are relevant to this discussion:

  • Interaction responsiveness

    This is the speed at which an application responds to our interactions, our typing a character or selecting an individual item, or issuing an individual command.

    AJAX, Flash, and other technologies have vastly improved this type of responsiveness in Web 2.0 apps. There are still restrictions, but this type of responsiveness is rarely a problem any more. It has never been a problem for client-based software, except when the hardware was simply too underpowered, or an inappropriate technology (like Java) was used.
  • Invocation responsiveness

    This is the speed with which an application instance can be invoked. In other words, how long does it take to bring up the application in order to do some work in it?

    This is an area that Web 2.0 applications are poor at. Web 2.0 apps need to be downloaded into the browser at every invocation. Browsers are heavy pieces of client software, and tend not to be left pre-loaded in phones, so the invocation of the browser is another issue that tells against Web 2.0 apps. Finally, few phones give equal priority to bookmarks as to installed application icons, so reaching a Web 2.0 app requires a multistep process -- start the browser, open the bookmark list, choose a bookmark, log in. This is an easy problem to solve though, and is a good idea for a nice, simple utility.

    An example of poor invocation responsiveness is the way people will often use a physical phone directory in preference to a web based one, because turning their computer on, starting it up, starting up the web browser, and going to the online directory takes far longer than picking up the phone book. The fact that searching for names can be much faster online than in the book (an example of interaction responsiveness) is often irrelevant.

    Interestingly, mobile phones and PDAs in general make great efforts to improve invocation responsiveness, being designed to be constantly turned on, carryable, etc., so any reduction in invocation responsiveness really cuts against the grain.
So, Web 2.0 apps are now responsive in interaction, but still poor in invocation. The invocation issue is exacerbated in a mobile environment because of the unreliability of the mobile data connection. Which leads into the next topic.


The reliability of any application can be expressed via a simple equation.

Let's take reliability as a number between 0 (never works) and 1.0 (works 100% of the time), ie. a probability of something working.

Let's then write the reliability of a component as R(component).


R(system) = R(component1) * R(component2) ...

In other words, the reliability of a system is the product of the independent reliabilities of its components. (This requires the reliabilities to be independent -- if they are dependant the easiest way to handle this is to collapse them into one measurement.)

So, the reliability of client-based software is:

R(client software) = R(client app) * R(client OS) * R(client HW)

Or, in English, the reliability of client-based software is the product of the reliabilities of the client application software itself, the client operating system it's running on, and the client hardware.

As a specific example, the reliability of DreamConnect 3 (a UIQ 3 contacts manager) is:

R(DC 3 app) = R(DC3) * R(UIQ3) * R(phone)

Until recently R(UIQ3) was pretty poor, so R(DC 3 app) overall was unsatisfactory. However, now all reliabilities are up, and R(DC 3 app) is at a level where a user can be happy. From the user's perspective, it is tempting to think only the final reliability matters, but users are more sophisticated than that. They can deduce that R(UIQ 3) was poor, for example, and that will encourage them to move to a different platform. Users can even differentiate between R(OS) and R(HW) if they have enough experience. As ISVs, we have direct control only over R(app), but we do have indirect control over R(OS) and R(HW) by deciding what platform and hardware to support. It is worth bearing this in mind.

So, how about Web 2.0 apps? What does their reliability equation look like?

R(web app) = R(AJAX app) * R(browser) * R(client OS) * R(client HW) * R(network) * R(server app) * R(web server) * R(server OS) * R(server HW)

As you can see, there are lot more components involved. Let's quickly work through them:
  • AJAX app: This is the component of the Web 2.0 app that runs inside the browser on the client machine. It may use some technology other than AJAX, but I'm just using that as a convenient label.
  • Browser: The browser is an important component of this type of solution -- it has the misfortune of being used as a development environment but needing to meet the expectations of a user application.
  • Client OS and Client HW: Same as for normal client software, except the reliability of the local storage has less of an impact on this scenario, since it is used only for invoking the client OS and browser, and not for storing the application data.
  • Network: The reliability of the network is a critical part of the functionality of a Web 2.0 app. The app is invoked across the network, various amounts of functionality are implemented in the server, and all data is stored on the server. The network reliability is thus fairly critical.
  • Server app: This is the component of the application that runs on the server side -- it often involves database code, (and the underlying database software, which is usually very reliable), etc.
  • Web server: The web server software itself, which is important to the function of a Web 2.0 app. Web servers are generally very reliable pieces of software.
  • Server OS and HW: The server's operating system and hardware, which is generally very reliable, more so than client equivalents.

So, what's the end result? Well, as mentioned above, R(server) component (R(web server) * R(server OS) * R(server HW)) is very reliable, and we could probably approximate it as approaching 1.0, and so remove it from the equation. This still leaves:

R(web app) = R(AJAX app) * R(browser) * R(client OS) * R(client HW) * R(network) * R(server app)

We can further simplify this by saying that R(app SW) = R(AJAX app) * R(server app) and we could assume that, since this is under the control of the developer, it's likely to equal R(client app). So:

R(web app) = R(app SW) * R(browser) * R(client OS) * R(client HW) * R(network)

Now we can see that Web 2.0 software is less reliable than client software by the following amount:

R(web app unreliability factor) = R(browser) * R(network)

In the past, R(browser) has been very poor, and has dramatically impacted the reliability of any Web 2.0 software. I would argue that R(browser) is still a significant issue, and counts heavily against web software, including on a PC. Of course, the impact of R(browser) is less than, say, a storage failure, so long as the software is designed properly (ie. regular saving of information -- Google has just recently recognised this by putting a very regular auto-save feature into the Web 2.0 app I'm using to write this).

On the other hand, R(network) varies widely between desktop-bound PCs and mobile smartphones. R(network) nowadays is usually quite high for fixed networks, but for mobile networks it is still quite low, especially for 3G and when moving. For example, I only need to travel ten minutes west to drop out of 3G coverage into 2G, and few minutes further (into the mountains) to drop out of 2G coverage as well. If I were using a Web 2.0 mapping/routing application (such as Google maps), it would fail me almost as soon as I left the city heading west.

In conclusion, then, R(network) is an absolute killer for Web 2.0 style apps on the mobile. Michael Mace observed this in a less formal way a while back.


Privacy is an issue that hasn't really surfaced yet. Since I have a background in security (working on secure OS's as well as Internet security), it's one that I'm keenly aware of.

At present, Web 2.0 apps are either about sharing information, which reduces the privacy concerns, or simply make promises about privacy. There are limited technological systems in place to ensure the privacy of your data.

I have a family blog. It is restricted to only the people that I invite, namely my family. Because I've restricted it to just these people, I can feel free to write about my family's private life. Or can I? What assurance do I have that programmers at Google aren't poring over the (rather boring and very unsordid) details of my life? What assurance do I have that Google won't suddenly copy my private ponderings to the top of every search result they return to their millions of users? Well, I have Google's word. That's all.

Does Google's word protect me from a mistake in their software? No. Does Google's word protect me from a malicious programmer within (or even outside) Google? No.

Imagine this: it is 2017, MS has collapsed under its own weight. Google rules supreme. For some reason, you want to bring a suit against Google, and you are preparing your legal arguments. Using Google Office's word processor. Which saves the text on Googles servers. Encrypted by software that runs on Google's servers. How easy is it for Google to capture your password (they don't need to change the software on your machine -- it's uploaded to your machine every time you open it, so they just change it on their server, which they have every right to do and you can't prevent them doing) and to decrypt and pore over your arguments? Google may desire to do no evil, but how can we trust them to keep their word?

In contrast, client-based software allows firewalling, packet sniffing, and so on, to ensure absolute security.

But the current situation is much worse than that. I'm not even aware of any Web 2.0 apps that provide encryption. Let alone anonymization (so that the app provider can't snoop on your behavior). But both of these, in combination as often as possible, are crucial privacy protections. We're so used to relying on the inaccessibility (except by direct physical access) of our storage, but that's not a part of the Web 2.0 world.

How does encryption work for Web 2.0? Well, it only works when a) you don't want to share the data publicly, and b) you don't want the server to process the data (channel encryption, such as SSL, can still be used, though). So any document, calendar, or database should be encrypted, with the decryption key known only to you. If you wish to share pieces of this, those pieces should be stored separately, with no links back to the encrypted data (which would unnecessarily violate the security of your main data store). Why, then, aren't Google calendars encrypted? Or Google mail messages, etc.? Well, because no-one cares about privacy. Yet.

And what about anonymization? This is a technology that's useful when your data needs to be processed by a server, but doesn't need to be associated with you in particular. For example, a search query doesn't need to be associated with you (unless you want it to be, in order to benefit from the search engine's knowledge of your interests), neither does a location-based services request. Does Google search or Google maps use anonymization? No, because people aren't asking for it and it has a cost associated with it (you need a third party -- the anonymizer -- and it doubles the traffic in the cloud).

While both of these technologies have costs (encryption increases processor load and slightly increases network load), their benefits will eventually become so clearly important that we will see them implemented. I don't have time to talk about all the concerns here, but Bruce Schneier's blog is a great source for this sort of thing. Unfortunately, Web 2.0 apps are difficult to validate (because they're so easy to modify and can even present different versions to different users), so this is another stroke against Web 2.0 apps.


Phew! This has been a long trek. But at the end we can see that, while Web 2.0 apps make sense for some situations on desktop PCs, they have significant disadvantages for mobile usage.

In my next post, I'll talk about a third way, namely the Web Services model, in which client applications use web services to deliver a powerful solution. This is something that smartphones can excel at.


Google has released Google Gears which is an attempt to reduce the impact of R(network) described above. Google Gears allows Web 2.0 apps to work with a client-side cache while disconnected from the network, and to synchronise the local cache with the server when the network is available.

This is a great piece of technology, if it works, since it massively reduces the impact of R(network) just as connected clients (to be discussed in my next post) do. Basically, it transforms Web 2.0 apps into connected clients. Web 2.0 apps still have the disadvantage of R(browser), of course (not to mention the memory and performance impacts of the browser and associated technologies), but this is a worthwhile improvement.


Candide said...

Thanks for writing this.

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