For many application developers, the fastest, easiest way to introduce a mobile solution was to "chop down" an existing Web-based application. Users that had a device with a browser could then access the applications. However, because the resulting applications were not designed for the navigation capabilities of a mobile device or the smaller bandwidth, the user experience suffered. These problems can be solved by using a thick client instead of a thin client.

With a thin client, there is nothing running on the device except the presentation. All the content is on the host. The data, along with the rules to display it, are sent down and rendered on the local machine. Everything is done on the server; every request requires going back to the host. With a thick client, however, the presentation engine is on the local machine, which does the work.

The need for thick clients is driven by the complexity of the information and the presentation demanded by mobile users. Mobile users, too, want robust applications and a good user experience. Years ago with the PC, users went to a Web site and got straight HTML. PC users said, "That's not good enough." Then came dynamic HTML, Java applets, Flash, and great plug-ins.

Users want the same thing in the wireless world. They want their information quickly, and displayed the way they want to see it.

The next generation of mobile devices has adopted a thick-client paradigm. Newer devices, such as those from Motorola and Palm, use J2ME (Java 2 Platform, Micro Edition), which is a thick-client environment. These devices provide an environment for developers to make thick-client applications instead of thin-client, browser-based ones.

Advantages
The greatest advantage of a thin client involves application deployment. If you have to distribute 1,000 applications to wireless devices, you would have to get 1,000 users to come back to the office and cradle their devices. With a larger group, this could be a nightmare. With a thin client, there is no need for users to cradle the device; you just change the back end. Some vendors have addressed the thick-client deployment issue with over-the-air programming (OTAP), which will be covered later in this article.

A thick client, however, provides several key benefits. First is the ability to do local processing and local data storage. With a thin client, modifying one item could require making several trips back to the host. And, because the bandwidth in the wireless world is so small, bringing pages down is a long, arduous task. A thick client, however, enables mobile users to work offline with the local data that is brought down; everything is done locally.

For example, if you're getting a stock quote in a thin-client environment, you would have to go to the server and bring down the input screen to enter the stock symbol. Then, you have to get the data and bring down the information (which is usually much more than you need) to your mobile device.

With a thick-client environment, the input screen is already on the device; you just enter the stock symbol (a very small package) and hit "enter." On the return trip, the host sends back only the key information because the display screen is on the mobile device.

The advantage of a thick client's local processing ability can be seen when a user makes a mistake while entering data. With a thin client, the user would be prompted again, requiring another trip. With a thick client, you could use an "if" statement to determine if the information is correct before sending it to the host, which saves time.

On most networks, because of the amount of data, sending a Web page could take more than a minute. Waiting a long time for information does not help users in a mobile sense. Users of robust applications, such as CRM (Customer Relationship Management), need information quickly. These applications need a thick client. With a thick client, you are sending and receiving fewer characters, which takes much less time (and costs less, too).

Another key benefit of a thick client involves coverage ­ or the lack of it. A mobile application that uses a thin client is useless if the user does not have coverage. With a thick client, users can continue to work even if they do not have coverage. Data can be downloaded at the beginning of the day and worked on without having to use the network.

Disadvantages
The user experience is very important with mobile devices, and browsers, which are used in a thin-client environment, simply lack the presentation management needed to get the job done. On a desktop PC, where data can be sent very quickly and users have a mouse and a large screen, this is not noticeable. However, on a small wireless device with minimum bandwidth, the user experience is greatly affected.

Using a browser on mobile devices is an arduous task ­ especially on phones. A very high bandwidth is required to actually use the device. Even with GPRS (General Packet Radio Service), the bandwidths are not going to be significantly better in the near future to make browsers more effective and create a more positive user experience. And, users will still have the disadvantage of a small display and limited navigation capabilities of a stylus or thumbwheel. A thick client provides features that yield a more positive user experience, such as one-click activation and the use of keystrokes and menu items instead of hyperlinks.

The main disadvantage with a thick client is application deployment. Typically, the mobile devices would need to be cradled to deploy the application. However, as mentioned previously, the deployment challenge in a thick-client environment can be solved with over-the-air programming (OTAP), which allows applications to be deployed and revisioned over the air. This enables users to access very robust applications without the deployment hassles because the devices never have to be cradled.

You should use a thick client (with OTAP) if:

• You are working with documents or trouble tickets where you need to view and manipulate a lot of information
• The mobile device must be useful in an out-of-coverage situation
• The user needs to access the data quickly

The compelling reason to go wireless is the ROI (return on investment). You do not give an employee a wireless device because it is "cool;" the objective is to make a process more efficient. You want to take the process, such as communicating with a field repairperson, and provide a tool that makes that mobile user more efficient, meaning it reduces cost and increases productivity. This is why you give a user a mobile device.

ROI means you are paying for a mobile device and airtime but, as a result, you are making the user much more efficient. This is negated if the device is only useful half the time because it is slow, or the user does not have coverage. All the advantages provided on a wireless device are taken away by the user who has to sit and wait for information. A thick client with OTAP lets you provide a more positive user experience and overcome these issues, enabling you to get a better return on your mobile investment.