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Microbrowsers

The microbrowser is the most visible part of any wireless Internet application, as it is the only part of the solution that the end user sees. It is also the only part of the solution that is executed on the client device; the data, business logic, and content-generation routines all reside on the server. For these reasons, the microbrowser usually dictates the features that are available for any particular client device.

You have to choose a microbrowser that will meet the needs of your application. For mobile phones, where the browser is embedded on the device and cannot be changed, this means you will also be making a device decision. In turn, by choosing a particular device, you usually will also be tied to a certain wireless network. Fortunately, at this time, a single vendor, Openwave, provides the majority of browsers for this class of device.

For more capable devices, no such limitation exists. Several browsers are available for Palm, Pocket PC, and RIM devices. Many of the browser vendors are also wireless service providers that provide wireless network connectivity as well as hosting services. More information on these services is available later in this chapter. For now, we are going to focus on the technologies and vendors involved with the microbrowser itself.

Technology

The following paragraphs discuss some of the most common features found in wireless microbrowsers. This is not an exhaustive list, but it does provide a good starting point for comparing the features offered by different vendors.

Markup Languages

The markup language dictates the content types and capabilities that are available for wireless Internet applications. Most mobile phones support HDML, WML, or cHTML, while PDA browsers usually support WML or HTML. In some cases, the browser may support multiple markup languages. Microsoft's Pocket Internet Explorer, for example, supports HTML, WML, and cHTML. Unfortunately, not all browsers display the markup language the same. A WML site might work great in one browser but cause another browser to give a fatal exception. For this reason, content has to be catered to both the device and the browser on which it is going to be displayed.

In the future, we may not have to worry about the large number of markup languages, as many of the technologies, including WAP and i-Mode, are converging on XHTML as the markup language of choice.

Note 

An in-depth look at markup languages and content-generation techniques is provided in Chapter 13, "Wireless Languages and Content-Generation Technologies."

Image Support

Not all browsers provide the same level of support for images. Many of the mobile phone browsers support black-and-white wireless bitmap (WBMP) images, while browsers on the more advanced devices may provide full JPEG and GIF support. WBMP files are bitmap images suitable for wireless devices, whereas JPEG and GIF files are common desktop image formats. You would be wise to limit the number of images on your wireless Web sites to minimize the download times over bandwidth-constrained networks.

Push Technologies

Support for push technologies is growing in importance for wireless Internet users. The most common technologies include HDML notifications and WAP Push. The Openwave HDML browser supports HDML notifications. Browsers that support WAP version 1.2 or later support WAP Push, although support on the WAP gateway is also required for this functionality. (More information on Push messaging can be found in Chapter 5, "Mobile and Wireless Messaging.")

Offline Support

The ability to access offline content is the most recent feature being added to many microbrowsers. Initially, this feature was in the form of a browser cache, but it has evolved to include access to persistent data stores and, on Pocket PC devices, local Web servers. This trend is expected to continue, as the rollout of 3G wireless networks is not providing the true pervasive access to wireless data they were expected to.

Web Clippings

Palm developed the Web-clipping architecture to provide support for advanced, feature-rich, HTML-based applications. It separates the static components of the Web site (such as images, HTML templates, etc.) from the dynamic content (data that changes frequently). The static information is then transformed into the Web-clipping application format (.pqa file) and deployed to the device in advance. Since the HTML templates and images are not downloaded at runtime, advanced user interfaces can be created without performance penalties. The Web-clipping format is supported on all wireless Palm OS-powered devices. GoAmerica offers a similar technology called MobileClips for Go.Web microbrowsers.

Security

The type of security supported depends on the device and wireless protocol being used. The most common form of security for wireless Internet applications is encryption of the communication stream between the microbrowser and the gateway or Web server. For WAP applications, this support is provided by WTLS, while for many HTML applications it is provided using SSL/TLS. (Detailed information on mobile and wireless security is provided in Chapter 6, "Mobile and Wireless Security.")

Device Support

Many device manufacturers either include a microbrowser or recommend a browser for use on their devices. These browsers usually are tested extensively and work well on the device with which they are included. If you are unhappy with the default browser, you usually have the option to replace it with one of your choice. You simply have to find a browser that supports the mobile operating system and chipset you are using, then download it to the device. This is true for all devices except mobile phones, which typically ship with an embedded microbrowser that cannot be replaced.

Microbrowser Vendors

This section provides an overview of the leading vendors and their products. We do not make recommendations for any vendors, as this is a decision that must be made in consideration of the features of the applications that are going to be deployed. Moreover, it is common that applications will be developed for, and deployed to, more than one type of device and more than one flavor of microbrowser.

Openwave Mobile Browser

URL	www.openwave.com/products/device_products/mobile_browser/index.html/Markup
Markup Languages	HDML, WML, XHTML-MP, cHTML
Operating Systems	Usually embedded on mobile phone OS

Summary:

The Openwave Mobile Browser is by far the most common microbrowser being used today. By mid-2002, close to 50 device manufacturers had licensed the Openwave Mobile Browser for use on almost 200 mobile phones. There are now more than 70 million shipped devices that include this browser. A complete list of the devices using the Openwave Mobile Browser is provided at http://upmkt.openwave.com/dev_phones/phones.cfm. (Note: The Openwave Mobile Browser is commonly known as the UP.Browser. The UP stands for Unwired Planet, the former name of the company.)

Openwave is the creator of HDML, and the company has the only browser on the market that supports it. Version 3.x of the Openwave Mobile Browser is based on HDML. As WAP grew in popularity, Openwave released the 4.x series of browsers with native WML support. These browsers also have HDML translation support for backward compatibility. The most recent release of the Openwave Mobile Browser is version 6.2. It has native support for WAP 2.0, XHTML Mobile Profile, WML 1.x, WAP Push, WML GUI for M-Services, MMS, and cHTML. A full summary of the browsers and their related SDKs is available at http://developer.openwave.com/resources/sdk.html.

Microsoft Pocket Internet Explorer

URL	www.microsoft.com
Markup Languages	HTML 3.2, WML, cHTML, XHTML
Operating Systems	Windows CE 3.0, Windows CE .NET (Pocket PC, Pocket PC 2002)

Summary:

Microsoft's Pocket Internet Explorer (PocketIE) is the most capable microbrowser available. It has complete support for HTML 3.2, with support for tables, forms, and frames. In addition, the latest versions have added support for WML and cHTML. PocketIE also supports Microsoft JScript, Bitmap, GIF, and JPEG image types. For security it supports SSL versions 2.0 and 3.0.

When using PocketIE, you can access many existing Internet sites without modification. It also has automatic state detection to determine if the device is connected to the Internet. If it is not, it diverts the browser to a cached version of the Web page, if available.

AvantGo Client

URL	www.avantgo.com
Markup Languages	HTML, JavaScript
Operating Systems	Pocket PC, Palm OS, RIM, Symbian OS

Summary:

The AvantGo client browser was built with offline support in mind. Content is delivered using the channel concept, where users can preselect the channels they are interested in and synchronize the corresponding content to their device. A channel represents a single Web site or application. Applications are written in HTML along with JavaScript. The AvantGo browser comes preinstalled on many mobile devices. It is a good choice for cross-platform deployments. It works best when used with the AvantGo M-Business Server. In December 2002, iAnywhere Solutions (www.ianywhere.com) made an offer to purchase AvantGo. By the time you read this, the acquisition should be complete.

GoAmerica Go.Web

URL	www.goamerica.com/goweb/
Markup Languages	HTML, WML
Operating Systems	Palm OS, Windows CE 2.11 and 3.0, RIM, 32-bit Windows

Summary:

The Go.Web browser comes with the Go.Web Internet service from GoAmerica. It offers support for both HTML and WML, allowing you to access most wireless Internet applications. Because it supports a broad range of mobile operating systems, it is a good choice for applications that need to be deployed to a variety of devices. The latest versions of Go.Web offer complete offline support with store-and-forward message capabilities. In addition, Go.Web supports push capabilities as defined in WAP 1.2.

Note 

The features supported for each version of Go.Web depend on the operating system on which it is being used.

Neomar Microbrowser

URL	www.neomar.com/products/index.html
Markup Languages	WML
Operating Systems	Palm OS, RIM, Windows CE, J2ME

Summary:

The Neomar Microbrowser is available for all leading PDA-style devices, allowing you to create your WML content once and view it on many devices. Neomar has put emphasis on creating a friendly user experience by incorporating data compression, support for GIF and WBMP images, and on-device caching. If you are looking for offline data or push capabilities, you can install a plug-in for the browser, called the Neomar Intelligent Client Engine (ICE).

For security, Neomar has implemented WPKI support, with support for WTLS 2.0 and HTTP authentication. Similar to Go.Web, the Neomar Microbrowser is often used with Neomar's wireless Internet service offering.

Palm Web Browser

URL	www.palmos.com/dev/tech/webclipping
Markup Languages	HTML, cHTML
Operating Systems	Palm OS

Summary:

The Palm Web Browser is a full-featured HTML browser. It enables access to any URL on the Internet, whether designed for the Palm OS or not. It will automatically adapt desktop Web content to the appropriate size of the Palm handheld screen. While this does not work perfectly for every Web site, it does allow the user to access a whole new set of content that was previously unavailable without customization. In addition, it provides the ability to save information for offline viewing and caches a history of visited sites.

The browser maintains support for the Web-clipping architecture, allowing developers to create more advanced client applications without having to worry about the associated download times over wireless networks. The Palm Web Browser is available for devices running Palm OS 5.0 and above.

Opera Software

URL	www.opera.com/devices/
Markup Languages	HTML
Operating Systems	Symbian OS, Linux, QNX

Summary:

The Opera browser is best known for its cross-platform capabilities; it runs on seven different operating systems: BeOS, Symbian OS, Linux, Mac, OS/2, QNX, and Windows. It is a high-performance browser that has full support for HTML on mobile platforms. The Symbian reference design includes support for Opera. Other manufacturers such as Sharp and Psion include the Opera browser with their devices. Other features of the Opera browser include support for JavaScript, HTML 4.0.1, HTTP 1.1, XML, and SSL 2.0 and 3.0.

Device-Specific Browsers

In addition to the browser products covered so far, a number of proprietary browsers have been created by device manufacturers. These browsers all are embedded on mobile phones and are WML-based. They usually are similar to the Openwave Mobile Browser in appearance and feature set.