Untethered access to Exchange Server data
In what amounts to a mere blip on the corporate timeline, email has evolved from a novelty to a necessity. From corporate managers to mail clerks, everyone has come to depend on email and the growing list of features that groupware applications (e.g., Microsoft Exchange Server) offer. A natural outgrowth of our dependence on these messaging platforms is an increasing need to stay connected to them, regardless of time or location.
Providing this connectivity presents a considerable challenge for IT staff who must forge a secure, manageable, and cost-effective solution that also offers the flexibility and accessibility users require. Many traditional remote access solutions rely on the speed of wired networks for satisfactory performance, which, in turn, limits flexibility. However, remote access solutions tailored for wireless networks can provide users with nearly infinite flexibility. To survey the current wireless products, I looked at three vendors’ Wireless Application Protocol (WAP)-based solutions as well as the vendors’ enhanced features that give mobile workers untethered access to Exchange Server data. A basic understanding of WAP will help you appreciate these products’ offerings.
WAP 101
Simply put, WAP is a protocol stack. More specifically, WAP is a standards-based communication-protocol suite and application environment for wireless communication. WAP is streamlined for devices such as Personal Digital Assistants (PDAs) and mobile phones that offer limited RAM, ROM, processor speed, and displays. In addition, it works well in low-bandwidth, high-latency wireless networks. The WAP Forum has published WAP specifications at http://www.wapforum.org.
A simple WAP implementation includes a WAP browser (aka a microbrowser), a WAP gateway, and a WAP content provider. The WAP browser resides on a handheld device such as a mobile phone or PDA. The WAP gateway usually resides on your wireless service provider’s network and provides access to another network, such as the Internet. The WAP content provider can be any server that renders information in Wireless Markup Language (WML) that the server transmits to the microbrowser. Figure 1 illustrates this configuration.
The three products I tested employ a WAP solution similar to the architecture that Figure 1 shows, in which the WAP content provider is the interface to a back-end Exchange Server. As such, the WAP content provider acts as a proxy for mobile users accessing their Exchange Server mailbox. To gain a better understanding of WAP, you can map the components of the WAP protocol suite to their Web-based cousins.
WML and HTML. WML is a tag-based, XML-compliant, streamlined language for use with microbrowsers on wireless devices. To accommodate the inherent latency of wireless networks, WML documents (aka cards) support only basic formatting. The WML author combines the cards into decks as large as 1400 bytes for transmission in one burst. WML also supports limited scripting capabilities with WMLScript, which is similar in function to JavaScript in HTML. WMLScript economizes on network transmissions by having the client perform tasks locally.
WML was derived in part from Handheld Device Markup Language (HDML). However, HDML came to market too early to incorporate XML, so vendors have left HDML behind in favor of the more forward-looking WML. The two languages are compatible; however, their differences can cause minor anomalies depending on the manufacturer and version of your microbrowser.
WSP and WTP and HTTP. The Wireless Session Protocol (WSP) implements WAP’s session-level services. The Wireless Transaction Protocol (WTP) is a liaison between the WSP and lower-level protocols, repackaging data much like HTTP does, as well as managing transmissions and acknowledgements.
WTLS and SSL. The Wireless Transport Layer Security (WTLS) protocol provides encryption and decryption services for WAP similar to those that Secure Sockets Layer (SSL) provides for HTTP. Although WAP’s built-in security is functional, it raises concern among those implementing WAP solutions because it forces them to depend on the security implementation that their wireless carrier provides. For example, when I use my WAP phone to access the Sprint PCS Wireless Web, all transmissions between Sprint’s WAP gateway and my phone use WTLS and RC4 128-bit encryption. During translation to HTTP over SSL (HTTPS—assuming I’m using SSL to communicate with a secure Web site), the carrier’s WAP gateway briefly decrypts transmissions that go through the gateway and out to the Internet. Although this translation takes place on a secure server on the carrier’s premises, some IT managers reject security implementations that they don’t directly control. You can move the translation security gap to the security of your private network by purchasing a WAP gateway on which encrypted traffic will flow unimpeded from users’ WAP devices. However, although hosting a WAP gateway provides a more stringent security model, this setup presents its own complications.
WDP and UPD and TCP. Just as TCP and UDP help hide the intricacies of the network and data link layers from the rest of the protocol stack, the Wireless Datagram Protocol (WDP) hides the details of the wireless network. WDP works with the wireless network types available in WAP devices. For example, if your carrier is AT&T, you’ll use the company’s packet-switched Cellular Digital Packet Data (CDPD) network. Sprint uses a circuit-switched Code Division Multiple Access (CDMA) network. And Verizon’s circuit-switched Global System for Mobile Communications (GSM) network uses Time Division Multiple Access (TDMA). WDP handles the intricacies of these different networks and makes the details invisible to the other WAP layers as well as to the end user. Table 1 outlines the leading wireless transmission technologies.
The Future of WAP
WAP is currently the standard for wireless communication in many parts of the world. In Japan, WAP has a legitimate competitor, NTT DoCoMo’s i-Mode, but the real threat to WAP’s existence is evolution. XML will probably evolve into the next Internet standard, displacing WML as the solution for content encoding. High-speed third-generation wireless networks and new devices will emerge, providing opportunities that enhanced protocol standards can best exploit. However, in the 2- to 4-year interim, WAP will continue to serve mobile users well. In addition, WAP’s XML roots will help it develop to meet the evolving needs of wireless applications.
Testing Basic WAP Solutions
Because of my background, I always look at a solution from two sides: the end user’s experience, which is concerned mainly with a product’s features and functionality; and the administrator’s experience, which includes cost considerations, ease of deployment, supportability, and security. In reviewing wireless solutions, I looked at how each of the selected products performs in these areas.
Using a WAP phone to send and receive email takes some getting used to. Before I tested the products in this review, I’d never used a WAP browser to access email. I’ve used Outlook Web Access (OWA) quite a bit and am familiar with the quirks and limitations of a browser interface to my Exchange Server mailbox. However, my experience didn’t prepare me for viewing email on the tiny display of a telephone or the challenge of entering text on a numeric keypad. I quickly learned the value of URL bookmarks, telephones that provide Text on 9 Keys (T9) predictive typing, and brief replies.
Mobile users want as much functionality as a WAP phone can offer. Thus, access to the most important of, if not all of, their mailbox folders is essential. Another key feature is the integration of contact information. For example, users want to be able to search for and initiate calls and email messages to persons in their Contacts folder or on the Exchange Server’s Global Address List (GAL). Infowave Software’s Exchange Connector to a Web Phone (ECWP), the WAP component of its Wireless Business Engine 3.5, lets you access the Microsoft Outlook Inbox, Calendar, Contacts, and Tasks with a WAP Browser. I could use this solution to search the contact list and initiate a call or email message. The Wireless Business Engine’s Task options, which Figure 2 shows, were full-featured and user-friendly. Wireless Knowledge’s Workstyle Server 3.0 for Exchange 5.5 provides similar telephone integration as well as access to the GAL. This solution also lets you navigate to folders within your Inbox, Deleted Items, and Sent Items but doesn’t offer access to Tasks. UltiVerse Technologies’ UltiWAP and FreeVerse also provide access to the Inbox, Calendar, Contacts, Tasks, GAL, Deleted Items, and Sent Items, and let you easily sort and search mailbox contents on the fly.
The value of each of the solutions from Infowave, Wireless Knowledge, and UltiVerse will depend on your mobile users’ habits. Access to the GAL is a necessity for a full-featured WAP solution, but the more mailbox access, the better.
Beyond Basic WAP
Although you can find hard-core WAP phone users who have become adept at reading their email on tiny displays and typing responses on numeric keypads, WAP phones are, at best, a temporary means to bridge the connectivity gap created when users are away from their offices. For most, the value of this bridge is dubious. Thus, the wireless access industry has developed some interesting ways to work around the limitations of a WAP phone.
Composing email. One of the first problems you encounter with a WAP phone is how to make composing an email message easier. One approach to this problem is to choose a WAP device that provides a more friendly means of inputting text. WAP browsers are available for both Palm and Win32 devices, such as Pocket PCs. With the proper add-ons, such as a wireless modem or a phone card kit that lets you use your cell phone as a wireless modem, you can use a handheld device to access the WAP proxy server and use a touch keyboard or character recognizer to enter text.
So how does this approach make composing an email message easier? Using character recognition, such as the service a Palm device provides, you can basically write freehand using Palm's Graffiti alphabet, and the device recognizes the characters as you write them. After you master the skill, writing in Graffiti is much faster and easier than using a numeric keypad. A touch keyboard lets you use a stylus to tap out messages on a miniature keyboard. Neither or these methods are easier to use than a full-sized PC keyboard, but they’re huge improvements over a numeric keypad. A numeric keypad must represent the entire alphabet on nine keys, so you must cycle through the options each key represents to reach the letter you want. For example, you must press the 7 key four times to enter an S. Typing a simple sentence in this way is tedious at best. Therefore, using a touch keyboard or character recognizer greatly improves the usability of a WAP device.
Another technology that is just emerging is the multifunction phone. These new-generation phones integrate PDA functionality that includes PDA-style text entry. Other phones include slide-on minikeyboard attachments that closely resemble the keypad on Research in Motion (RIM) BlackBerry device.
A simple way to easily respond to an email message is to have a list of preconfigured responses that you can use a couple of keystrokes to select. Workstyle Server provides this functionality by maintaining a list of responses as part of each user’s data, that it stores in an SQL database. Workstyle Server lets you define as many as 20 customized responses. From the response menu on my phone, I could choose a predefined response or select from recent responses I’d already typed. Figure 3 shows the Workstyle Server response menu choices as they appear on a Phone.com browser. Infowave also provides configurable responses and a recent response list, although Wireless Business Engine doesn’t store these responses in an SQL database. Instead, it stores them in a hidden folder in users’ mailboxes, eliminating the need for an additional database engine.
UltiVerse took a completely different approach by offering a hybrid solution for remote access that combines the functionality of its WAP-based proxy server, UltiWAP, and its hosted telephony services, FreeVerse. The marriage of these two solutions offers a clever workaround to the physical limitations of entering text on a WAP phone. The UltiWAP server acts as a proxy to Exchange Server databases. It also functions as a client to FreeVerse, augmenting UltiWAP’s basic functionality by giving you the ability to append your recorded voice responses (i.e., .wav files) to emails. I accessed this service from the voice response menu on my WAP phone, which provided the option to immediately call FreeVerse and record a response or enter a callback number that FreeVerse would use to call me. The latter option is useful if you’re using a WAP browser on a nontelephone device, such as a PDA. I chose to call immediately, and connected to the FreeVerse telephony server. After I connected from my phone, I recorded a message and sent it to the recipient. This solution worked well most of the time, but several times I couldn’t connect or the recording process failed.
Configuring notifications. Constant accessibility makes a cell phone compelling for mobile users. As long as you have a decent battery and don’t stray too far into the boonies, people can reach you. Most wireless carriers use Short Message Service (SMS) to augment WAP phone functionality so that you can also use your phone as a pager. An important feature of a WAP solution is the ability to leverage a phone’s paging functionality to notify you when an important email message arrives. Thus, you benefit from having many configurable rules that define when your phone pages you.