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For some time, the Departement of Defense (DOD) has been investing in data communications networks, both for strategic and tactical applications. One of the major drivers for this in the tactical arena has been the need to utilize scarce bandwidth resources more efficiently. These efforts have resulted in a better class of service being provided to users, as hardwired, dedicated, low-speed circuits have been replaced with a higher-speed shared backbones. As the military upgrades its communications by putting in place common user information infrastructures based on current network technologies, it can take advantage of COTS software to perform a variety of tasks. Pre-eminent among the throng of applications being adapted by the military is the The World-Wide Web (WWW) [Berners-Lee et al, 1994]. The WWW is perhaps the most successful middleware ever releasedóit allows access to distributed system services over IP networks, and permits applications to exchange information across different operating systems in a way that is straightforward and easy for programmers to implement while retaining a common appearance to the user. Notices to Airman (NOTAMs) report time-critical aeronautical information that is either not known sufficiently in advance to permit publication on aeronautical charts or other publications, or is of a temporary nature. NOTAMs often have direct impact on safety of flight since they alert aircrew and planners of navigation aid outages, closed runways, and other hazards. The current system uses the AWN to provided dedicated connections to the NOTAM database maintained by the FAA (NOTAMs are generated manually as alphanumerics). The Air Force is the responsible agency for distribution of NOTAM information for all the services. The dedicated links provide by the AWN have become oversubscribed and more difficult to manage, leading to inconsistent performance and spooling of products for deferred delivery. In addition, the extension of NOTAM information to deployed areas has been difficult at best. Changing to a common user communications network can improve NOTAM distribution and reporting performance. With Air Force systems such as Tactical Secure Data Communications (TASDAC) and Theater Deployable Communications (TDC), as well as strategic assets such as the Nonsecure Internet Protocol Router Network (NIPRNET) and the forthcoming Global Broadcast System (GBS), higher-speed service is possible. Shifting to World Wide Web distribution presents an inexpensive solution, since specialized client software is not required. But the most significant benefit of deploying applications on the Web is the ability to create cross-platform applications without the cost of creating and distributing several different versions of the software. Applications that use the Web server as an interface between the end user's Web browser and the application on the server generate HTML output that users can view on any platform. Web clients are ubiquitous and cost little. The advantage of using browsers is the ability to control the appearance and functions of the interface that the NOTAM requester sees from a central WWW server. This characteristic allows changes and updates to be less involved, since client software is not tied to the server implementation. Web browsers provide simple, easy-to-use interfaces and can be hosted on inexpensive desktop computers, laptops, and UNIX workstations. The technology is extensible by the use of client-side executables and scripting capabilities. The labor and cost involved in coordinating the maintenance and distribution of applications and maintenance upgrades can often be greater than the initial development cost of the application. Changes made to Web-based applications on the server take effect immediately for all users, eliminating problems inherent in having different versions in use at the same time. Web applications can take advantage of client-side processing with downloadable components (such as Java), enabling Web browsers to instantly download changed components. This makes immediate maintenance upgrades possible whenever changes are made. Web technology also incorporates the information protection functions need to perform authentication, encryption, data integrity, and verification tasks to protect NOTAM data. The Air Forceís Electronic Systems Center, with support from MITRE, worked with HQ AFFSA, HQ AWS and the Federal Aviation Administration to reach agreement on a proposal to transition NOTAM support to the Web. This will result in substantial improvements:
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