17.2 Requirements and Qualities
The Luther architecture was designed to meet two sets of complementary requirements. The first set governs the applications to be builtnamely, enterprise applications for field service workers. These requirements are directly visible to customers, since failure to meet them results in applications that do not perform according to expectationsfor instance, an application that may work correctly but perform poorly over a wireless network. The second set of requirements involves introducing a common architecture across products. This reduces integration time, brings products to market faster, increases product quality, eases introduction of new technologies, and brings consistency across products.
Overall, the requirements can be separated into six categories:
Existing procedures, business processes, and systems
Field service workers must move about while performing their tasks. Furthermore, they must move about in an environment rich in machines, hazards, and other people. In order to interact with back-office systems, the devices used by workers must access remote servers and data sources without being tethered by a landline to a local area network. Because of the variety of Inmedius customers, these wireless networks may need to be of varying capacity and availability.
Part of the Inmedius competitive advantage is its high-fidelity user interfaces, which allow a worker to focus on the task at hand without being hindered by the interface or the access device. Different devices have different screen footprints, and the Luther architecture must facilitate the display of meaningful information on each of them. This does not mean constructing a single user interface and adapting it to all device types. Instead, Luther must support the rapid construction of interfaces that filter, synthesize, and fuse information in ways that are displayable on a particular device and useful to its user.
Variety of Devices
Field service workers use a variety of computing devices in the field. No one device will suffice for all field applications, and each has limitations that must be addressed by the Luther architecture. Inmedius must engineer performance-enhancing solutions to run on all of these devices, which include:
Personal data assistant (PDA) devices such as Palm Pilot, Handspring Visor, vTech Helio, IBM WorkPad, and Apple's Newton and MessagePad 2000
Pocket PC devices such as Compaq iPAQ, Casio EM500, HP Jornada, and Phillips Nino
Handheld, pen-based tablets running Windows CE such as Fujitsu Stylistic and PenCentra and Siemens SIMpad SL4
Handheld Windows CE PC devices with pen and keyboard such as Vadem Clio, HP Jornada 700 series, NEC MobilePro, Intermec 6651 Pen Tablet Computer, and Melard Sidearm
Wearable computing devices such as Xybernaut MA-IV, Via family of products, and Pittsburgh Digital Greenhouse's Spot
Different classes of device have different memory footprints, processor speeds, and user input devices that can radically affect a user's interaction style from one class to another. For example, a wearable computer can bring the power of the desktop computer into the field, making client applications as sophisticated there as they are in the office. Users in this case also have a plethora of input devices to choose from, including keyboard, voice, pen, and custom devices.
On the other hand, the processor speeds, memory footprints, and available input devices for the PDA class are severely limited, which means that user interactions that can be engineered for these devices are also constrained. Still, PDAs are extremely important in the various contexts in which field service workers perform their tasks. The Luther architecture must address the variability of the users' interaction styles, which are limited by differences in hardware capability among the device classes.
Existing Procedures, Business Processes, and Systems.
Field service workers are only one part of most enterprises. Information gathered by them must be stored in the back office; instructions for them come, partially, from outside the field; and many applications already support existing business processes.
To respond to these needs, the Luther architecture must intergrate its functions with a worker's existing procedures and processes, enable applications to be hosted on servers and databases from many vendors, and simplify the integration of applications with legacy systems
Enabling faster construction of applications is one of the main motivations for Luther. There are a number of aspects to this goal, including:
Encouraging software re-use and making it easier for applications to work together. This avoids wasting valuable resources to "re-invent the wheel."
Enabling a build-first, buy-later strategy for enterprise functions (e.g., work flow).
Providing a stable platform for adoption of new features and emerging technologies that span applications, such as location sensing, automatic detection and identification of nearby physical objects and services, and advanced user interface features like synthetic interviewing.
The Luther architecture must provide enterprise application developers with a framework and infrastructure that even out the differences in client device capabilities and provide application servers with the following distributed application features.
Scalability. The Luther server framework must facilitate scalability with no impact on performance. That is, the addition of any number of domain-specific components over time must have no impact on the performance of the application software, nor must it cause the re-engineering of client applications. In addition, client applications must be easily reconfigurable to make use of added capability. The framework must also support the ability of applications to discover new capability and to dynamically reconfigure themselves to make use of it.
Load balancing. The Luther architecture must support load balancing in a distributed environment. Most of the computation in its applications will be performed on the server side, with the results sent to the client. As more and more clients access the capability from a given server, the application server infrastructure will have to detect heavy loads on a given server and offload processing to application server components located on different server nodes within the enterprise. Similarly, the enterprise environment application must be able to detect a node failure and shift to another application server in the enterprise to continue execution. In both cases, load balancing must be transparent to the user, and in the first case it must also be transparent to the client application.
Location independence. To support load balancing, domain-specific application capability must be distributed, and the Luther architecture must support this. To be able to change locations dynamically, applications must be location independent.
Portability. Enterprise application environments invariably comprise a set of heterogeneous server hardware platforms. The Luther architecture framework will have to allow the software to run on myriad platforms in order for enterprise applications to work.