Loewe GmbH is a German consumer electronics firm, founded in 1923 and located in Kronach, Germany. Loewe's most important product sector is television sets, which are characterized by contemporary design, innovative engineering, and simple operation. The technology inside Loewe televisions lives up to the promise made by their remarkable exterior styling, often compared to pieces of dramatic, modern sculpture.

Loewe's latest technological advance is a fully-integrated Digital TV module, now entering production, that gives users convenient access to digital programs. This integrated solution eliminates the need for a set-top box, streamlines the design of the television console, and simplifies control of the digital functionality for the customer.

The new Digital TV's development team is credited with another technical success for Loewe. But beyond the creation of a new television function, they are also responsible for the testing of a new tool that will help manage the complexity of the company's subsequent designs.

Software Engineer Michael Zeitler used the Digital TV project to explore the possibilities of system modeling and an object-oriented design methodology for real-time systems. The tool his team put to work during the project was ARTiSAN Software Tool's Real-time Studio Professional.

The choice of Professional culminated a six-month search by Zeitler and his group. They were looking for a UML-based modeling tool that would help them define functional system architectures and validate system and software behavior before implementation, as well as improve productivity by enhancing team communication.

Greater Complexity Requires a More Complete Tool

"In the past, we did our designs in a structured, top-down way, but as systems became more complex, we believed we had to shift to a new paradigm," Zeitler explains. "We were looking for a new way and decided to run a trial project using an object-oriented approach."

After comparing Professional with a variety of competitors, the Loewe team decided to use Professional during the creation of the Digital TV module.

Professional's single environment provided all members of the team with an up-to-date, shared view of each aspect of system definition. "Professional had the tools we wanted for our development," Zeitler recounts. "It was the only product that offered a process. The competitors had lots of diagrams, but no integrated process. The language the tool uses is very common to our way of thinking about problems, so we felt very comfortable in the beginning, because all the stereotypes-like tasks, mailboxes, and all the real-time stuff-were already in the tool."

Adding Innovation to an Established Design

Following a month's experimentation on a trial version of Professional, Loewe sponsored a one week, on-site training course, to familiarize his team with both the principles of object-oriented analysis and design and in the use of the tool itself. By the end of the week, Zeitler says, "we were feeling quite confident. We decided to set up a trial project to get some experience, to train people in that methodology so we could use it later on other product lines."

His five-person team of systems analysts and programmers moved on to the Digital TV project, using Professional to define their system, design their software, and document the total system.

The team's design challenge was to integrate the reference software and hardware design for an MPEGII decoder into an existing television design. Included were the control mechanisms to drive the MPEG chip and the software required to decode the MPEG stream. The set's new user interface would incorporate automatic channel searching, channel switching, and an onscreen electronic program guide.

"We had to adapt the reference software's embedded drivers to our existing system," says Zeitler, "because we were not exactly following the reference implementation- and we had to add our own application on top of it. Our application software was written partly in C and partly in C++, with all the real-time control and the graphical user interface done in C++."

The team began with hardware modeling from a software point of view. Professional's System Architecture Diagram allowed them to capture the design's physical hardware, including boards, ports, and buses. Capturing information about the system eventually allowed the software developers to undertake low-level tasks, such as device driver development, knowing they had on-line access to the latest hardware-software interface requirements.

Online Object-Oriented Modeling

Continuing the object-oriented development process, the team relied heavily on advice from ARTiSAN's Real-time Perspective (RtP) Mentor. The RtP Mentor is an online reference to all process topics including process life cycle, modeling techniques, and management. Not limited to typical product help screens, RtP Mentor provides an in-depth understanding of the how's-and-why's of system and software modeling.

"We began with requirements capture, defining use cases, and constraints," recalls Zeitler. "Throughout the process, we were very strict in following the process as described by the RtP Mentor. After finding use cases and constraints, we continued to define the system scope and do architectural modeling based on the advice of the RtP Mentor."

Drawing on this system definition, the team created Use Case diagrams that captured system functionality. The next step was to fit those Use Cases into Action Models, then build complete Object Sequence Diagrams. Professional uses Class Diagrams to capture the software design as a collection of objects. In turn, Sequence Diagrams model the communication and collaboration of those objects to achieve specific system functionality.

Directing Complexity to Success

The process worked exactly as its managers hoped, prompting Loewe to implement object-oriented analysis and design using ARTiSAN tools for a broad range of new projects.

"It would have been very much harder to control these complex devices using only a document-based approach-the way we worked before," comments Zeitler. "Professional helped us keep all the requirements and analyses in one place. Working through the database and the dictionary, everyone on the team had the same insights."

"It's the first time we used a CASE tool in this company, and the experience was very good," Zeitler concludes. "All the reports out of the tool and all the documents were up to date. Nobody had to worry about updating documents. In the beginning, it was a trial project for systems engineering. Now, we're expanding the use of the ARTiSAN tool. It's an easy tool to introduce, and it won't disrupt our development. This project showed us that it works."