At first glance, these applications may seem to have little in common, aside from the fact that all are based on Matisse and are being developed by the University of Amsterdam and its commercial software arm, Power Computing and Communications.

Look closer, and you'll see that they share characteristics that take advantage of Matisse's strengths. All involve complex data, often involving multiple media types; all required considerable design flexibility to respond to rapidly changing business requirements. "The Matisse data model is very flexible, and the technology is scalable," says Dr. L.O. (Bob) Hertzberger, a professor in the University's computer science department. As a result, PCC is able to use Matisse both as a rapid prototyping tool and a platform for application delivery, he says.

CD MegaStore
The flexibility has proved key in developing applications for the music industry. PCC is working with Free Record Shop, the largest music retailer in the Netherlands, on applications that promise to change the ways consumers choose and buy music and other multimedia entertainment such as DVDs . The applications are based on an e-commerce framework developed at UvA, called MegaStore, which is designed to provide sophisticated searching capabilities as well as high performance.

Free Record Shop plans to use these applications as a major part of its "bricks and clicks" strategy to extend its considerable retail presence. That presence comprises nearly 300 stores: 170 in Holland under the Free Record Shop brand, plus several other Dutch music retailers as well as top store chains in Belgium, Norway and Finland.

Today, in these stores, customers can listen to CDs before deciding to buy, and even, in some outlets, hear digitized music clips. Free Record Shop wants to take the idea much further, using digital media to create new applications that expand customers' options both in stores and via the Internet.

"We would like to digitize [media and other information] once, store in a database once, then use it for several purposes," says Wouter Hurts, financial director at Free Record Shop Holding N.V.'s headquarters near Rotterdam. For instance, the same underlying system could be used to let customers browse and select music at each store, as well as for Internet shopping and broadcasting the music that plays in the background in stores.

Entering one of Free Record Shop's stores, consumers could use a multimedia listening booth to search for music by artist or album, listen to audio clips or view promotional or other video clips, then either choose to buy existing CDs or select tracks that will be burned onto a CD and shipped to them. Free Record Shop also plans to offer similar capabilities direct to consumers via the internet. "We are trying to create a more personalized experience" by letting customers search for, hear and combine tracks in new ways, Hurts says. The self-service approach has another benefit, he says: "We need to reduce staff-related costs." Free Record Shop is currently using a pilot application with around 1000 CDs' worth of material. It hopes to start rolling out elements of the system to stores in coming months.

Building these new capabilities requires a new approach both to technology and to business relationships.

The technology is being built as a distributed system that may include systems at stores, a data center for back-end database processing, CD burning towers and links to other music-industry companies. In the pilot, full system functionality such as the back-end data processing and burning towers is being demonstrated at UvA.

At the heart of the new system, the MegaStore framework uses the flexibility of Matisse's object store to provide a catalog that lets shoppers search for music by artist, album or song name, or in less-obvious ways, such as by instrument. Matisse also stores music clips in different formats: medium-quality, to be played to consumers in listening booths in stores, and low-quality, for internet shopping; both use Matisse's built-in capabilities to let consumers start or stop listening at any point in the data stream.

In the production application, a system at each store would hold a Matisse-based catalog that lets consumers search for music they are interested in, and might also cache multimedia clips for performance reasons. The store-based catalog system would connect to the main multi-media database, distributed across multiple server nodes at a data center using technology provided by the University. This would store medium-quality clips that can be downloaded to the stores on request, plus a copy of the catalog and low-quality clips used to provide a Web-based shopping service. New music tracks and information about them can be entered or changed within the system via a standard ODBC interface, using UvA-developed editing tools.

Free Record Shop is working with the music industry with the goal of extending the system to support the idea of combining customer-selected tracks from different artists or albums, and burning them onto a custom CD. The trick is to provide this capability while protecting record labels' copyright, a particularly difficult area when dealing with transmitting digitized music over the Web.

The MegaStore architecture allows the original raw music data to remain at record company sites, so they have no fear of digitized music falling into unauthorized hands. Instead, the raw files could be transmitted in encrypted form over the network to a CD tower only when a customer makes a purchase. Alternatively, if the record labels permit, the encrypted songs could be stored in the UvA multimedia database ready for burning onto CD. "We want to show the industry they have the opportunity to safely distribute music," Hurts says. "They know they can count on a fee payment for every use." Free Record Shop is using the pilot system to gather feedback from the industry, Hurts says. PCC plans to provide the service on an Application Service Provider basis, allowing Free Record Shop to pay according to its use of the system.

Though Matisse's multimedia capabilities were essential in developing the system, the database's flexibility was its most important feature, according to the University's Hertzberger. As you'd expect when exploring uncharted business territory, the system design specifications changed many times during development, he says. Matisse can respond because the database model can be changed at any time within the life cycle of an application, says Ammar Benabdelkader, a primary developer of the MegaStore system at the University.

The ability to model complex data is also vital. That is even more apparent in a conceptually similar system that is currently under development for a Dutch retailer. The application will let music-store employees, and perhaps also customers, search for sheet music in a large variety of ways, to match very specialized needs.

For instance, someone looking for music for a particular musical ensemble, with a very specific lineup of instruments, would be able to search for scores available for just those instruments as well as searching by composer, publisher, title, or publication series. "The database models are very complex," Benabdelkader says. Matisse fits the job partly because of the richness of the data types that it supports, he adds. For instance, the system will include audio clips, and of course images of the sheet music itself.

Also, Matisse supports inverse relationships between objects defined within the data model, he notes. This automatically maintains referential integrity between the objects within the database, so that if an object is deleted Matisse automatically updates other objects that refer to it. This greatly simplifies the development of applications with complex data models. In contrast, a traditional relational database might require numerous keys to be created and maintained in order to provide similar search facilities, creating considerable complexity in design and overhead in execution.

The combination of flexibility and the ability to deal with complex data also characterizes other Matisse projects. Read on for a description of the other projects created at the University of Amsterdam.

Automatic Debiting System Simulator
Virtual Laboratory