Providing web services with legacy GIS
Prof. Dr. Dieter Keller
SHH GmbH Fritz-Müller Strasse 107
D-73730 Esslingen
Telephone: +49 711 31508-109
E-mail: keller@shhinfo.de
Abstract
Most of today’s GIS-work has to do with viewing, analyzing especially filtering and
updating previously collected data. In other words the data that is already available
in most cases, but captured in legacy systems, that are tied to the desktop or to
LANs in a classical two tier architecture. But the data has to be made accessible to a
broader audience in order to yield its real asset. The Internet especially its WWW
service offers new techniques of integrating different systems containing different
data in the form of unique web services. The paper describes a modern flexible and
inexpensive three-tier system architecture wrapped around an “old” legacy system
architecture. Key technologies like CORBA and J2EE are discussed in the context of
this modern architecture as well as the usage of XML based SVG graphics and the
role of the OpenGIS intermediate format GML. But all those technologies don’t make
much sense, if there is no clear business model behind them.
The Utility-It-Environment
NIS [Network Information Systems] are special representations of GIS [Geo-
Information Systems]. One popular application of NIS is the support of business
processes in utility companies. A utility company runs into serious problems if the
support task for kernel business processes is not sufficiently fulfilled anymore. For
this, there can be the following reasons:
- The business processes changed and are not represented correctly in the NIS
- The technical basis of the data processing system is not supported by the
manufacturer anymore.
- The customers acceptance of the system is too small.
- New technical evolutions offer considerably more efficient solutions in modeling
of the business processes.
The last item includes the wish of a flexible adaptation of the legacy systems in the
form of a constant evolution. This becomes more and more important for dynamic
markets. After the liberalization the European utility market is a highly dynamic
market. So, the legacy systems form a high potential risk and a drawback for rapid
development in many enterprises. The following situations demonstrate the problem:
- The knowledge monopoly of individual employees is a bottleneck; it causes the
dependence on people.
- Changes of the legacy system lead to unexpected side effects and are
responsible for the general attitude: Never change a running system.
- The maintenance costs are high - compared to the corresponding
improvements.
- The system has a high failure rate - the failure rates can be caught only
through few employees.
Taking a closer look onto this list, we immediately realize that the NIS-customers
and -providers share the same problems. This is because the problems are due to
standard-problems of the information technology. Most of the time the provider had
those problems 1-3 years earlier.
The NIS Legacy System
In the following chapters our own legacy NIS will be used as an example for the
constant evolution that will finally lead to Web Services.
Fortunately, our legacy NIS, Paris, has to fight comparatively little with problems of
the above mentioned kinds since it is still relatively "young". When the product was
shipped for the first time in 1997, it was a typical desktop NIS with a CAD frontend
(MicroStation) and a local data container (MS-Excel). Already 2 years later, the
product changed and was shipped as a fully equiped client/server NIS using all
advantages of this technology in a Local Area Network [LAN] environment. An
outstanding feature of the legacy system can be described best by “Modelling
instead of Programming". In other words the NIS offers a simple object-oriented
modeling (including inheritance) which is based on an integrated GIS databasearchitecture.
In the utility sector usually inflexible industry-specific shells are used for approaching
business processes. Instead of this, our legacy NIS offers a flexible object modelling
that directly adapts to business processes. As a starting point for an object modelling
process, object libraries for electricity, gas, water, waste water and long-distance
heating are provided, so object modelling never starts from the scratch.
When switching to the client/servers architecture a new software layer was
established, that allowed almost every relational database system to be connected
with the NIS (Oracle, DB2, Interbase etc.).
From the NIS point of view the legacy system supports currently most of the
business processes of utility-companies. Office-tools are simply integrated and the
connection to other programs can be simply realized by data exchange. But the
liberalization of the markets goes hand in hand with company fusions high/dynamic
changes in the IT. The future will bring a lot of changes.
