Systems Architecture and The Problem with GIS
Systems Architecture
How well do most AM/FMGIS systems fit into our defined architecture? Since most AMIFIWGIS s are
graphic driven models with links to data, rather than data-driven models with links to graphics, the
answer is, “not very well.” Most AIWFIWGIS decisions have traditionally been made on evaluation of
the application specific functionality. The fact that many AM/FM/GIS can be linked to databases lulls
the user into thinking they are looking at an enterprise-wide solution. The methodology described above
changes the relative value given in the decision process to features to integrating capability and
manageability of the application. The system called for in this architecture has to be a good citizen
sharing data with and providing services to other applications.
As this decision approach becomes more common it will accelerate the movement away from the isolated
AM/FM/GIS systems we are familiar with, to systems that look much more like the new client-server
business systems in which utilities are investing.
Single and Two Tier Architecture - Where we have been:
Today, most corporate information models represent two tier and single tier architectures. Single tier is
reminiscent of monolithic systems with large applications on them and connected terminals. Later,
applications were decoupled (to some degree) from the data into a client-server architecture, and then the
data were distributed. Not all theses systems were true client-server. There may be some degree of
shared data, but the proprietary graphic user interface is integrally linked with the application, and often,
some of the data. Another GIS with its own graphic user interface could not access the data of another
system without an interface. The interface will probably have some unique maintenance and
management requirements that will have to be modified when the software on either side of the interface
is upgraded. When we refer to the term ‘islands of automation’ we are describing two tier systems.
These systems dominate the corporate environment today. A majority of the systems which are being
implemented today are still two tier.
Three Tier Architecture -The
key to three tier computing is that the end user need not know how the data are organized in order to
access and use the data. Simplicity is managed through system architecture and philosophy. Three tier
architecture separates the system into presentation, application (or business rules or methods), and
database (Figure 1.)
Figure 1. The layers within Three Tier Architecture
The presentation layer can be thought of as the common, graphic user inte~ace (GUI). Whether this is
agreed upon or not, Microsoft has made a major step toward providing a standard graphic user interface
to the industry at large. In the future, applications will come together in a single window environment,
which shares a common presentation layer.
The philosophy of three tier architecture is that business methods and rules are shared within the
application layer, rather than programmed into each different application. An example of this is the
number of redundant network models which exist throughout the corporation. To be a competitive entity,
the corporation will have to find cost-effective business models where the margins of operation are well
understood. With all the different models that currently exist this will be hard to do -- not to mention the
hassles of integrating these systems. Today, the AM/FM/GIS has a network model, the Supervisory
Control and Data Acquisition system (SCADA) or Distribution Management System has a model, the
planning department has a model, there is likely a model for transformer load management, and the list
goes on. In the future, a single network model will reside as a shared method in the application layer for
all to use.
Communication between the GUI and application layer occurs through Active X, AKA: Object Linking
and Embedding (OLE). While following in the steps of Microsoft often feels like a forced march,
vendors who agree to expose and share their business rules by providing access to their system via Active
X, agree to making their system interoperable with many different applications – providing synergistic
advantages to their users.
An example of what it was like without Active X follows: if one were working in Microsoft Word, one
had to leave Word to perform a calculation in Excel. Today, with Active X, an Excel spreadsheet can be
modified inside a Microsoft Word document. An example of how this would apply with more of a utility
specific application follows:
If the utility network model was built with an AM/FM/GIS which was Active X compliant, then
one could easily link real-time data (which is in a format that is Active X compliant) to the
AM/FM/GIS network model. Calculations from Excel could be dropped into the graphic as well.
The graphic might, in turn, be dropped into the Word document and emailed somewhere in the
corporation. Provided that the receiving person had network access to the real-time data, the
email would arrive as a small application, ready for viewing. The real-time link between
AM/FM/GIS and SCADA is inherent in the design. The need to write integration software
between two separate applications has been eliminated because vendors are adopting a common
solution for communication between applications.
