funding forced the Division to choose only the 
essential elements to be implemented in the 
initial phase leaving further development 
subject to the availability of funding. As you 
will find out from the papers in this session 
(Otoo, 1994), (Medved, 1994) and (Chaly, 
1994), astounding developments have taken 
place and a unique solution has been found for 
the exchange of digital data in a federated 
multidatabase environment. 
6. PROJECT MANAGEMENT, 
MONITORING AND CONTROL 
The project was configured as a full target 
system including all the essential components. 
The system was designed as top down system 
to provide a sensible working system. All the 
necessary connectivity was established. At 
this point a bottom up approach was adopted 
for the implementation and integration of the 
system components. The requirements for 
integrating GIS vendor products and 
establishing translators became quite apparent. 
Normally, before starting a project of this 
magnitude, it is essential to establish test suites 
to ascertain whether the system can perform 
according to the design criteria. We relied on 
simple test criteria in our limited funded 
initiative. For example, the data available in 
CCOGIF format was displayed in one of the 
GIS systems and compared to the same data 
translated to Delta-X and transferred to the 
same GIS. In addition the data within Delta-X 
was displayed using PEX. This three way test 
provided confidence in the reliability of the 
data translation and conversion process. 
Developing comprehensive test procedures is 
in progress to assess the accuracy and 
reliability of network transaction and other 
features of the system. Data transfer between 
Delta-X clients with different GISs, was 
undertaken via our SUN 690 server, and 
communication between our Delta-X server 
and another server was also successfully 
tested. 
7. TESTING AND EVALUATION 
The success of the implementation of Delta-X 
and GIS Spatial Browser can be attributed to 
the stability and the reliability attached to the 
Alpha release which is one step ahead of the 
prototype. The successful integration with 
GIS software and the adaptability to 
technology changes can be seen in the alpha 
release, if you consider that the project started 
in 1989 when this latest technology was not 
350 
available. The system is capable of integrating 
new versions of existing GISs and adopting 
new protocols and standards. Today, we are 
witnessing high speed network inter- 
connectivity and the shrinking of the gap 
between LANs and WANs. These are 
technological advances that will certainly have 
an impact on the final system implementation. 
The evaluations performed on the system have 
enabled us to determine whether the system 
meets the performance criteria and to develop 
techniques to tune the system to achieve the 
design criteria. Both theoretical and practical 
analysis were conducted to re-evaluate user 
requirements and introduce new ideas and 
features through revision and reengineering, 
8. MANAGEMENT FRAMEWORK: 
BEYOND TECHNOLOGY 
The administration of a system such as Delta- 
X requires a management framework. For 
example, if data federation is implemented, a 
number of policies have to be established to 
control the federated environment. Policy 
such as authorization, security, charges for 
data transfer and many others require 
management decisions. For example, it may 
be that the data holder prefers to put a 
disclaimer to avoid any legal implications in 
the public use of the data. These are issues 
and policies for senior management to decide 
on. 
9. FUTURE IMPLEMENTATION 
STATUS 
The implementation of Delta-X is still in 
progress. However a substantial portion of 
the system is operational. The current 
implementation runs three servers and one 
Delta-X master. These use INGRES and 
ORACLE database management as the 
underlying databases. 
All server currently run some flavour of the 
UNIX operating system and are 
interconnected using ethernet. All remote 
communication, either between servers or 
between a server and client uses SUN remote 
procedure calling over TCP/IP protocols The 
common query language for remote data 
access is SQL. This is restructured to the SQL 
flavour of the host DBMS of the DxServer. 
While the development has been challenging 
both from research and academic point of 
view, its main motivation has been the desire 
  
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