The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008
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2. METHODS
2.1 Data storage (at the ZAIK/RRZK)
A persistent, sustainable, secure storage of data is very
important for all kinds of projects that handle data. This has to
be organized in a clearly arranged and ordered structure.
Moreover only authorized users should be permitted to access
the data storage. Furthermore, it is essential to backup or
archive data to ensure the recovery of destroyed data. Hence e.g.
the German Federal Office for Information Security (BSI)
follows the just given principles for the storage and
management of data (BSI 2008). Considering the mentioned
facts and guidelines of the DFG, the cooperation with a
computing center is indispensable for an interdisciplinary
project.
The storage of data at the Regional Computing Center
(RRZK)/the Center for Applied Computer Sciences (ZAIK) of
the University of Cologne is organized in different stages.
These are the Storage-Area-Network (SAN) based Disk Storage,
the Andrew File System (AFS) and the High Performance
Computing (HPC) - File System (see Figure 1).
Figure 1. Data storage at the ZAIK/RRZK (Kalle 2005)
In this contribution, the focus will be on AFS, a distributed
networked file management system (file database). Besides
sharing and synchronizing federated file storage, main
advantages of the AFS are aspects like security, scalability, and
user administration by an Access Control List (ACL).
Furthermore, AFS supports location inference, cross platform
access (e.g. UNIX, Linux and Microsoft Windows) and simple
archive and data backup (AFS 2008).
2.2 Databases
The persistent, consistent and efficient management and storage
of a huge amount of data sets is the central duty of a Database
Systems (DBS). A DBS is a combination of a database (DB)
and a Database Management System (DBMS) (Elmasri and
Navathe 2005). The real storage of data operates at the DB. The
DBMS is the software that enables the management of data in a
specified data model. The characteristic properties or rather
requirements of a DBS are data independence, central data
management, multiuser access, data security, data integrity
(redundance-free data storage), access control, processing of
requests, and operating system independence (Brinkhoff 2008).
Data models are described in several structures. In this context
relational and object-relational models and databases are
important. Relational database models are identified with
connected database tables that store the data like IBM DB2,
Microsoft Access or MySQL. Object-relational database models
manage objects that are stored in linked relational data tables
like Oracle Spatial or PostgreSQL (Tiirker and Saake 2005).
They are qualified to be geodatabase systems on condition that
they have a corresponding extension (Brinkhoff 2008).
2.3 Metadata
The term metadata describes data that contain information
about data e.g. quality, author, location, and year of publication
for a book. The common use of metadata is to describe data and
enable a better search. For more explanations on metadata and
the importance of see Yeung (2007).
The metadata structure should follow recent standards and
principles. These are basically spatial data standards from the
Open Geospatial Consortium (OGC), the International
Organization for Standardization (ISO), the Dublin Core
Metadata Initiative (DCMI), and the World Wide Web
Consortium (W3C) (Bartelme 2005 and Nogueras-Iso et al.
2005). For example the geo-metadata follows the guidelines of
ISO Norm 19115 (IS019115 2003).
2.4 Web-Interface and WebGIS
The main duty of a web-interface is the representation of
information at the World Wide Web. The implementation of a
web-interface is predominantly carried out with the platform
independent markup language HTML/XHTML ((Extensible)
Hyper Text Markup Language). In addition the client-side
scripting language PHP (Hypertext Preprocessor) is used for
dynamic web pages as well as CSS (Cascading Style Sheets) to
describe the style of the web-interface. A combination of PHP
and SQL (Structured Query Language) is used to customize the
interaction between the database and the web-interface. The
encrypted SSL (Secure Sockets Layer) technology including a
digital certificate ensures a secure communication via internet
e.g. for web browsing or data exchange (Open SSL 2008).
In recent years the presentation of GIS and cartographic
functionalities (web mapping) in the internet became more and
more important (Asche and Herrmann 2003). Hence a WebGIS
is absolutely essential to visualize, manage, and analyze spatial
geodata within a web-interface. ESRI’s ArcGIS Server
connected with ArcSDE (Spatial Database Engine) provides an
opportunity to realize a WebGIS (ESRI 2008).
3. TR32 DATABASE DESIGN
The essential duty of the TR32 data management SP is to
enable data storage and exchange for different SPs. In addition
backup functionalities have to be implemented as well as
corresponding metadata for the project data. With regard to the
project duration, it is important to design a stable and
sustainable system, called the ‘TR32 Database’ (TR32DB).
As a result of the interdisciplinary background of the TR32, the
TR32DB stores a multiplicity of different data: measured and
purchased project (geo-) data. The measured project data
comprise data that are collected of the various TR32-SPs. The