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Role/Rule Network Properties
Feature
Complex Circuit
edge
Simple Structures
Junctions Airbreaks
Snapping Circuit Only Circuit feature
Structures class can move and snap
Airbreaks to other features during
the network build
process
Snapping Circuit An optimal snapping
tolerance Structures tolerance is required for
Airbreaks the build process
Sources Structures Sources and Sinks
and Sinks ancillary roles are
applied to all identified
structures based on the
Str. #. Str. # = 0 are
sources, Str. # = xxxxS
are sinks.
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Structures network features.
Airbreaks AIRBREAKS may be
reset as barriers i.e.
enabled is false,
depending on network
implementation
Weight Circuit Feature length is a used
as a weight constraint
Table 2. Geometric Network Parameters
35 Metadata
Creating and managing metadata for database objects is an
important component of GIS implementation, and has profound
impact on tracking data update. Metadata provides complete
information on GIS data, including data properties (usually
derived from the data source) and documentation (often user-
input information).
Metadata on geographic data properties will include data
source, scale, resolution, accuracy, projection, and its
reliability. Additional documentation may be designed to track
data update cycles, to provide information on projects for which
the data was created, and to provide details on data
completeness.
4. HARDWARE INFRASTRUCTURE
The hardware infrastructure and the adopted technology
solution complement one another, and both are jointly
employed to provide support for database maintenance with
regards to data security.
The first line of security is usually provided by the storage
solutions. Storage vendors have standardized on RAID storage
solutions for data protection. Optimal RAID configurations are
available that balances data access performance with data
protection.
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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B2. Istanbul 2004
The second line of security is managed by the software
architecture in the empirical implementation, and this involves
two security layers:
1. SQL 2000 has in-built security protocols that ensure
that data stored in the RDBMS are protected against
unauthorized access. These involve protocols for
creating database users, roles and access to specific
databases and tables within the SQL database.
2. The second security layer is provided by ArcSDE in-
built functionality. ArcSDE tools are available to
create database users and grant different roles to
authorized users in order to edit, update, query or
manipulate the geodatabase from clients’
applications.
5. IT BEST PRACTICES
Until very recently, one often ignored factor in corporate
database maintenance is risk management, including software
disaster management and recovery all of which are essential
components of modern business processes.
In this implementation, we recognized that implementing a new
business-critical application requires the identification of
business continuance strategies and the implementation of
technologies and procedures that (i) ensure that corporate data
is maintained in a secure, reliable state, and (ii) maximize the
database availability to users to support their defined roles
Effective business continuance strategy is addressed by
focusing on two factors - (i) the maximum level of downtime,
if any, that is acceptable for maintaining business operations;
and (ii) the minimum level of employee interaction with the
system that is mandatory for maintaining business operations.
After determining these requirements with respect to acceptable
levels of downtime and employee-system interaction in the
event of a failure, the hardware and software requirements for
meeting those expectations are identified. Existing on-site
hardware and softwarerare assessed and tied into the new
system wherever applicable.
Low-Cost Strategy: If some downtime is acceptable, a
relatively basic hardware solution can be put into place utilizing
a simple tape backup device as the interface for archiving
snapshots of the data. In this scenario, the data and application
can be restored from the tapes after a hardware or software
failure has been resolved. This is a relatively inexpensive
approach, but it can take some time to restore the application
and data.
Mid-Cost Strategy: If being "up and running" as quickly as
possible is important, a more advanced hardware/software
configuration and redundant hardware devices may be required.
Then, if the main system fails, a secondary device (of equal or
lesser capability) containing a real-time copy of the application
and its data comes online to meet the client's minimal
requirements until the main system is restored. In addition,
tape backups would be run to keep a relatively current copy of
the data offsite. This is a somewhat more expensive and
slightly more complicated approach, but business continuance
is maintained at a higher level.
