Databases Reference
In-Depth Information
Example.
In the use case, if we assume that the flight search engine crawls information
from arbitrary airline websites, which publish flight information according to a standard
vocabulary, there is a risk for receiving incorrect information from malicious websites.
For instance, such a website publishes cheap flights just to attract a large number of
visitors. In that case, the use of digital signatures for published RDF data allows to
restrict crawling only to verified datasets.
Definition 13 (Reputation).
Reputation is a judgement made by a user to determine
the integrity of a source. It is mainly associated with a data publisher, a person, organ-
isation, group of people or community of practice rather than being a characteristic of
a dataset. The data publisher should be identifiable for a certain (part of a) dataset.
Metrics.
Reputation is usually a score, for example, a real value between 0 (low) and
1 (high). There are di
ff
erent possibilities to determine reputation and can be classified
into manual or (semi-)automated approaches. The manual approach is via a survey in a
community or by questioning other members who can help to determine the reputation
of a source or by the person who published a dataset. The (semi-)automated approach
can be performed by the use of external links or page ranks.
Example.
The provision of information on the reputation of data sources allows conflict
resolution. For instance, several data sources report conflicting prices (or times) for a
particular flight number. In that case, the search engine can decide to trust only the
source with a higher reputation.
Definition 14 (Believability).
Believability is defined as the degree to which the infor-
mation is accepted to be correct, true, real and credible.
Metrics.
Believability is measured by checking whether the contributor is contained in
a list of trusted providers. In Linked Data, believability can be subjectively measured
by analyzing the provenance information of the dataset.
Example.
In the flight search engine use case, if the flight information is provided by
trusted and well-known flights companies such as Lufthansa, British Airways, etc. then
the user believes the information provided by their websites. She does not need to verify
their credibility since these are well-known international flight companies. On the other
hand, if the user retrieves information about an airline previously unknown, she can
decide whether to believe this information by checking whether the airline is well-
known or if it is contained in a list of trusted providers. Moreover, she will need to
check the source website from which this information was obtained.
Definition 15 (Licensing).
Licensing is defined as a granting of the permission for a
consumer to re-use a dataset under defined conditions.
Metrics.
Licensing can be checked by the indication of machine and human readable
information associated with the dataset clearly indicating the permissions of data re-use.
Example.
Since the example flight search engine aggregates data from several data
sources, a clear indication of the license allows the search engine to re-use the data
from the airlines websites. For example, the LinkedGeoData dataset is licensed under
the Open Database License
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, which allows others to copy, distribute and use the data
