Information Technology Reference
In-Depth Information
Location Exposure Policy.
Produre combines traditional location tagging system and
online social network. Therefore, the friend relationship in ONS can be used to make
location exposure policy in location tagging system. In other words, a user
u
in the
system can decide which users are allowed to know his location so that these users will
be notified when
u
is one of their proximities (i.e., is near them) . A location exposure
policy of
u
's can be represented as
P
ui
=
,where
F
is the set of target
users of this policy, i.e., the users who are covered in this policy item.
A
is the set of
action of this policy. An action can be allowing or not allowing users in
F
to know the
location information of
u
.
F, A, ST, ET
2.2
Steps of Produre
The working process of Produre which is shown in Fig. 1 is described as follows.
- Step 1 - Request Generation:
A client
c
raises a request of proximity discovery,
and the processing center receives the request.
- Step 2 - Policy Checking:
The processing center
C
checks
c
's location exposure
policy to determine the set of users who are allowed to exist in the returning results
to
c
.
- Step 3 - Proximity Calculation:
For each user
u
i
obtained in Step 2, the process-
ing center
C
makes comparison of the set of
u
i
's location tags with the set of
c
's
location tags, and calculates the size (say
N
ci
) of the intersection of those two sets.
If
N
ci
>N
m
, then the processing center
C
will regard user
u
i
as a proximity of
the client
c
and put
u
i
into a proximity set
S
p
of
c
.
- Step 4 - Proximity Ranking:
The processing center
C
ranks each element
u
pi
(i.e., a user) in
S
p
according to
c
's credibility degree with respect to
u
pi
.Atlast,
the processing center
C
returns the first
θ
elements in
S
p
to
c
and the value of
θ
can
be adjusted according to the system requirement.
- Step 5 - Credibility Adjustment:
The client
c
views some of the results (users)
who possibly are his proximities, and contacts some proximities to do something
(e.g., going shopping together, or sharing the fee of a taxi...). After that, the client
will adjust his credibility degrees with respect to those users according to his own
evaluation on them.
After Step 5, the working process of a single proximity request is done. The changed
credibility degrees are stored in the system for later use, i.e., dealing with the following
proximity requests.
2.3
Algorithm for Users' Credibilities
In Produre, when a client issues a proximity discovery request, the system will present
the result page. Then he may view some of the results (users) who possibly are his prox-
imities, and contact some proximities to do something (e.g., going shopping together,
or sharing the fee of a taxi...). After that, the client will have his own evaluation with re-
spect to the proximities who the client has contacted with. According to the evaluation,
if the client regards a proximity as a true proximity, the credibility of the client with
respect to that proximity will increase. In contrast, if the client regards that proximity
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