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User Modeling for Personalized Web-Based Systems 221
8.3 User Model Life Cycle – User Modeling Process
User Model life cycle is defined by a sequence of actions performed by an adaptive web-based
system during user’s interaction with a system. The process is depicted in the Figure 8-2,
adopted from [13]. It separates the process into three distinct stages:
1. collection of data about user,
2. user modeling,
3. adaptation (use of user model).
In the first stage, system collects data about user and use them to create and update user
model in the second stage. Created user model is successively used in the third stage for the
adaptation itself, so the desired effect is achieved.
Data about
user
1. Collects
data
2. Processes
Adaptive
web-based
system
data
User model
User
modeling
3. Processes
model
Adaptation
Adaptation
effect
Figure 8-2. User model life cycle according to [13].
The process has a cyclic character, as an adaptive system continuously acquires new data
about the user (influenced by already performed adaptation and thus already filled user
model) and continuously refines the user model to better reflect reality and thus to serve as
a better base for personalization.
8.4 User Modeling Servers
In the beginning of user modeling, it was performed by the application systems, without
a clear distinction of user modeling components and components performing other tasks [39].
However, as user model construction and maintenance is a complex process which ends up
in a hard-to-develop, complex applications, research was oriented on the creation of generic
user modeling systems, called also user modeling shell systems or more recently user modeling
servers.
Apart from the primary effect of alleviating application developers from “re-inventing
the wheel”, designing their own representations of user model, characteristics and modeling