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history that can be used to analyze the patterns
and preference of the users. Operation log is used
to track the modification of the DRSC objects for
auditing and recovering. There are two kinds of
services provided: log recording service and log
analysis service.
we can calculate the similarities between the users
or between the resources.
3.2. The Composition
of a DRSC Object
The above five components constitute one DRSC
object as shown in Figure 2. Importantly, these
service components do not need to exist in one
computer, but rather be distributed over the Inter-
net. However, the behavior of a DRSC object is
configured by its properties, such as the links to the
corresponding components. To add, SCA supports
multiple interfaces through one implementation,
which results in the flexibility to the applications
of a DRSC object. What this means is that the
component applications can be implemented in
different languages, such as Java, C++and COBOL
etc. according to the corresponding specifications
that can be downloaded from OSOA's web site
(SCA Specification 2009).
The four components: Metadata, Content, An-
notation and Log are all based on the ID compo-
nent. The ID component consists of the pointers
to the other four components. When the stored
information of one resource in the four components
changes, they will notify ID component to update
the registration. The high flexibility of a DRSC
object is that it can be automatically integrated
with different transportation protocols such as Web
Service, MQ, HTML, REST and so on.
This service component model of digital re-
sources has the advantages as follows: it simplifies
the development, composition and distribution
process in assembling a solution of digital re-
source management; it improves the portability,
reusability and flexibility in managing the digital
resources; and it also reliefs the burden of the
organizations by hiding the details of the backside
technology from them.
For one kind of digital resource, there are two
steps to create a DRSC object for it. The first step
is to refine and classify its properties and functions
into the five components and the second step is
3.1.5. Annotation Component
This is a component with properties of score,
tags, comments and usage-status. As discussed
in section 1, the annotation information is dif-
ferent from the metadata in several ways. The
first difference is that metadata is given by the
experts, but annotations are given by users who
might not have the expertise knowledge. Sec-
ondly, metadata is chosen from a controlled word
list, while annotation is freely given as the user
wishes. Thirdly, the quality of metadata can be
guaranteed while the qualities of the annotation
vary a lot. However, the advantage of annotations
is that they are evolving with time so that they
can reflect the current understanding of the DRSC
object, while the metadata is normally fixed after
it is created. There is much research on how to
create a dynamic taxonomy from tags, if you're
interested, see (Hunter et al. 2008) (Marlow et al.
2006) for example.
The scores can be used to calculate the qual-
ity of a DRSC object, and help the ranking of the
search results. Comments are free text description
of the user's opinion or notes, which can be pro-
cessed by text mining or combined with tags by
extracting the keywords from them. Usage-status
is optional according to the content type of the
DRSC object, which helps the users to manage
their learning or studying processes. Usage-status
can also be used to help the calculation of the
tightness between user and resource. These an-
notations can also be used in collaborative filter-
ing for recommendation. We use a tuple with six
elements to represent the annotations for a DRSC
object given by a user: <user, resource, score, tags,
comments, usage-status>. From the annotations,
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