Journal of Software Engineering and Applications, 2011, 4, 442-445
doi:10.4236/jsea.2011.47051 Published Online July 2011 (http://www.SciRP.org/journal/jsea)
A Mixed Method Approach for Efficient
Component Retrieval from a Component
Repository
Jasmine Kalathipparambil Sudhakaran1, Ramaswamy Vasantha2
1Rashtreeya Vidyala College of Engineering, Bangalore, India; 2Department of Information Science and Engineering, Rashtreeya
Vidyala Col le g e of Engi n eering, Bangalore, India.
Received April 21st, 2011; revised May 19th, 2011; accepted May 28th, 2011.
ABSTRACT
A continuing challenge for software designers is to develop efficient and cost-effective software implementations. Many
see software reuse as a po tential solution; however, th e cost of reuse tends to ou tweigh the potentia l benefits. The costs
of software reuse include establishing and maintaining a library of reusable components, searching for applicable
components to be reused in a design, as well as adapting components toward a proper implementation. In this context,
a new method is suggested here for component cla ssification a nd retrieval wh ich cons ists of K-near est Neighbor (KNN)
algorithm and Vector space Model Approach. We found that this new approach gives a higher accuracy and precision
in component selection and retrieval process compared to the existing formal approaches.
Keywords: Software Reuse, Component Retrieval, Vector Space Model Algorithm
1. Introduction
Many software organizations realized that developing the
software using reusable components could dramatically
reduce development effort, cost and accelerate delivery.
But the non-existence of a standard searching technique
for finding the suitable component and also the lack of
appropriate tool in this field contributed towards in large-
scale failures in their approach. From the past studies on
this field, it is found that researchers are tried with dif-
ferent approaches to improve the adaptability of the
component but very few studied had taken place in im-
proving the efficiency of component retrieval. Fuzzy
linguistic approach is familiar in the information retrieval
process [1]. In this paper we have used an algebraic
model namely Vector Space model in which text docu-
ments are represented as vectors of identifiers, such as,
index terms which is used in information filtering, in-
formation retrieval, indexing and relevancy rankings
along with K-Nearest Neighbor(KNN) algorithm for
classification of documents. The paper is structured as
follows. Section 1 starts with a discussion of what is
meant by software reuse and a reusable component. Sec-
tion 2 talks about present scenario in the component re-
trieval process. Section 3 presents methodology adopted.
Section 4 mentions some concluding remarks and the
relevance of related models which can be extended from
the vector space model and various combination algo-
rithms which can contribute towards further extension of
this work are pointed out.
1.1. What Is Software Reuse?
Software reuse at its most basic level consists of mak-
ing use of any existing information, component or prod-
uct when designing and implementing a new system or
product.
There are differing opinions as to which activities con-
stitute genuine software reuse. Replication of an entire
software program does not count as reuse. Reuse of as-
sets is dependent upon both similarities and differences
between the applications in which the component is be-
ing used [2].
Many organizations already practice a limited form of
reuse, for example, most developers have libraries of
components that they have developed in previous pro-
jects, or they use standard libraries, which are available
with many programming languages [1]. About 30% of
the cases, it is a very ad-hoc method of reuse, and it will
work very well on a small scale and it will not be suitable

A Mixed Method Approach for Efficient Component Retrieval from a Component Repository443
for entire organizations [3]. Instead, businesses need to
implement a systematic reuse program in order to gain
the full advantages of reuse.
1.2. What Can Be Reused?
The definition of a reusable component is “any com-
ponent that is specifically developed to be used, and is
actually used, in more than one context” [3]. This does
not just include code; other products from the system
lifecycle can also be reused, such as specifications and
designs, and even requirements on occasion [4].
‘Components’ in this case can be taken to include all
potentially reusable products of the system lifecycle,
including code, documentation, design, requirements etc.
There are various criteria that should be satisfied in
order for an asset to be successfully reusable. These are
grouped into General, Functional and Technical require-
ments [5]. General requirements focus on aspects such as
compliance with relevant standards, completeness, mod-
ularity and simplicity. All components should conform to
the General requirements. Functional requirements in-
clude such concerns as which business processes it will
simulate or automate, and how well it does this. Func-
tional requirements mainly concern Vertical or Domain-
specific assets and tend to be very specific to each in-
formation domain. Lastly, Technical requirements refer
to criteria such as interoperability, portability, commu-
nication, security etc [2].
There are different levels of reuse, which can be
considered [3]. At the highest level, entire applications
can be reused on different platforms provided they are
portable. Sub-systems can be reused within different ap-
plications, possibly within different domains. Reusable
assets can be also being built in-house, retrieved from
legacy systems or can be bought from an external
source.
2. Present Scenario in the Component
Retrieval Process
Existing approaches to software component retrieval
process cover a wide spectrum of component encoding
methods and search or matching algorithms. The en-
coding methods differ with respect to their soundness,
completeness, and the extent to which they support an
estimate of the effort it takes to modify a component.
Text-based encoding and retrieval is neither sound nor
complete. Its disadvantages have been thoroughly in the
information retrieval literature [5,6]. Lexical descrip-
tor-based encoding approach also suffers from a number
of problems about developing and using classification
vocabulary [7]. Software specific challenges include the
fact that one-word or one-phrase abstractions are hard to
come by in the software domain [8]. From the user’s
point of view, lack of familiarity with the vocabulary is
also pointed out as draw back in using a component
retrieval system effectively [9]. In this context Vector
space Model will be a promising solution for component
retrieval process [10,11].
3. Methods Used
3.1. Vector Space Model Approach
It is an algebraic model in which documents and que-
ries are represented as vectors [12] as follows:
dj = (w1,j,w2,j,...,wt,j)
q = (w1,q,w2,q,...,wt,q)
Each dimension corresponds to a separate term. If a
term occurs in the document, its value in the vector is
non-zero. An indexed collection of documents is repre-
sented as a term table which has documents as fields
and words as primary key for row. The (D)i(Word)j-th
entry of this table records how many times the j-th
search term appeared in the i-th document. The fol-
lowing Figure 1 shows a sample vector space model.
The first major component of a vector space search
model is the concept of a term space. A term space con-
sists of every unique word that appears in a collection of
documents. The second major component of a vector
space search model is term counts. Term counts are sim-
ply records of how many times each term occurs in an
individual document. This is represented as a table. By
using the term space as a coordinate space, and the term
counts as coordinates within that space, we can create a
vector for each document. As the number of terms in-
creases, the dimensionality of VSM also increases. Fig-
ure 2 shows the structure of the word database and Fig-
ure 3 shows the structure of the rank table.
For these words documents and corresponding ranks
will be stored in the rank tab le.
Based on the ranking terms are compared as “ranked
higher than”, “ranked lower than” or “ranked equal to” th e
second, making it possible to evaluate complex informa-
tion according to query criteria. Here search vector space
Figure 1. A sample vector space model.

A Mixed Method Approach for Efficient Component Retrieval from a Component Repository 444
Words d1 d2 d3 d4 … dn
1 1 1 1 0 1
3 0 2 1 0 1
0 1 3 0 0 2
0 0 0 0 0 0
Figure 2. Structure of word database.
Dno Rank
d1 1
d2 3
… …
dn 1
Figure 3. Structure of rank table.
search model ranks the documents it finds according to
the estimation of their relevance, making it possible for
the user quickly to select the components according to
their requirements [7,13].
Relevancy rankings of documents in a keywor d search
can be calculated, using the assumptions of document
similarities theory, by comparing the deviation of angles
between each document vector and the original query
vector where the query is represented as same kind of
vector as the documents.
It is easier to calculate the cosine of the angle between
the vectors instead of the angle:
2
2
cos dq
dq



A cosine value of zero means that the query and doc-
ument vector are orthogonal and have no match (i.e. the
query term does not exist in the document being consid-
ered).
3.2. The Document Classification Algorithm
Employed
KNN classifier is an instance-based learning algorithm
that is based on a distance function for pairs of observa-
tions, such as the Euclidean distance or Cosine. The
k-Nearest Neigh bour (kNN) classifier algorithm has been
studied extensively for text categorization by Yang and
Liu [6]. In this classification paradigm, k nearest neigh-
bors of a training data are computed first. Then the simi-
larities of one sample from testing data to the k nearest
neighbors are aggregated according to the class of the
neighbors, and the testing sample is assigned to the most
similar class. The similarity in score of each neighbour
document to the test document is used as the weight of
the categories of the neighbour document [ 8]. If ther e are
several training documents in the k nearest neighbour,
which share a category, the category gets a higher weight.
In this work, we used the Cosine distance to calculate the
similarity score for the document representation.
One of advantages of KNN is that it is well suited for
multi-modal classes as its classification decision is based
on a small neighborhood of similar objects (i.e., the ma-
jor class). So, even if the target class is multi-modal (i.e.,
consists of objects whose independent variables have
different characteristics for different subsets), it can still
lead to good accuracy. A major drawback of the similar-
ity measure used in KNN is that it uses all features
equally in computing similarities. This can lead to poor
similarity measures and classification errors, when only a
small subset of the features is useful for classification
[5].
3.2.1. Ste ps for KNN Using Average Cosine
Step 1: Select k nearest training documents, where the
similarity is measured by the cosine between a given
testing document and a training document.
Step 2: Using cosine values of k nearest neighbors and
frequency of documents of each class i in k nearest
neighbors, compute average cosine value for each class i,
Avg_Cosine (i) .
Step 3: Classify the testing document a class label
which has largest average cosine.
In order to reduce the dimensionality of VSM and
keep useful information, we first compute concept vec-
tors for given categories. Then, using the concept vectors
as projection matrix, projection of both training and test-
ing data is done. Finally, we apply KNN algorithm on the
projected VSM model that has reduc ed dimensionality.
3.2.2. Steps of Combined Approach for Vector Based
Algorithm and K-Nearest Neighbor Algorithm
Step 1: Compute a concept vector for each category us-
ing true label information of training documents and then
construct concept vector matrix C (w-by-c), where c is
the number of categories.
Step 2: Do projection of VSM model A (w-b y-d) us ing
concept vector matrix C (w-by-c) (i.e., C^T * A ).
Step 3: Apply KNN with the projected VSM model
(i.e., c-by-d matrix).
4. Conclusions and Future Work
A novel KNN classification algorithm combining model
and evidence theory is proposed in this paper. The new
method not only overcomes the main shortage of lazy
learning in traditional KNN, but also takes the distances
between samples to be recognized and samples in
k-neighbors into account. At the same time the method
resolves the unrecognizable cases of unknown samples.
Applying the classification algorithm into the document
recognition, experimental results show its satisfied rec-
ognition rate and fast categorization speed.
There are also models based on and extending the
vector space model such as generalized vector space
model, Topic-based Vector Space Model and latent se-

A Mixed Method Approach for Efficient Component Retrieval from a Component Repository 445
mantic indexing etc and also combination algorithms
which consists of clustering, Singular Value Decomposi-
tion(SVD)-based Algorithm, Naive Bayesian Algorithm
and variations of KNN algorithm. Future work can be
aimed in these directions.
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