3.2 Model Design
3.2.1 Idea Review
In a virtual enterprise, each company that
participates in a sub-task, whether it is core
enterprise, compact partner, semi-compact partner,
or loose partner, needs to share information which
includes the performance of a partner completing a
sub-task, the constraint information that VEOMC
manages each virtual work team. (Dragoi George et
al, 2006) Obviously, it is of great importance to
share this information as soon as possible. Suppose
that there is a communication network being used in
the virtual enterprise, which allows data set (or file)
to be transferred from one company computer to
another. This example is illustrated in Figure 2:
In Figure 2, vertex V1, V2... Vm refers to
computers that process information in each virtual
Figure 2: Sample graph.
enterprise entity; edge e1, e2... en, means file
information to be transferred; T(ex) means time
needed to transfer Files ex; C(Vy) means the
processing capacity of computer Vy, i.e. the number
of files that can be transferred at a time. File transfer
must occupy all the time required of two relevant
computers transferring files. C(Vy) = 1 means that
the computer Vy can only transfer one file once.
What needs to be solved here is to arrange the
transfer so as to cost as little time as possible to
complete the transfer of all documents. The total
time is called “completion time” in the Operations
Research. (Hua Chen et al, 2006)
To facilitate the establishment of the model, the
problem is described as follows: there are 13 entities
in the virtual enterprise model, including one
VEOMC, four core working groups and eight other
working groups. Assume that each entity has only
one computer, and each computer is represented as a
vertex in Figure 3. There are 12 files to be
transferred between entities within a day. Edges in
Figure 10 represent file transfer. In this network, for
all x, y, T(ex) = 1, C(Vy) = 1, we are to find out the
schedule of the transfer and the corresponding
completion time. The graphical model is shown in
Figure 3:
Figure 3: Model Design.
It is concluded from Figure 3 that we should
figure out the shortest time of file transfer with
constrains of limited computer processing capacity
and transfer time.
To simplify the calculation, here are some basic
assumptions:
(1) Communication network graph is a simple
undirected graph. There are no overlapping
edges between any two vertices, which means
all the information transferred between two
computers can be included in one file.
(2) Preparation time of files to be transferred is
negligible, namely, zero. So the process of
communication network file transfer can be
continuous.
(3) The transfer time of each file is a fixed number.
(4) All files are independent of each other, and there
is no order or priority among them.
(5) There allows no interruption during the process
of transfer. Once a file is being transferred, it
has to be finished continuously.
(6) Communications network won’t break down
during the transfer process.
(7) Suppose the time required is identical, T(ex) =
1.
(8) Each computer can only process one file once,
i.e. C(Vy) = 1.
3.2.2 Model and Solution in the Local
Cluster Environment
The assumption that the transfer time of each file
T(ex) = 1, and each computer's processing capacity
C(Vy) = 1, makes the problem-solving relatively
simple. If all the files are to be transferred in the
shortest possible time, files have to be processed in
OPTIMISED MODEL OF INFORMATION TRANSFER IN VIRTUAL ENTERPRISES IN CLOUD COMPUTING
ENVIRONMENT
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