Research of Educational Resource Sharing Mechanism Based on Grid
Wen-guang An 1, Hong-jun Li2, Tao Wang1
1
2
Department of Information Management and Engineering,Hebei Finance University, Baoding, China
Foreign Languages Department,Great Wall College, China University of Geosciences,Baoding, China
(anwenguang@126.com, hongjun_lee@126.com, hbjrwt@gmail.com)
Abstract - The current educational resources distribute
disorder, it can’t give full play to the role of the underlying
network. This paper briefly describes grid architecture,
carries out a theoretical study of educational resources
construction based on grid, and discusses some issues in
depth, such as resource management, resource description,
discovery and transmission of resources.
Keywords - Grid, Educational resources, Sharing,
OGSA
With the improvement of network technology and the
popularization of information technology in education,
online education has been paid more and more attention.
Each school is building its own network of educational
resources, which not only enable the students to keep
learning at any time, but also give full play to the effect of
various kinds of educational resources. However, the
current sharing of educational resources is very low; there
is a lack of communication between various schools. How
to integrate and manage the dispersed resources
effectively, make a balanced distribution between the
schools, play the role of online education, and meet all
kinds of resources requirements of school to maximize? It
has a very large practical significance. Grid technology
can better solve this problem.
I. INTRODUCTION OF GRID
Grid is an emerging technology, which is in constant
change and development. It is the proposed concept that
borrows from the power grid (Power Grid). In its
viewpoint, all resources on the Internet will achieve
interoperability, connectivity, each of information and
Resources Island will be connected, which can provide
people with geographic position, specific resources
irrelevant transparent service. Grid is the third milestone
after the Internet, World Wide Web in development of the
Internet. [1]
A. The concept of grid
Grid is a kind of infrastructure. It connect
geographically dispersed computing hosts together to
form a “super computer” on the basis of the Internet, and
achieve a comprehensive, controlled sharing of physical
resources, software resources, and storage resources. [2] Be
known as “The father of grid computing”, Ian Foster, in
“The Grid: Blueprint for a New Computing
infrastructure” to the grid made such a definition: "Grid is
a group of emerging technology that be built on the
Internet, it will integrate high-speed Internet, highperformance computers, large databases, sensors, remote
equipment, and offer more resources, functions and
services for technical personnel and ordinary people. The
internet primarily provides E-mail, web browsing and
other communications functions for people, and Grid
function is stronger, which make people more transparent
use computation, storage and other resources."
B. Characteristics of grid
1) Resource distribution: The distribution of grid is
reflected in the distribution of grid resources. Grid is
composed of geographically distributed computers and
storage devices.
2) Resource sharing: Grid completes the computing
tasks by focusing the dispersed resources, and resource
sharing is a means of resource focused. It can eliminate
Information Island, and realize the application’s
interoperability. Grid and computer network is different,
computer networks is hardware connectivity, while grid
achieve application-level connectivity.
3) Dynamic diversity: Grid can provide a dynamic
service, and adapt to change. Grid devices increases and
decreases without affecting grid are other parts of
function and performance.
4) Low cost: Using a variety of existing hardware and
software resources to support various applications, it not
only save costs, but can promote the rapid increase in the
level of interdisciplinary research.
II. THE GRID ARCHITECTURE
The establishment of grid architecture is a
prerequisite to realize the application of grid. Being
involved in all aspects of grid technology has gradually
formed the corresponding norms and agreements. Grid
system built by in strict accordance with the
standardization technical means is the key to realize data
versatility and cross-platform.
So far, the mainstream of grid architecture mainly has
three types and follows:
A. Ian Foster's five hourglass structures (Five-Level
Sandglass Architecture)
The most basic idea of Five-Level Sandglass
Architecture is: the protocol as the center, emphasizing
service and the importance of API and SDK. Five-Level
Sandglass Architecture is divided into application layer,
convergence layer, resource layer, link layer and
structural layer. [3] Shown in figure 1.
Fig.1 The level of division of Hourglass structure
From the above figure we can see, the core protocol is
stored between resource layer and link layer. Core layer
must first accept the mapping of the various agreements
from the top, and then map core agreement to the lower.
And all the host of grid computing must adapt to these
agreements. So the number of the core protocol should
not be too much, and make the structure become an
hourglass structure.
OGSA achieve all of the core grid services by a set of
relatively uniform interface, and can easily construct a
hierarchical structure, higher level of service.
C. Globus Alliance's Web Services Resource Framework
(Web Service Resource Framework, WSRF)
WSRF adopts a completely different definition with
grid services: resources are state, services are stateless.
According to the specific information exchange and
related XML, WSRF defines Web service resources (WSresource). [5] Through the establishment of method of the
relationship between a state resources and Web services,
it defines the description specifications and extended
standard of Web Services Resource (WS-Resource) in
certain message exchange and related XML mode, thus
makes effective management for the service states, life
period, services and other service groups, accelerate the
integration of the grid and Web services, and the research
community and industry standards.
This paper considers constructing the grid architecture
of educational resources based on OGSA. OGSA
architecture consists of four main layers, from bottom to
top as follows: physical resources and logical resources
layer, Web services and WSRF extend layer of definition
grid services, service layer based on OGSA architecture,
and the application layer. Here describes the hierarchical
structure of educational resources grid. Shown in figure 3.
B. Ian Foster, etc., put forward the Open Grid Services
Architecture (Open Grid Services Architecture, OGSA)
based on the web services and Five-Level Sandglass
Architecture
The most basic idea of OGSA is emphasize "service".
In OGSA framework, all are abstracted for service,
including a variety of computing resources, storage
resources, networks, programs, databases and so on. In
short, all are services. This concept is conducive to
manage and use gird through the unified standard
interface. [4] A brief description of grid services is shown
in Figure 2.
Fig.3 Education resource grid architecture based on OGSA
According to this hierarchy structure, we make clear
the current main task: management of resources,
description and discovery of resources, and transmission
of resources, etc.
III. MANAGEMENT, DESCRIPTION AND
DISCOVERY OF RESOURCE
Fig.2 Schematic diagram of grid services
Description of educational resources relates to the
content of educational resources, applicable resources
objects, teaching method requirements, and process
requirement. Here we mainly introduce the content of
educational resources. The type of education resources is
abundant. It includes text, audio, video, PPT, multimedia
courseware, etc. Of course, there are other application
services, such as paper, e-books search system, video on
demand systems, real-time communication system. OGSA
and SRF abstract it as services that all of these storage
resources, information resources, databases and so on. In
order to realize the sharing of educational resources, we
must firstly manage these services in grid of educational
resource.
The task of grid resource management is to manage a
variety of scattered resource in gird, so that more resource
requesters can share the same resource in grid. [6]
According to business needs, the resource requester can
use multiple resources in gird simultaneously or
successively, without the need that the resource requester
pays extra labor. The objectives of resource management
include the following:
A. Provide users with a simple interface to access
resources
The actual use of resource management module hides
the complex technology details of resources, physical
resources are abstracted as logical resources and it
provides services for users.
the registration and sharing of resource to the cancellation.
[8]
At this point, resource manager needs to have the basic
functions, including resources registration, resource
discovery, deploy resources, resources agency and
resources for cancellation.
The current service discovery mechanism mainly is
UDDI (Universal Description, Discovery and Integration,
Universal Description, Discovery and Integration).[9]
UDDI is a set of the standard specification of information
registration Centre based on Web, distributed, web
services drafted by UDDI.org, it also contains a set of
method that service providers can register their Web
services, so that service user can discover these services
realization standards of accessing protocol. The core
component of UDDI is registration center. It describes the
Web service by using WSDL (Web Service Description
Language), it is the definition language of interface of
web service, and it can describe three basic properties of
the web service:
1) What services do: the operations (methods)
provided by services;
2) How to access services: interactive data formats
with services and the necessary agreements;
3) Where services locate: protocol-related addresses,
such as the URL.
Figure 4 is the simple service structure diagram built
between service providers, service registration center, and
service users.
B. Coordinate shared use of resources
Resource management module uses queuing strategies,
time-sharing strategy or other strategies to determine how
requesters to use the same resource. These strategies are
to determine. Based on the characteristics of the resource
itself and the owner of the development of strategies. At
the same time, Resource management module also
supports a need that the requester asks the use of multiple
resources.
C. Replaces the requester to use resources, and establish
a secure mechanism that uses grid resources.
As the super user, resource manager work in the
resources instead of gird users. When user requests,
resource manager creates an activity place- user container
for the user in the local resource, container allow user to
use resource in the container. Container strictly defines
the rights and the operating owned by user. [7] By this way,
it avoids the hidden trouble that a number of grid users are
active in the same local account of the resources. When
requested, containers can be dynamically created, and
when request is over, containers can also be automatically
revoked. The number of user container in the same
resource is little; it won’t bring a large administrative
burden.
In addition to other using process of management of
resource, the more important is the entire life-cycle of
management of resource, namely the whole process from
Fig.4 service structure diagram
IV. TRANSMISSION OF RESOURCES
On the basis of effective resource management, the
use of resources is essential to transmit resource from the
hands of provider to user. [10] Grid environment requires a
fast, safe, efficient and reliable transport mechanism.
GridFTP is a common data transfer protocol of data
management in computing environment of Globus gird. It
supports GSI security mechanisms, three controls, parallel
transmission and other functions, It supports the following
features:
A. Parallel data transmission: large bandwidth with use
multiple TCP streams over a single TCP flow, parallel
data transfers is provided support by the FTP command
extensions and data channel extensions.
B. Grid security infrastructure (Grid Security Infrastructure, GSI) and Kerberos authentication support: The
user controls all kinds of data integrity and confidentiality
level setting. This feature provides the robust and flexible
authentication, integrity and confidentiality mechanisms
for transmission of documents.
C. Third-party control of data transmission: Support for
large distributed community management of data sets. It
makes the third party to control the transmission between
the storage servers.
D. Block data transmission: there exists the ability to
place the data split across multiple servers, thereby
enhance the aggregate bandwidth. GridFTP supports subblock data transmission through the extended definition in
the Grid Forum (Grid Forum) draft.
E. Part of the file transfer: Different from standard FTP
application program transferring the entire file, new FTP
commands support sent the certain areas of files.
F. Reliable data transmission: Recovery method can
handle transient network failures and server failures, and
can restart a failed transfer.
G. Manual control of TCP buffer size: maximum support
for TCP / IP bandwidth.
H. Integration testing (Instrumentation): support to return
to restart and performance marker.
V. CONCLUSION
The emergence of grid technology provides the
technical support for the widespread development of
educational resources. On the one hand, it provides a new
solution to solve distributed, dynamic and magnitude of
information processing, and on the other hand, it can
make the existing network resources more fully utilized.
The development of grid-based environmental education
resources greatly promote the development of education
information, but its application is still in its infancy, it still
need more in-depth research in order to make it better
promote and use.
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