HUBERT ZARZYCKI EUGENIA FRONCZAK
University of Technology and Life Sciences in Bydgoszcz
A PRACTICAL APPROACH TO COMPUTER SYSTEM ARCHITECTURE FOR AN AGRO-FOOD INDUSTRY INFORMATION CENTRE
Summary
This article presents the architecture of a computer system with a remote access to the database of the agro-food industry. The developed model of the cooperation centre demonstrates the methods and techniques of construction, which comprise the usage of information technology to process data representing traditional affiliations of the agrarian manufacturers and food processing enterprises and groceries revenues. The database solution is in particular connected with the movement of the flux and physical transfer of the products from the production location to the processing and distribution, and with the technical means and software application choice essential to the realization of the communication and information function and with the data means for the tech and code infrastructure within the created data warehouses.
Keywords: computer system architecture, agro-food industry, Oracle Application Server, Oracle HTTP Serwer, PL/SQL Web Toolkit, Oracle Process Management and Notification, Oracle Application Server 11g, Oracle Application Server WebCache.
1. Introduction
Nowadays the social attitude towards the large distributive networks is changing to the worse. The need to consume the products of the highest quality and the safest food leads to the situation when consumers tend to prefer buying groceries in a traditional way.
Wholesale markets become more important among intrastate and interstate foodstuff distribution. Wholesale markets, especially of fruits and vegetables, contribute to the adjustment of the farming productions to market needs, but also cause the quality and state of safety of the products to improve, and contribute to price stabilization and elimination of the intermediaries. They also have an impact on the processes of the manufacturers groups formation. Well organized wholesale markets contribute to the development of the region, bring benefits to the food manufacturers by eliminating of the intermediaries and also lead to the upswing of the quality of the products and also to the advancement of the agriculture and countryside in general.
Because of the fast development of the global processes on the Polish market of the agrarian and food products and associated dynamic changes in wholesale and retail trade, wholesale markets are forced to introduce some modifications. Those changes are based on the extension of the market offers and wholesale market services. The process also demands the supply of farming material quality and the usage of the proper technology adjusted to the needs of agro-food processing. Another essential aspect is to meet all consumers expectations and needs.
At the present moment on Polish market of agro-food products the consumer requirements are raising and that is why food security conditions should be fulfilled, and, additionally, there is
a need to assure high effectiveness of product parameters, and to improve customer service. The development trends in food economy cannot be realized without effective information exchange. Proper functioning of the food chain aims to control all cells of the material production and processing. This goal cannot be reached without the help of efficient information networks.
The information center, presented in this work is a suggestion of how these tasks could be accomplished. Such an up-to-date solution would improve the exchange of information, providing considerable logistic and quality support on the Polish agro-food market.
2. The agro-food industry information center concept
The computer architecture aimed to tackle information center tasks for the agro-food industry should be based on the client-server model. It is the characteristic solution since it is the server application that needs to be an infrastructure fragment, which is essential to the service. Additionally, server application has to be able to operate within the database. To implement information system with the remote access the following products are needed:
• Database server – stores the structure data,
• Application server – aimed to run and use the application. Set of services such as HTTP server, application container (PLSQL, CGI, J2EE, PHP, Perl, etc.), infrastructure of the applications management and users, and other functions.
A lot of server applications are available on the software market. Free server applications have limited functions. They do not have essential technical support and usually are intended to work with undemanding applications. On the other hand, recognized manufacturers (Oracle Application Server, BEA WebLogic, IBM WebSphere, JBoss and NET Microsoft) provide complete and comprehensive service.
Tailored to the problem is the choice of the compatible Oracle products and database including Database Server 11g, Oracle Application Server (OAS) 11g, Oracle Designer [1].
OAS is an excellent database and analytic package which is intended to create progressive internet-oriented applications. The fact that the network server environment based on Apache implements a data encryption protocol SSL is an advantage. Thanks to that, the highest requirements of the e-business security solutions are fulfilled.
In the information center model, architecture compatible with OAS 11g application server would be applicable. The HTTP server would play an important role within this solution. The server is able to run applications depending on users’ needs. HTTP server runs applications using modules (plugins) suitable for a technology, where application developed by the user was made. Such applications can use the database.
Application server OAS supports the HTTP and XML Internet standards. The usage of the OAS and Oracle database environment properties will greatly facilitate the preparation of communication features and data structures essential to the information center creation. At the same time it will ensure scalability, which is needed to extend the system envisaged.
3. Implementing the information system within the trade center
The proposed information system for farmers and partners provides for the usage of the database as a repository for both the center of agro-food industry, and users and metadata essential for the server application work.
The architecture of the implemented information system is presented in figure 1.
Figure 1. Computer architecture aimed to tackle information center tasks for agro-food industry Source: Based on Drelichowski, Zarzycki, Sikora, [2].
Procedures and functions designed to handle the information center will be stored using PL/SQL. PL/SQL is a superset of SQL, which allows the loop, conditional orders, error handling and etc. Procedures written in PL/SQL generate sites based on the HTML tags. Blocks of code can have its own local variables. PL/SQL is available in the Oracle Web Toolkit package [1].
Client communication with the system would be possible thanks to the HTTP server module mod_plsql. This plug-in replicates browser requests for the particular virtual path (default one is /pls) calling the stored procedures [3]. Stored procedures generate HTML code, which is transmitted later to the PL/SQL model where it is returned to the browser. PL/SQL model connects to the database using configuration parameters recorded on the DAD descriptor (DataBase Access Descriptor) [2].
The remote access to the information center will be possible by using the Internet. Procedures of the users service, data import and export, statistics and pricing will be implemented by the:
• Start-up of the Internet browser (Internet Explorer, Mozilla Firefox, Opera, Maxthon, Avant Browser etc.),
• Typing in the url address of the information center,
• Data processing in accordance with the information contained on the site.
The center data structure of the agro-food industry will be based on the already existed constructions, norms and solutions (such as DBR). Regional Data Bank (BDR) is the largest collection of structure information on the economic, demographic, and social situation in Poland, and also on the natural environment state of the regions. This is a state interface with the regional database access run by the GUS. Regional Data Bank allows for the conducting of the multidimensional statistic analysis. It also enables comparison of the units of territorial division. Web site with the access of the Regional Data Bank database is presented in figure 2.
Figure 2. Central Statistical Office web site – Regional Data Bank Source: www.stat.gov.pl [4].
4. Application server architecture with the single-machine installation
The breakdown of the operation memory, CPU, disks controller etc., in the single-machine installation system leads to termination of work. Even in the case of such installation, application of particular mechanisms cause the improvement of the reliability of the system. This is especially important in the case of program failures.
Figure 3 shows the characteristic server application architecture in installation on the single server.
Figure 3. General application server architecture in a single-machine installation process Source: Based on the example OAS 11g.
The improvement of the OAS (10g and more modern ones) server application reliability can be done by the applying of the reproduction processes mechanisms. This mechanism can include HTTP server, J2EE server and other components responsible for the application. Reproduction processes is based on the distribution of the users requests between alternative executive processes. If there is a failure of one process, the users service can be continued by the multiply equivalent.
Another way to improve the server application (and the security server) is to use components of OPMN types (Oracle Process Management and Notification), which are used to verify continuing activities and to repair them if needed [5]. This component runs the server application processes and then monitors their activity and stores the data on performance and detected faults. When the failure is detected, OPMN tries to rerun the process. Thanks to that self-repairmen, server application processes and security servers are almost indestructible.
The replication mechanism allows for protecting against the loss of the OAS 11g application state. This mechanism involves the replication status of each application performed between multiple processes performing applications.
5. Cluster architecture of the application server
Cluster architecture can be applied when the information center for the agro-food industry runs or when it expands to the multiple-machine system. The characteristic feature of the architecture is the hardware redundancy. Then, the different parts of the OAS server application are dispersed among a number of real machines. When one of the servers fails, the rest of them are capable to submit the users requests. Figure 4 presents the application server architecture on number of machines. Various web technologies are underlined here (simplified scheme of the OAS 11g architecture).
Figure 4. The general architecture of the (OAS 11g) cluster server application Source: Masewicz [6] and Drelichowski, Zarzycki, Sikora [2].
Clustering available in Oracle 11g improves not only the reliability but also scalability of the whole system. Clustering of the particular parts of the server is one of the most common methods of the system adjustment to the users needs. This is a commonly used technology to expand various elements of the information infrastructure, especially server applications. If the demand for the system to be used in the trade center increases it will be enough to add appropriate server application components.
Oracle Application Server 11g distinguishes two types of cluster architecture of server applications. These are the architecture of the active-active type and active-passive type. In those architectures, particular parts of the server applications are so amplified as to ensure continuity of work in a critical situation. Moreover, for the active-active architecture the improvement of the cluster solution performance compared to the results of the installation based on the single node are noted.
In the later development of the system the need to create additional advanced applications connected with the database when using additional procedural language other than PL/SQL can
emerge. In such case Oracle allows for the usage of the most popular programming languages such as C++, Java, Perl, etc. Moreover, Oracle HTTP Server contains plug-ins for applications in those languages. The interface of the lower OCI (Oracle Call Interface) level is designed for use with the level of C/C++.
Oracle also provides a so-called precompiler application for different programming languages. Precompiler transforms the program with the SQL instructions to the program understood for the precompiler C. SQLJ precompiler could be an alternative way to get access to the data in Java application. This precompiler operation is similar to the precompilers from the Pro (Pro C/C++) groups. The database access is done here by the usage of the JDBC interface (Java DataBase Connectivity). SQLJ precompiler is the Java program with the submerged SQL codes translated to the codes with the references to JDBC which are later compiled.
Another way to improve the system is the installation of the buffering WebCache module. This module allows for the HTTP requests transmission to the number of server applications using a separate machine which highly improves the user support system.
In WebCache configuration, the number defining the maximal size of requests which server application can receive from WebCache is assigned to each server application. The relative distribution of requests among application servers dependents also on the maximum number of requests. For example, if the capacity of the server application X is 200 and for the server application Y is 100, then server X will be receiving only 33.3% of the requests and server Y will be receiving 66.6% of the requests [7]. The process of the user request service is illustrated in figure 5.
Figure 5. The process of user request service
The user requests service using buffering WebCache server processes as follows: 1. The user sends the HTTP request to the buffering WebCache server. 2. WebCache returns the required document.
3. If WebCache does not have the document stored in the memory then the request is sent to the server application.
4. After the request is received, application server will verify the user and check its permissions. After successful user authentication, application server will do the request. If the need to communicate with the database emerges, the proper connection will open (Oracle Net adapter).
5. Application server forwards the results to the buffering WebCache server.
6. In the buffering WebCache server the copy of the request result is stored in the WebCache server.
7. Buffering WebCache server forwards the reply-document of the case to the user. 6. Conclusions
The information system based on the Oracle 11g database and on the compatible server application OAS can meet all the requirements that are related to the implementation and development of an information center for agro-food industries. It has a full range of services and tools that can support the development center. Oracle 11g is a versatile product well adjusted to the Internet. Oracle Application Server Package provides simultaneous support for a large number of users, reducing the maintenance costs and the use of already existing system components in other applications. OAS is the perfect solution for the concepts, which require the latest data management techniques and the ability to remotely access the data.
Information Center with the database and with built-in data warehouse can ensure complex support of decision-making processes of agricultural producers and agro-food processing firms. Additional measures should be given to the collection of information which allows for the achievement of the integrated database for the regional agriculture supported by the resources and structures of GUS database. Then the center would be able to collect and process data characterized by the long amendment cycles – for example, data from agricultural censuses. Bibliography
[1] Loney K.: Oracle Database 11g: The Complete Reference. McGraw Hill 2008.
[2] Drelichowski L., Zarzycki H., Sikora M.: Drelichowski L., Zarzycki H., Sikora M.: Project: Platform cooperation industry model on the example of agro-food industry for the Wielkopolska region, Poznan 2009.
[3] Kozielski S., Małysiak B., Kasprowski B., Mrozek D.: Bazy danych, struktury, algorytmy, metody. rodowisko Oracle Application Server w internetowej aplikacji inteligentnego systemu lingwistycznego, WKŁ 2006.
[4] www.stat.gov.pl.
[5] Zakrzewicz M.: Serwer aplikacji OracleAS 10g w architekturach o podwyszonej niezawodnoci, X Konferencja PLOUG, Pozna 2004.
[6] Masewicz M.: Klastrowe architektury serwera aplikacji Oracle Application Server 10g, Politechnika Poznaska, Pozna 2007.
ARCHITEKTURA SYSTEMU KOMPUTEROWEGO DO REALIZACJI ZADA CENTRUM INFORMACYJNEGO DLA BRAN Y ROLNO-SPO YWCZEJ
Streszczenie
W artykule przedstawiono architektur systemu informatycznego ze zdalnym dostpem opartego na bazie danych dla rozwiza w brany rolno-spoywczej. Tworzony model branowego centrum współpracy pokazuje metody i techniki budowy, na które składaj si tradycyjne powizania producentów rolnych z przedsibiorstwami przetwórstwa i obrotu artykułami spoywczymi oraz wykorzystanie technologii informacyjnych. Metody te zwizane s z przemieszczaniem strumieni zasileniowych i dokonaniem fizycznego transferu produktów z miejsc wytwarzania do miejsc ich przetwarzania i dystrybucji, wyborem rodków technicznych i rozwiza softwarowych niezbdnych do realizacji funkcji komunikacyjno-informacyjnych oraz ze ródłami danych dla infrastruktury techniczno-programowej w tworzonych hurtowniach danych.
Słowa kluczowe: Architektura system komputerowego, Oracle Application Server, Oracle HTTP Serwer, PL/SQL Web Toolkit, Oracle Process Management and Notification, Oracle Application Server 11g, Oracle Application Server WebCache.
Hubert Zarzycki Eugenia Fronczak
Department of Computing in Management University of Technology and Life Sciences
ul. Kaliskiego 7, bud. 3.1., 85-796 Bydgoszcz, Poland e-mail: hzar@utp.edu.pl
