DESIGN AND ARCHITECTURAL ISSUES OF CONTEMPORARY WEB-BASED INFORMATION SYSTEMS

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DESIGN AND ARCHITECTURAL ISSUES OF CONTEMPORARY WEB-BASED INFORMATION SYSTEMS
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    DESIGN AND ARCHITECTURAL ISSUES OF CONTEMPORARY WEB-BASED INFORMATION SYSTEMS B. Molnár a,* , Á., Tarcsi a,   a  Eötvös Loránd University, Faculty of Informatics, Information System Department, Budapest, Hungary   ABSTRACT The rapid changes of information technology led to the  proliferation of Web-based Information Systems (WIS). There has  been already some research on the general model for analysis and design of WIS. This paper attempts to define a comprehensive framework for integrating the various viewpoints of model for WIS. Several components that compose of a WIS as analyzing and designing element are investigated and described as modeling element and enabling tool for creating consistent and integrated system. The major modeling components are: the Web site, semi structured document, business processes, element of knowledge management, the enterprise and information architecture, and autonomous software components providing functional services. These elements are integrated into a unified framework exploiting  partly the object-oriented paradigm and partly other approaches for information system modeling. The outlined WIS model incorporates the most recent approaches for various paradigms of traditional information systems analysis and the most modern different approaches of WIS. The research result would be useful  both theoretically and practically as it could present a comprehensive model for WIS assisting our understanding of  properties of WIS and supporting, at the same time, a framework for being able to formulate a practical development method for achievement of WIS by organizations making the most of Web. * Corresponding author: (molnarba@inf.elte.hu)  Keywords   Software architecture, Information System Architecture Web services, Service-Oriented Architectures, Web Information Systems, Zachman Framework 1   INTRODUCTION T HE PAST DECADES  has presented a dramatic change of the use of information technology within organizations and enterprises. To control the inherent complexity of structure of large-scale information systems and information resources, various IS architectures have been elaborated to describe and to keep in hand the several layers, tiers and components of architecture. Architecture provides a kind of synthesis through providing views and viewpoints that can be realized by various models  proposed in different methodologies for architecture and information systems analysis and design. A web information system  ( WIS  ) is database-intensive and/or transaction intensive information system that is implemented and made accessible over the web by user access via web browsers or via mobile devices. In web information system, data is obtainable through web interfaces that are manifested in semi-structured document format including a navigation structure among the documents and pages organized into some kind of networks or hierarchy; moreover there are links to sites outside the system as well. Furthermore, there should also be services for retrieving and modifying data out of the system or from the underlying database. Service-Oriented Architectures  ( SOA ) have appeared after the WIS being in existence for a while; they achieved large success within the Web communities, especially at WIS. Rather than pure technology improvements SOA intends to increase manageability and sustainability of information systems and to better align  business requirements and technology implementations. Therefore it is reasonable to link SOA to the concept of enterprise architecture  (  EA ). As the enterprise architecture  provides a global framework to deal with the inherent problem of WIS modeling, design and operation. In addition, the change processes occurring during the life of a WIS dedicated to an organization are typically concurrent and interact with one another. To handle the complexity of changes and change management some concepts are required namely the concept of the life history,  the life cycle  of systems, and the life history of entities or   classes (of objects) . We should use these concepts to distinguish between two behavioral aspects of WIS. The terms of life history of systems means ―the actual sequence of steps a system has gone or will go through during its lifetime‖, and life cycle seen as ‗‗the finite set of generic phases and steps a system may go through over its entire life history‘‘ [ 1]. Thus, life history and life cycle are in fact orthogonal, as shown in a typical life history example is provided in [2]. A WIS fitting into the Enterprise Architecture of an organization has a static perspective representing the structural aspects at a specified point in time and a dynamic perspective capturing the various stages of architecture development that happens to a WIS as an application system [2]. These two perspectives may reflect the changes that take place at component level of architecture of a WIS  –   both statically and dynamically - , however there is a need to represent the time dimension at components of development, implementation and operation level, i.e. the life history of components  or entities . Although the development of the logic of a Web Application is similar to the conventional software development the process of implementing the web-based information systems behind these applications has, however, shown the deficiencies of the existing   The Project is supported by the European Union and co-financed by the European Social Fund (grant agreement no. TÁMOP-4.2.2_B-10_1-2010-0030).    methodologies for modeling, analysis and design and the need for the specification, design and implementation of new mechanisms. The WIS contains traditional information systems element and semi-structured XML documents which behaves actively beside other important parts of the system. The XML documents make use of active hyperlinks and other features of Web and Web services. This paper wants to elaborate a modeling framework for WIS taking into account of the development of past decades considering the various architectural and technological component and solution. We discuss the proposed model and show how the earlier T ABLE 1. A  MAPPING SCHEMATICALLY BETWEEN   Z ACHMAN ARCHITECTURE AND SOA‘ S COMPONENT   Aspects Perspectives   what    how   where   who   when   why  Contextual Fact, business data Business Service Chain of Business Process, Workflow Business entity, function Chain of Business Process, Workflow Business goal Scope Conceptual Underlying Conceptual data model Service Service composition Actor, Role Business Process Model Business Objective Enterprise Model Logical Class hierarchy, Logical Data Model Service Component Hierarchy of Service Component User role, service component BPEL, BPMN, Orchestration Business Rule System Model Physical Object hierarchy, Data model Service Component Hierarchy of Service Component Component, Object Choreography Rule Design Technical Model Detail Data in DBMS Service Component Hierarchy of Service Component Component, Object Choreography, Security architecture Rule specification Components Functioning Enterprise Data Function Network Organization Schedule Strategy created methodologies and methods for analysis, design, implementation and management can be used to construct web- based applications in a framework to combine aspects of data,  behavior, state and presentation and exploit the various  perspectives and aspects of approaches to make consistent information systems. An attempt is made in this research to create a (1) firstly a comprehensive model including the relevant aspects of WIS, (2)  based on the model a methodology and related methods to support the design process 2   RELATED WORKS There were already attempts to put into a unified framework the modeling of WIS at a given point in time taking into account of the existing technology and approaches. A general model for WIS using an object-oriented approach is described in [3]. The use of semi-structured, active XML documents and a disciplined design approach are discussed in [5] to construct web-based applications. Another paper [6] presents a design methodology for a systematic design process to organize and maintain large amounts of data in a Web site, in the form of a hypermedia design methodologies. For large-scale WIS design [10] contains a method. Beside the different analysis and design model for WISs, the concept of architectural approach is that can be used in model creation, the various IS architectures have been used to assist in understanding the relationship between the various perspectives, aspects, components and single models [7], [1], [2]. Zachman architectures developed for information systems. TOGAF is developed by Open Group on Architecture Framework. It contains two main parts: The Architecture Development Method (ADM) and the Foundation Architecture with generic functions/services on which specific architectures and building blocks can be built [8]. The service orientation is emerging at multiple organizational levels in business, and it leverages technology. The service-oriented architecture (SOA) can be considered as a technical architecture, a business modeling concept, a piece of infrastructure, an integration source, and thereby an architecture for contemporary WIS [9]. While each of the above approaches overlaps with some of the features of our work, the contribution we make is to address at  problems that concludes the dynamical behavioral of WIS-s in several aspects and how to handle at modeling level the issues of consistency, integration, confidentiality, accuracy and timelines. 3   INFORMATION SYSTEM ARCHITECTURE The  Information System Architecture  represents the structure of certain components of information processing systems, their relationships among components, those technological principles and directives of organization of which the main purpose is to support business. The description of how a system was internally built depicted  primarily the technological components, especially the software  building blocks. The  Zachman Framework   ([7]) can be considered as the first important phenomenon that pinpointed to the fact that software architectures were not enough. While software architectures represent internal system details (using, for example, E-R and DFD diagrams)  Information System Architecture  focuses on the high-level business and information system processes. We perceive  Enterprise IT Architecture  as the suite of strategic and architectural disciplines that includes the Information, Business System, and Technical Architectures. An  Enterprise Architecture  can be divided into several levels:  Business (systems) architecture  - Defines the structure and content (information and function) of all business systems in the organization.  Information (or Data) Architecture    –   represents main data types that support business; furthermore the structure (including interdependencies and relationships) of information required and in    use by the organization;  Application Architecture    –   defines applications needed for data management and business support; the collection of relevant decisions about the organization (structure) of a software system, and the architectural style that guides this organization. Technical Architecture    –   represents the main technologies used in application implementation and the infrastructures that provide an environment for information system deployment. Technical architecture describes and maintains the integrity of the hardware, T ABLE 2. A  MAPPING SCHEMATICALLY BETWEEN   Z ACHMAN ARCHITECTURE AND SOA‘ S COMPONENT   Aspects Perspectives   what    how   where   who   when   why  Contextual Fact, business data Business Service Chain of Business Process, Workflow Business entity, function Chain of Business Process, Workflow Business goal Scope Conceptual Underlying Conceptual data model Service Service composition Actor, Role Business Process Model Business Objective Enterprise Model Logical Class hierarchy, Logical Data Model Service Component Hierarchy of Service Component User role, service component BPEL, BPMN, Orchestration Business Rule System Model Physical Object hierarchy, Data model Service Component Hierarchy of Service Component Component, Object Choreography Rule Design Technical Model Detail Data in DBMS Service Component Hierarchy of Service Component Component, Object Choreography, Security architecture Rule specification Components Functioning Enterprise Data Function Network Organization Schedule Strategy software, and infrastructure environment required to support the  Business Systems Architecture and  Information Systems  Architecture.   3.1   Control architecture: The product of dynamic modeling Control architecture  provides a temporal view on the dynamics of data, application, and technology. The temporal dimension and  behavior of data and/or information reflected in the form of entity life history, life cycle, state chart or state transition diagram. However, there are no established and widely accepted formalism and approaches at developmental control, operational control, and maintenance control to keep in hand the ever changing environment and provide a descriptive method to support handling the related issues.  Developmental control   handles all the changes occurring in the  process of new application development over time. Also called version control or  software configuration management  , developmental control records various aspects (who, what, and when) of each change made. Operational control   concerns the performance and integrity of current data, applications, and technology configuration. In WIS, the changes may happen at both documen t (XML / HTML) level and data  level, sometimes parallel; both changes indicates alteration on the application (logic) level as well. This is when maintenance control   becomes a critical issue. How can we manage these changes without severely disrupting the existing operations of the business? What will be the impact of a certain change to specific parts of the organization? Who are in charge of what? Some of these are included in the ―impact   analysis‖  portions of modern data dictionary systems. The business  processes within information function of organization should  provide adequate answers within the ITIL (Information Technology Infrastructure Library, [17]). 3.2   Service-Oriented Architectures (SOA) and the WIS Service-oriented computing   (SOC) is considered as a new information technology paradigm. It utilizes services as fundamental, reusable elements for developing applications / solutions. One of the basic components of SOA approach is the concept of services that maps the business services to information services in the form of Web-services . The SOC paradigm and Web-services together provide an appropriate approach for building Web based information systems (WIS) that has as a definite feature of the collaboration i.e. the comprising element work together in an interactive manner within a dynamically changing environment. The WIS-s making use of SOC have - as an advantage - the direct connection to the organization business processes, workflows, activities and tasks. The  Business Process Modeling (BPM) realizes this direct mapping between the organizational level services and the information system level services. The Business Process Execution Language for Web Services (BPEL) is an example for an executable language that implements the results of BPM. As the size of Web applications grows, it becomes clear that  better models, methods, methodologies and tools are required to deal with their increasing complexity. A model and a design methodology of WIS promotes the idea that the large and complex Information Systems made available by the Web technology should be modeled and designed as large scale Information Systems embedded into business and organizational environment. The model and design methodology should take into account both the socio-technological environment and the Web and / or software engineering approaches. WIS analysis, modeling and design methodology should include 1.   aspects of computing on the Internet, 2.   distributed transaction processing,    3.   knowledge management, 4.   hypermedia - the Web site, 5.   intranets, 6.   and extranets 7.   XML / HTML documents either as Web pages or information resources, 8.   database management systems and data warehouses, 9.   document management systems, 10.   Enterprise Architecture, Service Oriented Architecture, Web services. a.   Mediator;  b.   wrapper architecture for Web applications; c.   Web servies - software agents. 11.   Business processes analysis and management the Web site - online business processing. 12.   Information Security: integrity, confidentiality, accuracy, availability, timeliness - information infrastructure. 13.   Performance and scalability issues. The core of WIS is an information system in the traditional sense. Models, analysis and design approaches of conventional information system are evolved trough decades, the most important modeling approaches applied nowadays include: 1.   Data- flow diagram method ([ 20],[21],[22 2.   entity-relationship method ([23 3.   Relational analysis; 4.   Functional analysis, hierarchy and decomposition; 5.   Business and information event analysis and mapping to state transition of the conceptual information and/or data model. The WIS‘s goals can be formulated as to support networked organizations in the integration of specialized Web sites into a common set of tasks for them and providing organizational computing network properties. The overlapping of WIS and conventional business IS appears in the form of data processing systems, data base management, report systems, and decision support systems. The difference between a set of Web pages, typical Web Applications and a WIS can be described as follows: WIS supports  business process (Business Process Modeling, BPM) and is usually tightly integrated with other IS. WIS can also be viewed as database applications for structured as well as semi-structured data (XML / HTML). There is a comprehensive meta-model for WIS ([3]) that overarching all views, aspects and perspectives from semi-structured documents to knowledge management. There are models in object-oriented style for all element of Wang‘s meta -model and the components of meta-model can perceived as artifacts of Zachman architecture and put into the proper cells (Table 2). The semi-structured documents embodying hypermedia or hypertext document plays a crucial role in the most modern IS as WIS ([24],[25], [26]). Historically documents have been used in displaying, interchanging, and retaining information. The so-called form documents have been used in traditional IS as well, srcinally for presenting user interfaces, displaying the underlying data structures, and demonstrating the related transactions; later on, the form documents have become the typical layout for the WIS user interfaces using the HTML standard. Within the context of an organization, the activities of creation, exchange and modification of documents comprise a series of tasks within business processes that all together makes workflows. Each relevant workflow can be represented as directed acyclic graph having tasks or information processes in its nodes. The document flow within business can be mapped to the information flow of a single workflow that is implemented by information technology;  previously the base of realization was the traditional IS, nowadays the business processes are carried out by WIS. This phenomenon can be summarized as evolution of the information processing  paradigm, shifting from the process-oriented, data intensive application typically represented and designed in object-oriented style to document-oriented   computing. The development of information technology has led to the active semi-structured documents. The documents  –   e.g. the form documents intended to collect data  –  , contain procedures for information processing as it is required at a given time at a certain position within the workflow, thereby the documents demonstrate active behavior. Conceptual Model   Business activity and work practice   model   Behaviour model of concepts / entities   Functional Services   WIS   Semi-structured   data Viewpoint   WIS Architectural Viewpoint   WIS Functional Viewpoint   WIS Dynamic Behaviour    Viewpoint   Consistency and reconciliation of    model element   Zachman framework   TOGAF   Enterprise Architecture Integration   Service Oriented Architecture   Implementation model   WEB site   WEB document (XML/   HTML)   Control    Architect   ure   Event   Dynamic document   Object / entity life cycle   Fig. 1. A view of WIS integrated model 3.3   Architectural viewpoint An overall architecture approach assists in creating and conceptualizing a comprehensive model for WIS. As WIS not only a variant of information systems but it is a new technological approach for realizing information system. The most modern architectural approach is SOA that slowly  becomes the typical basic architecture for a large number of WIS. The mapping the elements, models are outlined in Table 1, Table 2. 3.4   WIS Functional Viewpoint The business processes carried out by WIS can be described by object-oriented analysis and design methods. The business  processes realized by WIS demonstrate the functional side or functional services of IS. A business process can be modeled by using three fundamental types of object classes:    Conceptual mapping of entities or concepts , - objects represent the structured data in WIS;    event  , - represent events of routine operations (e.g., order  processing) , decision activities;    document   - information entities that enter the system (e.g., electronic order applications), or that are produced  by the system (e.g., online business reports and client side scripting XML/HTML documents), or stored the system as semi-structured data (XML documents). Beside the above mentioned parts the WIS generally contains    knowledge management components as well, namely, organizational learning, mapping some cognitive activities onto a st ructures representing cognitive properties (―cognizant‖ element [3]): production rules, semantic networks, cognitive maps, or other forms of knowledge and knowledge representation. All of the models covering each single part of WIS use the object-oriented paradigm making comparable, verifiable, through cross-checking pair of models. The object-oriented framework  provides an explicit logical schema of WIS, and can be tailored and T ABLE 3.   Z ACHMAN ARCHITECTURE ‘ S RELATIONSHIP TO SOA  AND WIS   J. A. Zachman S. H. Spewak Entities= what   Data Architecture Activities= how  Applications Architecture Locations= where  Technology Architecture People= who  Time= when  Motivation = why  Planner Objectives/Scope (Contextual) List of Business Objects Class =Class of Business Thing List of Business Processes Process=Class of Business Process List of Business Locations  Node=Major Business Location List of Organizations important to the Business People=Major Organizations List of Events Significant to the Bus. Time=Major Bus. Events List of Bus. Goals/Strategies Ends/Means=Maj. Bus. Goals/Crit, Suc. Factor Scope Owner Enterprise Model (Conceptual) Semantic Model Object Class =Business Entity  Association =Bus. Relationship Business Process Model Proc.=Bus. Process, Web Services  I/O=Bus. Resources,  Documents  Business Logistics System  Node=Busin. Location Link=Business Linkage Work Flow Model People = Organization Unit Work=Work Product,  Documents  Master Schedule Time=Bus. Event Cycle=Bus. Cycle Business Plan Ends=Bus. Objective Means=Bus. Strategy Enterprise Model Designer Information Systems Model (Logical) Logical Data Model  Ent  .=Data Entity  Reln =Data Relationship Application Architecture Proc.=Application Function, Web Services ,  Method   of Object Class, I/O=User Views, Semi- structured documents  System Geographic Deployment Architecture e.g. Distributed System Arch.  Node=I/S Service. (Processor, Storage,  Logical Application Component  . etc.) Link=Relationship between Logical Appl. Comp. Human Interface Architecture People=Role Work=Deliverable, Semi-structured documents  Processing Stucture Time=System Event, Orchestration  Cycle=Processing Cycle Business Rules Ends=Structural Assertion, Means=Action Assertion, System Model Builder Technology Model (Physical) Physical Data Model  Ent  .=Segment/Table/etc  Reln =Pointer/Key/etc System Design Proc.=  I/S Services  I/O=Data Elements/Sets,  XML / HTML documents  System Architecture/Technology Architecture Physical Application Comp.  Node=Hardware/Systems Software Link=Line Specifications Presentation Architecture People=Screen Format,  HTML / XML interface  Work=User Control Structure Time=Execute, Choreography  Cycle=Component Cycle Rule Design Ends=Condition Means=Action Technical Model Subcontractor Detailed Specifications (Out-of-context) Data Definition Repository  Ent  .=Field  Reln =Address Programs Supporting Software Components Proc.=Language Statement I/O=Data Item, XML Field  Network Architecture  Node=Address Link=Protocol Security Architecture People=  Identity ,  Authentication ,  Authorization , Work=Job Timing Definition Time=Interrupt Cycle=Machine Cycle Rule Specification Ends=Sub-condition Means=Step Compo-nents Functioning Enterprise Data Function Network Organization Schedule Strategy actualized based on the requirements of a specific WIS. 3.5   Integration within the tier of control architecture T We have now at least five separate dimension or aspect of IS (Fig. 1). An optional synthesis of the five aspects can be formalized into a dynamic depiction as it follows: A business process starts with Web page descriptions, presentation or design. Each of the operators of the Web page initiates messages to other types of objects. The four possible outcomes in response to an initial message: a)   The message  from the Web site object invokes another Web site object.  b)   The message triggers a knowledge object, which might be an element for representation of knowledge. c)   The message evokes a  software agent   or Web service  (e.g., a search engine), which might in turn trigger a business  process.  d)   The message passes through a network or Enterprise Bus Service, and then starts a Service  realizing a business  process, usually, by triggering an event   of the business  process. e)   After a business process starts, its entity  (conceptual mapping of physical real-world objects), document  , and event   objects are triggered subsequently. f)   Each of the objects of the business process activates the corresponding architecture  elements (network service, other service component, logical, physical application or information component, etc). g)   The objects of the architecture elements send messages to other information architecture objects 3.6   WIS Semi-Structured Document Viewpoint The Web is playing a critical role as a source of information. Most of Web-based applications are document centric. Most of business  processes in an organization are carried out through workflows making use of documents as information source and transmitter. Moreover, the Internet technology accelerates business processes to  be implemented by Web-based applications. T From the viewpoint of human-computer interaction, Web-based document actualize the structured and semi-structured data through the computer-user interface of the WIS, and specify the dialogue between users (clients) and the WIS. A central part of WIS is the Web pages and Web semi-structured data in the form of XML/HTML documents for the users on the network (Intranet, Extranet, Internet). Presentations of information to the users and requests for input from the users are the two facets of Web sites from the viewpoint of the WIS. With the documents implemented in extensible markup language (XML), the relationship and information exchange between the Web pages and the associated business processes and knowledge representation is realized. 3.7   WIS Dynamic Behavior Viewpoint The intrinsic nature of WIS is the dynamic behavior in every component, the user interface and its semi-structured document and the underlying IS, but not only in respect the data content however the data an processing structure as well.  Behavior  : A behavior means a method of processing a document implied in a business document. Behaviors include (1) general computation logics, (2) rules of defining and controlling business  processes such as business rules, (3) data integrity constraints
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