Evolution of Technology through Procedural, Object Oriented, and Component Based to Service Oriented

Size: px

Start display at page:

Download "Evolution of Technology through Procedural, Object Oriented, and Component Based to Service Oriented"

Trevor Edgar Hunt
6 years ago
Views:

1 Seth, A., Aggarwal, H., & Singla, A. R. (2011, Summer). Evolution of technology through procedural, object oriented, component based to service oriented. Journal for Computing Teachers. Evolution of Technology through Procedural, Object Oriented, and Component Based to Service Oriented Ashish Seth Ideal Institute of Technology Himanshu Aggarwal Punjabi University Ashim Raj Singla Indian Institute of Foreign Trade Abstract The software evolution has had distinct phases or layers of growth. These layers are built up one by one over many years, with each layer improving over the previous one and fulfilling the need at the time. Software evolution begins with understanding the concept of 1 and 0 (i.e., bits) that gives rise to machine language, followed by assembly language, procedure oriented, object oriented, component oriented, and service oriented. The paper illustrates advances in the software technology along with their scope. 1. Introduction Development in software technology continues to be dynamic. New tools and techniques are continuously announced in quick succession. This has forced the IT industry and players in this industry to continuously look for new approaches to software design and development. These rapid advances appear to have created a situation of crisis within the industry. Right from the origin of software and programming languages we have seen a drastic evolution in software technology to meet the issues that arise due to technology crises. Initially, software was developed to automate manual task like recordkeeping, maintaining transaction records, etc. The early 1970s witnessed the age of procedure oriented language, dividing the problem into sub problems and writing procedures for that sub problem and then integrating all procedures to provide a solution to the problem. But with this approach we are unable to relate to realworld problems, as writing procedures for them using procedure oriented language is not easy. So the concept of object oriented came into the picture and gave birth to objectoriented language. Tasks became much easier and it is now simpler to write code for real world problems. As the technology is moving very fast, so the people s needs and expectations are increasing day by day. After the evolution of the objectoriented approach, the demand was for a centralized application that would be able to automate the complete business process. This gave rise to component based software development, which is developed in general and is then customized by the user organizations according to their requirements. With fast changes in technology and increasing competition, demands are becoming more dynamic in developing applications, which can fulfil ad hoc demands of business. This need resulted in the new concepts in technology known as service oriented architecture (SOA). This concept is fully utilized in the Webbased environment where services are registered in common repositories and authorized users can access them under defined protocols. This paper illustrates each of the following software technology one by one. Technology Evolution Procedural Programming Object oriented Programming Component based Programming Service oriented Programming Figure 1. Technology evolution 2. Procedural Approach Since the invention of computers, many programming approaches have been tried. With the advent of languages such as C, structured programming became very popular and was the main technique of the 1980s. It gives programmers the power to write moderately complex program fairly easily. Some characteristics that are exhibited with structured programming are as follows: Principal emphasis is on accomplishing things. Large problems are divided into smaller ones and are mapped to functions. Most of the functions share global data and thus data moves freely from one function to another and hence transforms data from one form to other. Program design employs top down approach.

2 2 A following code snippet shows how to write a procedure using C for adding two numbers //declaration int add (int,int); //definition int add(int c, int d) int sum= c+d; return sum; Thus in this approach each of the tasks is identified in terms of function and is declared as shown above. The program is composed of several functions and data move freely form one function to another (see Figure 2). Function 1 Function 2 Function 3 Main Program GLOBAL DATA Figure 2. Structure of procedural program Although being powerful and capable of writing complex programs, certain limitations are identified with this approach that resulted in the creation of next generation languages. The following are the shortcomings of proceduraloriented programming style: Real world problems are unable to be modeled very well. Many important data items are placed as global and thus are accessed by all the functions. If the program code is too lengthy, the problem of maintainability arises. 3. Object Oriented Programming Approach The major motivating factor in the invention of the objectoriented approach was to remove the shortcomings encountered (listed above) in the procedure oriented approach in the following way: Real life problems are modeled by reflecting objects as real life entities. Data is treated as critical elements in the program development that does not allow them to be shared globally. Data tied more closely to the function that operates on them. Lengthy programs can be easily managed as the entire code is viewed as different objects, each reflecting real time entity. Objects are basic run time entities in an object oriented system. They may represent a person, place, bank account, table of data, or any real life entity that the program has to handle. Program objects should be designed in such a way as to represent realworld objects. Objects can be represented as data and functions (see Figure 3). OBJECT NAME Data Functions Figure 3. Object representation Concepts that are used extensively with object oriented programming are classes, data abstraction, encapsulation, inheritance, polymorphism, and dynamic loading. Objects primarily serve two purposes: They help to understand real world. They provide a practical basis for computer application. A following code snippet shows how to declare object using C++ for adding two numbers //class declaration Class Sum //class name Int num1, num2; //data Int add (int a,int b) return (a+b); Public static void main() Sum obj=new Sum(); Obj.add(2,4); //object declaration

3 3 Overcoming the shortcomings of the procedure approach to programming, object oriented approach is summarized to have the following advantages. Offers better implementation. Offers better data security. Offers better code reusability. Provides more flexibility. Supports creation of more manageable programs. software architecture. These commercial offthe shelf (COTS) components can be developed by different developers using different languages and different platforms. This can be shown in Figure 4 where COTS components can be checked out from a component repository, and assembled into a target software system. 4. Component Based Software Engineering (CBSE) Overcoming the shortcomings of technology in 1995, the need of component based development arose, which provided such advantages as heightened ease of management of complex problems, reduced development, increased productivity, improved quality, etc. Component based software development approach is based on the idea of developing applications using components. Components are analogous to functions or procedures in a procedure oriented development. A component is a more abstract form and is capable of performing a specific functionality. Component based software systems are developed by selecting appropriate offtheshelf components and then assembling them with a welldefined software architecture. CBSE is a process that aims to design and construct software systems using reusable software components. CBSE emerged from the limitations of objectoriented development to support reuse effectively. Components may be constructed with the explicit goal of allowing them to be generalized and reused. CBSE is about creating a software package in such a manner as to be able to easily reuse its constituent components in other similar or dissimilar applications. It includes writing high level code that glues together pieces of prebuilt functionalities or software building blocks called components. A component is the basic unit that makes up a system. It may be hardware, software, or firmware and may be subdivided into other components. Additionally, a component is a software object meant to interact with other components, encapsulating a certain functionality or a set of functionalities. A component must have a clearly defined interface through which it is associated with other components and conforms to a prescribed behavior common to all components within an architecture. Components with no clear interface are the same as declaring a class with all its member functions as private. This new software development approach is very different from the previous traditional approach in which software systems can only be implemented from scratch. This approach is based on the idea that software systems can be developed by selecting appropriate offtheshelf components and then assembling them with welldefined Figure 4. Componentbased software development (Cai, Lyu, Wong, & Ko, 2000, p. 371) Many of the languages available today have provisions to develop components, such as C# that provides a strong feature to develop components, which it refers to as Assembly or Libraries. They are of two types private and shared. The following code snippet shows how to develop an assembly that add two numbers using C#. //declare using directives namespace Math //this namespace may contain various //mathematical operations //declare code for addition public int Add(int num1,int num2) return (num1+num2); To create an assembly directly from one or more source files, we need to use the following command: C:\> csc /out :<assembly name> /target : library <filename1, filename2,.> To reference an assembly, we need to add the /reference switch while creating the executable. The following command is used to reference an assembly: C:\> csc /out : <executable name>/ target : exe /r : <assembly name1; assembly name2.;> <filename1, filename2, >

4 Although CBSE offers enormous advantages and benefits, the following are the disadvantages identified with this approach: Components development is a complex task Lack of components Component

4 4 Although CBSE offers enormous advantages and benefits, the following are the disadvantages identified with this approach: Components development is a complex task Lack of components Component maintenance costs Reliability and sensitivity to changes Unsatisfied requirements Lack of trust 5. Service Oriented Architecture (SOA) The basic SOA is not architecture only about services. It is a relationship of three kinds of participants: the service provider, the service discovery agency, and the service requestor (client) (see Figure 5). The interactions involve the publish, find, and bind operations. These roles and operations act upon the service artifacts the service description and the service implementation. In a typical servicebased scenario a service provider hosts a network accessible software module (an implementation of a given service). The service provider defines a service description of the service and publishes it to a client or service discovery agency through which a service description is published and made discoverable. The service requestor uses a find operation to retrieve the service description typically from the discovery agency (i.e., a registry or repository like UDDI), and uses the service description to bind with the service provider and invoke the service or interact with service implementation. Service provider and service requestor roles are logical constructs, and a service may exhibit characteristics of both. which language to compile the page s code (C# in this case). The class attribute tells ASP.NET the name of the class of object to activate for incoming requests addressed to this service using directive, tells the compiler to import the namespaces and System. Web Services contain the fabricated features needed to write a Web Service. [WebMethod] is used to declare that method exposed to Web client is treated as Web Service. <%@WebService = C# Class= Sum %> //The previous header line tells ASP.net that //this file contains web service written in //C# language and that the name of a class //providing that service is Sum //using the namespace (think them of as references) //required for a web services using System; using System.Web.Services; //Declare a new class for our new service // it must inherit form the systemprovided // base class WebService which is in //System.Web.Services public class Sum : WebService //place function in this class //marking them as WebMethod [WebMethod] Public int Add(int num1,int num2) //perform the logic you want //in this case, adding two numbers return (num1+num2); 6. Comparison of Technologies Figure 5. Basic SOA architecture Web Services are selfdescribing services that will perform welldefined tasks and can be accessed through the Web. Service Oriented Architecture (SOA) is an architecture paradigm that focuses on building systems through the use of different Web Services, integrating them together to make up the whole system. The following is an example of Web Service that adds the two numbers. The code starts with the standard ASP.NET salutation %@...%. In it, the Web Service directive tells the ASP.NET that the code on the page is to be exposed as Web Service. The language attribute tells the ASP 6.1 CBSE VS. SOA Component based architectures and serviceoriented architectures seem to have the same goal: to provide a foundation for loosely joined and highly interoperable software architecture, enabling efficient, errorfree software development. Nearly all evolution in recent years has had this intention: to develop a type of architecture that allows loose coupling and high reusability of its components. These attributes should allow more efficient, faster, and errorfree software production. In more abstract terms, one evolutionary step enhanced the previous step and helped to get closer to these objectives. There is no clear dividing line between Service Oriented Architecture and Component Based Architecture. In

5 5 principle, SOA is the enhancement of CBSE as the individual services are single components, which can be linked to gain new business logic, new services, or a new component. But the difference between SOA and CBSE seems to consist of two major points: Services have to be publicly accessible. Models for consumption will probably be developed, though not necessarily be free. But through registries (UDDI) it should be possible to find services like other business partners in the yellow pages. Services have to be largely from implementation specific attributes. For users and customers it is irrelevant if the service is released with Java,.NET, or Perl. 6.2 Comparison of Different Component Technologies Table 1 provides the comparison among current component technologies and a simple summarization of their different features. Table 1. Comparison of Current Component Technologies (Cai, Lyu, Wong, & Ko, 2000, p. 375) Development Environment Binary Interfacing Standard Compatibility and Portability Modifications and Maintenance Services Provided Dependency Dependency Implementation CORBA EJB COM/DCOM Supported by a wide range of Underdeveloped Emerging strong development environment A binary standard Not Binary Based on COM for component Standards Java Specific. interaction is the heart of COM Particularly strong in standardizing language bindings; but not so portable CORBA IDL for defining component interfaces, need extra modifications and maintenance A full set of standardized services; lack of implementations Strongest for traditional enterprise computing Portable by Java specification; but not very compatible Not involving IDL files, defining interfaces between component and container. Easier modifications and maintenance Neither standardized nor implemented dependent Strongest for general web client Not having nay concept of sourcelevel standard of standard language binding Microsoft IDL for defining component interfaces, need extra modification and maintenance Recently supplemented by a number of key services dependent Strongest on the traditional desktop applications As technology is moving toward distributed environment, security becomes a major concern. Security is a not a goal in and of itself, but it is a business enabler. Peterson (2007) points out that Robert Garigue said, security is like brakes on a car. Because we have brakes we can drive faster. SOA security architects, this is your mantra. Find ways that you can deliver security services to your organization while enabling your business to grow (Peterson, 2008, Putting it all together, 2). Each progression in distributed computing from objectorientation to componentbased design and now to serviceorientation has introduced unique security considerations (see Table 2). Table 2. Security Concern for Distributed Technologies (Peterson, 2008, 4) Paradigm Security Implications Object Orientation Abstract models(objects) used to bundle data and methods Vendor or implementation provides security mechanisms, authentication, authorization, audit for object processing runtime (ex. Java authentication and authorization services in JDK)) Component Based Design Technology specific implementation model for distributed programming Component t model provides implementation specific security models. (contains security in EJB) Service Orientation with Web Services Services designed as autonomous and standardized programs with an emphasis on reuse Interoperable industry standards deal with message security, identity, federation and service security. 7. Conclusion Evolution in technology is an ongoing process. The more the technology advances, the more is the thrust of making the things simpler. Although the procedural approach has very wide differences with the objectoriented approach, it is hard to draw a clear line between CBSE and SOA. However, SOA is seen as a new type of architecture that defines interfaces so that service can be used in context. Unlike CBSE, SOA is more capable of handling the on demand requirements. References Cai, X., Lyu, M. R., Wong, KF., & Ko, R. (2000). Componentbased software engineering technologies: Development frameworks and quality assurance schemes. Proceedings AsianPacific Software Engineering Conference (APSEC' 2000), Singapore, Peterson, G. (2008) Security in SOA It's the car, not the garage. SOA Magazine, 15. Retrieved from

6 6 Other Sources of Information Brown, A. W., & Wallnau, K. C. (1998). The current state of CBSE, IEEE Software, 15(5), Peterson, G. (2007). Thinking about Robert Garigue, 1 Raindrop Blog, Retrieved from /thinking_about_.html Pour, G. (1998). Componentbased software development approach: New opportunities and challenges. Proceedings Technology of ObjectOriented s, TOOLS, 26, Pour, G. (1999). Enterprise javabeans, javabeans & XML expanding the possibilities for Webbased enterprise application development. Proceedings Technology of ObjectOriented s and Systems, TOOLS, 31, Seth, A., & Seth, K. (2010). Adoption to Service Oriented Architecture, International Journal of Advanced Research in Computer Science, 1(2), 15. Szyperski, C. (1998). Component Software: Beyond ObjectOriented Programming. New York: Addison Wesley. Author Information Ashish Seth Assistant Professor Ideal Institute of Technology, Ghaziabad, India Phone: ashish_may13@rediffmail.com Prof. Seth finds interest in writing articles on emerging technologies. He is pursuing research in the area of SOA and Web technologies. Dr. Himanshu Aggarwal Associate Professor Punjabi University, Patiala, India himagrawal@rediffmail.com He is having good exposure in ERP implementation at various levels. Dr. Ashim Raj Singla Associate Professor Indian Institute of Foreign Trade, New Delhi, India asingla@iift.ac.in He has expertise in ERP and provides consultancy in a number of projects for integrated enterprise application for SME s. He has also written book on ERP.

Chapter 8 Web Services Objectives

Chapter 8 Web Services Objectives Describe the Web services approach to the Service- Oriented Architecture concept Describe the WSDL specification and how it is used to define Web services Describe the