Web Services Technology - Essay Example

Web services technology Name: Course: Tutor: Date: Web services Introduction With the emergence and increase in online businesses and e-commerce, web sites become the major tool used in the facilitation of tasks and other businesses. Roughly speaking, web services can be considered to be applications that run online and can be published, located and invoked across the internet. These services are interdependent in their functionality as such contribute to harmonious working and functioning with other web services. Other web services may depend on other services in order to perform their tasks. The very basic examples of web services that can be pointed out in this paper include using an application to get stock prices information, obtaining weather reports and forecasts or even the very common task of making reservations. A formal definition of web service can be given as encapsulated, loosely coupled contracted functions offered through standard protocols that are applied online in order to facilitate the delivery of service through the internet in a less involving means. “Encapsulated” as used in the definition refers implementing functionalities in a way that is not visible from the outside world. “Loosely coupled” on the other hand means having modules implemented in a way that changing way of implementation of one function does not affect the operational standard of the others. It means that change of the invoking function is not necessary if the implementation of the dependent function is changed. “Contracted” is used to refer to availability of publicly available descriptions of the functionality behavior, including aspects such as methodology of binding the function as well as the input and output parameters. Web services are important part of distributed systems. They form just another paradigm of distributed systems. For effective functioning of web services, there are components that interrelate in their functioning. These components include service brokers which in this case perform duties of look up service between the relevant service provider and service requestor. Service provider on the other hand forms another component which publishes its services to the service broker. The last component is the service requester which requests services from the service provider through the service provider (Webster, 2000). Web services are a fast proliferating technology that is gaining momentum in the globalized economy. Many organizations are implementing the same especially towards the realization of a software-as-a-service model of operation. Technologies applied in web service realization Web services use XML as the major building block. This building blocks is embedded on top of HTTP protocol thus problems in relation to fire walls cannot be experienced easily. XML therefore is the mostly used and widely accepted form for exchange of data and its corresponding semantics in web services. Other layers which make up and build the web services stack include Simple object access protocol (SOAP), web services definition Language (WSDL) and Universal discovery description integration (UDDI) (Montalbano, 2001). SOAP is a protocol that ensures that web services run in an heterogeneous environment and ensure that the data transfer between functions are independent of any run time environment. Ts major task is to define a simple mechanism for expressing applicator semantics by providing a modular packaging and encoding mechanism for encoding data within modules. Web services will at any time need a description of the network services in order to operate properly. WSDL describes these services by use of XML grammar. It is used to provide documentation for distributed systems therefore its major objective is to enable applications to communicate in an automated manner devoid of any manual interruption. The major difference that can be realized between the SOAP and WSDL is that SOAP specifies the talk or communication between the requesting service and the providing service while on the other hand WSDL describes the services offered by the provider. The description offered by the WSDL in most cases can be used to generate a desired SOAP message to access the services as intended. The final aspect as far as web services are concerned is the UDDI. This is a standard designed to provide a directory that is easy to search. The directory in itself should contain information with regard to businesses and their respective web services offered. In simple terms it can be seen as representing a service broker that ensures that any request made by the requester is made available to the relevant service provider. The discussed protocols are essential in the implementation of web services. XML being the building block for the services, these protocols work hand in hand in order to establish a harmonious functioning environment that ensures that the services are offered without fail. The services need to be offered in an encapsulated manner that is devoid of tight coupling. The SOAP, WSDL and UDDI protocols are very important in ensuring that the functionalities of the web services do as expected. Good web services are loosely coupled. Tightly coupled web services are not desirable as they are bound to cause problems in its implementation and usage. Tight and loose coupling As mentioned in the previous section, low coupling is desirable not only in web services but also in any system developed. There are number of couplings that correspond to low coupling. These include message coupling, data coupling and sample coupling. In all these cases modules do not share most functionalities and therefore any change in any module or a web service will not necessitate the change of functionality of another web services. Web services can only communicate with each other by use of parameters or message passing. High coupling on the other hand involves the interdependence of web services. It is characterized by content coupling, common coupling and external coupling. Content coupling is a situation whereby one module relies on the internal workings of another module. Changing the behavior of a certain module therefore will affect the operation of another module. If two webs services share global variables then the same are tightly coupled as it implies the fact that changing the variable will affect the way the two services operate. Most organizations are turning to the use of web services in the delivery of their services to the clients, web services therefore should be loosely coupled in order to ensure their autonomy. With the shift by many organizations from use of licensed software to the software-as-a-service (SaaS) mode, web services are proving to be of great use. SaaS is a technique that is gaining popularity with many organizations and therefore goes hand in hand with web services. Software-as-a-service In today’s globalised business economy, software is ubiquitous. Software applications are used across multiple economies to track business operations and manage business operations. Over time businesses have used software that is run on the internal infrastructure of their own. This has been the cause of many difficulties especially ones associated with financial use. Due to this constraint, many businesses are running to software-as-a-service model since the traditional software license models have begun to seem antiquated. Software-as-a-service in general allows customers to pay monthly fee only while running applications on the service provider’s infrastructure. It necessitates no need for the purchase of infrastructure or development of software applications. Software-as-a-service is therefore a software delivery method that provides access to software and its functions remotely as a web based service. In this concept of business as a service organizations are given the ability to access business services and provide the same services to their clients at a relatively cheaper cost that is considerably less than that of paying for licensed software. Software-as-a-service ensures the limited use of finances in ensuring the availability of functionalities that could have been realized at a greater cost. The software is hosted remotely and therefore allow users the chance of using the already available hardware rather than acquiring new ones. Organizations have no need to handle installation, set up and even daily maintenances of the software (Hickman, & De Smedt, 2000). Another perspective in which software-as-a-service can be viewed is in cases where organizations rent storage or lease storage space from third party providers. This considerable reduces the cost aspect of the institution. The internet provides a transfer medium upon which data is transferred from the client to the service provider. Through the internet, the client is able to access the services or data elements. These software used for access of information and data from the service provider allow the client to perform such tasks as data backup and data transfers via the internet. The main advantage introduced by the adoption of software-as-a-service is the fact that it reduces cost of operation in an institution. The reduction in the cost of operations is introduced due to the fact that there is no need to buy hardware, purchase systems and even pay support staff. Web services are recognized as the major boost toward the achievement of this concept of software-as-a-service. With the application of web services in business models, users are able to access services without the need to be in physical proximity to the service. It allows users to be able to service themselves easily without the need for an intervening staff or a support assistant. This, in a great sense, reduces the cost incurred in dispensation of the services by the organization (Herman, 2002). Characteristics of a web service As discussed earlier, web services are increasingly becoming the choice of use in realization of software-as-a-service concept. In these sense however, web services has already been used widely in many organizations. In as much as many organizations implement different kinds of web services, there are some basic similarities and characteristics that are common in all web services. These include the following: i. XML-based At data representation and data transportation layers XML is basically used to carry out those particular tasks. XML is advantageous in that it eliminates any networking, operating system any platform binding of any sort. In general web services can be viewed as highly interoperable software application at the core (Meehan, 2001). ii. Loosely coupled A client’s ability to interact with the web service is not in any way affected or tied by the service directly. In as much as the web service interface can change from time to time, a users activities cannot be compromised and the normal operations and functionalities of the web service will always run and give the expect output. A loosely couple system as seen in the case of web services, allows the implementation of software and applications that are manageable and easy to integrate and implement. iii. Coarse-grained Web services are made in a manner that provides a coarse grained implementation approach. It allows for a right amount and implementation of the right business logic. Fine grained applications are good for and individual methods are not in any way useful for a corporate level implementation (Kiely, 2001). iv. Ability to be synchronous or asynchronous Web services are able to be synchronous or asynchronous. In synchronous sense, the services are able to bind the client to its execution. These web services in synchronous mode allow the clients to block and wait for the service to complete its operation before continuing. Asynchronous operations on the other hand allow the client to invoke a service and then execute other functions that may or may not be relational to the invoked service. Web services therefore have this characteristic of allowing the synchronous as well asynchronous execution of services. Asynchronous ability allows the system to achieve loose coupling which in reality a desired characteristic in web services. v. Supports Remote Procedure Calls (RPCs) XML based protocols are used by clients to invoke procedures, functions as well as methods on remote objects. Most web services therefore support remote procedure calls. The importance of remote procedure calls is the fact that, it exposes the input and output parameters that a web service must support at any particular time. Web services make remote procedure calls a reality by providing services of its own, similar and equal to those of traditional components. vi. Supports document exchange XML allows representation of not only data but also it supports document exchange. Most web services therefore allow the representation and exchange of documents easily and compatibly. Discussed above are the major characteristics of web services. These characteristics apply to the types of web services that exist. Types of web services In this paper, two types of web services are identified. These are the “Big” web services and the RESTful web services. Big web services in this paper are referred to those web services that use XML messages implemented by a simple object access protocol (SOAP) standard and an XML language defining a message architecture and message format. They contain a machine comprehendible description of the services offered by the web service which is written in web service description language (WSDL). The other type of web services identified is the RESTful web service. This term stands for the representational state transfer web service. The difference with the “big” services is that, RESTful web services do not require XML messages or any of the WSDL used by the “big services”. They offer better integration with http and therefore are suited for basic and ad hoc integration scenarios (April, 2002). State full vs. stateless web services State full web services are services that maintain the state of service both within and between transactions. A session is associated with a specific client. In this case stateful web services maintain data consistency by updating the functions each time a transaction committed. Stateless on the other part do not maintain the state of a transaction across method invocations. Stateless web services will not maintain communication standards across networks but the opposite will be realized in a state full web service. A state full one is therefore useful and desired as it facilitates a standard mode of communication across different platforms. Conclusion Web services are gaining popularity in the globalized economy. The same technology has proliferated to the business community at a faster rate as many people rush to implement it. Many organizations who have adopted the concept of software-as-a-service have had no option but to use web services in their implementation and realization of effective service. With the fast rate of proliferation of the services, there is a possibility that in the next few years all organization would have adopted its use in their businesses. Reference April, C. (2002). OASIS serves up messaging standard; ebXML Messaging service spec to enable secure business transactions. Inforworld.com. Herman, J. (2002). E-enabling your enterprise. Business Communications Review. BCR Enterprises. 2(1). 32-25. Hickman, S., & De Smedt, P. (2000). ebXML Is Emerging As a Reliable Standard - Proof of Concept Demonstrates its Viability As EDI Alternative. Electronic Buyers’ News. 42(2), 52-56. Kiely, D. (2001). E-business language of choice? InformationWeek. 4(3). 6-12. Meehan, M. (2001). EDI, ebXML groups agree to cooperate. Computerworld. 4(2). 72-78. Montalbano, E. (2001). ebXML: What's ahead? CRN. 23(2). 87-91. Webster, J. (2000). An Alphabet Soup of B2B Standards --SOAP, ebXML, UDDI and others will slowly gain momentum. Internet Week. 6(5). 8-12. Read More