Hebrews The Genre Of Hebrews - 805 Words

Hebrews 6:1-8 #1 – The Genre The genre of Hebrews is an epistle to the Hebrews. #2 – Generic or Intrinsic conception The generic conception of Hebrews 6:1-8 is that Christians should spiritually mature and go unto perfection, not falling away from God because of persecutions. #3 – Observations - Literary: o In Hebrews 6:1-8, there are proportion and illustration present. Chapter 6 is proportioned because the chapters around it are talking about Melchisedec, but there is nothing mentioned about Melchisedec in Chapter 6. This chapter is to emphasize spiritual maturity and God’s faithfulness to the saints so that they can persevere through persecutions. The author also uses an illustration to assert how Christians can be mature. He uses the illustration of how the earth bears herbs after receiving rain, which can be hardships. However, those who do bears nothing are to be burned, possibly referring to hell. - Grammar: o Hebrews 6:1-8 is beginning with the word â€Å"therefore.† In order to understand why the author is starting Chapter 6 with therefore, it is important to read from last half of Chapter 5 and rest of Chapter 6. The author of Hebrews talks about the order of Melchisedec in Chapter 5. However, he interrupts that by mentioning that â€Å"[they] are dull of hearing (Rom 5:11).† He continues the order of Melchisedec in Rom 6:20. Thus, the author is starting Chapter 6 with an interruption so that more can be explained to those that are dull of hearing for a betterShow MoreRelatedAuthorship, Audience And Genre Of The Gospel Of Matthew1467 Words   |  6 Pages1. Authorship, audience and genre of the Gospel of Matthew Authorship: Most scholars, but not R.T. France (2007, pp14-22), believe that Matthew’s Gospel was written by a scribe, not the Apostle Matthew and that it was written approximately between AD 80- 90. France states that if the book was written at this time- it was within Matthew’s lifetime, and thus authorship cannot be proven. A key reason pointing to the Gospel being written by a scribe is that the Gospel was written in Greek and thatRead MoreHebrews, No, One Really Knows Who Is Or Are?868 Words   |  4 PagesHebrews In the book of Hebrews, no, one really knows who is or are the authors. However, it is inclined that due to the references it makes to the letters that Apostle Paul that he was the author. Jesus preexistence and creatorship (Hebrews 1:1–4; Colossians 1:15–17). The giving of gifts by the Holy Spirit (Hebrews 2:4; 1 Corinthians 12:11). The humiliation of Christ (Hebrews 2:14–17; Philippians 2:5–8). The new covenant (Hebrews 8:6; 2 Corinthians 3:4–11). Later it would be challenged becauseRead MoreThe Three Paradigms of Biblical Studies Essay852 Words   |  4 PagesThe academic study of the Hebrew Bible encompasses thousands of scholars from around the world. These scholars use various methods developed by other disciplines in order to study ancient texts along with other approaches that are distinctive to the biblical studies. Biblical scholars have recently divided the profession into three paradigms which are commonly referred to as the three worlds. Particularly, some scholars focus on the world within the text; others explore the world in front of theRead MoreEssay on The Bible Story: The Old Testament2039 Words   |  9 PagesTo speak of the Hebrew Scripture is to speak of story, a story stretching from the very beginning of time to only a few centuries before the beginning of the Common Era. It is to speak of richness of content, of purpose and of reality and to engross oneself in an overarching narrative that, depending on your personal convictions, continues to the present day. Within this richness is found a wide variety of different events and experience, told through a series of genre ranging from foundationalRead MoreAnalysis Of Daniel 7 : 1-141249 Words   |  5 Pages as it is widely considered within the literary category of apocalyptic literature which the subsequent sections of this pa per will explore further. Daniel can be divided into three sections, based on language: a Hebrew introduction (Ch. 1); an Aramaic section (Ch. 2-7); and a Hebrew section (Ch. 8-12). Within these three language divisions exist two literary sections, first, the Tales (Ch. 1-6) followed by the Visions (Ch. 7-12). These two sections, though existing within the language divisionsRead MoreThemes from Genesis 1-111238 Words   |  5 PagesTHE PENTATEUCH IS A RICH COLLECTION OF GENRES. DISCUSS WITH SPECIAL EMPHASIS ON ITS LEGAL CATEGORIES. 1. Introduction. The Pentateuch consists of the first five books of the Old Testament: Genesis, Exodus, Leviticus, Numbers, and Deuteronomy; called Torah in Hebrew. The term Pentateuch is from the Greek for Penta (five) teuchos (books). Both Jewish and Christian traditions view these five books as a single unit, forming the backbone of the rest of the Bible. Both traditions placeRead MoreThe Word of God as Used in the Old Testament1508 Words   |  7 Pagesas writers of sacred texts. â€Å"Somehow they were a people who learned how to listen to and hear the Word of God† (Rohr Martos, 2011, p. 23). In this process of listening and hearing, God’s work of self-revelation became a lived experience for the Hebrew people that is reflected in the OT. As such, the OT becomes a ‘record of God’s self-revelation† (Rohr Martos, 2011, p. 22). The bible itself is not divinely written (as it appears that some fundamentalist Christians may believe). Nor were any ofRead MoreThe Greek And Roman Religion943 Words   |  4 Pagesthe nature of reality and the place of human beings and human behavior in the greater scheme of things.† And lastly, it is critical thinking. â€Å"The Hebrews believed that God created heaven and earth.† They believed that their doings are their accountability and if wrong doings occur, it is their responsibility to correct or improve themselves. The Hebrews recorded their beliefs in bibles, which can be summarized as the history of their association with their gods. The bible summarizes the world andRead MoreMeaning Of Psalm 119934 Words   |  4 Pagesthe Psalter and the longest chapter in Scripture. It is also the most intricate with regard to structure. The format of Psalm 119 is an alphabetic acrostic, meaning that the first letters of each line in Hebrew follow through the alphabet, 8 lines per letter, thus 8 lines x 22 letters in Hebrew = 176 lines. One message of this psalm is that we are to live a lifestyle that demonstrates obedience to the Lord, who is a God of order that is the acrostic structure not of chaos. The psalm opens with twoRead MoreSlavery : The Old Testament4666 Words   |  19 Pagesand s ources? - Does the passage merge into the claimed context? The aforementioned questions will be used as a guide throughout the study. The Passage Exodus 21: 2-11 1 Now these are the judgments, which thou shalt set before them. 2If thou buy an Hebrew servant, six years he shall serve: and in the seventh he shall go out free for nothing. 3If he came in by himself, he shall go out by himself: if he were married, then his wife shall go out with him.4If his master have given him a wife, and she have

Three Theories of Cognitive Development Free Essays

Three Theories of Cognitive Development The Swiss psychologist and philosopher Jean Piaget (1896-1980) is well-known for his work towards the cognitive sciences. Arguably one of his most important contributions involves his theory of cognitive development. In this theory, thinking progresses through four distinct stages between infancy and adulthood. We will write a custom essay sample on Three Theories of Cognitive Development or any similar topic only for you Order Now Similar in scope to Piaget’s theory is Information Processing, in which human thinking is based on both mental hardware and mental software (Kail, Cavanaugh). A final theory on cognitive development was established by the Russian psychologist Lev Vygotsky (1896-1934). Vygotsky proposed that development is a collaborative effort between child and partner. While these three theories attempt to explain a similar topic in different manners, each can be considered an important aspect to cognitive development in infancy and early childhood. Through analyzing and comparing these theories, scientists are able to better understand how child development occurs and the process it takes in creating a functional human being. Piaget’s Theory Children are naturally curious: this is the claim Piaget proposed when explaining that children of all ages create theories about how the world around them works. They accomplish this through the use of â€Å"schemes,† referring to mental structures that organize information and regulate behavior. Infants group objects based on the actions they can perform on them. Later in development, schemes become based on functional or conceptual relationships, not action. This means that schemes of related objects, events, and ideas are present throughout development (Kail, Cavanaugh). Schemes change constantly, adapting to children’s experiences. Intellectual adaptation involves two key processes that work together: assimilation and accommodation. Assimilation is the process of taking in new information into previously existing schemes. Accommodation involves altering existing schemes in light of new information. Assimilation and accommodation are usually in equilibrium. But when disequilibrium occurs, children reorganize their schemes to return to a state of equilibrium, a process Piaget called â€Å"equilibration. † According to Piaget, revolutionary changes in thought occur three times over the life span, which are divided into four stages. Sensorimotor period (0-2 years): Infants adapt and explore their environment. Reflexes are first modified by experience. At 8 months, intentional behavior occurs. Soon, infants become active experimenters, and repeat actions with different objects for the purpose of seeing what will happen. An important aspect of the first stage is object permanence- the understanding that objects exist even if they cannot be seen. Not until at about 18 months do infants have a full understanding of object permanence. Soon after, the onset of symbols, including words and gestures, become apparent. Preoperational thinking (2-7 years): Children do not understand others’ different ideas and emotions (egocentrism). They also have trouble focusing on multiple features. A child in the preoperational stage has a narrowly focused type of thought (a term Piaget called centration). For example, in what is known as a conservation problem, children tend to focus on only one aspect of the problem. In conservation of length, they concentrate on the fact that, after the transformation, the end of one stick is farther to the right than the end of the other, when in fact each stick is similar in length. Concrete operational period (7-11 years): This stage is characterized by the appropriate use of logic. A child is able to sort objects according to its size, shape, etc. Also, children will now take into account multiple aspects of a problem. For example, a child will no longer perceive a wide and short cup to contain more liquid than a normal, tall cup. Egocentrism begins to disappear: the child can now view things from another’s perspective (even though that person may be wrong). Formal operational period (11 years and up): Individuals move beyond concrete experiences and begin to think more abstractly, reason logically, and draw conclusions from information available. Also changing is the way an adolescent thinks about social matters. The future is beginning to be thought of in relation to what he or she can become. Information Processing In this view, human thinking is based on mental hardware (allows the mind to operate) and mental software (basis for performing particular tasks). There are several different aspects to this theory. Learning and cognitive development can happen through habituation, classical and operant conditioning, and imitation. Habituation is the diminished response to a stimulus as it becomes more familiar. Constantly responding to insignificant stimuli is wasteful, so habituation keeps infants from devoting too much energy to non-important events. In classical conditioning, a stimulus elicits a response that was originally produced by another stimulus. No new behaviors are learned, but an association is developed (Huitt, W. and Hummel, J). For example, a toddler may frown when he hears water running in the bathroom because he realizes that it is time for a bath. Operant conditioning emphasizes reward and punishment. This helps children form expectations about what will happen in their environment. Imitation is important in older children and adolescents. This process entails a â€Å"watch and learn† kind of approach. A boy can learn how to play basketball by watching a professional athlete, and an infant may imitate an adult waving her finger back and forth. A special kind of memory, â€Å"autobiographical memory,† emerges in the preschool years. These are memories of significant events and experiences in one’s own life. Infants have basic memory skills that enable them to remember past events. In addition to these skills are the language skills and sense of self obtained during the preschool years. Vygotsky’s Theory Lev Vygotsky incorporated the role that society and culture have on an individual throughout cognitive development. According to Vygostky, children rarely grow cognitively by themselves; they learn and progress when they have others by their side. This is contrasting to Piaget’s theory and Information Processing, where the individual growth takes place mostly alone. In his theory, Vygotsky developed the idea of the zone of proximal development. This refers to the â€Å"zone† between the level of performance a child can achieve when working independently and a higher level of performance that is possible when working under the guidance of more skilled adults or peers. This follows the idea that cognition develops first in a social setting and slowly comes under the child’s control. A factor that aids this shift is known as scaffolding. This is a style of teaching in which the teacher decides the amount of assistance given to match what the child actually needs. Scaffolding is based off the premise that children do not learn readily when they are constantly told what to do or when they are left to struggle through a problem. Finally, Vygotsky viewed private speech as an â€Å"intermediate step toward self-regulation of cognitive skills. Private speech can be defined as comments that are not intended for anyone else but the child to hear, and are designed to help children regulate their behavior. This theory holds that cognitive development is not characterized as a solitary undertaking, but a collaboration between expert and novice. Compare and Contrast All of these theories attempt to measure the biological and psychological changes appare nt in child development. They look to categorize specific behaviors, and associate them with current stages in growth. However, each theory is different in that it looks for different behavior patterns. Also, Piaget’s Theory and the Information Processing Theory can be grouped together due to the fact that they look at a child as an independent being, not cognitively dependent on its environment. However, Vygotsky views a child’s development as being reliable upon its surroundings (e. g. its peers, parents, teachers etc). Disputes These three theories are just that; theories. None of them have been scientifically proven and accepted by all scientists. Instead, they have formed the basis by which we conduct study and research of cognitive development today. Theories will always be open to criticism and review, and Piaget’s theory has specifically been scrutinized by scientists and researchers. Some believe that Piaget underestimated the cognitive competence in infants and young children. A main theme of modern child development is that of an extremely competent infant. Also, many scientists have found that certain components of Piaget’s theory are not testable. For example, accommodation and assimilation prove to be too vague to test scientifically. In Vygosky’s Theory, some critics point out the overemphasizing of the role of language. Also, his â€Å"emphasis on collaboration and guidance has potential pitfalls if facilitators are too helpful in some cases. An example of that would be an overbearing and controlling parent. † Criticism is not meant to diminish the importance of these theories, but to foster more research in the field of cognitive development and improve our understanding of how children grow. Conclusion These three theories of cognitive development are meant to measure something that is physically not able to be measured. They take a look at how children behave, and attempt to classify each behavior accordingly. How to cite Three Theories of Cognitive Development, Papers

Towards Introducing and Implementation of Soa Design Antipatterns free essay sample

Service Oriented Architecture (SOA) is an architectural practice followed by organizations to reduce total cost of ownership, ease of maintenance in software development implementing various SOC principles. Dissatisfactory performance of SOA projects has stimulated the developers to analyze the SOA worst practices or antipatterns. Our research aimed at identifying these wrong practices in implementation of SOA, i. e. antipatterns. In this paper, four antipatterns SOA==SOAP, using plain WSDL, web service discovery only through UDDI, and service for an application have been identified and presented in SOA antipattern template. These antipatterns are related to the use of SOAP, WSDL, UDDI and basic service definition, which initially seemed to be correct but later resulted into reduced performance benefits. Keywords- Service, Service Oriented Computing, SOA, Design patterns, Antipatterns. Introduction Service Oriented Computing (SOC) is the latest design paradigm used to implement distributed systems. Service Oriented Architecture (SOA) implements various service orientation principles, which are designed for organizing and utilizing distributed capabilities that may be under the control of different ownership domains. It comprises of a set of components as services that can be invoked and whose interface descriptions are published and discovered [1-3]. The popularity of SOA has motivated designers to document its applications and implementations. Many best practices in the form of design patterns have been defined for SOA. They capture expert knowledge about best practices in software design, in a form that allows that knowledge to be reused and applied in the design of many different types of software. Some of the solutions have stood the test of time while others have not. These blemishing design patterns lead to the concept of Antipatterns. Antipatterns are specific repeated practices that appear initially to be beneficial but ultimately result in undesirable consequences Documentation of antipatterns helps the programmer to be aware of the common wrong practices, and hence improves the project statistics. There are various problems in adaptation of SOA, which result into the dissatisfactory performance of SOA projects. These problems are to be seriously catered; hence practitioners have started addressing different bad or worst practices of SOA implementation in form of antipatterns. SOA is a logical way of designing a software system to provide services either to end-user applications or other services distributed in a network via published and discoverable interfaces. There are several available SOA best practices and design patterns, which are currently used in the implementation of SOA based projects [14, 15, 22, 26, 29, 32]. Antipatterns have been addressed by practitioners after year’s long experience in the field. A survey on different antipatterns was performed exploring various worst practices and the causes of the failure of SOA projects [9, 14, 23, 28]. Antipatterns for SOA have already been documented [16-20, 25, 28, 31], but our major concern was on the SOA design antipatterns. Moreover, they have been described at different levels of abstraction, which makes them appear independent and isolated. After studying various SOA implementations, case studies [9, 12, 18, 32], News agency Service project of Signett IT enabled services, Travel Portal project [20] and few others [28-32] , it has been observed that there are some flaws in implementation of SOA. Since SOA is still in its nascent stage. Its success and importance still needs to be proved. Four antipatterns have been identified in this research work. They concentrate mainly on SOA design. These are SOA==SOAP, Using Plain WSDL, Web service discovery only through UDDI and Service for application. The first antipatterns SOA==SOAP focuses on ignorance of other parallel approaches to SOA. Second antipattern focuses on improper representation of service using WSDL. Third antipattern recommends the use of REST services which do not require any service registry to be discovered and prefers using customized registries. The fourth antipattern highlights the wrongly implemented concept of service forgetting the basic service design principles. The proposed antipatterns focus on SOA design and would definitely reduce certain overheads and result into a successful SOA implementation. It is sincerely hoped that these antipatterns would help the programmers to design a successful strategy for SOA implementation in their project. Some of the domain areas such as request change, data handling have been left unexplored and few more antipatterns can be identified. A framework for building SOA applications could also be developed which would integrate various features necessary features for SOA implementations. The rest of the paper is organized as follows. Section II of the paper briefly explains the antipattern template that will be used to describe the proposed antipatterns. Section III explains each of these proposed antipatterns along with their implementation and re-factored solutions. The fourth section provides future work in this direction of research and the conclusion of the paper followed by the references used. SOA Antipattern Template Antipatterns describe a commonly occurring solution to a problem that generates negative results i. e. seemingly well but in fact, wrong solutions. Design patterns and antipatterns are closely related. Former defines commonly applied solutions to well known problems, while later are the specific repeated practices that initially appear to be beneficial but ultimately result in undesirable consequences. An essence of antipattern is two solutions. First is the commonly occurring problematic solution that generates wrong results, another is the re-factored solution i. e. the esolved, reengineered and beneficial form of antipatterns. Those that describe only the negative solution are called pseudo antipatterns [31]. There are various problems in the adaptation of SOA, which result into the failure of SOA projects. These problems are to be seriously catered; hence practitioners have started addressing different bad or worst practices of SOA implementation in form of antipatterns. Antipatt erns proposed by different organizations have been fragmented and have been focusing on the complete SOA life cycle i. e. from the origin of concept to realization. The pioneer work on the subject focused primarily on object oriented antipatterns. It should be known that object oriented patterns and service oriented patterns have a subtle difference between them. Some of the object oriented design patterns form the major antipatterns for SOA such as No legacy Antipattern and vice versa. The SOA antipatterns discussed in the next section utilize the following SOA antipattern template to document the common dysfunctional practices in the adaptation of SOA. It specifies the name, root cause, primal forces, description and the name of the antipattern to which the current antipattern is similar to. Patterns have a problem and a solution while antipatterns have two solutions (instead of a problem and a solution). The first solution generates negative consequences (forces that must be resolved). The second solution is a migration (or refactoring) from the first solution that provides dramatically improved benefits and much reduced consequences. Like design patterns, antipatterns should also follow a general profile format for their representation [9]. Following is the antipattern template used to describe SOA design antipatterns. It comprises of a number of required and optional sections. The core sections are the general form of the antipattern and the re-factored solution. ? Antipattern Name: The Antipattern name is a unique noun phrase. The name is used for future reference to the principles contained in the antipattern. They form the basis for an organization’s terminology when members discuss and document software and architectures. ? Also Known As: This identifies additional popular or descriptive names and phrases for this Antipattern. ? Root Causes: These are the general causes for the antipattern. They can be one or more of the following values: Haste: It is popularly said ‘Haste makes waste’. Hasty decisions lead to compromises in software quality. As successive project deadlines are missed, anything that appears to work is considered acceptable, regardless of quality. Apathy: It refers to not caring about solving known problems. It is a basic unwillingness to attempt a solution. Narrow-mindedness: It is the refusal to practice solutions that are otherwise widely known to be effective. Sloth: Automatically generated interface stubs and skeletons make the task of constructing a distributed system relatively easy. The ease of creating and changing interfaces leads to the deadly sin of sloth—lack of configuration control. Avarice: Architectural avarice means the modeling of excessive details, which results in excessive complexity due to insufficient abstraction. Ignorance: It is the result of failing to seek understanding. The problem of ignorance (implementation dependency) often occurs in the migration of applications to distributed architectures. Pride or resp onsibility: Often, developers unnecessarily invent new designs when knowledge from preexisting systems, products, and standards are readily applied through architecture mining. Reinvention involves many unnecessary risks and costs. Primal Forces: Forces are concerns or issues that exist within a decision-making context. In a design solution, forces that are successfully addressed (or resolved) lead to benefits, and forces that are unresolved lead to consequences. The choices include any of the following: -Management of functionality i. e. meeting the requirements. -Management of performance refers to meeting the required speed of operation. -Management of complexity means defining abstractions. -Management of change controlling the evolution of software. -Management of IT resources refers to controlling use and implementation of people and IT artifacts. Management of technology transfer refers to controlling the change in technology. ? Re-factored Solutions. This section explains a re-factored solution that is structured in terms of solution steps. Proposed SOA Antipatterns Design patterns are proven solutions to a task presented in a standard format and antipattern are the wrong ways of doing a task which initially seemed to be correct. Here, certain domain areas were identified as most error prone areas of SOA implementation, hence probable areas of finding new antipatterns. This was on the basis of the implemented module, case studies and study of the subject. SOA comprises of different architectures as shown in Fig1. Based on these designing of a service oriented application can be further broken up as service design, service composition design and service inventory design. [pic] Figure1: Layered architectures. SOA design is further categorized as Service Design (SD), Service Composition Design (SCD), Service Inventory Design (SID), and Service Oriented Enterprise Design (SOED). The identified domain areas prove to be the weaker links of SOA and need to be implemented correctly and carefully. Few of these domain areas are concept of service, service scalability/load balancing, service discovery, service composition, data sources, security and request change. In this paper, SOA==SOA, using plain WSDL, web service discovery only through UDDI and service for an application are identified as antipatterns and these are discussed in the following subsections. 1 SOA==SOAP Practitioners implementing SOA often consider that, the three standards required for implementing web services are the Simple Object Access Protocol (SOAP), Web Services Description Language (WSDL), and Universal Description, Discovery, and Integration (UDDI). SOAP is an XML-based protocol to support communication between a Web service, its clients, and UDDI registry. WSDL is an XML-based standardized interface definition language used to describe what a web service can do, where it resides, and how it can be invoked. A WSDL file associated with a Web service contains important details about the Web-service interface for client-service interaction. UDDI standard is used to publish, discover, and manage Web services in an UDDI registry. Although it is a good and most preferred way to implement web services, the other ways to create light weight services should also be preferred. A REST (Representational State Transfer) web service is basically a simplified model where everything is wrapped around the HTTP send/receive protocol. Using services based on SOAP envelop always, may be an overhead, whereas that same work could be done using lightweight approach like REST using traditional methods. The main responsibility of accessing the service in the SOAP-WSDL process lies on the consumer. He will have to programmatically extract the Web service SOAP message in order to do something useful with it in the application. Although core services holding logic should be bind in an SOAP envelop but simple data handling services , CRUD operations should be implemented using traditional Http methods viz. GET, PUT, POST, DELETE i. e. through RESTful way. REST emphasizes resources with a uniform interface for addressing them, while SOAP based RPC emphasizes processes with a uniform interface for invoking them. With a RPC-based architecture, there is no limit to the number of processes. In REST we can everything get by only four basic methods GET, POST, PUT and DELETE of the Http standard, and make the resource addressing handle the variability. For services representing basic CRUD operations, REST way of implementing services is simpler and lightweight. 1 Re-factored Solution In the development of Web service based SOA applications, the designing of services should not be adamant to a traditional style but other approaches should equally be used when and where required. Both the approaches SOAP based and REST based have been compared in the following paragraphs and depending on the requirement, appropriate method for implementing services could be selected. Both these approaches are not the counterparts and can be used together in the same application. 1 Approach REST and SOAP are parallel ways of implementing web services. Let us first discuss these two different approaches of implementing web services. REST is an architectural style that prescribes the use of standards such as Http, URL, Resource representations (XML, HTML, Gif etc. ), MIME Types etc. [11]. The RESTful web service makes available URL to a resource and it may allow the client to specify the format of the returned resource i. e. HTML or an XML document. The service itself may be described using WSDL (Web Service Description Language) or WRDL (Web Resource Description Language) and can be accessed either as a resource or using JSON (Java Script Object Notation). RESTful services are stateless; each request from client to server must contain all necessary information. All resources are accessed with generic interface (Http GET, POST, PUT, DELETE). These resources are named using URI (Uniform Resource Identifier). The client may progress from one state to another using interconnected URL representation. In SOAP method, provider creates and implements a web service interface on an existing application. He has to create a XSD (XML Schema Document) and WSDL contract in order to distribute the web service details to potential consumers. Consumer obtains WSDL contract for consumption through UDDI registry. Then the consumer implements the WSDL in a specific platform Java, C#, PHP, Perl and creates a caller application. Client sends multiple requests using the same URL for all transactions. It is the responsibility of the SOAP server to a parse the SOAP message and determines which method to invoke. The returned data would not contain any URL, since a URL that points to a SOAP service is just to the SOAP server. In REST all decisions are made based upon the URL and the Http method selected while in SOAP, server receives all messages, peeks into the SOAP envelop and then distributes each message to the appropriate application for processing. 2 Proxy servers Proxy servers play a major role as web intermediaries for a web application. Below we briefly discuss their functionality for a web service. In the REST approach, the URL identifies the resource that is desired. The Http method identifies the desired operation. The Proxy server decides based upon the identified resource and the Http method whether or not to allow the operation. Using XLink (the XML hyperlink technology) in addition to providing a URL to the target resource, data about the resource could also be provided using Xlink:role. The application can dynamically make decision about what resource is to be accessed next. In SOAP based approach, proxy server cannot directly allow or disallow the message since it is unaware of the desired contents or resources. Either the proxy server should understand the semantics of each SOAP application that a client will access, but for that the proxy server will need to be updated for each new SOAP application. 3 Caching It refers to the ability to maintain a copy of the desired resources in order to improve the performance. In the REST approach, The response of a resource contains an indication in the Http header of whether the results are cacheable or not. If it is, cache servers make a local copy, which can be returned for the same request if repeated. A SOAP message is always with a POST method, which makes the cache server unaware of the actual intention of the request type (GET or POST). Moreover the SOAP URI is always to the SOAP server which prohibits the cache server again from knowing the actual resource requested. Hence no caching is possible with SOAP. 4 Generic Interface Generic interfaces imply generalized functionality and hence support scalability whereas application specific or custom interface interfaces may need some additional functionality to be called in a generic context. In REST, every resource has a generic interface namely Http GET, PUT POST, and DELETE which enable caching and proxy servers to do their work. Whereas in SOAP, There is no defined standard set of methods. Any type of methods could be defined which makes customization on application basis and reduces scalability. 5 Interoperability Interoperability means sharing the data amongst multiple applications. The more interoperable software programs are, the easier it is for them to exchange information. In REST, Interoperability is based on standardization. REST relies on standards of addressing and naming resources (URI), resource interfaces (GET, POST, PUT etc. ), representations (HTML, XML etc. ), and media types (MIME types). In SOAP, each SOAP message provides its own unique method of naming a resource. Each SOAP application defines its own interface hence interoperability is possible only for closed systems where all participants are known prior. REST and SOAP do not replace each other, each of them have their uses but when making high performance and client rich websites REST can provide a significant improvement. Traditional way of implementing SOA only through SOAP also leads to other antipatterns. REST style needs no registry and makes resources directly available hence it also helps in overcoming the following two antipatterns viz. Discovery of web service through UDDI and Using plain WSDL to define service interface. 2 Standard Representation Following the Standard Antipattern Template [14] and SOA Antipattern Template [31], the above proposed antipatterns can be described as follows: Antipattern Name: SOA==SOAP Also known as/ similar to: Not Applicable Root Cause: The common and fundamental reasons for the problem can be coined as haste, apathy, ignorance. Primal Forces: These are certain architecture and development related concerns or issues present in most decision making context. They greatly affect the design and development process and in this case it can be management of functionality and management of technology transfer. Misuse of these above mentioned forces leads to the development of this antipattern. Description: SOAP-WSDL is considered to be the only way of implementing SOA by companies implementing SOA for the first time. Solution: Although SOAP-WSDL is the established way of SOA implementation through web services but other alternative ways like REST should be equally considered. For CRUD applications RESTful services should be preferred and for application specific services holding core logic SOAP based services should be preferred. 3 Implementation The above antipatterns were derived after final implementation of both the ways of implementing web services i. e. SOAP and REST. Following are few screenshots of their implementation i. e. SOAP-WSDL based web service in . Net hrough Visual Studio 2008 and REST Based web service in java through Netbeans7. 0. 1 Fig. 2 represents a structure of SOAP based service. It shows various methods which are application specific and need not have a generic structure. Figure2: Structure of SOAP based service Fig. 3 shows the structure of REST based service. It reflects certain methods like getJSON() to retrieve java script object notation form of data, getXML() to re trieve its XML format. [pic] Figure3: Structure of REST based service. The Fig. 4 below shows the interface of the REST based web service. In it the resources are available in the form of URI (Uniform Resource Identifier) in the returned page. User can access these web services by simple clicking on the URL shown, the getXML() or getJSON() methods are called accordingly. [pic] Figure4: REST based web service. 2 Using Plain WSDL WSDL (Web Service Description Language) is used to define service interfaces. It describes two different aspects of a service: its signature (name and parameters) and its binding and deployment details (protocol and location). WSDL describes services in three layers: Layer 1: It describes the interface of a service. Layer 2, describing the binding of a web service i. e. protocol and format for which web operations are provided. Layer 3 defines the physical location i. e. address URL where service is available. WSDL does not contain full interface of a service, it does not have any semantic information. A WSDL file does not specify how to access next desired service, how long a service usually runs, who is allowed to call it, how much a service call cost and many other non functional attributes. All these aspects must usually be known in order to manage a service in a large SOA landscape. With future WSDL versions this might change. 1 Re-factored Solution Service Description should be provided in a separate format and WSDL should be generated from it when required. WSDL files can be extended internally with additional XML elements and attributes or externally with supplementary files [20]. WSDL allows elements representing a specific technology under various elements defined by WSDL. These elements are known as extensibility elements. Extensibility elements allow vendors to expose their Web Services as EJB’s, Remote Java Objects and . NET objects without having to write SOAP bindings for them. Currently, the WSDL specification introduces specific binding extensions for the SOAP, HTTP GET/POST, MIME protocols and message formats. Using the extensibility mechanism a service developer can describe commonly used services such as EJB, . NET and Java Objects. The consumer of the service can use the WSDL and generate the necessary client side stubs to invoke the endpoints in the native protocol. This approach has a several advantages. The service developer does not have to spend time in exposing his service with SOAP bindings. Also, invocation of the service will be faster since the call will occur over the native protocol, and less time will be spent for SOAP marshalling and un-marshalling. A service can have multiple bindings associated with it and the consumer of the service will have the choice of selecting one binding or the other. Implementation The Fig. 5 below shows the standard WSDL file for a simple web service in java. [pic] Figure5: Standard WSDL representing a service. In the Fig. 6 code segment the information for locating the EJB is stored in lt;ejb:portgt; section of the WSDL definition and the information for invoking the EJB is stored in the lt;wsdl:bindinggt; section. [pic] Figure6: WSDL extensions using WSDL4J. 2 Standard Representation According to SOA Antipattern Template [31], the above proposed antipatterns can be described as follows: Antipattern Name: Using Plain WSDL to define all service interfaces. Also known as/ similar to: Not Applicable. Root Cause: It can be the result of h aste, sloth and ignorance. Primal Forces: Management of change, management of complexity and management of technology transfer. Description: Simple WSDL describes only two different aspects of a service: its signature (name and parameters) and its binding and deployment details (protocol and location). This does not describe various non functional attributes like how to access next desired service, cost of service etc. Solution: WSDL files can be extended internally with additional XML elements and attributes or externally with supplementary files. Certain extensibility mechanisms have been defined for specific purposes like, those supported by WSDL4J for ejb’s. Techniques for defining WSDL extensions have been proposed [12] and are one of the major research areas in WSDL. 3 Web service discovery only through UDDI In a real SOA enterprise infrastructure with hundreds of services, it is safe to assume that service endpoints are going to constantly be subjected to changes in areas such as location (URL), policy (security, etc) or contract (WSDL, operations). A common practice to accomplish that is to have client application to resolve service metadata such as endpoints or policies against a service repository. In order to address these challenges, the big SOA vendors  (Microsoft, Oracle, IBM etc. ) created a standard that with the purpose of modeling service metadata information that could be used to enable service discovery capabilities. The standard was known as Universal Data Discovery and Integration (UDDI) and, unfortunately, it became the cornerstone of SOA governance products. UDDI has proven to be an incredibly ineffective mechanism to enable service publishing and discovery. The SOA models created with UDDI are incredibly complex to implement and use. They end up becoming another bottleneck of SOA. 1 Re-factored Solution While building SOA application, the complexities of UDDI should be avoided and instead use a simpler mechanism to facilitate the discovery and query of services. This can be achieved by implementing a 100% RESTful API that allows querying the entire service registry using plain HTTP GETs methods. There is no requirement of centralized registry. More advantages of REST are discussed in previous section. User defined or application specific registries can also be defined like Oracle’s OSR (Oracle service registry), But these application specific registries are very complex and far from the reach of a simple programmer. Standard Representation According to SOA Antipattern Template [31], the above proposed antipatterns can be described as follows: Antipattern Name: Discovery of web service through UDDI. Also known as/ similar to: Not Applicable. Root Cause: It can be haste, sloth and ignorance. Primal Forces: Management of performance, management of IT resources and management of technology transfer. Description: Since SOA literatures and previous implementation of the technology, effectively present the usage of UDDI as the central registry for SOA services, the new small projects consider it to be an un-detachable component of SOA. The truth lies behind the fact that UDDI is incredibly complex and difficult to implement. Even and Microsoft have refrain from their UDDI registries. In such case, adhering to UDDI seems to be right but in fact not the perfect way of service discovery. Solution: Customized registries according to the application should be created. Various other registries using JNDI (Java Naming and Directory Interface), OSR (Oracle Service Registry) can also be used in an SOA application. REST based services should be preferred for data access services. They are directly accessed through URI’s hence require no central registry. Service for an application In the development phase of the module it has been observed that the first step in implementation of SOA, if taken mistakenly can prove to be a useless investment. Services are supposed to be designed for achieving main goals of SOA viz. reusability, interoperability, increasing organizational agility etc. Many IT developers with object orie nted experience implement SOA in the way they started Object oriented software. Services are designed application specific. No enterprise level service classification is involved. Service just become another way of creating an application, hence, provides no business benefits. Large numbers of services are designed, leading to another antipattern: Service Silos. These services have little or no reuse across applications. 1 Refactored Solution Proper training and education of basic SOA goals and principles should be given to the involved members before the actual work begins on the project. The service design should also follow basic SOA design principles [12]: 1) Standardized Service Contract: Services in the same inventory should follow same design contract. ) Service Loose Coupling: Services should be loosely coupled with customer requirements and their own surrounding environments. 3) Service Abstraction: Service contract should contain only the essential generic information. 4)Service Reusability: Services should have reusable enterprise logic. 5) Service Autonomy: Services should be autonomous i. e. their runtime environment should be under their control. 6) Service Statelessness: State information should not be maintained with service itself. 7) Service Discoverability: Services should be effectively discovered and interpreted through suitable mechanisms. 2 Standard Representation According to SOA Antipattern Template [31], the above proposed antipatterns can be described as follows: Antipattern Name: Service for an Application. Also known as/ similar to: Not Applicable. Root Cause: It can be haste, apathy, sloth and ignorance. Primal Forces: Management of functionality, management of change, management of complexity and management of technology transfer Description: Services are built for use within an application forgetting the basic service design principles. Solution: The services should be classified as intra application and inter application. Inter application services should be designed for interoperability. Application specific services if required should be at the lowest level and callable only by the generic services providing interface to the service consumer. Services at lowest level should further be properly identified as entity services, task services and utility services [15]. Services should essentially follow basic design principles for a successful SOA implementation. Conclusion and Future Work It has been observed that amongst the large number of addressed SOA antipatterns, failures are mainly due to limited number of interrelated antipatterns focusing mainly on the SOA design. Four antipatterns SOA==SOAP, Discovery of web service through UDDI, Using Plain WSDL to define all service interfaces, Service for an application were identified and represented. The above conclusions and derivations were based on the case studies and SOA implementation, using both, SOAP based and REST based services. In this paper we mainly emphasized SOA design antipatterns. Some of the domain areas such as request change, data handling have been left unexplored and few more antipatterns can be identified.