Applying Learning Theory in the Classroom

Applying Learning Theory in the Classroom The two main influential learning approaches are the behaviourist and the cognitive approach to learning theories. This report critically evaluates how learning theories are applied in the 14-19 Applied Science classroom. It examines how behaviourism, although an outdated theory, is still relevant in the modern classroom and is still used in developing the rewards and sanctions policies of the modern school. The impact of Piagets theory of cognitive development is evaluated and what possible difficulties might arise if they were applied exactly as Piaget dictated. The impact of adhering rigorously to Piaget maturational stages is criticised and how it might not be possible to adhere to set ages for progression in a school. Kolb, Vygotsky and Bruners constructivist approaches are compared and shown that, when applied to a motivated class they work as they were originally intended and yet when applied to a more disaffected class, they arent as easily applied. The science classroom is an inherently dangerous place for students to work in (Frost, Turner, 2005, p.168). It is therefore necessary to instil a level of ‘discipline in the students, to ensure they minimize the dangers to themselves and others in the science classroom. It is necessary to ‘condition (Child, 1997, pp.114-121)the students to behave when certain commands are issued. Behaviour theorists believed that the mind was a blank slate ‘tabula rasa and that we could observe the response to stimulus that happened to an organism. Watson thought that a response is more likely to be connected to an environmental event (stimulus), if that stimulus-response is repeated regularly and with a short period of time between them (Child, 1997, p.115). Thorndike showed that the student is less likely to repeat negative stimulus-responses, which therefore means that there will be an increase in the positive stimulus-responses, until a correct response is repeated regularly. The stimulus-response is then reinforced whenever a positive result is produced (Child, 1997, pp.114-121). Skinner made several conclusions from his findings in Operant Conditioning (Child, 1997, pp.119-121). The steps taken in the conditioning process must be small. Regular rewards are required at the early stages, but once the conditioning is reflexive, rewards can be given less regularly. The rewards must come immediately or shortly after a positive response to ensure maximum effectiveness (feedback) (Child, 1997, pp.114-121) When discussing learning theories, its necessary to mention Pavlov due to the importance held in his work, even if it doesnt really directly affect the classroom. Pavlov pioneered the idea of classical conditioning with his famous experiment where he taught dogs to salivate, when a stimulus was applied, just before food was given to them. The dogs eventually associated the ringing of the bell with the arrival of food and salivated in anticipation of the food arriving (Child, 1997, pp.116-118). Pavlovs work does not directly link to teaching in the classroom, but it does apply, in that the students may be conditioned, to have a memory or a response to an event that happens within the classroom environment. During my lessons I tried to implement Watson, Thorndikes and Skinners theory of Operant Conditioning in the classroom to modify the behaviour of the class. The goal was to condition the students to reflexively stop talking when I moved to a certain area of the room; using the theory that the students would repeat behaviour that received a positive response, and not repeat behaviour that received a negative response. I initially started to modify their behaviour by moving to the left of the front desk, holding my hand up and waiting for silence in the same spot, every time I required them to stop talking and listen. Initially it was necessary to ask for silence and remind them that I was waiting to talk. In some cases it was necessary to issue a sanction as per the science departments rules of two warnings, then issuing a detention or keeping them in for part of their break if, if they didnt stop talking quickly enough. If the class stopped talking quickly, they would be rewarded wit h praise and if the lesson had gone well a class reward of a game or competition at the end, if it was appropriate. Positive feedback about performance is said to have a positive effect on future performance. Skinner called it reinforcement; Thorndike called it The Law of Effect (Child, 1997, pp.115-121). McAllister et al. (1969) found that praising students not only acted as a positive reinforcement of behaviour, but that the praise may have also worked by causing peer group pressure in the class to reduce inappropriate behaviour, because the negative behaviour reflected on the class as a whole (McAllister et al., 1969). Banduras Social Learning Theory would say that the students were not only being conditioned to respond to the teacher, but also learning from their peers actions as to what was appropriate behaviour in the classroom (Atherton, 2009) By the end of the six weeks, the students were starting to respond to the successive approximation as described by Skinner (Child, 1997, p.121)positively and required reminding less that I was waiting to talk to them. It was evident that they much preferred the positive response of listening and being allowed to continue with whatever activity I had planned, to the negative response of not listening and receiving a sanction, before continuing with the activity I had planned. It could be said that they were suffering from Learned Helplessness (Atherton, 2009a)and had given up on being able to change the lesson by negative behaviour. Due to the need to provide a safe working environment in the classroom, I also worked on the class responding to the command ‘STOP when they were carrying out laboratory work. The idea being that if ‘STOP was said loudly to the whole class, that they automatically stop what they are doing, stop talking, turn to where the teacher is in the classroom and prepare for instructions that are important or safety related. â€Å"In the early stages of conditioning, continuous reinforcement is needed to establish the Stimulus-Response link.† (Child, 1997, p.119) The difficulties whilst trying to implement these theories was down to the amount of time involved in getting the students responding to the stimulus positively. The theory of being able to reward the students for responding positively and sanction them if they dont isnt appropriate in this situation, due to the serious nature of the command. If the students dont respond to it, it could ultimately end up with dire consequences in an emergency situation. The ‘STOP command in particular was a difficult one to implement due to its infrequent use and the seriousness of its use that was implied to the students. If the command was overused, then it would lose its importance as something serious, but on the other hand if it wasnt practiced enough, the students would not respond appropriately when the command was issued. Another interesting situation that arose was from the attention-monopolising students, in that the more demanding students are prepared to put up with the minor inconvenience of the negative reinforcement if they get the attention time from the teacher. (McAllister et al., 1969) Seeing the students more frequently, I am sure that they could be conditioned quicker and show the innate response more readily than when I was only able to see them a few times a week. Behaviourism is evidently still relevant in the modern school (McQuillan, 1998), even if it is a somewhat outdated theory. Schools still have their sanctions policies based around Operant Conditioning and negative reinforcement with various levels of warnings and detentions in place for negative behaviour. This will remain effective for as long as policy makers allow these sanctions to be used. However, Skinners belief that we are all blank slates and what goes on inside our black boxes (Child, 1997, pp.119-121) when we learn is not important, is not relevant anymore.(Child 1997, pp.113-121) The students I have worked with and taught are all very unique in their personalities and show completely different ways of learning. To say that the learning processes they go through are only related to external stimulus and their response to that stimulus does not correlate with what has been observed in the classroom. Constructivist Theory has played a big part in the current educational environment in schools. Driver and Easley introduced constructivism as it is known now to the science community in 1978. (Solomon, 1994, p.3)They stated what was previously an inaccessible theory for science, accessible to the scientific educational community. The 14-19 classroom allows us to look at how Piagets Theory of Cognitive Development is applied. Piaget observed that children go through four distinct stages of cognitive maturation (Burton, 2001, pp.237-239) Stages of Cognitive Development (Atherton, 2009b) In the 14-19 classroom, according to Piagets theory, all the students have reached the Formal Operational stage of cognitive development and are capable of developing hypothetical situations and understand abstract concepts. Students should be able to apply their understanding of a situation and in theory be able to hypothesise what would happen in a given event. (Child, 1997, pp.191-207) From experience it is clear that not all students reach the Formal Operation stage at the same time and in fact the 11 year and up boundary is not as clear cut as that (Child, 1997, p.202-203). Within my Year 9 KS3 classes the majority of the students were at the Formal Operation stage of development and were capable of taking an abstract idea, such as levers and moment of a force and applying their knowledge and understanding to derive the equation for calculating the moment of a force themselves. A complex operation that required the students to both assimilate and accommodate (Child, 1997, p.192) the new information they were processing, a task which some found difficult, but all were able to eventually complete. With the Year 10 Applied Science class only a small portion of the class were at the point where they could process abstract information or make a hypothesis. Unlike the year nine class they had to be walked through every new concept step by step (Burton, 2001 p241). When they were given the task of hypothesising why something had happened, for example, where did the glowing light from heated calcium carbonate come from, they were unable to comprehend that the glowing was not related to the heating itself, but was actually an endothermic reaction. Even with a step by step explanation and clearly showing how the reaction was occurring, only a small portion of the class were able to assimilate and accommodate the schema. ‘Teaching at middle and upper school level should begin from concrete considerations, building up, where applicable, to more abstract reasoning.'(Child, 1997, p.203). Piagets theory of distinct maturational stages poses an interesting problem for teachers and educational authorities. Should a student be moved into a more advanced class or year because of their age, or should they move up a level when they reach a stage in their learning ability? From experience with the two different classes, its quite apparent that these boundaries are not as clear as Piaget was led to believe. If a school was to teach students based on their stage of cognitive development; how long could a student be held back for, before the age gap between their classmates was too much? Some students may after all never reach the Formal Operations stage. Vygotskys theory says that the childs higher mental processes are developed through the child working with other more knowledgeable persons than themselves.(Kozulin, 2003, p.19). He theorised that there was a Zone of Proximal Development (ZPD) that was the boundary between a childs Zone of Actual Performance and their potential level of understanding. The child can access their ZPD with the assistance of a more ‘competent (Kozulin, 2003, p.20) person guiding them.(Chaiklin, 2003, p.43) Vygotskys Social Constructivist theory moved away from the didactic approach of teaching, which often led to students developing their own misconceptions and not being able to apply their scientific knowledge ‘flexibly to new situations (Karpov, 2003, pp.67-73), to a more socially guided, active approach to learning, where students learnt from their teacher, peers and themselves. Kolbs four stage experiential learning cycle, is similar to both Vygotskys theory of a ZPD and Bruners theory of scaffolding the learning. Kolbs cycle builds on the learners concrete experience and goes through three distinct stages, reflective observation, abstract conceptualisation and active experimentation, before returning to the now new concrete experience,.(Burton 2001, p.246) Similarly Bruner theorised that students built on their past experiences and that by applying a spiral curriculum, they would able to return to subject areas and build on them when they were more capable of dealing with the more complex areas of the curriculum. He saw the teacher as a guide, leading the student through the learning process by scaffolding their learning with appropriate material and as the student progressed less scaffolding is required.(Burton, 2001, p.241) When applying these theories it is important to be aware that students are all at different stages of learning. Some students have a more advanced understanding, which puts them in a completely different ZPD, concrete experience or stage in their scaffolded learning, to students who have a lower level of understanding. With the KS3 class the students were all in the 5-7 range for target grades, therefore it was a lot easier to plan how they were going to progress in the lesson. A clear understanding of where they were in relation to their ZPD or their concrete knowledge was available and it was therefore a lot clearer, what was required to get them to a new Zone of Actual Performance or to the next stage in Kolbs cycle. They had all reached Piagets formal operation stage and were able to develop their knowledge independently. With the GCSE Applied Science class it wasnt as easy to apply the theories. The students target grades ranged from G-A., therefore ascertaining where their concrete knowledge lay or where they were in their Zone of Actual Performance was quite challenging. Such a large spread of stages meant it was often necessary to take a didactic approach to try and provide a basic foundation level of knowledge for the lower attaining students, so that they could access the lesson. In some cases students were never able to access the lesson due to their complete disaffection from the subject or school in general. Most of the class had not reached the formal operation stage and some struggled in the concrete operational stage at times. A good example being when one of the students struggled with the concept of limestone having nothing to do with the fruit. Finding the middle ground, where the higher attaining students wouldnt be bored waiting for the lower attaining students to get on task or understand what to do was extremely challenging, and at some points, felt completely pointless trying to apply social constructivist theory to the lesson planning with such a wide range of grades in the class was one of the key problems when trying to apply these theories to the lessons. It was however (in retrospect) interesting being able to see two different sides to how social constructivist theory is applied in the classroom. With the higher attaining, less disaffected KS3 students, it was a lot easier to see how the theories could be effectively applied to their lessons, how they benefitted from the teacher acting as a guide and their interest in the lesson meant that they were able to access it and move forward in their learning. It was always clear at which point in the learning process each students was at and what was required to move them onto the next level in the learning cycle. With the more disaffected, lower attaining students, in the GCSE Applied Science class it was so much harder to effectively apply these theories in the lesson. I tried on several occasions to teach lessons where I acted as the guide through their learning process; the students (in theory) would build on their experiential learning and move forward in their knowledge and understanding of the subject. In fact what happened was that the students panicked at the thought of not having the teacher dictating to them each step of the lesson and what they must do. The concrete experience for some was so limited that they were unable to apply it to the lesson and very quickly, if they were not given step by step instructions as to what to do next, they would be off task and cause other students to go off task as well. Therefore it seemed that the behaviourist theory, in particular Skinner, was being followed, as the positive reward was completing the step. Within the GCSE class there were several students who were classed as having Special Educational Needs (SEN), this ranged from Social Emotional Behavioural Difficulties (SEBD) to Dyslexia and Dyspraxia. Since the revised national curriculum was brought in to effect in September 2000, these students have had the right to a place in the classroom alongside students without any SEN.(Peacey, 2001) Students with SEN are to be included in the lessons and not treated as separate entities to the non-SEN students. Effectively inclusion was brought in to ensure that all students had access to exactly the same educational opportunities as other students. Too see inclusion in practice is very different to reading about it on paper though. Within the class the students suffering from Dyslexia and Dyspraxia, worked fairly diligently, and although at times they found it a struggle organising themselves for course work or in taking notes, they caused little disruption to the other students. They had the extra help required and were catered for in examinations and course work; they were effectively being included. The students who were listed as having SEBD on the other hand, would have appeared to an outsider to relish in the opportunity to be able to disrupt learning; they spent more time being removed from the class than learning itself. Yet if their backgrounds were to be looked into, it would be apparent that it was an achievement being in school that day and it was quite understandable that science was not their top priority, when they might not have even had breakfast that morning. Their inclusion in the lesson was negatively impacting on other students who were not on the SEN register and did not need to be specially included into the class to due to disruptive behaviour. This leads to the question ‘When should a student not be included in a classroom?, which at this point in my limited experience, I am unable to answer. In conclusion, behaviourism is still always going to be prominent in the modern school as a way of leading students towards becoming more disciplined and focused in their studies, via the rewards and sanctions policies on which they are based. When applying the cognitive learning theories, it is necessary to be aware that not all of the students are going to be starting at the same level, some may well be significantly below the level of other students and are only grouped together because of their age. Therefore the materials to be taught are not necessarily going to be accessible to all of the class all of the time unless they are developed to be inclusive for all the students, which is the current aim of the government (Peacey, 2001). The only viable option would be to group classes closely by attainment level as opposed to age, which is unlikely to happen. References ATHERTON, J.S., 2009, Learning and Teaching; Social Learning Theory (Bandura), [Online] (Updated Nov. 2009). Available: http://www.learning-theories.com/social-learning-theory-bandura.html [12/Dec/2009]. ATHERTON, J.S., 2009a, Learning and Teaching; Behaviourism, [Online] (Updated Nov. 2009). Available: http://www.learningandteaching.info/learning/behaviour.htm#operantconditioning [15/Dec/2009]. ATHERTON, J.S., 2009b, Learning and Teaching; Convergent and Divergent Learning [Online] (Updated Nov. 2009). Available: http://www.learningandteaching.info/learning/converge.htm [15/Dec/ 2009]. ATHERTON, J.S., 4 November 2009, 2009c-last update, Learning and Teaching; Learned Helplessness, [Online]. Available: http://www.learningandteaching.info/learning/learned_helplessness.htm [19/Dec/2009]. ATHERTON, J.S., 2009d, Learning and Teaching; Piagets Developmental Theory [Online, [Online] (Updated Nov. 2009). Available: http://www.learningandteaching.info/learning/piaget.htm#Keyideas [19/Dec/2009]. BURTON, D., 2001. Ways Pupils Learn. In: S. CAPEL, M. LEASK and T. TURNER, eds, Learning to Teach in the Secondary School. 3rd edn. London: RoutledgeFalmer, pp. 235-249 CHAIKLIN, S., 2003. The Zone of Proximal Development in Vygotskys Analysis of Learning and Instruction. Vygotskys Educational Theory in Cultural Context. 1st edn. Cambridge: Cambridge University Press, pp. 39-64 CHILD, D., 1997. Cognitive Formation and Cognitive Development. Psychology and the Teacher. 6th edn. London: Cassel, pp. 185-213 CHILD, D., 1997. Learning Theory and Practice. Psychology and the Teacher. 6th edn. London: Cassel, pp. 112-151 DYSON, A., FARRELL, P., POLAT, F., HUTCHESON, G. and GALLANNAUGH, F., 2004. Inclusion and Pupil Achievement. 578. Newcastle: University of Newcastle. FROST, J. and TURNER, T., 2005. Planning Practical Work. Learning to Teach Science in the Secondary School. 1st edn. Oxon: RoutledgeFalmer, p. 168 GIEST, H. and LOMPSCHER, J., 2003. Formation of Learning Activity and Theoretical Thinking in Science Teaching. Vygotskys Educational Theory in Cultural Context. 1st edn. Cambridge: Cambridge University Press, pp. 267-288 HUITT, W. and HUMMEL, J., 1997, 1997-last update, An Introduction to Operant (instrumental) Conditioning. [Online]. Available: http://chiron.valdosta.edu/whuitt/col/behsys/operant.html [15/Dec/2009]. KARPOV, V.Y., 2003. Vygotskys Doctrine of Scientific Concepts. Vygotskys Educational Theory in Cultural Context. 1st edn. Cambridge: Cambridge University Press, pp. 65-82 KOZULIN, A., 2003. Psychological Tools and Mediated Learning. Vygotskys Educational Theory in Cultural Context. 1st edn. Cambridge: Cambridge University Press, pp. 15.-38 LEACH, J. and SCOTT, P., 2002. Designing and Evaluating Science Teaching Sequences: An Approach Drawing Upon the Concept of Learning Demand and a Social Constructivist Perspective on Learning. Studies in Science Education, 38(1), pp.115-142 MCALLISTER, L.W., STACHOWIAK, J.G., BAER, D.M. and CONDERMAN, L., 1969. The Application of Operant Conditioning Techniques in a Secondary School Classroom. Journal of Applied Behaviour Analysis, 2(4), 277-285. MCQUILLAN, P.J., 1998. Educational Opportunity in an Urban American High School: A Cultural Analysis. 1st edn. Albany: State University of New York. PEACEY, N., 2001. An Introduction to Inclusion and Special Educational Needs. In: S. CAPEL, M. LEASK and T. TURNER, eds, Learning to Teach in the Secondary School. 3rd edn. London: RoutledgeFalmer, pp. 218-233 SOLOMON, J., 1994. The Rise and Fall of Constructivism. Studies in Science Education, 23(1), pp.1-19 ZEMBYLAS, M., 2005. Three Perspectives on Linking the Cognitive and the Emotional in Science Learning: Conceptual Change, Socio-Constructivism And Postructuralism. Studies in Science Education, 41(1), pp.91-115.

Characterization of Hamlet, Gertrude and Ophelia Essay

Hamlet is a character of extraordinary complexity and depth. No simple formula can serve to solve his mystery. A different Hamlet might have killed his uncle Claudius on the strength of the Ghost’s accusation, ascended the throne, married Ophelia and lived happily ever after . But such a typical hero was not likely to be of interest to Shakespeare. We can also say that in Hamlet Shakespeare presents a murderer and revenger who is both ruthless and reluctant and his death is the ultimate result of his being charged by the Ghost to carry out instructions which were offensive to his moral principles. Like other tragic heroes of Shakespeare he is also endowed with exceptional qualities like royal birth, graceful and charming personality among his own countrymen. He has a high intellectual quality as Ophelia observes: O what a noble mind is here overthrown! / The courtier’s, soldier’s, scholar’s eye, tongue, sword, / Th’ expectancy and rose of the fair state ,/ The glass of fashion , and the mould of form ,/ Th’ observed of all observers. [Act III, Scene I] In spite of possessing all these high qualities which rank him above the other characters the flaw in his character leads to his downfall and makes him a tragic hero. The tragic flaw in the character of Hamlet is that he thinks too much and feels too much. He is often disturbed by his own nature of ‘self analyses’. What is required of Hamlet is prompt action, whereas he broods over the moral idealism which leads to his delay in action. When he gets an opportunity to kill Claudius, he puts aside the thought because he cannot strike an enemy while he is at prayer. Several causes account for his inaction . By nature he is prone to think rather than to act. He is a man of morals and his moral idealism receives a shock when his mother remarries Claudius after his father’s death. Chance too plays an important part in shaping his character. Chance places him in such a position in which he is incapable of doing anything. He becomes inconsistent and is no longer a person who reaches a conclusion only by reasoning. Like other tragic heroes Hamlet too has to face conflict, both internal and external. The internal conflict is between his moral scruples and the act of revenge which he is called upon to perform. Love of his father, the dishonor of his mother and the villainy of his uncle prompt him to take revenge while his nobility, his moral idealism, his principles and his religion revolt against such a brutal act. The result is that, torn within himself, he suffers mental torture. Hamlets wants to take revenge against Claudius, the murderer of his father, the usurper of his rights to the throne and the seducer of his mother . In Hamlet Shakespeare presents a revenger who is both ruthless and reluctant . As a revenger he must act, on behalf of outraged virtue, to restore a violated order, set right what is ‘out of joint’. But the act he is impelled to do, involves him in evil of the kind which he would punish. As the ruthless revenger he exemplifies in his own person the evil which is inseparable from the good in human nature; as the reluctant revenger he can symbolize the good’s abhorrence of it. As compared to Fortinbras and Laertes, Hamlet is slow in taking revenge because of his habit of thinking long and deep. Bradley clearly describes this condition and says he suffered from melancholia, a pathological state which may well develop into lunacy. (p. 121) There is an another aspect of Hamlet’s characterization i.  e. his madness. T. S Eliot argues that ‘the madness of Hamlet lay in Shakespeare’s hand; in the earlier play a simple ruse, and to the end, we may presume, understood as a rule by the audience. For Shakespeare it is less than madness and more than feigned. ’ (p. 102) By pretending to be mad, Hamlet kept open the safety valve and could speak order to relieve the pressure on his mind. This is what T. S Eliot means when he uses the words â€Å"more than feigned. † Samuel Johnson (1765) also considers his madness as fabricated even in his (Hamlet’s) treatment of Ophelia. Johnson says in this regard, ‘He plays the madman most, when he treats Ophelia with so much rudeness, which seems to be useless and wanton cruelty. ’ (Johnson, 1765) Shakespeare’s characterization of Gertrude and Ophelia in Hamlet is paradoxical as it challenges as well as complements the contemporary social traditions and norms. Gertrude is the best example of this paradox that is manifested through her extraordinary supremacy over all the major characters of Hamlet, her influence in the court matters and state affairs and her blind obedience to Claudius. Ophelia is also active in her domestic domain but her interest are restricted to amorous and matrimonial maters only and they are further directed by his father Polonius and brother Laertes. She is an epitome of traditional feminist expressions of the age that require chastity, compliance and acceptance of male dominancy from women. Ophelia remains passive in the domestic and emotional domain. Ophelia has no identity of her own and all her domestic and amorous matters are directed by her father. Polonius endeavors to fashion the life and attitude of Ophelia according to his own wishes. He considers his desires as her desires and tries to tailor her approach by various means. Ophelia is further guarded by his brother against any potential threat to her chastity and virginity. At Ophelia’s entry into Hamlet, her brother, Laertes escorts Ophelia advising her on her relationship with Hamlet. So right from the very start, Ophelia is under the sway of Laertes and Polonius. So her character is in complete conformity with the traditional values of that time. Polonius always responds from a position of authority over Ophelia, emphasizing his power as the decision-maker for her. Both her father and brother have a self assigned task of directing Ophelia how to act properly in every domain of her life. Although Shakespeare has characterized Ophelia as inferior to male characters, but characterization of Gertrude has dual characteristic. Sometime it challenges the traditions of the conformist society and sometime it itself become conforms to the values of the society by acting passively.

Love and Soul Mate Essay

Knowing that I would get to spend the rest of my life with my best friend is the best feeling EVER! Even after being married for years, my love still grows every day! I know I am with my soul mate and still can’t believe we have made it and have overcome so much in our life Knowing that I would get to spend the rest of my life with my best friend is the best feeling EVER! Even after being married for years, my love still grows every day! I know I am with my soul mate and still can’t believe we have made it and have overcome so much in our life njkj kj kj Knowing that I would get to spend the rest of my life with my best friend is the best feeling EVER! Even after being married for years, my love still grows every day! I know I am with my soul mate and still can’t believe we have made it and have overcome so much in our lifeKnowing that I would get to spend the rest of my life with my best friend is the best feeling EVER! Even after being married for years, my love still grows every day! I know I am with my soul mate and still can’t believe we have made it and have overcome so much in our lifeKnowing that I would get to spend the rest of my life with my best friend is the best feeling EVER! Even after being married for years, my love still grows every day! I know I am with my soul mate and still can’t believe we have made it and have overcome so much in our life Knowing that I would get to spend the rest of my life with my best friend is the best feeling EVER! Even after being married for years, my love still grows every day! I know I am with my soul mate and still can’t believe we have made it and have overcome so much in our life

Virtual Network For Development Execution - Free Essay Example

Sample details Pages: 11 Words: 3393 Downloads: 5 Date added: 2017/06/26 Category Statistics Essay Did you like this example? A Mobile Ad hoc Network (MANET) is a self-configuring network that is formed and deformed on the fly by a collection of mobile nodes without the help of any prior infra-structure or centralized management (Xiao et al., 2006). These networks are characterized as infrastructure less, mobile, autonomous, multi-hopped, self-organized and self-administered, having dynamic topology and unpredictable traffic patterns etc. A great deal of research is being carried out to solve various issues of MANET. These issues include Routing, MAC Layer Issues, Power Management, Transport Protocol, Quality of Service, Billing, Addressing, Service Discovery, Data Management and Security, etc., (Sesay et al., 2004), (Quan et al., 2004) and (Royer et al., 2004). Don’t waste time! Our writers will create an original "Virtual Network For Development Execution" essay for you Create order One of the most important questions in MANET is the middleware Konark, designed specifically for discovery and discovery of services available around the vicinity of any node. A service can be any hardware, software or any other entity that a user might be interested to utilize and Service Discovery is the process of discovering the services based on user preferences. An efficient and scalable approach to service discovery can lead to the development a large number of potential applications. For example, in a vehicular ad hoc network, vehicles might be interested in knowing the services provided by a near by fuel station. Similarly, in a battlefield soldiers might be interested in sharing the situation about the whole battlefields. Due to the dynamic nature of MANET, there are always spatial and temporal variations in the availability of services. Hence a service discovery strategy should be highly robust, efficient and dynamic in nature. In this paper we have proposed an efficient and flexible approach to service discovery in MANET by extending the work of (Danta et al., 2004). Rest of the sections are organized as follows: first we will provide a review of existing approaches to service discovery. We will then discuss our approach to virtual network architecture. Then we will discuss about the proposed model. Then the Simulation result. Finally we will conclude the paper with future work. LITERATURE REVIEW The service discovery protocols that have been proposed in the literature can be classified as directory less (e.g.IBM DEAPspace, UPnP and Konark) or directory based architecture (e.g. Salutation, JINI, SLP) (Cho et al., 2005) SLP (Sesay et al., 2004), (Service Location Protocol, 1999) and represents the service by means of URL and attributes. JINI is based on Java and uses Interfaces and RMI mechanisms for service discovery process. Due to the lack of semantic information, the protocols can only perform exact matching of services using identifier and attributes. To support service discovery based on semantics, DReggie (Sesay et al., 2004) (an extension of JINI) is proposed. DReggie semantically represents the services by means of DAML and compares the service using a PROLOG reasoning engine. GSD (Quan et al., 2004) also describes the services semantically by means of DAML. They group all the services based on semantics for efficient discovery of services. In order to address heterogeneity of MANET, (Helal et al., 2003) proposed a middleware Konark, designed specifically for discovery and delivery of device independent services in ad-hoc networks. (Danta et al., 2004) Proposed a totally different approach to service discovery by extending AODV protocol and provided service discovery at network layer. As a result when a service discovery request is initiated to discover a service, a route is also established towards the service provider. Hence, when the client wants to use the service, a new route request is not required. VIRTUAL NETWORK ARCHITECTURE Virtual network is based on service-oriented architecture. Implementation of virtual network in the form of an extensible set of distributed services enables on-demand user-driven creation of logical communication space. Moreover, since both distributed applications and virtual network are based on the same architecture, distributed applications can manage the virtual network. Separation of logical and physical communication space is based on indirect service invocation. Each physical node that constitutes virtual network contains a locally installed Overlay Service. The Overlay Service is a special-purpose service that receives, transmits, and delivers the messages in the virtual network communication space. The locally installed Overlay Service receives the messages from the distributed programs executing on local node and delivers them to the Overlay Service on the target node. The Overlay Service executing on the target node delivers the messages to the target services on behalf of the calling distributed programs. In order to invoke application services or coordination mechanisms, distributed programs use target service WSDL document to generate the proxy for the target service. Service proxy contains the instructions for formatting the SOAP messages for interaction with the target service and target service communication parameters. Indirect service invocation is achieved by the modification of the proxy communication parameters. Physical address of target service contained in the WSDL document is modified and redirected to the physical address of the local Overlay Service. Additionally, service proxy puts the logical address of target service into the header of the SOAP message. The Overlay Service on the local node accepts the message from the distributed program, analyses logical addresses in the message header, and redirects the received message to t he Overlay Service on the target node. The Overlay Service on the local node determines the physical address of the target node based on the locally stored mapping relation. Mapping relation is stored in the Naming Table document. The Overlay Service on the target node contains the service proxies for all locally installed services. It selects the proxy for the target service and delivers the message to the given service on behalf of the calling program. The path of the message through the network is determined during the run-time according to the virtual network mapping relation. To enable secure invocation of services in logical communication space of virtual network, we introduce certain extensions to the SOAP message structure. Figure 1 shows the structure of a SOAP message used for secure service invocation in communication space of virtual network. Elementary SOAP message, often called SOAP envelope, consists of SOAP body and SOAP header. SOAP body contains application-specific data used for regular service invocation. SOAP header is an extensible data structure. We use the SOAP header extensions defined in the WS-Addressing and WS Security specifications. WS-Addressing elements contain the information about logical addresses of the invoked services. WS-Security elements contain the security-related information about the encrypted and digitally signed portions of the SOAP message, encryption keys, and cryptographic and hash algorithms. Since all information necessary for message processing are embedded into the message, the message is self-contained and independent of the physical transport protocol. Overlay Service consists of five modules: Local Interface Directory (LID), Router, Address Resolution Manager (ARM), Secure Communication (SC), and Membership Manager. The Local Interface Directory (LID) module contains the proxies of the locally installed services. Each time new service is installed on the local physical node, it should be registered in the LID module of the local logical node. During the service registration, the LID module builds the service proxy for the registered service. Service administrator or an application for automated service installation starts the service registration by providing the WSDL document of the installed service to the LID module. Based on the information contained in the WSDL document, the LID module compiles the executable code of the service proxy and embeds it into the local file system. The executable code of the service proxy is used by the Router module during the delivery of messages to the locally installed services. The Address Resolution Manager (ARM) module maintains the information about the virtual network mapping relation. Mapping relation is stored in the Naming Table document as the (logical address, physical address) value pairs. The ARM module adds the records into the Naming Table if new node is joining the virtual network, removes the records from the table if an existing node is leaving the network, and updates the table if logical node migrates from one physical location to the another one. Joining and removing logical nodes to and from the virtual network are user-driven processes. Migration of logical nodes among physical nodes is application-driven process that can be initiated by an application monitoring network conditions, node workloads, node failures etc. The Secure Communication (SC) module performs the encryption/decryption and the digital signing of the SOAP messages. To keep the messages self-contained and independent of the physical transport protocol, the SC module performs message-level security in accordance with the WS-Security specification. The Router module is a central module of the Overlay Service. It coordinates the process of the delivery of messages to the target services. The Router module accepts the messages on input interface and routes them to the specified destination. If message destination is a local node, the Router module delivers the message to the locally installed service. Otherwise, it forwards the message to the Overlay Service on the remote logical node. Central unit of the Router module is SOAP Parser. SOAP Parser analyses addressing information contained in the header of the received message. Using embedded XPath expression, SOAP Parser fetches the logical address of the destination node from the SOA P message header. Logical address of the destination node is compared with the logical address of the local node. If two addresses match, the Router module delivers the message to the local service. If they differ, it forwards the message to the remote node. The Router module sends the message to the SC module to decrypt the message content and to verify the digital signature. During the analysis of the plaintext message, the Router module fetches the service name from the message header. Then it contacts the LID module in order to retrieve the proxy for given service. Using service proxy, the Router module delivers the message to the target service. The interaction scenario if message is designated to the remote logical node. The Router module contacts the ARM module in order to retrieve the physical address of the destination node. Before forwarding the message to the remote node, the Router module sends it to the SC module to encrypt and digitally sign the message content. Using the retrieved physical address, the Router module forwards the message to the Router module of the destination nodes Overlay Service. Service-oriented architecture of the virtual network enables on-demand creation of logical communication space according to the requirements of distributed applications. Distributed application administrators can manage the membership of the virtual network by adding and removing logical nodes dynamically. To join the network, new logical node has to exchange the virtual network mapping relation with the existing nodes. The Membership Manager is a module of the Overlay Service that coordinates the exchange of the virtual network mapping relation among logical nodes. The administrator of new node provides logical and physical addresses of this node to the local Membership Manager module. This module contacts the ARM module of an existing node in order to retrieve currently valid virtual network mapping relation. It extends the retrieved mapping relation with its own (logical address, physical address) value pair and embeds it into local ARM module. The process of joining new node to the virtual network finishes with propagation of the new node mapping relation record to all remaining members of the virtual network. Reverse algorithm will be started if an existing node is leaving the virtual network. Virtual network provides a basis for the development of advanced mechanisms for managing portability, reliability, and performance of service-oriented applications. Basic elements of an execution environment for virtual network based applications are shown in Figure 2. Service Deployment and Discovery subsystem and Reliability and Performance Management subsystem utilize virtual network to perform application transparent service migration. Service Deployment and Discovery is a distributed system for remote on-demand installation and uninstallation of services. Reliability and Performance Management monitors operability and load of network nodes. If non-operational node or node under heavy load is detected, Reliability and Performance Management subsystem instructs Service Deployment and Discovery subsystem to migrate services from such node to node offering better performance. At the same time, Reliability and Performance Management subsystem updates the naming table of virtual netwo rk, redirecting the messages for same logical node to different physical location. PROPOSED MODEL 1. SERVICE DISCOVERY IN MANET: We are proposing an efficient approach to service discovery for MANET by extending the concept proposed in (Danta et al., 2004). Nodes will be using an extension of AODV routing protocol to search on demand for a service provider along with an appropriate route to access that service. We are extending the concept of (Danta et al., 2004) by allowing a node to not only pull the service provider information on-demand, but a node will also be pushing the service advertisements periodically along with the route information. The novelty of our strategy is that unlike most of the service discovery protocols (e.g. JINI, UPnP, Deapspace and SLP), an appropriate path towards the service provider is available after the completion of service discovery process. In addition to employing AODV, we are also explicitly pushing the service advertisement to adjacent nodes along with appropriate routing information. This information can be saved by adjacent nodes based on their preferences and can also be propagated ahead. So, in most of the cases, a service discovery SREQ request can be served from nodes local service table and doesnt need to be propagated on the network. The integration of service discovery with the network layer is motivated by the survey done. The development of a cross layer service discovery solution is always useful in the network of energy constrained mobile devices because: 1) putting service discovery at the network layer will reduce the control messages Overhead 2) less number of messages is exchanged among devices, hence processing overhead is reduced. We believe that the periodic advertisements of services (as done in our approach) will not cause too much traffic overhead because a number of service advertisements can always be transmitted in a single message. Also, for each service discovery, service discovery and route determination is done in a single request. Hence, less number of messages is exchanged among nodes. However, the disadvantage of our approach is that it is dependent on routing protocol and can work only for AODV routing protocol. The details of our proposed approach in pseudo code are described. Every node will maintain a Routing Table to hold routing information and a Service table to maintain information about the services provided by it and other nodes along with other information like the life time of the services, the provider of the service etc. The nodes will periodically broadcast the services provided by it to its peer nodes by means of a message UPDATE_SERVICE_TABLE (UST). The message contains the service advertisements along with the routing information corresponding to the provider of each service. The receiving node can store the service advertisements it heard from its neighbour based on its preferences and interests. In addition, to avoid network congestion, if a node hears a service advertisement it reschedules its broadcast at a later time to avoid network congestion. If a node wants a service, it will first of all check its service table for a possible match. If a service is found in the service table, node can immediately requests the provider for the desired service. However, if no appropriate service provider is found in the local service table, a service discovery request SREQ will be issued to find out a service provider for this service. The SREQ is served based on Ad hoc On Demand Distance Vector Routing Protocol (Danta et al., 2004). The SREQ message is propagated along the network. Any node receiving the SREQ message will first check in its service table for corresponding service. If a match is found, an appropriate reply SREP message will be generated. If no match is found, the intermediate nodes will propagate the message SREQ to adjacent neighbours. In addition to that, it will cre ate a temporary reverse route towards source of the message. When a node receives an SREP message, it will check its routing table, delete the corresponding temporary reverse route and create a forward entry towards the destination. The node will then send the SREP message towards the source. The RREP message will contain complete details of the services it provides. 2. SERVICE ORIENTED COMPUTING Virtual computing for service-oriented applications introduces a level of indirection between distributed application and physical network. Virtual computing establishes logical communication space on top of physical network with an application-level defined addressing scheme. Distributed programs that implement coordination logic of distributed application are developed in logical communication space of virtual computing. Instead of addressing physical locations of application services and coordination mechanisms, they use logical addresses defined by virtual network computing. Using logical addressing, distributed application is logically separated from the physical network. Logical separation of distributed application and physical network enables application transparent migration of services, because distributed application uses logical service distribution. During the application execution, virtual network masquerades the changes in the physical locations of services from the coordination logic of distributed application. Organization of the virtual network is shown in Figure 4. Virtual network consists of logical nodes. Logical nodes are services that virtualize physical nodes into application-level controlled resources. Application-level control of physical nodes is enabled through application-driven management of virtual network mapping relation. Mapping relation determines the arrangement of logical nodes over physical nodes. Virtual network computing mapping relation allows the assignment of arbitrary number of logical nodes to the single physical node. Many-to-one characteristic of mapping relation enables the adjustment of virtual network computing to arbitrary configuration of physical network. Adjustment of the mapping relation during the application setup enables portability of distributed applications between different working environments, regardless of available number of network nodes and their physical addresses. Runtime adjustment of the mapping relation enables application transparent migration of services, which can be useful for managing the reliability and performance of distributed application. SIMULATION RESULTS To simulate our approach, we have developed our own simulation software. The simulator creates n nodes dynamically and links them randomly. Every node is randomly chosen to be either capable of storing or not storing advertisements. Nodes are randomly assigned a number of services. While simulation is running, after every half second, a random number of requests are generated and based on an improbability of 0.5 either a link is randomly created or broken. We have compared the results based on Request Acquisition Latency i.e. the time duration in which a service discovery request is initiated and the service discovery process is completed. The result when no service advertisement is broadcasted periodically with the result when broadcast capability is added. The situation when 50 nodes were simulated with a total of 25 services available on the network. In this situation, 174 requests were generated in a simulation time of 30 seconds. When no broadcasting was done 147 requests were replied with request acquisition latency between replied in between 0-0.2s. But when broadcasting was done, the 154 requests were replied in between 0-0.2s. This shows that by adding broadcasting functionality, performance of service discovery strategy has improved. Similarly in the case of 100 nodes, we can see that broadcasting of service advertisements has improved the request acquisition latency. CONCLUSION In this paper, we propose a model for development and execution of service-oriented applications based on virtual computing in mobile ad hoc network. The proposed approach is very flexible, efficient and can be adopted to work in any environment. Advanced mechanisms built upon the virtual network utilize logical communication space and service migration to provide distributed application portability, reliability, and performance. Virtual network computing consists of a set of distributed overlay services capable of receiving, transmitting, and delivering messages on behalf of application services. Service-oriented architecture of the virtual network enables user and application-driven management of logical communication space. As part of our future work, we plan to extend the virtual network computing infrastructure with an application-level routing procedure for anonymous communication to preserve the privacy of service providers and consumers. Furthermore, we plan to upgrade the virtual network with an extensible security framework that allows user and application-driven customization of the service access control, service usage tracking, and communication security by integrating custom developed security services into the virtual network. ACKNOWLEDGEMENT We wish to thank Mr. I. Jayaram ­Ãƒâ€šÃ‚ ­an, Assistant Librarian, Anna University, Coimbatore for providing the literature and Mr. Babu, Head, Department of CSE, Kings Engineering College for encouraging us to carryout research activity.