Essay --

2. Critical Literature ReviewWe relate the methods with prise to the criteria. The plan of the suggested approach is replacement, peignoir and migration.2.1Replacements of Legacy SystemsReplacement is not matchless of the policies. It may make sense to complete reshape of the legacy carcass from scratch. Reshaping the application from scratch is costly risky and metre overpowering, but has a technical thing that it fulfills the organizations demands by giving a solution jibe to need and demand.Replacement can take place either by a strategy or increment both last(predicate)y. If the legacy system has defined structures so replace it incrementally. 2.2Wrapping StrategiesThe wrapping is another approach used for the implementation of SOA from legacy code. The useful legacy code is sticked with code wrapper to be interconnected into an SOA system if the legacy system has a high business note value and good quality code, wrapping can be a good option. The problematic thing i n this approach is that it does not change the heavy features of the legacy applications that are being integrated. Wrapping will not authorize problems already present, such as problems in maintenance and Upgrading. In more cases, studying the internals of the legacy system is important and white-box modernisation tools are required.2.3Overview of wrapping techniquesSneed 11, 12 proposed a tool supported method for maintaining legacy code in spite of appearance an SOA environment. Legacy code Segments that accomplish a desired service or data reform are identified using Clustering tools and a new component is built by them. The new component is set(p) a WSDL interface, and a SOAP framework is used. The technique has been demonstrated by wrapping a COBOL calendar function extracted from the legacy ... ...antage is that it is time consuming skilled resources are necessary for this and source code is required. There is slake no general migration technique that can be applied th at solves all of the problems that a developer may face. The required goal can be achieved by combining two or more modernization strategies according to the advantages and disadvantages of every strategy in the context. The reuse of legacy system components and their exposition as services are not always easy. In certain situations their exposition, as services will have an increased risk and a greater cost than their replacement completely with a new SOA architecture. The problem of modernization of legacy system has no perfect solution. Choosing a strategy is ground completely on the objectives of the SOA architecture the budget and resources available and required time to achieve the project.