Migration of a Chosen Architectural Pattern to Service Oriented ...
Migration of a Chosen Architectural Pattern to Service Oriented ...
Migration of a Chosen Architectural Pattern to Service Oriented ...
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Chapter 1Introduction1.1 BackgroundWith each passing year, more and more systems become obsolete. New technologiesare invented. The old systems become useless not only because <strong>of</strong> technicalchallenges, but also maintenance becomes more and more costly and complicated.Those issues may force companies <strong>to</strong> change their old system. This change can beachieved in two ways. The first way is <strong>to</strong> replace the existing system with a newone. However, the approach seems <strong>to</strong> be accurate, there is one very importantissue in the way: cost. Replacing the old system is very costly in terms <strong>of</strong> moneyand time, which is required <strong>to</strong> create a new system almost from the scratch [51].<strong>Migration</strong> <strong>of</strong> large projects is a serious and risky task that requires careful analysis<strong>of</strong> feasibility and required efforts [48]. An example <strong>of</strong> seriousness <strong>of</strong> migrationis provided by Scott Bolling [17]. He participated in migration <strong>of</strong> a system. Themigration had 25 unsuccessful migration attempts. The second approach is <strong>to</strong>migrate from old systems <strong>to</strong> new systems that use the newest s<strong>of</strong>tware developmentparadigms and follow the recent technologies.Available literature related <strong>to</strong> migration <strong>of</strong> legacy systems shows that legacysystems migrate not only <strong>to</strong>ward specific applications like Multi-tier Applications[27] or Client Server Applications [63]. The systems migrate also <strong>to</strong> meetapproaches in s<strong>of</strong>tware development like Object Based Environment [72] [51],Product Line [18] or <strong>Service</strong> <strong>Oriented</strong> Architecture [75][48].<strong>Migration</strong> <strong>to</strong> Object Based Environment can be performed with help <strong>of</strong> wrappingtechnology. Application <strong>of</strong> the technology results in creation <strong>of</strong> wrappers. Awrapper is a new code that encapsulates the legacy code. The wrappers are called”Legacy objects”. Those objects provide interfaces that enable usage <strong>of</strong> wrappedcode. Application <strong>of</strong> this approach supports reimplementation <strong>of</strong> selected LegacyObjects independently. The legacy objects remain unchanged until a new andequivalent implementation is ready [51]. Wrapping technology distributes migrationeffort over time.1
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