Migration of a Chosen Architectural Pattern to Service Oriented ...

More documents

Recommendations

Info

Chapter 5. Guidelines 136The migration process identified few technology related issues affecting themigration. The issues were following:1. Encapsulation – The project had very poor implementation that even didnot include encapsulation of properties of classes.All the properties were accessiblevia ..Lack of access methods (get /set)did not allow migrate classes as there were. Additional implementation ofaccess methods was enforced by openESB. In fact this is very minor issuebecause today Integrated Development Environments (IDE) allows generatingaccess methods automatically. The IDEs allow also to identify placesin the code where a property is used explicitly. Both features helped torefactor code in required scope.2. Redundant operations – Connection to a service requires creation of a serviceclient in the application. Netbeans supports this activity by generationof stubs of services, ports, connections, operations and messages stubs automatically.IDE will generate only stubs of classes that are inputs foroperations or that are building blocks of operation input message. So farso good, but the problem arises in special circumstances as it was withmigrated project, namely one of the classes extended the other (CrComputerextends CrAsset) and this sub class (CrComputer) was neither a partof any existing operation of Canonical Resource service nor a part of anymessage accepted by this service. So when a user wanted to pass CrComputerobject through an operation which takes CrAsset as an argument(what is possible thanks to polymorphism), it was impossible because astub for CrComputer was not created; consequently a user has no possibilityto use CrComputer stub at all. Creation of CrComputer stub manuallydoes not work either because the IDE recognizes changes and before run, itrebuilds generated classes, besides there is no guaranty that autogeneratedclient does not depend on any “behind the scene” configuration files. Theonly possible solution was to create a “doing nothing” operation that takesCrComputer as an input- this operation ensures that the missing stub isgenerated properly.3. Dependency refresh – IDE generates and refreshes automatically dependenciescreated during project development, at least in theory. It appearedseveral times that a part of removed dependency was left somewhere in aWSDL document, configuration file or somewhere else. Each case causedhard to find problems.4. Schema inclusion – XML schema allows to include other schemas from thesame or different namespace and use imported elements/complex types asown. The problem arises when a schema that imports other schemas isused in a WSDL document, this in turn is an input for automatic client
Chapter 5. Guidelines 137generation. OpenESB cannot parse such schemas and prompts informationthat included file was not found. The file exists, moreover it was includedvia Nebeans build-in menu. The way around is to copy content of includedschemas to a current schema but it is neither elegant nor easy to maintain,because each change to “base” schema requires copping of its content to thecurrent schema.5. Deprecated methods – since the migrated application was a few years old, itcontained a few deprecated methods related mainly to operation on dates.During project building a user is informed that there are some deprecatedmethods that may cause an error and this is only a warning, but whilethe project starts a method that calls a service and contains deprecatedmethods is simply skipped without any information. This is quite seriousproblem during migration, because it may occur that a significant part ofAPI is deprecated. The problem can be eliminated relatively easy whenan official API is used because the API provides not only information thata method is deprecated; it also provides information which method/classshould be used instead. Usage of non-official API does not guarantee suchinformation.6. Schema namespaces – produces the most serious technology related problem,which was observed during the migration and it is related to variablecoping. Normally coping can be done in two ways.(a) The output variable of one activity is copied/casted to input variableof the second activity. It corresponds to Variable1 =Variable2.(b) Each element of Variable2 to copied to Variable1 manually. It correspondsto Variable1.element1= Variable2.element1 etc.The problem appears when two variables (Variable2 extends Variable1) arecasted (1st way) but they are from two different namespaces . It shouldwork, but usually it does not [40]. According to official forum [41]: “Ourtype cast feature isn’t perfect yet. There are quite many restriction for usingit.” All the problems should be resolved in future versions (The problemoccurs with Netbeans 6.7.1). There are at least three possible workarounds.There are at least three possible workarounds. The first is to create a versionof operation for each Variable1 extension and invoke directly appropriateoperation; the second is to add a flag that will allow BPEL process toinvoke a proper operation. The last is to avoid different namespaces. Thefirst solution was tested and it works fine.Migration was finally accomplished according to the guideline, it occurred tobe more difficult task that it was expected. The difficulties did not arrive fromguidelines adaptation problems but they were technology related. The technology,
Page 1 and 2:
Master ThesisSoftware EngineeringTh
Page 3 and 4:
AbstractContext: Several examples o
Page 5 and 6:
List of Figures1.1 Research methodo
Page 7 and 8:
List of Tables3.1 Summary of archit
Page 9 and 10:
3.3.1 Definition of Pattern Languag
Page 11 and 12:
Chapter 1Introduction1.1 Background
Page 13 and 14:
Chapter 1. Introduction 3technique
Page 15 and 16:
Chapter 1. Introduction 5was notice
Page 17 and 18:
Chapter 1. Introduction 7do not pro
Page 19 and 20:
Chapter 1. Introduction 9Chapter 4
Page 21 and 22:
Chapter 2. Related Work 11This chap
Page 23 and 24:
Chapter 2. Related Work 13(b) Chara
Page 25 and 26:
Chapter 2. Related Work 15Figure 2.
Page 27 and 28:
Chapter 2. Related Work 17Drawbacks
Page 29 and 30:
Chapter 2. Related Work 19Figure 2.
Page 31 and 32:
Chapter 2. Related Work 21Advantage
Page 33 and 34:
Chapter 2. Related Work 23between a
Page 35 and 36:
Chapter 2. Related Work 252. Applic
Page 37 and 38:
Chapter 2. Related Work 274. Mediat
Page 39 and 40:
Chapter 2. Related Work 292.3 Summa
Page 41 and 42:
Chapter 3. Architectural Patterns 3
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Chapter 4. Service Oriented Archite
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96: Chapter 4. Service Oriented Archite
Page 113 and 114: Chapter 5. Guidelines 1035.1 Patter
Page 115 and 116: Chapter 5. Guidelines 105Descriptio
Page 117 and 118: Chapter 5. Guidelines 107Result Con
Page 119 and 120: Chapter 5. Guidelines 109ContextAn
Page 121 and 122: Chapter 5. Guidelines 111Result Con
Page 123 and 124: Chapter 5. Guidelines 113System’s
Page 125 and 126: Chapter 5. Guidelines 115ViewSchema
Page 127 and 128: Chapter 5. Guidelines 117ViewViewCo
Page 129 and 130: Chapter 5. Guidelines 119ViewViewCo
Page 131 and 132: Chapter 5. Guidelines 121ViewViewPr
Page 133 and 134: Chapter 5. Guidelines 123FrontendFr
Page 135 and 136: Chapter 5. Guidelines 125complicati
Page 137 and 138: Chapter 5. Guidelines 127Concluding
Page 139 and 140: Chapter 5. Guidelines 129UsecasesTh
Page 141 and 142: Chapter 5. Guidelines 131puter (ext
Page 143 and 144: Chapter 5. Guidelines 133Group 3 ma
Page 145: Chapter 5. Guidelines 135Output: Du
Page 149 and 150: Chapter 5. Guidelines 139(a) Fronte
Page 151 and 152: Chapter 5. Guidelines 141Figure 5.1
Page 153 and 154: Chapter 5. Guidelines 143Figure 5.1
Page 155 and 156: Chapter 5. Guidelines 145FrontendSc
Page 157 and 158: Chapter 6. Conclusion 147There are
Page 159 and 160: Chapter 6. Conclusion 149RQ.6 How t
Page 161 and 162: References[1] http://www.soa-manife
Page 163 and 164: References 153[22] Frank Buschmann,
Page 165 and 166: References 155[46] Dirk Krafzig, Ka
Page 167 and 168: References 157[67] Xiaohong Qiu. Bu
show all

Migration of a Chosen Architectural Pattern to Service Oriented ...

Create successful ePaper yourself

Delete template?

Save as template?