Software Architecture Case Study: Applying Layer in SyncFree

Transcription

1 Software Architecture Case Study: Applying Layer in SyncFree Chien-Tsun Chen Department of Computer Science and Information Engineering National Taipei University of Technology, Taipei 06, Taiwan May This talk introduces how to apply the layer architecture in an open source data synchronization application- SyncFree Layer Review Introduce to SyncFree Layer Design Connect to OOAD Process

2 References (/2) References (2/2) (optional) 2

3 Layer Review Layer Introduce to Review SyncFree Layer Design Connect to OOAD Process What is layering? Layering is a technique to break a complicated (software) system in a organized way. AP 3

4 How many layers does an enterprise application need? Presentation Display of information, handling of user request Domain Logic that is the real point of the system Data Source Communication with databases, messaging systems, transaction managers You should decide where to run your layers in a distributed environment 4

5 Other layering schemes (/3) Other layering schemes (2/3) 5

6 Other layering schemes (3/3) You can draw layer diagram in this way 6

7 What is the difference between layers and tiers? Message Presentation Layer E'' 5. report AppWin Application Layer E' 4. wrap GameServer Service Layer E 2. rethrow 3. recover Browser (IE) Web (JSP) AP Server (EJB Server) Database Messaging System Transaction Management Acceptor Other Packages JVM E. throw Layer (vertical) Tier (horizontal) Layer Review Introduce to SyncFree Layer Review Layer Design Connect to OOAD Process 7

8 SyncFree is a file synchronization application 家中 辦公室 出差 SyncFree 使用案例 : 同時解決資料同步與資料備份的問題 () 啊, 電腦當機, 重新開機還是進不去 Windows! 資料都沒備份 資料總算是可以讀出來了, 但是有沒有什麼好方法可以解決資料使用與備份的問題? 聽說有一個軟體叫 SyncFree 還滿好用的, 可以解決你的問題 8

9 SyncFree 使用案例 : 同時解決資料同步與資料備份的問題 (2) 你可以買一個外接式硬碟, 在你的電腦上安裝 SyncFree, 讓 SyncFree 定時幫你將資料同步到外接式硬碟中 這麼好 可是, 還要花錢買軟體 SyncFree SyncFree 使用案例 : 同時解決資料同步與資料備份的問題 (3) SyncFree 是免費的自由軟體, 你可以自行下載安裝使用 SyncFree 如果我回家的時候也要工作, 可是我不想把 notebook 帶回家, 那麼有什麼方法可以讓我保持家裡和公司資料的一致性嗎? 9

10 SyncFree 使用案例 : 同時解決資料同步與資料備份的問題 (4) 使用 SyncFree, 你可以直接透過網路來同步資料 SyncFree SyncFree 使用案例 : 同時解決資料同步與資料備份的問題 (5) 或是把外接式硬碟帶回家, 並在家裡的電腦安裝 SyncFree 同步資料即可 SyncFree 0

11 DV D SyncFree 使用案例 : 同時解決資料同步與資料備份的問題 (6) 傑克, 真是太神奇了 好, 我決定要用 SyncFree 要去哪裡下載? Scenario : use SyncFree at home 住家 00 Mbps Ethernet 2? 執行同步軟體????? 內接式硬碟桌上型電腦 A ( 支援 USB.x 介面 ) 內接式硬碟 USB.x 桌上型電腦 B ( 支援 USB.x 介面 ) 外接式硬碟 ( 支援 USB 2.0 與 IEEE 394 介面 )

12 DV D Scenario 2: use SyncFree at office 辦公室 00 Mbps Ethernet?????? 執行同步軟體 外接式硬碟 ( 支援 USB 2.0 與 IEEE 394 介面 ) IEEE 394 桌上型電腦 C ( 支援 IEEE 394 介面 ) 內接式硬碟 內接式硬碟筆記型電腦 D ( 支援 USB 2.0 介面 ) Scenario 3: use SyncFree over Internet SyncFree 2

13 SyncFeee s functional requirements include five use cases 新增同步設定 執行同步設定 使用者 Watcher 修改同步設定 瀏覽同步紀錄 刪除同步設定 SyncFeee s non-functional requirements: easy to use, easy to extend Easy to use Wizard interface, GUI and console mode New sync. methods are easy to add Simple Copy, Extract Copy, Synchronization, New file manipulation protocol are easy to add File, Http, Ftp 3

14 Layer Review Introduce to SyncFree Layer Review Layer Design Client uses Presentation Layer Connect to OOAD Process upcall Application Layer Domain Layer How to divide an application into layers? Common and domain specification layer architectures Network, Web, and Enterprise Apps. Domain experts Separation of concerns Application i vs. domain, strategy (algorithm) vs. mechanism Finding suitable abstraction/perspective 4

15 SyncFree s architecture: A layered architecture with upcall Client uses Presentation Layer upcall Controller Controller + Sync. services Application Layer Sync. services Domain Layer File manipulation File manipulation Version Version 2 Define interfaces between layers Application UI Application (service) Domain Client uses Presentation Layer :MainWin :SyncController :ISyncListMaker :IFileManipulate Application Layer upcall sync(profile) synclist = makesynclist(src, dest) list (source) Domain Layer list(dest) SeparateFourKinds OfSyncInfo (synclist) createdirectory copyfile deletefile deletedirectory 5

16 Allocating functions into layers (/2) Client uses Presentation Layer Application Layer upcall Domain Layer Allocating functions into layers (2/2) 6

17 SyncFree: Java SyncFree: Java Presentation Layer Application Layer Domain Layer Layer Review Introduce to SyncFree Layer Review Layer Design Connect to OOAD Process 7

18 Analysis Review At the end of elaboration phase, architecture baseline is established 8

19 Iterative Planning: Phase plan and iteration plan (Larman, chapter 36) System Inception Elaboration Construction Transition Iteration Iteration 2A Iteration 2B Iteration 2C Iteration 3A Iteration 3B Iteration 3C Iteration 3D Iteration 3E Iteration 3F Iteration 3G Iteration 4 Iteration Requirements Analysis Design Implementation Test TR:2004/03/0 D:2004/03/5 TR2:2004/06/0 D2:2004/06/5 TR3:2004//05 D3:2004//5 :Milestone review Dx: Delivery x TRx: Test Review NewProjectWizardForm WizardState SyncFilespecs Conceptual Diagram /2 ProfileManager Profile..* SyncTime MainWin ObjectSyncService SyncListMakerFactory SyncList AboutForm <<interface>> ISyncListMaker * SyncInfo <<subsystem>> ServiceLayer Domain AbstractSyncStrategy Presentation Application Package: CanThink.Framework.IO.FileManipulate SimpleCopyStrategy ExactCopyStrategy SynchronizeStrategy 9

20 Conceptual Diagram 2/2 FileManipulateFactory FolderList FileManipulateEventArgs * FolderInfo FileManipulateProtocol <<interface>> IFileManipulate FileFileManipulate HttpFileManipulate FtpFileManipulate* Domain Collaboration diagram : New Profile Update UI New Profile 5: FillListView :MainWin 3: AddProfile (pro) 4: Save :ProfileManager : ShowDialog 2: pro := MakeProfile :NewProjectWizardForm.: * [i =..5 ] Next.2: Finish.3: Close 20

21 Collaboration diagram : SyncNow Can use MOMSyncService also. SyncNow (Name) :MainWin 2: DoSync (pro) :ObjectSyncService : pro := GetProfile (Name) :ProfileManager.: pro := find (Name) :Profile 2.: slist := MakeSyncList(pro) 2.2: ClearAllSortedList 23:SpearateFourKindsOfSyncInfo 2.3: (slist) 2.4: CreateDirectory 2.5: CopyFile 2.6: DeleteFile 2.7: DeleteDirectory Design Review 2

22 免費 開放原始碼 容易使用 跨平台 跨網際網路 擴充性為 SyncFree 的設計目標 容易安裝與使用 (wizard 介面與 console 模式 ) 擴充性 ( 支援多種同步資料的方法 ) 跨網際網路 ( 支援 HTTP, FTP) ProfileManager Profile Find Patterns /7..* MainWin ObjectSyncService SyncListMakerFactory SyncList Façade* <<interface>> ISyncListMaker * SyncInfo <<subsystem>> Top Package::ServiceLayer AbstractSyncStrategy ts St t SimpleCopyStrategy ExactCopyStrategy SynchronizeStrategy 22

23 ProfileManager Profile Find Patterns 2/7..* MainWin ObjectSyncService SyncListMakerFactory SyncList <<interface>> ISyncListMaker * SyncInfo Strategy <<subsystem>> Top Package::ServiceLayer AbstractSyncStrategy ts St t SimpleCopyStrategy ExactCopyStrategy SynchronizeStrategy ProfileManager Profile Find Patterns 3/7..* MainWin ObjectSyncService SyncListMakerFactory SyncList <<interface>> ISyncListMaker Object Factory * SyncInfo <<subsystem>> Top Package::ServiceLayer AbstractSyncStrategy ts St t SimpleCopyStrategy ExactCopyStrategy SynchronizeStrategy 23

24 ProfileManager Profile Find Patterns 4/7..* MainWin ObjectSyncService SyncListMakerFactory SyncList Up Call <<interface>> ISyncListMaker * SyncInfo <<subsystem>> Top Package::ServiceLayer AbstractSyncStrategy ts St t SimpleCopyStrategy ExactCopyStrategy SynchronizeStrategy NewProjectWizardForm WizardState Wizard* Find Patterns 5/7 ProfileManager Profile..* MainWin ObjectSyncService SyncListMakerFactory SyncList <<interface>> ISyncListMaker * SyncInfo <<subsystem>> Top Package::ServiceLayer AbstractSyncStrategy SimpleCopyStrategy ExactCopyStrategy SynchronizeStrategy 24

25 MainWin ObjectSyncService Find Patterns 6/7 FileManipulateFactory i l F t FolderList FileManipulateEventArgs * FolderInfo FileManipulateProtocol <<interface>> IFileManipulate Strategy FileFileManipulate HttpFileManipulate FtpFileManipulate* MainWin ObjectSyncService Find Patterns 7/7 FileManipulateFactory i l F t FolderList FileManipulateEventArgs Object Factory * FolderInfo FileManipulateProtocol <<interface>> IFileManipulate FileFileManipulate HttpFileManipulate FtpFileManipulate* 25

26 Code Review (C# version) SyncController- DoSync 26

27 Upcall in ObjectSyncService (subject): defining events (/3) Client uses Presentation Layer upcall Application Layer Domain Layer Upcall in ObjectSyncService (subject): notifying observers (2/3) uses Client Presentation Layer upcall Application Layer Domain Layer notify 27

28 Upcall in MainWin (observer): Client defining callbacks (3/3) uses Presentation Layer upcall Application Layer Domain Layer callback functions FileFileManipulate 28

29 HttpFileManipulate Conclusion Software architecture in context: We have introduced SyncFree s layer architecture Connecting architecture to OOAD process Do we missing anything? The Dependency-Inversion Principle (inversion of control) Exception handling Testing and debugging Question? 29

30 (Optional) Outline SRP The Single Responsibility Principle OCP Then Open-Closed Principle LSP The Liskov Substitution Principle DIP The Dependency-Inversion Principle ISP The Interface-Segregation Principle 30

31 What is the Dependency-Inversion Principle? Definition a: high-level modules should not depend on low-level modules. Both should depend on abstractions. Definition b: abstractions should not depend on details. Details should depend on abstractions. This principle is at the heart of framework design A naive layering structure violates the Dependency-Inversion Principle Policy layer is sensitive to changes all the way down in the Utility layer. Dependency is transitive. 3

32 A more appropriate model: each of the upperlevel layers declares an abstract interface for the services that it needs PolicyLayer can be reused in any context that defines lower-level modules that conform to the PolicyServiceInterface The lower-level level layers are realized form the abstract interface the dependency has been inverted Not only the dependency, but also the ownership are inverted We often think of utility libraries as owning their own interfaces. But when the DIP is applied, the clients tend to own the abstract interfaces and that their servers derive from them. 32

33 Dependency inversion can be applied wherever on class sends a message to another Naive model of a Button and a Lamp Dependency inversion i applied to the Lamp More testable Summary of the Dependency-Inversion Principle DIP: High- and low-level level modules should depend on abstractions, not depend on each other. It is the inversion of dependencies that is the hallmark of good OO design. If a system s s dependencies are inverted, it has an OO design. Otherwise, it has a procedural design. 33

34 Profile 34

35 upcall SyncFree 採用 Layered Architecture Pattern 35

36 Defining abstraction for synchronization algorithms: what is the commonality? Defining abstraction for file manipulation despite the protocols: what is the commonality? 36

37 Defining abstraction for synchronization algorithms: what is the commonality? 37

38 Defining abstraction for file manipulation despite the protocols: what is the commonality? 38