Tan Zhen Yong - Project Portfolio

Start of Extract [from: User Guide]

This is a simple way of backing up the current state of the address book before the user performs a complex series of commands that may not be undoable.

Start of Extract [from: Developer Guide]

Aspect: Type of command implemented
Alternative 1 (current choice): Command
Pros: Simple to implement; undo / redo mechanism does not need to know how to interact with Storage to undo a backup.
Cons: Accidental backups may be invoked, potentially overwriting an existing backup.
Alternative 2: UndoableCommand
Pros: Possible to undo a backup; prevents accidental overwrites of an existing backup.
Cons: The undo / redo mechanism needs to be extended to be able to redo / undo backups, increasing interaction with the Storage component.

Aspect: Location of backup file
Alternative 1 (current choice): data/intelli.xml.bak
Pros: Easy to locate for the user; file is always in a predictable location.
Cons: Accidental backups may be invoked, potentially overwriting an existing backup in the same location.
Alternative 2: Add a timestamp to the backup filename
Pros: Will not overwrite existing backups, can serve as rudimentary version control mechanism.
Cons: User may not be aware of how many backups they have created; might cause a lot of backups to exist, creating confusion.

Aspect: Interaction between Command and StorageManager
Alternative 1 (current choice): Extend setData() to also recieve the Storage component
Pros: In line with existing architecture, does not introduce global state.
Cons: All invocations of setData() have to be changed; but only one command uses StorageManager, creating unnessasary busywork.
Alternative 2: Make StorageManager a Singleton
Pros: Does not affect existing commands; easy for BackupCommand to access.
Cons: Changes architecture of app, introduces more global state.

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Start of Extract [from: User Guide]

If information was added that may be too sensitive to be in the address book, clearing the command history ensures that the information is permanently removed.

Start of Extract [from: Developer Guide]

Aspect: Type of clearHistory command
Alternative 1 (current choice): Command
Pros: History is permanently cleared.
Cons: Impossible to undo accidental clearing of history, meaning all undoable changes become permanent.
Alternative 2: UndoableCommand
Pros: Possible to undo accidental clearing of history.
Cons: Since the most likely use for clearHistory is for it to be permanent, having it be undoable is counterintuitive to user expectations.

Aspect: Behaviour of clearHistory command on empty history
Alternative 1 (current choice): Clear anyway and indicate success
Pros: Simple to implement, no additional cases to take care of.
Cons: May be confusing to declare an empty history cleared.
Alternative 2: Indicate that history is empty.
Pros: Clearer messages about the state of the command history.
Cons: More complex to implement, and the end result of clearing an empty history also results in a cleared history, meaning the user intention of clearing their history is fufilled regardless of which alternative is chosen.

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Start of Extract [from: User Guide]

A custom tag colour that is saved reduces confusion for the user and allows them to quickly identify people with the same tag quickly, especially if the address book is large.

Start of Extract [from: Developer Guide]

Aspect: Persistence mechanism for tag colours
Alternative 1 (current choice): Store in UserPrefs as GUI settings
Pros: Tag colour settings remain the same for different data files, more consistency for user.
Cons: Storage has to be extended to provide access to UserPrefs for Command, difficult to signal a tag colour change when no user data is modified.
Alternative 2: Store in XmlAddressBookStorage as user data.
Pros: Easier to signal tag colour changes to GUI.
Cons: Tag colours will be different depending on which data file is loaded, leading to inconsistency and confusion for the user.

Aspect: Location for storing tag colours
Alternative 1 (current choice): Global tag colour mapping
Pros: No possibility of two identical tags having different colours, easy to update all instances of one tag with new colour.
Cons: More difficult to indicate a tag colour change to the GUI as no user data is visibly modified+ Alternative 2: Each tag stores its own colour.
Pros: Easier to signal tag colour changes to GUI.
Cons: Possibility of identical tag containing different colours.

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Start of Extract [from: User Guide]

This allows PIs to find the most confident way in which two people are related in a relationship path. For example, a PI may use someone they know very well to contact someone they don’t via the least amount of people possible.

Start of Extract [from: Developer Guide]

Aspect: Implementation of modified Dijkstra’s
Alternative 1 (current choice): Extend the current Dijkstra algorithm in the GraphStream library.
Pros: Easy to implement since most of the algorithm is the same, easy to use with graph display.
Cons: Relies on external library for correctness, unable to guarantee correctness of external library.
Alternative 2: Implement modified Dijkstra’s from scratch.
Pros: Can ensure testablity and reliablity of own code, less reliance on external correctness.
Cons: More difficult implementation as it is from scratch, less compatability with graph display means integration between display and algorithm has to be manually written.

Aspect: Access to GraphWrapper from RelPathCommand
Alternative 1 (current choice): Make GraphWrapper a Singleton.
Pros: Easy to access from relPathCommand, no need to modify all commands like if setData() was extended.
Cons: Increases global state.
Alternative 2: Extend Command.setData() to take in GraphWrapper
Pros: Similar to how other components are allowed to interact with commands, better consistency.
Cons: Since the graph display is a GUI component, no straightforward way to have Command access it. Also means that every command’s setData() has to be modified to take into account an external parameter.

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Start of Extract [from: User Guide]

This allows PIs to quickly see who is related to a specific person, and filter out extraneous information.