B2B4U Developer Guide

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Acknowledgements

• This project is based on the AddressBook-Level3 project created by the SE-EDU initiative.

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Setting up, getting started

Refer to the guide Setting up and getting started.

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Design

Architecture

The Architecture Diagram given above explains the high-level design of the App.

Given below is a quick overview of main components and how they interact with each other.

Main components of the architecture

Main (consisting of classes Main and MainApp) is in charge of the app launch and shut down.

• At app launch, it initializes the other components in the correct sequence, and connects them up with each other.
• At shut down, it shuts down the other components and invokes cleanup methods where necessary.

The bulk of the app's work is done by the following four components:

• UI: The UI of the App.
• Logic: The command executor.
• Model: Holds the data of the App in memory.
• Storage: Reads data from, and writes data to, the hard disk.

Commons represents a collection of classes used by multiple other components.

How the architecture components interact with each other

The Sequence Diagram below shows how the components interact with each other for the scenario where the user issues the command delete 1.

Each of the four main components (also shown in the diagram above),

• defines its API in an interface with the same name as the Component.
• implements its functionality using a concrete {Component Name}Manager class (which follows the corresponding API interface mentioned in the previous point.

For example, the Logic component defines its API in the Logic.java interface and implements its functionality using the LogicManager.java class which follows the Logic interface. Other components interact with a given component through its interface rather than the concrete class (reason: to prevent outside component's being coupled to the implementation of a component), as illustrated in the (partial) class diagram below.

The sections below give more details of each component.

UI component

The API of this component is specified in Ui.java

The UI consists of a MainWindow that is made up of parts e.g.CommandBox, ResultDisplay, ContactListPanel, StatusBarFooter etc. All these, including the MainWindow, inherit from the abstract UiPart class which captures the commonalities between classes that represent parts of the visible GUI.

The UI component uses the JavaFx UI framework. The layout of these UI parts are defined in matching .fxml files that are in the src/main/resources/view folder. For example, the layout of the MainWindow is specified in MainWindow.fxml

The UI component,

• executes user commands using the Logic component.
• listens for changes to Model data so that the UI can be updated with the modified data.
• keeps a reference to the Logic component, because the UI relies on the Logic to execute commands.
• depends on some classes in the Model component, as it displays Contact object residing in the Model.

Logic component

API : Logic.java

Here's a (partial) class diagram of the Logic component:

The sequence diagram below illustrates the interactions within the Logic component, taking execute("delete 1") API call as an example.

How the Logic component works:

1. When Logic is called upon to execute a command, it is passed to an AddressBookParser object which in turn creates a parser that matches the command (e.g., DeleteCommandParser) and uses it to parse the command.
2. This results in a Command object (more precisely, an object of one of its subclasses e.g., DeleteCommand) which is executed by the LogicManager.
3. The command can communicate with the Model when it is executed (e.g. to delete a contact).
   Note that although this is shown as a single step in the diagram above (for simplicity), in the code it can take several interactions (between the command object and the Model) to achieve.
4. The result of the command execution is encapsulated as a CommandResult object which is returned back from Logic.

Here are the other classes in Logic (omitted from the class diagram above) that are used for parsing a user command:

How the parsing works:

• When called upon to parse a user command, the AddressBookParser class creates an XYZCommandParser (XYZ is a placeholder for the specific command name e.g., AddCommandParser) which uses the other classes shown above to parse the user command and create a XYZCommand object (e.g., AddCommand) which the AddressBookParser returns back as a Command object.
• All XYZCommandParser classes (e.g., AddCommandParser, DeleteCommandParser, ...) inherit from the Parser interface so that they can be treated similarly where possible e.g, during testing.

Model component

API : Model.java

The Model component,

• stores the contact list data i.e., all Contact objects (which are contained in a UniqueContactList object).
• stores the currently 'selected' Contact objects (e.g., results of a search query) as a separate displayed list which is exposed to outsiders as an unmodifiable ObservableList<Contact> that can be 'observed' e.g. the UI can be bound to this list so that the UI automatically updates when the data in the list change.
• stores a UserPrefs object that represents the user’s preferences. This is exposed to the outside as a ReadOnlyUserPrefs object.
• does not depend on any of the other three components (as the Model represents data entities of the domain, they should make sense on their own without depending on other components)

Each Contact also carries:

• a stable UUID (persisted in JSON), used when notes store cross-references to other contacts; commands that resolve @INDEX in note text use the displayed contact list at parse time.
• optional LastContacted for when the contact was last reached (flexible user phrasing, e.g. relative or absolute dates).
• LastUpdated, always present (LocalDateTime), typically set to “now” when a contact is added or edited through the usual code paths; used for ordering and display logic.
• a list of Note values: plain text plus an optional reminder; after parsing, stored text may contain @{UUID} cross-references to other contacts. Note command feedback uses Messages.formatNoteOutput (which uses Contact.getNotesString()); the GUI can resolve references when rendering (e.g. NoteLabel).
• a set of Tag instances; in practice some entries are RankedTag (a subclass of Tag) for ranked friend tags—the class diagram shows only Tag to keep the overview simple.

Implementation detail (omitted from the model diagram): both LastContacted and optional note reminders are represented using TimePoint from seedu.address.commons.core.timepoint for parsing and comparing those time phrases.

JsonAdaptedContact persists lastUpdated, lastContacted, and notes alongside the other contact fields.

Storage component

API : Storage.java

The Storage component,

• saves both contact list data and user preference data in JSON format, and reads them back into corresponding objects.
• inherits from both AddressBookStorage and UserPrefStorage, which means it can be treated as either one (if only the functionality of only one is needed).
• depends on some classes in the Model component (because the Storage component's job is to save/retrieve objects that belong to the Model)

Common classes

Classes used by multiple components are in the seedu.address.commons package.

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Implementation

This section describes some noteworthy details on how certain features are implemented.

Remove field on empty edit

Overview

The edit command supports removing optional fields (phone, email, address, last contacted date) by supplying the field prefix with no argument. For example, edit 1 p/ removes the phone number from the first contact.

Implementation

The following sequence diagram shows how the edit field removal mechanism works when the user executes edit 1 p/:

1. EditCommandParser detects the empty value for the p/ prefix and sets clearPhone = true in the EditContactDescriptor.
2. EditCommand#createEditedContact() checks the clear flag — if clearPhone is true, updatedPhone is set to Optional.empty().
3. Before applying the edit, the command validates that the resulting contact retains at least a phone number or email address.
4. The updated contact is saved to the model.

Design considerations

Aspect: How empty prefix values are handled:

• Alternative 1 (current choice): Dedicated boolean clear flags (clearPhone, clearEmail, etc.) in EditContactDescriptor.

  • Pros: Explicit intent — distinguishes "remove field" from "no change". Avoids null/sentinel confusion.
  • Cons: Adds extra fields and logic to the descriptor.

• Alternative 2: Use a sentinel value (e.g. empty string) to represent removal.

  • Pros: Fewer fields — reuses the existing Optional<Phone> field.
  • Cons: Sentinel values are error-prone and harder to reason about. Validation logic in Phone, Email, etc. would need special-case handling.

Undo/redo feature

The undo/redo mechanism is facilitated by Snapshot. It stores key information regarding a Model, stored internally as an List<Pair<String, Snapshot>> named snapshots and an int snapshotPosition is used to indicate the Snapshot being used. Additionally, Model implements the following methods:

• saveSnapshot(String description) — Saves the current Model state with a name for user reference.
• moveSnapshot(int offset) — Moves the Model by offset number of snapshots in its history.

Given below is an example usage scenario and how the undo/redo mechanism behaves at each step.

Step 1. The user launches the application for the first time. The ModelManager, the instantiable version of Model, will be initialized with the initial snapshotPosition of 0, and a singular snapshot in snapshots representing the ModelManager's current state.

Step 2. The user executes add n/John …​ command to add a new contact. The add command calls Model#saveSnapshot(feedback), where feedback is the string in the CommandResult from executing the AddCommand, "New contact added: John…​", thus a snapshot of the ModelManager after the add n/John…​ command executes to be saved in snapshot, and the snapshotPosition is incremented.

Step 3. The user executes delete 7 to delete the 7th contact which happens to be the most recently added contact. The delete command also calls Model#saveSnapshot(feedback), causing another snapshot to be saved into snapshots.

Step 4. The user now decides that deleting the contact was a mistake, and decides to undo that action by executing the undo command. The undo command will call Model#moveSnapshot(-1), which will decrement snapshotPosition, and restores ModelManager with data given by the snapshotPosition-th snapshot.

The following sequence diagram shows how an undo operation goes through the Logic component:

Similarly, how an undo operation goes through the Model component is shown below:

The redo command does the opposite — it calls Model#moveSnapshot(1). If snapshotPosition is less than snapshots.size() - 1, snapshotPosition is incremented, then the snapshotPosition-th snapshot is retrieved to restores the ModelManager to the state it represents.

Step 5. The user then decides to execute the command list. Commands that do not modify the address book, such as list, will usually not call Model#saveSnapshot() or Model#moveSnapshot(). Thus, the snapshotPosition remains unchanged.

Step 6. The user executes clear, which calls Model#saveSnapshot(). Since the snapshotPosition is not equal to snapshots.size() - 1, all snapshots after the snapshotPosition-th snapshot will be purged. Reason: It no longer makes sense to redo the delate 7 command. This is the behavior that most modern desktop applications follow.

The following activity diagram summarizes what happens when a user executes a new command:

Design considerations:

Aspect: How undo & redo executes:

• Alternative 1 (current choice): Saves a compact copy of the model.

  • Pros: Easy to implement.
  • Cons: May have performance issues in terms of memory usage even with reduced object size.

• Alternative 2: Save an 'undo/redo' version of each command.

  • Pros: Will use less memory (e.g. for delete, just save the contact being deleted).
  • Cons: We must ensure that the implementation of each individual command are correct.

{more aspects and alternatives to be added}

[Proposed] Data archiving

{Explain here how the data archiving feature will be implemented}

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Documentation, logging, testing, configuration, dev-ops

• Documentation guide
• Testing guide
• Logging guide
• Configuration guide
• DevOps guide

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Appendix: Requirements

Product scope

Target user profile:

• consultant of a medium-sized consulting or PR agency
• has a need to manage long term relationships with big companies and clients
• has a need to manage long term relationships with various services in order to best assist their clients
• prefer desktop apps over other types
• can type fast
• prefers typing to mouse interactions
• is reasonably comfortable using CLI apps
• tends to work by themselves
• does not share their computer with others

Value proposition: Allow better management of long term relationships with big companies and clients through a simple, unified interface. Provide users with quick, up-to-date access to clients’ data and relevant services necessary for quick and on-point responses.

User stories

Priorities: High (must have) - * * *, Medium (nice to have) - * *, Low (unlikely to have) - *

{More to be added}

Use cases

(For all use cases below, the System is the B2B4U and the Actor is the user, unless specified otherwise)

Use case: UC1 - Check User Guide

MSS

1. User requests user guide

2. B2B4U provides user guide

   Use case ends

Use case: UC2 - Add a contact

MSS

1. User requests to create a new contact with certain parameters

2. B2B4U saves the new contact

3. B2B4U displays confirmation that the new contact is saved

   Use case ends

Extensions

• 1a. The new contact is invalid

  • 1a1. B2B4U shows an error message

    Use case ends.

Use case: UC3 - View all contacts

MSS

1. User requests to list contacts

2. B2B4U shows a list of all stored contacts

   Use case ends.

Use case: UC4 - Delete a contact

MSS

1. User requests to view contacts (UC3)

2. User requests to delete a specific contact in the list

3. B2B4U deletes the contact

   Use case ends.

Extensions

• 1a. The list is empty.

  Use case ends.

• 2a. The given index is invalid.

  • 2a1. B2B4U shows an error message.

    Use case resumes at step 1.

Use case: UC5 - Filter contacts by criterion

MSS

1. User requests to list contacts which fulfill given criteria

2. B2B4U shows a list of all contacts which fulfill given criteria

   Use case ends.

Use case: UC6 - Sort contacts by criterion

MSS

1. User requests to list contacts sorted by a given criteria

2. B2B4U shows a list of all contacts in order of given criteria

   Use case ends.

{More to be added}

Non-Functional Requirements

1. Should work on any mainstream OS as long as it has Java 17 or above installed.
2. Should be able to hold up to 1000 contacts in storage.
3. Should always respond to user input within 250 milliseconds.
4. A user with above average typing speed for regular English text (i.e. not code, not system admin commands) should be able to accomplish most of the tasks faster using commands than using the mouse.
5. Should only be accessible to a single user.
6. Data should be stored locally and in a human editable text file.
7. Should work without requiring an installer.
8. Should work without reliance on a remote server.
9. Should only contain third-party frameworks/libraries/services which are free, open-source, and have permissive license terms (if any).
10. GUI should work well for standard screen resolutions 1920x1080 and higher, and for screen scales 100% and 125%.
11. GUI should be usable for resolutions 1280x720 and higher, and for screen scales 150%.
12. Should be packaged in a single JAR file of 100MB or less in size.

{More to be added}

Glossary

• Mainstream OS: Windows, Linux, Unix, MacOS
• JSON (JavaScript Object Notation): A lightweight text format used to store and transfer structured data.
• API (Application Programming Interface): A defined set of methods that allows one component of the system to interact with another component.
• GUI (Graphical User Interface): The visual interface through which the user interacts with the application, built using JavaFX.
• CLI (Command Line Interface): A text-based interface where users interact with the application by typing commands.
• Private contact detail: A contact detail that is not meant to be shared with others
• Command: A structured line of text entered by the user to instruct the application to perform a specific action.
• Contact: A single entry stored in the contact list, containing one or more pieces of contact information such as name, phone number, email, or address.
• Displayed list: A subset of contacts displayed after applying a search, filtering, or sorting operation.

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Appendix: Instructions for Manual Testing

Given below are instructions to test the app manually.

Launch and shutdown

1. Initial launch

   1. Download the jar file and copy into an empty folder

   2. Double-click the jar file Expected: Shows the GUI with a set of sample contacts. The window size may not be optimum.

2. Saving window preferences

   1. Resize the window to an optimum size. Move the window to a different location. Close the window.

   2. Re-launch the app by double-clicking the jar file.
      Expected: The most recent window size and location is retained.

Deleting a contact

1. Deleting a contact while all contacts are being shown

   1. Prerequisites: List all contacts using the list command. Multiple contacts in the list.

   2. Test case: delete 1
      Expected: First contact is deleted from the list. Details of the deleted contact shown in the status message. Timestamp in the status bar is updated.

   3. Test case: delete 0
      Expected: No contact is deleted. Error details shown in the status message. Status bar remains the same.

   4. Other incorrect delete commands to try: delete, delete x, ... (where x is larger than the list size)
      Expected: Similar to previous.

Saving data

1. Dealing with missing/corrupted data files

   1. Prerequisites: Ensure that app is closed. preferences.json and config.json files are present in the same folder as the jar file.

   2. Test case: Delete data file (if present) and launch the app.
      Expected: App loads with no contacts. A new data file is created when a contact is added.

   3. Test case: Corrupt data file (e.g. by adding random text to the file) and launch the app.
      Expected: App loads with no contacts. The data file is overwritten when a contact is added.