Developer Guide

• Acknowledgements
• Setting up, getting started
• Design
  • Architecture
  • UI component
  • Logic component
  • Model component
  • Storage component
  • Common classes
• Implementation
  • [Proposed] Undo/redo feature
    • Proposed Implementation
    • Design considerations:
  • [Proposed] Data archiving
• Documentation, logging, testing, configuration, dev-ops
• Appendix: Requirements
  • Product scope
  • User stories
  • Use cases
  • Non-Functional Requirements
  • Glossary
• Appendix: Instructions for manual testing
  • Launch and shutdown
  • Deleting a person
  • Saving data

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Acknowledgements

• {list here sources of all reused/adapted ideas, code, documentation, and third-party libraries – include links to the original source as well}

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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, PersonListPanel, 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 Person 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 person).
   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 address book data i.e., all Person objects (which are contained in a UniquePersonList object).
• stores the currently ‘selected’ Person objects (e.g., results of a search query) as a separate filtered list which is exposed to outsiders as an unmodifiable ObservableList<Person> 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 UserPref object that represents the user’s preferences. This is exposed to the outside as a ReadOnlyUserPref objects.
• 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)

Storage component

API : Storage.java

The Storage component,

• can save both address book data and user preference data in JSON format, and read 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.

[Proposed] Undo/redo feature

Proposed Implementation

The proposed undo/redo mechanism is facilitated by VersionedAddressBook. It extends AddressBook with an undo/redo history, stored internally as an addressBookStateList and currentStatePointer. Additionally, it implements the following operations:

• VersionedAddressBook#commit() — Saves the current address book state in its history.
• VersionedAddressBook#undo() — Restores the previous address book state from its history.
• VersionedAddressBook#redo() — Restores a previously undone address book state from its history.

These operations are exposed in the Model interface as Model#commitAddressBook(), Model#undoAddressBook() and Model#redoAddressBook() respectively.

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 VersionedAddressBook will be initialized with the initial address book state, and the currentStatePointer pointing to that single address book state.

Step 2. The user executes delete 5 command to delete the 5th person in the address book. The delete command calls Model#commitAddressBook(), causing the modified state of the address book after the delete 5 command executes to be saved in the addressBookStateList, and the currentStatePointer is shifted to the newly inserted address book state.

Step 3. The user executes add n/David …​ to add a new person. The add command also calls Model#commitAddressBook(), causing another modified address book state to be saved into the addressBookStateList.

Step 4. The user now decides that adding the person was a mistake, and decides to undo that action by executing the undo command. The undo command will call Model#undoAddressBook(), which will shift the currentStatePointer once to the left, pointing it to the previous address book state, and restores the address book to that state.

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#redoAddressBook(), which shifts the currentStatePointer once to the right, pointing to the previously undone state, and restores the address book to that state.

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#commitAddressBook(), Model#undoAddressBook() or Model#redoAddressBook(). Thus, the addressBookStateList remains unchanged.

Step 6. The user executes clear, which calls Model#commitAddressBook(). Since the currentStatePointer is not pointing at the end of the addressBookStateList, all address book states after the currentStatePointer will be purged. Reason: It no longer makes sense to redo the add n/David …​ 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 the entire address book.
  • Pros: Easy to implement.
  • Cons: May have performance issues in terms of memory usage.
• Alternative 2: Individual command knows how to undo/redo by itself.
  • Pros: Will use less memory (e.g. for delete, just save the person 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:

• NUS tutors teaching CS mods who want to deal with the contacts of students, tutors and course instructors in a specific course
• prefer desktop apps over other types
• can type fast
• prefers typing to mouse interactions
• is reasonably comfortable using CLI apps

Value proposition: proposes an efficient way for TAs to add, modify and access contact details of student, tutors, instructors for a specific course, which makes it more convenient to help students with learning, connect with other TAs and reach out to staff in case of unexpected situations.

User stories

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

Priority	As a …​	I want to …​	So that I can…​
* *	tutor	see usage instructions	refer to instructions when I forget how to use the App
* * *	tutor	add new contacts	keep the contact list updated with contact details and session
* * *	tutor	delete contacts by contact ID	remove contacts from the contact list in case they have
* * *	tutor	search contact list by name	locate details of contacts by name without having to go through the entire list
* *	tutor	search contact list by contact ID	locate details of contacts by contact ID without having to go through the entire list
* *	tutor	list all contacts from the course	view all contacts and their contact details and session in the contact list
* * *	tutor	list all contacts by session	view all contacts and their contact details in particular session in the contact list

{More to be added}

Use cases

(For all use cases below, the System is the TAConnect program and the Actor is the tutor, unless specified otherwise)

Use case: UC1 - Add a new contact in the contact list

MSS

1. Tutor enters add command including details of a contact.
2. TAConnect parses the command input.
3. TAConnect validates that the command is correctly formatted and all required fields are correctly updated.
4. TAConnect adds the new contact in the contact list.
5. TAConnect saves the updated contact list to the local data file.

6. TAConnect displays a success message showing details of the new contact.

   Use case ends.

Extensions

3a. TAConnect detects an error in the command (invalid type or incorrect format).

• 3a1. TAConnect shows an error message specifying the issue and correct format.

• 3a2. Tutor re-enters the command.

  Steps 3a1-3a2 are repeated until the type entered is correct.

  Use case resumes from step 4.

4a. TAConnect finds that the added contact already exists in the contact list.

• 4a1. TAConnect rejects the duplicate entry.

• 4a2. TAConnect shows an error message indicating that the added contact already exists.

  Use case ends.

5a. Storage operation fails due to I/O error.

• 5a1. TAConnect displays an error message indicating that data could not be saved.

  Use case ends.

5b. Storage file is corrupted.

• 5b1. TAConnect shows an error message indicating that the data file is corrupted.
• 5b2. TAConnect attempts to back up or recreate the storage file.
• Use case resumes from step 5 if recovery succeeds; otherwise, use case ends.

Use case: UC2 - Delete a contact in the contact list

MSS

1. Tutor enters list to view the current contacts and their indexes.
2. TAConnect shows the list of contacts with index numbers.
3. Tutor enters delete INDEX to remove the intended contact.
4. TAConnect validates that the INDEX refers to a contact in the displayed list.

5. TAConnect removes the contact from the contact list, saves the updated data, and confirms the deletion.

   Use case ends.

Extensions

3a. Tutor enters an INDEX that is not a positive integer.

• 3a1. TAConnect shows an error message describing the valid index format.

• 3a2. Tutor re-enters the command with a valid INDEX.

  Use case resumes from step 3.

4a. The specified INDEX does not correspond to any contact currently displayed.

• 4a1. TAConnect informs the tutor that the index is invalid.

  Use case resumes from step 3.

5a. Storage operation fails due to an I/O error.

• 5a1. TAConnect displays an error message indicating that the data could not be saved.

  Use case ends.

Use case: UC3 - Search contacts in the list by name

MSS

1. Tutor enters find KEYWORD to locate a contact.
2. TAConnect parses the command and checks that at least one keyword is provided.
3. TAConnect filters the contact list to contacts whose names contain the keyword(s).
4. TAConnect displays the filtered list to the tutor.

5. Tutor uses the displayed contact details to reach out to the intended person.

   Use case ends.

Extensions

2a. Tutor omits the keyword or enters only whitespace.

• 2a1. TAConnect shows an error message indicating that at least one keyword is required.

  Use case resumes from step 1.

3a. No contact matches the supplied keyword(s).

• 3a1. TAConnect shows a message indicating that no contacts were found.

  Use case ends.

5a. Tutor wishes to refine the search.

• 5a1. Tutor enters another find command with different keyword(s).

  Use case resumes from step 1.

Use case: UC4 - List all contacts in the course

MSS

1. Tutor requests to list all users as well as their contact types and session for the particular course

2. TAConnect shows a list of all users as well as their contact types and session for the particular course

   Use case ends.

Extensions

2a. The list is empty.

Use case ends.

Use case: UC5 - List all student contacts in a specific session

MSS

1. Tutor enters list s/SESSION to list student contacts for a specific session.
2. TAConnect parses the command input and validates that the session identifier is present and correctly formatted.
3. TAConnect filters the contact list to entries with tag student that match the specified session.

4. TAConnect displays the filtered list of student contacts for the specified session.

   Use case ends.

Extensions

2a. TAConnect detects an invalid command syntax or missing/incorrect session format.

• 2a1. TAConnect shows an error message specifying the issue and the correct format.

• 2a2. Tutor re-enters the command.

  Steps 2a1-2a2 are repeated until the data entered are correct.

  Use case resumes from step 3.

3a. No matching student contacts exist for the specified session.

• 3a1. TAConnect shows a message indicating no student contacts were found for that session.

  Use case ends.

4a. Storage operation fails due to a data retrieval or I/O error.

• 4a1. TAConnect displays an error message indicating that data could not be accessed.

  Use case ends.

Non-Functional Requirements

Performance requirements

1. Should execute core commands (i.e. add, delete, find) within 1 second under usual conditions.
2. Should be able to handle up to 2500 users and 250 sessions without a noticeable sluggishness in performance for typical usage.
3. Should automatically save after each successful modification command (i.e. add, delete) without affecting UI responsiveness.

Usability requirements

1. A tutor 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.
2. A new user should be able to learn and perform basic commands within 10 minutes under the help of user guide.
3. The user interface should provide consistent layout and feedback messages across all mainstream OSes.

Scalability requirements

1. The internal data structures (contact list) should efficiently support search and retrieval operations in O(n) time complexity.
2. Should allow easy addition of new commands without modifying existing core logic.

Other requirements

1. Should work on any mainstream OS as long as it has Java 17 installed.
2. All unit and integration tests should pass before release, maintaining at least 90% test coverage.

Glossary

• Contact ID: For students or tutors who are not full-time employees of NUS this is their matriculation number (eg. A01234567X). For tutors or instructors who are full-time employees of NUS, the TAConnect program will assign a contact ID with the format FTE-{INITIALS}, so a NUS full-time employee that has a name Betsy Crowe will have the contact ID FTE-BC. If multiple contacts have the same initials we will append a number, representing the number of times this initial has been used, in front, so if the contact ID FTE-BC already exists and another NUS full-time employee that has a name Bob Charlie is added, the contact ID will be FTE-BC2.
• Contact: The user’s name, contact ID, email and optionally a Telegram handle.
• Contact Type: The category of a contact, i.e. student, tutor, course instructor, staff
• Mainstream OS: Windows, Linux, Unix, Mac
• Session: A period of lab or tutorial during which tutor is responsible for delivering the class.
• Tutor: Teaching assistant in a NUS CS-coded course
• UI (User interface): The visual and interactive components of TAConnect through which users issue commands and receive responses.

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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.

3. { more test cases …​ }

Deleting a person

1. Deleting a person while all persons are being shown

   1. Prerequisites: List all persons using the list command. Multiple persons 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 person 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.

2. { more test cases …​ }

Saving data

1. Dealing with missing/corrupted data files

   1. {explain how to simulate a missing/corrupted file, and the expected behavior}

2. { more test cases …​ }