Developer Guide

• Acknowledgements
• Introduction
• Setting up, getting started
• Design
  • Architecture
  • UI component
  • Logic component
  • Model component
  • Storage component
  • Common classes
• Implementation
  • Borrow/return feature
    • Implementation
  • Find book feature
    • Implementation
• 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
  • Adding a book
  • Deleting a book
  • Editing a book
  • Deleting a person
  • Saving data
• Appendix: Planned Enhancements

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Acknowledgements

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

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Introduction

• This Developer Guide documents the architecture and design of ExpressLibrary, along with some advanced information about the implementation details of ExpressLibrary’s features.

• The Developer Guide is written to aid present and future librarians, who may be technically gifted, in extending ExpressLibrary features by providing them the necessary knowledge on how ExpressLibrary works.

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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 has two classes called Main and MainApp. It is responsible for,

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

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

The rest of the App consists of 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.

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 deletePerson 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, BookListPanel, 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 or Book object residing in the Model.

Logic component

API : Logic.java

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

How the Logic component works:

1. When Logic is called upon to execute a command, it uses the ExpressLibraryParser class to parse the user command.
2. This results in a Command object (more precisely, an object of one of its subclasses e.g., AddCommand) which is executed by the LogicManager.
3. This results in a Command object (more precisely, an object of one of its subclasses e.g., AddPersonCommand) which is executed by the LogicManager.
4. The result of the command execution is encapsulated as a CommandResult object which is returned back from Logic.

The Sequence Diagram below illustrates the interactions within the Logic component for the execute("deletePerson 1") API call.

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 ExpressLibraryParser class creates an XYZCommandParser (XYZ is a placeholder for the specific command name e.g., AddPersonCommandParser) which uses the other classes shown above to parse the user command and create a XYZCommand object (e.g., AddPersonCommand) which the ExpressLibraryParser returns back as a Command object.
• All XYZCommandParser classes (e.g., AddPersonCommandParser, DeletePersonCommandParser, …) 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 ExpressLibrary data i.e., all Person objects (which are contained in a UniquePersonList object) and all Book objects (which are contained in a UniqueBookList).
• 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. Similar process for Book objects as well.
• 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 express library data and user preference data in json format, and read them back into corresponding objects.
• inherits from both ExpressLibraryStorage 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 expresslibrary.commons package.

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Implementation

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

Borrow/return feature

Implementation

The borrow feature will allow the user to mark a book as borrowed by a person. Similarly, the return feature will allow the user to mark a book as returned to the ExpressLibrary by a person.

It implements the following commands:

• borrow PERSON_INDEX b/BOOK_INDEX d/DUE_DATE
• return PERSON_INDEX b/BOOK_INDEX

Given below is an example usage scenario of the borrow command:

The user executes borrow 1 b/2 d/23/11/2023 command to lend the 2nd book in the book list to the 1st person in the Person list.

The BorrowCommand class will first retrieve the Person object and Book object from the given indexes and create a copy of them (since they are immutable) called editedPerson and bookToBorrow.

Then, it calls borrowBook on editedPerson and passes in the Book object bookToBorrow. This will add the book to the person’s Set of books field. Similarly, the class also calls loanBookTo on bookToBorrow to update the book’s fields with the borrower, the borrow date (current date) and the due date details.

Given below is an example usage scenario of the return command:

The user executes return 2 b/1 command to return the 1st book in the book list from the 2nd person in the person list.

The ReturnCommand class will first retrieve the Person object and Book object from the given indexes and create a copy of them (since they are immutable) called editedPerson and bookToReturn.

Then, it calls returnBook on editedPerson and passes in the Book object bookToReturn. This will remove the book from the Person’s Set of books field. Similarly, the class also calls returnBook on bookToReturn to update and remove the person from the book’s borrower field as well as clear the borrow and due dates.

Find book feature

Implementation

Given below is an example usage scenario and how the findBook command progresses from step to step.

Step 1. The user launches the app and enters findBook The command to look for any books with the keyword The in its title (non case-sensitive). MainWindow#executeCommand() is called, which passes the control over to the Logic component by calling LogicManager#execute().

Step 2. ExpressLibraryParser#parseCommand is called to parse the given findBook command text, which calls FindBookCommandParser#parse to further parse findBook command text. This ultimately produces a FindBookCommand object. The logic manager then calls FindBookCommand#execute on the new object which passes control to the Model component.

Step 3. FindBookCommand#execute will call Model#updateFilteredBookList to update the FilteredList of books which is then reflected in the UI because BookListPanel#BookListPanel() constructor sets BookListPanel.fxml to be constantly viewing the book list. The Model component then passes control back to the Logic component.

Step 4. FindBookCommand#execute returns a CommandResult object to the LogicManager#execute, which then passes control back to the UI component.

Step 5. MainWindow#executeCommand then uses the CommandResult to display feedback to the user on the UI which states: “{Number of books that match keyword} books found!”

The following sequence diagram shows how the findBook operation works:

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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:

• Has a need to manage a significant number of books and library users.
• Has a need to quickly access a particular book or person.
• Has a need to track if due dates of books borrowed are approaching/expired.
• Can type fast.
• Prefers typing to mouse interactions.
• Is reasonably comfortable using CLI apps.

Value proposition: Manage users and books faster, quickly find users or books faster than a typical mouse/GUI driven app.

User stories

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

Priority	As a …​	I want to …​	So that I can…​
* * *	librarian	add a new book that has not been added in the app	track the status of the new book
* * *	librarian	edit the details of a specific book	track any changes to the book
* * *	librarian	delete a book	not track it if the book is no longer in the library
* * *	librarian	have the data automatically saved in hard drive	refer to the data in the future
* *	librarian	be able to keep a record of all the people who have borrowed books	better manage the library
* *	librarian	add the book to the contact details of the person who borrowed them	rent the book out while keeping track of the book and the due date
* *	librarian	remove a book from a patron if the patron has returned the book	allow the book to be borrowed by other patrons
*	advanced librarian	edit the data file	adjust the data to suit my needs

Use cases

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

Use case: Delete a person

MSS

1. User requests to list persons.
2. ExpressLibrary shows a list of persons.
3. User requests to delete a specific person in the list.

4. ExpressLibrary deletes the person.

   Use case ends.

Use case: Book is borrowed by a person

MSS

1. User requests to list persons.
2. ExpressLibrary shows a list of persons.
3. User requests to add a book to a specific person in the list.

4. ExpressLibrary adds a book field to the person.

   Use case ends.

Extensions

• 2a. The list is empty.

  Use case ends.

• 3a. The given index is invalid.

  • 3a1. ExpressLibrary shows an error message.

    Use case resumes at step 2.

Non-Functional Requirements

1. Should work on any mainstream OS as long as it has Java 11 or above installed.
2. Should be able to hold up to 1000 persons and books without a noticeable sluggishness in performance for typical usage.
3. 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.
4. Should be able to load the application within 2 seconds.

Glossary

• Mainstream OS: Windows, Linux, Unix, OS-X
• ISBN: International Standard Book Number which is a commercial book identifier that is intended to be unique. Consists of 10 to 13 digits.

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Appendix: Instructions for manual testing

Given below are instructions to test the app manually.

Launch and shutdown

• 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 people and books.

• 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.

Adding a book

• Adding a book while all books are being shown.

  1. Test case: addBook t/Diary of a Wimpy kid a/Jeff Kinney i/9780810993136
     Expected: A book and its details is added into the book list.

  2. Test case: addBook 0
     Expected: No book is added. Error details shown in the status message. Status bar remains the same.

  3. Other incorrect delete commands to try: addBook, addBook 5, ...
     Expected: Similar to previous.

Deleting a book

• Deleting a book while all books are being shown.

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

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

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

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

Editing a book

• Editing a book while all books are being shown.

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

  2. Test case: editBook 1 t/Diary of a Wimpy kid a/Jeff Kinney i/9780810993136
     Expected: First book is edited. Details of the book are changed according to the input.

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

  4. Other incorrect delete commands to try: editBook, editBook 3, ...
     Expected: Similar to previous.

Deleting a person

1. Deleting a person while all persons are being shown.

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

   2. Test case: deletePerson 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: deletePerson 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: deletePerson, deletePerson x, ... (where x is larger than the list size)
      Expected: Similar to previous.

Saving data

1. Dealing with missing data files.
   1. Delete [JAR file location]/data/expresslibrary-{version_num}.json if it exists.

   Expected: Launch ExpressLibrary and you should be able to see sample data with people and books.

2. Dealing with corrupted data files.

   1. Prerequisites: expresslibrary-{version_num}.json should exist in [JAR file location]/data. If it does not exist, launch ExpressLibrary and use any command that will change the data of the ExpressLibrary (e.g. addBook, borrow, etc.) and the expresslibrary-{version_num}.json file will be automatically generated.

   2. To simulate a corrupted file, go to [JAR file location]/data/expresslibrary-{version_num}.json and make changes so that the file would be invalid (e.g. remove a comma/bracket).

   Expected: Launch ExpressLibrary and you should see that ExpressLibrary will be empty.

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Appendix: Planned Enhancements

Given below are some of the planned enhancements to ExpressLibrary current features.

1. Currently all ExpressLibrary fields do not have any character limit, resulting in extreme inputs being truncated in the GUI. We plan to set an appropriate character limit for each field in order to counteract this and wrap the fields if the GUI cannot fit the fields in one line.

2. Currently each person can borrow an unlimited books, we plan to fix this by limiting the number of books a person can borrow in a future update.

3. Currently, ExpressLibrary assumes that there is only one copy of each book in the library which is obviously quite unrealistic. We plan to solve this by creating a BookInstance class in the future to account for different copies of the same book in the library.

4. Email addresses are only validated based on regex (specifically RFC5322 standard) and not whether it is actually a valid email. We plan to use internationalised domain names in a future update in order to truly validate an email address.

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