Principles of Software Construction Objects, Design, and Concurrency


Software engineers today are less likely to design data structures and algorithms from scratch and more likely to build systems from library and framework components. In this course, students engage with concepts related to the construction of software systems at scale, building on their understanding of the basic building blocks of data structures, algorithms, program structures, and computer structures. The course covers technical topics in four areas: (1) concepts of design for complex systems, (2) object oriented programming, (3) static and dynamic analysis for programs, and (4) concurrent and distributed software. Student assignments involve engagement with complex software such as distributed massively multi-player game systems and frameworks for graphical user interaction.

After completing this course, students will:

See a more detailed list of learning goals describing what we want students to know or be able to do by the end of the semester. We evaluate whether learning goals have been achieved through assignments and exams.


Tu/Th 3:30 - 4:50 p.m. in TEP 1403

Jonathan Aldrich, TCS 422, office hours: see calendar

Bogdan Vasilescu, TCS 326, office hours: see calendar

Our TAs also provide an additional 15h of office hours each week; see details in the calendar.

The instructors have an open door policy: If the instructors' office doors are open and no-one else is meeting with us, we are happy to answer any course-related questions. Feel free to email us for appointments; we are also available over Zoom.

Course Calendar


The schedule below is a rough draft of our plans, but likely to change.

Date Topic Reading assignments*
Tue, Jan 17 Introduction
Wed, Jan 18 Rec 1 IDEs, Build systems, Libraries, CI
Thu, Jan 19 OO basics, Dynamic dispatch, Encapsulation
Tue, Jan 24 IDEs, Build system, Continuous Integration, Libraries Required: Effective Java, Items 15 and 16
Wed, Jan 25 Rec 2 Introduction to Git
Thu, Jan 26 Specifications and Unit Testing, Exceptions Recommended: Java Precisely (Ch 3, 4, 9, 10, 11); JavaScript: The Good Parts (Ch. 3, 4, 9), TypeScript Handbook (Basics, Everyday Types, Object Types)
Mon, Jan 30 HW 1 due Intro to OO and Libraries
Tue, Jan 31 Test case design Unit Testing Best Practices
Wed, Feb 1 Rec 3 Unit testing
Thu, Feb 2 Object-oriented analysis & UML
Mon, Feb 6 HW 2 due Testing
Tue, Feb 7 Responsibility assignment UML and Patterns, Ch. 9--11, 15-017
Wed, Feb 8 Rec 4 Design and UML
Thu, Feb 9 Inheritance & Delegation
Mon, Feb 13 HW 3a due Intro to Design (design checkpoint)
Tue, Feb 14 Design Patterns
Wed, Feb 15 Rec 5 Inheritance and Delegation
Thu, Feb 16 Midterm 1
Tue, Feb 21 Refactoring and Anti-patterns Design Patterns Explained on Observer and Decorator
Wed, Feb 22 Rec 6 Anti-patterns and Refactoring
Thu, Feb 23 Introduction to GUIs and Concurrency
Mon, Feb 27 HW 3b due Intro to Design
Tue, Feb 28 (Towards) Web Apps
Wed, Mar 1 Rec 7 GUI intro
Thu, Mar 2 Asynchrony & Concurrency Concurrency model and the event loop + How JavaScript works
Tue, Mar 7 No class, Spring Break
Wed, Mar 8 No recitation, Spring Break
Thu, Mar 9 No class, Spring Break
Tue, Mar 14 Concurrency: Safety & Immutability
Wed, Mar 15 Rec 8 Concurrency & Promises
Thu, Mar 16 Distributed Systems -- Events Everywhere
Fri, Mar 17 HW 4 due Designing Complex Software (UI)
Tue, Mar 21 Libraries and Frameworks
Wed, Mar 22 Rec 9 Frameworks
Thu, Mar 23 API Design
Mon, Mar 27 HW 5 due Designing Complex Software (God Cards)
Tue, Mar 28 Organizing Systems at Scale: Modules, Dependencies, Breaking Changes The Java Module System Chapter 1 or JavaScript Module Systems Showdown
Wed, Mar 29 Rec 10 Test Double (Fakes, Mocks & Stubs)
Thu, Mar 30 Midterm 2
Tue, Apr 4 Design for Robustness & Distributed Systems
Wed, Apr 5 Rec 11 GitFlow and Code Review
Thu, Apr 6 Git Workflows in Practice
Friday, Apr 7 HW 6a due Framework Design
Tue, Apr 11 More Design Patterns
Wed, Apr 12 Rec 11.5 Refactoring
Thu, Apr 13 No class, Carnival
Tue, Apr 18 Static Analysis
HW 6b due Framework Implementation
Wed, Apr 19 Rec 12 Advanced Git Operations
Thu, Apr 20 DevOps
Tue, Apr 25 Containers & Cloud
Wed, Apr 26 Rec 13 Design Pattern Review
Thu, Apr 27 Finale: Toward SE, Teams, Process
Fri, Apr 28 6c due Framework Plugins
Tue, May 2, 1-4pm Final exam

* = For details, see Canvas

Course Staff

Professor Jonathan Aldrich
Professor Bogdan Vasilescu


Head TA: Matt Davis
Jake Zych
Hamza Khalid
Can Cao
Ruiying Chen
Ariane Correa
Eileen Xiao
Terry Li
Terry Peng
Haozhe Yang
Meixuan Li
Stella Yan
Teresa Wan
Minyi Zou

Course Syllabus and Policies



Evaluation will be based on the following approximate percentages:

This course does not have a fixed letter grade policy; i.e., the final letter grades will not be A=90-100%, B=80-90%, etc.

Homework grading and regrading. We try to be transparent in our rubrics in our assignments. Feel free to ask instructors or TAs clarification questions about the rubrics before the assignment is due. If you disagree with a grade, please submit a regrade request within 7 days on Gradescope. Regrade requests need a justification, explaining why our assessment is inconsistent with the rubric. Regrade requests without such justification will be closed.

Quizzes. You should expect a quiz at the start of nearly every lecture. When a reading assignment is given, the quiz will typically touch on the content from the reading material. Otherwise (and sometimes in addition), the quiz centers around the content from the most recent lecture or two. We mainly administer quizzes through Canvas. A quiz will typically have 1-2 questions and you will receive partial credit just for participating.

While the quizzes are there to encourage you to come to class, it is perfectly understandable that you may miss a few lectures due to sickness and other unavoidable conflicts. We will therefore ignore up to four missed quizzes no questions asked. So no need to email us for the occasional absence. However, if you are going to be out for more than 2 weeks due to extenuating circumstances, shoot us an email---we can accommodate that.

Attendance and remote participation

This course, including recitations, is marked by the registrar as IPE ("delivered in-person, students are expected to be in the classroom during the course's scheduled meeting time"). There is a dedicated remote section for students who cannot attend in person and have university-level approval.

We hope that we can conduct the course in person for the entire semester, as we believe this will provide a much better experience. However, the pandemic situation is constantly evolving and we will follow university policies as they change.

We understand that different students have different backgrounds and different concerns and we will try to be flexible. We do not expect that everything will be fully back to normal for everybody (whatever normal means in the first place). If you are concerned about in-person interactions, we recommend to first talk to your advisor and then reach out to us.

We will record all lectures and make them available to remote students and (on a case by case basis) students who miss lectures due to quarantine, illness, or other reasons. Recordings may not be shared to protect the FERPA rights of all students in the classroom. For remote students, we expect that they attend the remote section live after having watched the recordings.


This course will occasionally assign mandatory readings, from the two text books below. The CMU library has both physical and electronic copies of these books. You can access all of these books for free electronically. Those available via CMU library are indicated below; you can either search the CMU library catalogue or follow the links below, and follow the instructions under "Available Online" or "View Online."

In addition, we list several optional readings that may be helpful with specific topics in the course. Especially if Java/Javascript is new to you, you might want to consider exploring additional books.

Time management

This is a 12-unit course, and it is our intention to manage it so that you spend close to 12 hours a week on the course, on average. In general, 4 hours/week will be spent in class and 8 hours on assignments. Please feel free to give the course staff feedback on how much time the course is taking for you.

Late work policy

We understand that normal life events, including projects and exams in other courses and technical difficulties out of your control, can interfere with your ability to complete your work on time. Our philosophy is that our late work policy includes built-in flexibility but that the policy will be uniformly applied to all students in all circumstances. Exceptions to this policy will be made only in extraordinary circumstances, almost always involving a family or medical emergency with your academic advisor or the Dean of Student Affairs requesting the exception on your behalf.

For most homework deadlines you may turn in your work up to two days late using either free late days (see below) or 10% per day penalties. Work turned in more than two days late will receive feedback but no credit, i.e., a 100% penalty. (See an important caveat below for how penalties are applied to late work.) Some homework deadlines may explicitly disallow late work, and you are responsible for correctly understanding the late policy for each homework assignment and its sub-parts.

Each student starts the semester with five free late days which will automatically be applied to your individual (non-partner-based) assignments until you have used all five free late days. A late day is automatically applied when your work is late; you may not defer a free late day to be used on a later assignment. We will make separate late day provisions for partner-based assignments.

When we apply a late penalty to late work (e.g. a 10% one-day penalty or a 100% no credit penalty) we assess the penalty incrementally at a rate of 1% every five minutes until the full penalty is assessed.

To better understand this late policy consider the following example scenario. Suppose a homework assignment is due Tuesday night (ostensibly at 11:59 p.m.) and you have one free late day remaining. You may turn in your work:

Research to Improve the Course:

For this class, we are conducting research on teaching and learning. This research will involve some student work. You will not be asked to do anything above and beyond the normal learning activities and assignments that are part of this course. You are free not to participate in this research, and your participation will have no influence on your grade for this course or your academic career at CMU. If you do not wish to participate, please send an email to Chad Hershock ( Participants will not receive any compensation. The data collected as part of this research will include student grades. All analyses of data from participants’ coursework will be conducted after the course is over and final grades are submitted. The Eberly Center may provide support on this research project regarding data analysis and interpretation. The Eberly Center for Teaching Excellence & Educational Innovation is located on the CMU-Pittsburgh Campus and its mission is to support the professional development of all CMU instructors regarding teaching and learning. To minimize the risk of breach of confidentiality, the Eberly Center will never have access to data from this course containing your personal identifiers. All data will be analyzed in de-identified form and presented in the aggregate, without any personal identifiers. If you have questions pertaining to your rights as a research participant, or to report concerns to this study, please contact Chad Hershock (

Collaboration policy

We expect that your work on assignments, projects, and exams will be your own work. Thus, you may not copy any part of a solution to a problem that was written by another student, or was developed together with another student, or was copied from another unauthorized source such as the Internet. Unless explicitly allowed by the assignment, you may not look at another student's solution, even if you have completed your own, nor may you knowingly give your solution to another student or leave your solution where another student can see it.

Here are some examples of behavior that are inappropriate:

In your solutions you will often reuse existing code as libraries or frameworks and build your own solution with those. You may import code through package managers (npm, maven, gradle) without further documentation. If you copy code into your repository (either entire file(s) or code snippets), you need to acknowledge the source.

If any of your work contains any statement that was not written by you, you must put it in quotes and cite the source. If you are paraphrasing an idea you read elsewhere, you must acknowledge the source. Using existing material without proper citation is plagiarism, a form of cheating. If there is any question about whether the material is permitted, you must get permission in advance.

We use automated systems to detect software plagiarism. These automated systems are highly effective and, so far, have detected software plagiarism almost every semester.

It is not considered cheating to clarify vague points in the assignments, lectures, lecture notes, or to give help or receive help in using the computer systems, compilers, debuggers, profilers, or other facilities.

Some assignments are specifically noted as group projects. For these, interpret "you" in the preceding paragraphs to mean "you and your partner(s)."

Any violation of this policy is cheating. The minimum penalty for cheating (including plagiarism) will be a zero grade for the whole assignment; a typical penalty will be -100% on the assignment. Dishonesty while discussing an academic integrity issue (i.e. lying to course staff) usually results in an 'R' in the course. All violations of this collaboration policy will be referred to the appropriate University disciplinary board, with possible additional disciplinary action. For more information, see the [University Policy on Academic Integrity]( Integrity.htm).

There is no statute of limitations for violations of the collaboration policy; penalties may be assessed (and referred to the university disciplinary board) after you have completed the course, and some requirements of the collaboration policy (such as restrictions on you posting your solutions) extend beyond your completion of the course.

If you have any question about how this policy applies in a particular situation, ask the instructors or TAs for clarification.


If you wish to request an accommodation due to a documented disability, please inform the instructor as soon as possible and contact Disability Resources at 412.268.2013 or

Audit Policy

If you desire to audit the course, our general requirement is that you complete Homeworks 1, 2, 3, and 4 at the level of proficiency expected for a student to pass the course. Solutions do not need to be fully complete, but we encourage you to attempt to do so; submitting complete solutions will increase the chance that your solution meets our expectations for passing work. We additionally encourage you to attend lectures and recitations, but you are not required to do so. You should not attend our midterm exams or final exam.

Your health matters

When we say "your health matters" we mean exactly that: Your health matters. We don't intend to imply that other peoples' health does not matter, or that your health matters more or less than theirs. We know that CMU can be a stressful, risky environment, and your health is the health that is relevant in this conversation. Worries about Covid-19 and possible remote classes do not help.

Please take care of yourself. Do your best to maintain a healthy lifestyle this semester by eating well, exercising, avoiding drugs and alcohol, getting enough sleep and taking some time to relax. This will help you achieve your goals and cope with stress.

All of us benefit from support during times of struggle. You are not alone. There are many helpful resources available on campus and an important part of the college experience is learning how to ask for help. Asking for support sooner rather than later is often helpful.

If you or anyone you know experiences any academic stress, difficult life events, or feelings like anxiety or depression, we strongly encourage you to seek support. Counseling and Psychological Services (CaPS) is here to help: call 412-268-2922 and visit their website at Consider reaching out to a friend, faculty or family member you trust for help getting connected to the support that can help.

If you are worried about affording food or feeling insecure about food, there are resources on campus who can help. Email the CMU Food Pantry Coordinator to schedule an appointment:

Respect for diversity. It is our intent that students from all diverse backgrounds and perspectives be well served by this course, that students’ learning needs be addressed both in and out of class, and that the diversity that students bring to this class be viewed as a resource, strength and benefit. It is my intent to present materials and activities that are respectful of diversity: gender, sexuality, disability, age, socioeconomic status, ethnicity, race, and culture. Your suggestions are encouraged and appreciated. Please let us know ways to improve the effectiveness of the course for you personally or for other students or student groups.

Accommodations for students with disabilities. If you have a disability and have an accommodations letter from the Disability Resources office, we encourage you to discuss your accommodations and needs with us as early in the semester as possible. We will work with you to ensure that accommodations are provided as appropriate. If you suspect that you may have a disability and would benefit from accommodations but are not yet registered with the Office of Disability Resources, we encourage you to contact them at

Informal feedback on this course

We are planning many changes to this course in this semester and not everything will work out smoothly the first time. We’d like you to provide ongoing feedback on your experience in the course, so that we can take into account your experience and adapt our practices to make the course work for you.

Outside of the regular course meetings and Piazza, you can submit feedback about anything in the course per email to the instructors or ask TAs to forward them anonymously. We will read every message submitted and use your feedback to try to improve the way we are teaching.