Final Project • You need to work on a substantial project in this class. • If you are already involved in a research project... • ... it is fine to figure out a way to use it in this class. • If not, that is fine too.
Final Project • You need to work on a substantial project in this class. • If you are already involved in a research project... • ... it is fine to figure out a way to use it in this class. • If not, that is fine too. • Not looking for a research project alone.
Final Project • You need to work on a substantial project in this class. • If you are already involved in a research project... • ... it is fine to figure out a way to use it in this class. • If not, that is fine too. • Not looking for a research project alone. • Can also implement an existing paper.
Final Project • You need to work on a substantial project in this class. • If you are already involved in a research project... • ... it is fine to figure out a way to use it in this class. • If not, that is fine too. • Not looking for a research project alone. • Can also implement an existing paper. • Extend an existing project (e.g., an open source project).
Final Project • You need to work on a substantial project in this class. • If you are already involved in a research project... • ... it is fine to figure out a way to use it in this class. • If not, that is fine too. • Not looking for a research project alone. • Can also implement an existing paper. • Extend an existing project (e.g., an open source project). • Extend one of the previous labs.
Final Project • The project should not be an impediment to taking this class.
Final Project • The project should not be an impediment to taking this class. • Aim is to provide a way for students to get their hands dirty.
Final Project • The project should not be an impediment to taking this class. • Aim is to provide a way for students to get their hands dirty. • If the project worries you come talk to me we will find something for you to do.
Providing Feedback • This is my first time doing teaching a class without training wheels.
Providing Feedback • This is my first time doing teaching a class without training wheels. • Unlikely that no one will be unhappy throughout the semester.
Providing Feedback • This is my first time doing teaching a class without training wheels. • Unlikely that no one will be unhappy throughout the semester. • If you are unhappy you can try and fix things:
Providing Feedback • This is my first time doing teaching a class without training wheels. • Unlikely that no one will be unhappy throughout the semester. • If you are unhappy you can try and fix things: • Complain in office hours, or over e-mail.
Providing Feedback • This is my first time doing teaching a class without training wheels. • Unlikely that no one will be unhappy throughout the semester. • If you are unhappy you can try and fix things: • Complain in office hours, or over e-mail. • Google form linked in course policy for anonymous complaints.
Providing Feedback • This is my first time doing teaching a class without training wheels. • Unlikely that no one will be unhappy throughout the semester. • If you are unhappy you can try and fix things: • Complain in office hours, or over e-mail. • Google form linked in course policy for anonymous complaints. • Promise to listen to all complaints, not necessarily act on them.
One last bit of Administrivia...
Academic Honesty • Sadly this needs to be said.
Academic Honesty • Sadly this needs to be said. • Please don't plagiarize (projects, quizzes, whatever), and please cite your sources
Academic Honesty • Sadly this needs to be said. • Please don't plagiarize (projects, quizzes, whatever), and please cite your sources • First time teaching, first semester at NYU.
Academic Honesty • Sadly this needs to be said. • Please don't plagiarize (projects, quizzes, whatever), and please cite your sources • First time teaching, first semester at NYU. • Really think highly of everyone here, don't shatter my illusion.
Academic Honesty • Sadly this needs to be said. • Please don't plagiarize (projects, quizzes, whatever), and please cite your sources • First time teaching, first semester at NYU. • Really think highly of everyone here, don't shatter my illusion. • If you need help, need better grades for some reason ... come see me.
Academic Honesty • Sadly this needs to be said. • Please don't plagiarize (projects, quizzes, whatever), and please cite your sources • First time teaching, first semester at NYU. • Really think highly of everyone here, don't shatter my illusion. • If you need help, need better grades for some reason ... come see me. • We can figure out a way to fix this sort of thing.
Academic Honesty • Sadly this needs to be said. • Please don't plagiarize (projects, quizzes, whatever), and please cite your sources • First time teaching, first semester at NYU. • Really think highly of everyone here, don't shatter my illusion. • If you need help, need better grades for some reason ... come see me. • We can figure out a way to fix this sort of thing. • If you get caught, I will use every instrument at my disposal.
Distributed Systems
What is a distributed system?
Main Characteristics (for us) • Comprised of several processes, each running on its own "computer" • For the purposes of this class node. • Time for processes to communicate is significant compared to an instruction. • Partial failures : some processes can fail while others remain alive. • In contrast to traditional programs where everything fails or nothing does.
Assumptions: Message Passing • Only considering message passing. • Processes communicate by sending each other messages. Process 0 Process 1 • Other models (shared memory) can be shown to be equivalent.
Assumptions: Message Passing • Only considering message passing. • Processes communicate by sending each other messages. Ping Process 0 Process 1 • Other models (shared memory) can be shown to be equivalent.
Assumptions: Message Passing • Only considering message passing. • Processes communicate by sending each other messages. Ping Process 0 Process 1 Pong • Other models (shared memory) can be shown to be equivalent.
Assumptions: Async Network • Asynchronous Network : Messages from different processes can be reordered. P2 P1 P0 Time
Assumptions: Async Network • Asynchronous Network : Messages from different processes can be reordered. P2 P1 P0 Time
Assumptions: Async Network • Asynchronous Network : Messages from different processes can be reordered. P2 P1 P0 Time
Assumptions: Async Network • Asynchronous Network : Messages from different processes can be reordered. P2 P1 P0 Time
Assumptions: Async Network • Asynchronous Network : Messages from different processes can be reordered. P2 P1 P0 Time
Assumptions: Async Network • Asynchronous Network : Messages from different processes can be reordered. P2 P1 P0 Time
Assumptions: Async Network • Asynchronous Network : Messages can be arbitrarily delayed. P2 P1 P0 Time
Assumptions: Async Network • Asynchronous Network : Messages can be lost. P2 P1 P0 Time
Assumptions: Fail Stop • Fail Stop: Failed processes do not send messages. Process 0 Process 1
Assumptions: Fail Stop • Fail Stop: Failed processes do not send messages. Process 0 Process 1
Assumptions: Fail Stop • Fail Stop: Failed processes do not send messages. Ping Process 0 Process 1
Why distributed system?
Three Main Reasons
Three Main Reasons • Fault tolerance
Three Main Reasons • Fault tolerance • Survive some forms of failures or bug.
Three Main Reasons • Fault tolerance • Survive some forms of failures or bug. • Scalability
Three Main Reasons • Fault tolerance • Survive some forms of failures or bug. • Scalability • Use more resources than a single computer can provide.
Three Main Reasons • Fault tolerance • Survive some forms of failures or bug. • Scalability • Use more resources than a single computer can provide. • Geographic Reach
Three Main Reasons • Fault tolerance • Survive some forms of failures or bug. • Scalability • Use more resources than a single computer can provide. • Geographic Reach • Work even when information is spread across large distances.
How to reason about distributed systems?
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