Notes

tags: Learning Ask 6 questions to familiar a new thing: Why What Where When Who How

tags: TCP,Network,5W1H TCP Fast Open(TFO): WHY TFO is proposed? TCP Three-Way Handshake for every new TCP connection is too expensive. WHAT is the TFO? TCP Fast Open (TFO) is a mechanism that aims to reduce the latency penalty imposed on new TCP connections. HOW the TFO reduce the latency on new TCP connections? TFO allows data transfer within the SYN packet. WHEN the TFO is avaiable. TFO support is now avaiable in Linux 3.7+ kernels, and should be enabled by a viable option in both client and server side. ...

tags: CoDel,Network source: “Controlling Queue Delay - ACM Queue.” Accessed January 11, 2022. https://queue.acm.org/detail.cfm?id=2209336. Bufferbloat What is the bufferbloat? In the internet, large buffer is used everywhere: PC Router/Swtich/ISP Server The large may cause delay. Why the bufferbloat still with us and made increaingly critical by two trends? Cheap memory. Complicate network paths. How to sloves the problem? AQM(active queue management) is the known solution, but it’s difficult to implement, so even it has been known two decades but still not been widely deployed. ...

tags: Network,Bufferbloat,AQM

tags: Fun Story

tags: Networking 101: Primer on Latency and Bandwidth,Fun Bugs source: https://web.mit.edu/jemorris/humor/500-miles I remember this story when I’m reading the section “Speed of Light and Propagation Latency” in High Performance Browser Networking. It’s funny to record it.

tags: High Performance Browser Networking,Network Defination: Latency - Time cost between sending and receiving, lower is better. Bandwitdh - throughtput, higher is better. Things affect to Latency: Distance of fiber, Speed of Light, that could be optimized by CDN. Bufferbloat of router, large buffer make queue delay, addressed by CoDel. ISP gateway.

tags: Org Mode,How to Write source: https://github.com/vikasrawal/orgpaper

tags: Note-Taking,How to Write,Zettelkasten,读书笔记 source: Ahrens, Sönke. How to Take Smart Notes: One Simple Technique to Boost Writing, Learning and Thinking: For Students, Academics and Nonfiction Book Writers. North Charleston, SC: CreateSpace, 2017.

tags: TCP

tags: Title Case,Emacs source: https://github.com/duckwork/titlecase.el

tags: Learning English,Online: Title Case source: The Chicago Manual of Style. Seventeenth edition. Chicago: The University of Chicago Press, 2017.

tags: Online Tools,Title Case source: https://titlecase.com/

tags: Learning English,Writing

tags: Learning English,Title Case source: “The Programmer’s Way to Write in Title Case Using Emacs Lisp.” Accessed January 10, 2022. https://hungyi.net/posts/programmers-way-to-title-case. Genernal correct title cased phrase: Uppercase the first letter of most words e.g. “There Is No Spoon” Not capitalize ‘small’ and ‘unimportant’ words e.g. “Long Live the King” Always capitalize the first and the last words, even if they’re small e.g. “The Land and Save We Live On” Capitalize sub-phrase as if they were their own title ...

tags: quorum,一致性，Distributed Systems,Patterns of Distributed Systems,Paxos,Patterns of Distributed Systems: Paxos source: martinfowler.com. “Quorum.” Accessed January 7, 2022. https://martinfowler.com/articles/patterns-of-distributed-systems/quorum.html.

tags: Paxos,分布式,Patterns of Distributed Systems source: martinfowler.com. “Paxos.” Accessed January 7, 2022. https://martinfowler.com/articles/patterns-of-distributed-systems/paxos.html.

tags: Career source: “How to Quit like a Boss.” Accessed January 7, 2022. https://jmsbrdy.com/blog/leaving-spring/. HN: https://news.ycombinator.com/item?id=29830296 From the article: Avoid communication failures: your manager should not be surprised by your leaving. Do have regular, clear, frank conversations about your career with your direct manager. Do tell your manager clearly if there’s something you’re looking for in your career which your current role isn’t providing. Don’t withhold concerns or aspirations from your manager. The worst you do above: ...

tags: Blockchain,Smart contracts,Web3 source: “Crypto: The Good, the Bad and the Ugly.” Accessed January 7, 2022. https://seldo.com/posts/crypto-the-good-the-bad-and-the-ugly. The good: Smart contracts allows anybody to execute arbitrary code in the network. And use money to avoid abuse, as every action in the smart contract cost money(computing resource). Finaacial engineering: new money. Entertainment: NFT, a big dream(culture) for everybody who loves crypto. True cloud computing: Smart contracts again. Web3 The bad: Environmental impact: the grievously wateful nature of PoW. But it’s changing. Interactions at boundaries: private(isolate) network. DAOs have a major boundary problem: not a legally binding contract, without goverment support. Governace GAS fee limit scale Incentives for participation: how money come in to this system? Web3: is a currency a practical model for general computing? The ugly: NFTs, ICOS.

tags: Ethereum

tags: Smart contracts,Ethereum,Ethereum development source: ethereum.org. “Ethereum Local Development Setup.” Accessed January 7, 2022. https://ethereum.org. Local development node: Use Hardhat to build the ethereum development environment. And also there are some tools that based on Hardhat: scaffold-eth: forkable Ethereum dev stack focused on fast product iterations Ganache: A tool for creating a local blockchain for fast Ethereum development. Tools that based on Ganache: Python based: brownie Testing tools: Waffle: ethers.js Truffle: Web3.js

tags: Smart contracts,Ethereum,Ethereum development source: ethereum.org. “Deploying Your First Smart Contract.” Accessed January 7, 2022. https://ethereum.org.

tags: Blockchain Proof,Ethereum

tags: PoA source: https://en.wikipedia.org/wiki/Proof%5Fof%5Fauthority

tags: IRT,CTT,Educational Measurement source: Hambleton, Ronald K, and Russell W Jones. “Comparison of Classical Test Theory and Item Response Theory and Their Applications to Test Development,” 1993, 11.

tags: Educational Measurement

tags: Educational

tags: IRT,读书笔记 source: Yu, Chong Ho. “A Simple Guide to the Item Response Theory ( IRT ) and Rasch Modeling.” Accessed January 6, 2022. https://www.semanticscholar.org/paper/A-Simple-Guide-to-the-Item-Response-Theory-(-IRT-)-Yu/f42efb1bcf38f6650a8b16650e2811e8803cd4ec. IRT is about fitness or simplicity for test. There are two versions of IRT: IRT - three parameters. Rasch modeling - one parameter only. Three parameters: A - discrimination, how effectively this item can discriminate students’s proficient between highly and less. B - difficulty, or the threshold, tells us how easy or how difficult an item is. G or C - guessing, indicates the item correct by guess. One parameter: keep the A parameter constant and ignoring the G parameter. ...

tags: Algorithm,Bigdata,Educational Measurement

tags: Freelance source: “How I Took My SaaS from Idea to Sold in 14 Months | Masilotti.Com.” Accessed January 6, 2022. https://masilotti.com/idea-to-sold-in-14-months/. Building in public: teased new designs and features, documented decisions, UX with polls.

tags: Python source: “init_subclass.” Accessed January 6, 2022. https://til.simonwillison.net/til/til/python_init-subclass.md.

tags: Rust,Online Tutorial source: https://cheats.rs/

tags: Bigdata

tags: Bigdata,Streaming,Stateful Stream Processing source: Kreps, Jay. “Why Local State Is a Fundamental Primitive in Stream Processing - O’Reilly Radar.” Accessed January 5, 2022. http://radar.oreilly.com/2014/07/why-local-state-is-a-fundamental-primitive-in-stream-processing.html. Why local state is much faster than a distribut database. local state can easily restore by some middleware like Kafka: by writing changes to a Kafka topic.

tags: Bigdata,Flink,Dataflow Model,Streaming source: “Streaming 102: The World beyond Batch – O’Reilly.” Accessed January 5, 2022. https://www.oreilly.com/radar/the-world-beyond-batch-streaming-102/. Three more concepts: Watermarks: Useful for event time windowing. All input data with event times less than watermark have been observed. Triggers: Signal for a window to produce output. Accumulation: The way to handle multiple results that are observed for the same window. Streaming 101 Redux What: Transformations Where: windowing Make a temporal boundary for a unbounded data source. ...

tags: Bigdata,Streaming source: Akidau, Tyler, Robert Bradshaw, Craig Chambers, Slava Chernyak, Rafael J. Fernández-Moctezuma, Reuven Lax, Sam McVeety, et al. “The Dataflow Model: A Practical Approach to Balancing Correctness, Latency, and Cost in Massive-Scale, Unbounded, out-of-Order Data Processing.” Proceedings of the VLDB Endowment 8, no. 12 (August 2015): 1792–1803. https://doi.org/10.14778/2824032.2824076.

tags: Bigdata,Flink,Streaming source: Akidau, Tyler. “Streaming 101: The World beyond Batch.” O’Reilly Media, August 5, 2015. https://www.oreilly.com/radar/the-world-beyond-batch-streaming-101/. Streaming: a type of data processing engine that is designed with infinite data sets in mind. Other common uses of “streaming” that will be avoid in the rest of the post: Unbounded data: A type of ever-growing, essentially infinite data set. Unbounded data processing: An ongoing mode of data processing, applied to the aforementioned type of unbounded data. Low-latency, approximate, and/or speculative results: These types of results are most often associated with streaming engines. Limitations of streaming To beat batch at its own game, you really only need two things: ...

tags: DAO,Web3 source: Foundation, Ethereum. “DAOs, DACs, DAs and More: An Incomplete Terminology Guide.” Accessed January 5, 2022. https://blog.ethereum.org/2014/05/06/daos-dacs-das-and-more-an-incomplete-terminology-guide/.

tags: DAO,Online Tutorial source: https://aragon.org/dao

tags: Freelance source: Dan. “My Writing Finances, 2021 | Dan Moren.” Accessed January 5, 2022. https://dmoren.com/2022/01/03/my-writing-finances-2021/.

tags: Freelance source: “I Make $3K/Mo from a Browser Extension! (+ December 2021 Updates).” Accessed January 5, 2022. http://newsletter.tonydinh.com/issues/i-make-3k-mo-from-a-browser-extension-december-2021-updates-966892. HN: https://news.ycombinator.com/item?id=29803817

tags: Web3 source: Continuations by Albert Wenger. “Web3/Crypto: Why Bother?” Accessed January 5, 2022. https://continuations.com/post/671863718643105792/web3crypto-why-bother.

tags: Ethereum,MetaMask,Online Tools source: https://www.skiff.org/updates/skiff-ens

tags: Web3,Online Tools,Real Problems That Web3 Solves, Part 1 source: https://metamask.io/ MetaMask has implemented private key login via a Chrome extension and now has 21 million users. In theory, something like this could have existed a long time ago. In practice, the existence of blockchains and the need for better UX for cryptocurrency incentivized much more investmenets in these tools.

tags: Web3,Smart contracts source: Bill Prin’s Personal Page. “Real Problems That Web3 Solves, Part 1,” January 3, 2022. https://billprin.com/2022/01/03/real-problems-web3-solves.html. What exactly is the difference between Web3, blockchain, and cryptocurrency You can think of blockchain and cryptocurrency as technological implementation details, and Web3 as the communities, businesses, and social relationships that form on top of that technology. A similar analogy would be the original World Wide Web, which could have been construed as a rebrand of the underlying technologies of HTML over HTTP over TCP/IP. Those protocols have served as the foundation for virtually all web content for the last 30 years, but it’d certainly be unfair to describe “the Web” as merely a rebranding of HTML/HTTP/TCP/IP since what happens on top of those protocols is much bigger than just the protocols themselves. ...

tags: Blockchain,Ethereum source: https://ethereum.org/en/developers/docs/smart-contracts/ A type of Ethereum account. Some code deployed and running in some VM, like Ethereum Virtual Machine.