Posts Tagged ‘clojure’
Posted by Jakub Holý on July 31, 2014
- Video: The Unreasonable Effectiveness of Dynamic Typing for Practical Programs – a static-typing zealot turned friend of dynamic typing under the experience of real-world projects and problems shares thoughts about the limits of type systems (f.ex. both energy and torque are measured in N*m yet cannot be combined) and their cost: according to the Hanenberg’s experiment about static and dynamic typing => the time required to handle the time chacker > time to debug the errors that it would have caught. According to a review of issues at GitHub, only 2% of reported issues for JS, Clojure, Python, and Ruby are type errors and for a large, closed-source Python project type/name/attribute errors were 1%. “I have come to believe that tests are a much better investment [than static typing].” Rigorous type system/model => limited applicability (due to different needs) <=> modelling some things with types doesn’t cut it. “Are the costs of static typing offset by a few percent fewer defects? Is agility more important than reliability?” “Static types are anti-modular” – too a tight coupling. “Static type checking comes at the expense of complexity, brittleness and a tendency to monoliths.“
(Personally I miss static typing – but that is perhaps due to having relied on it for so long.)
- ThoughtWorks Tech Radar July 2014 (pdf): f.ex. Ansible in Adapt, Masterless Chef/Puppet in Trial, Machine image as a build artifact: Trial, PostgreSQL for NoSQL: Trial, Adopt Dropwizard (Rest 4 Java), Go lang, Reactive Extensions across langs [JH: RxJava, RxJS, ..]; Asses Property-based (generative) testing, … . Other highlights: Mapbox (open-source mapping platform), OpenID Connect as a less complex and thus promising alternative to SAML/generic OAuth, Pacto/Pact for Consumer-Driven Contracts (contract => simulate consumers/stubb producers => test your REST clients against the contract so that the rest of tests can assume it is correct and use a stubbed client), Swagger for REST documentation.
- The madness of layered architecture – a nice critique of over-designed “enterprise” apps, why that is a problem (SRP, cost of code, unclear where to do a change, ….), why it is different from the successful layered network stack of Ethernet/IP/TCP/… (because in an app, all layers are on the same level of abstraction); bottom line: do not add a layer unless you have a really good reason (hint: the advice of a consultant/speaker does not count as one)
- Key Takeaway Points and Lessons Learned from QCon New York 2014 (viz @RiczWest) – “[..] deep insights into real-world architectures and state of the art software development practices, from a practioner’s perspective.” – architectures of Fb, Foursquare etc., continuous delivery, creating culture, real world functional programming, … .
- Questioning the Lambda Architecture (J. Kreps of LinkedIn) – maintaining the same processing in two very different systems (one batch, one stream & real-time) is a maintenance nightmare => improve the RT/stream processing to handle re-processing and thus both (using e.g. Kafka to store the data and thus be able to re-play them)
- Google: Checklist for mobile website improvement
- Google Dataflow and the transition from batch to stream processing – G. Dataflow might not be a Hadoop killer due to requiring that the data are in the Google Cloud but the trend is clear, going away from batch processing to more stream-oriented processing with tools like Spark, Flume etc. that are faster thanks to using memory better and more flexible thanks to not being limited to the rigitd two-stage model of map-reduce. (Reportedly, Google – the one that made Map-Reduce popular – doesn’t use it anymore.)
- OS X: Extract JDK to folder, without running installer
Society, economics, people
- HBR: The Power of Meeting Your Employees’ Needs – people feel better, perform better, are more engaged and likely to stay longer (=> profitability) when 4 basic needs are met: physical [energy] renewal (=> give opportunity, encourage to take a nap or do whatever that helps), value – feeling of being valued by the company, ability to focus, purpose (i.e. serving something larger than ourselves). “What’s surprising about our survey’s results is how dramatically and positively getting these needs met is correlated with every variable that influences performance. It would be statistically significant if meeting a given need correlated with a rise of even one or two percentage points in a performance variable such as engagement, or retention. Instead, we found that meeting even one of the four core needs had a dramatic impact on every performance variable we studied. [..] when all four needs are met, the effect on engagement rises from 50% for one need, to 125%. Engagement, in turn, has been positively correlated with profitability. [..] employers with the most engaged employees were 22% more profitable than those with the least engaged employees.“
“[..] those who were encouraged to take intermittent breaks reported they were 50% more engaged, more than twice as likely to stay with the company, and twice as healthy overall. Valuing and encouraging renewal requires no financial investment. What it does require is a willingness among leaders to test their longstanding assumption that that performance is best measured by the number of hours employees puts in – and the more continuous the better — rather than by the value they generate, however they choose to do their work.“
- The Pitchforks Are Coming… For Us Plutocrats – increasing inequality will eventually lead to the collapse of the sysem (at least so does teach the history). It is people – primarily the middle class – that are the source of the wealth of the society, they produce and also consume most. Thus it is necessary to support them …
- Why the U.S. Corporate World Became ‘A Bull Market for Corruption’ – Enron, GM, Goldman Sachs, … – we hear more and more the names of large corporations in the context of negligence and misues of their customers and investors. It seems that leadership (in the lead by example sense) has died out as well as the feeling of responsibility when one wields power over her customers/investors/markets. Instead, we have the me-first and money at any cost thinking. Organizations are designed to shield higher-ups from responsibility (meetings with no records…). High pay for short term gains, failure to punish high ranking people.
- (US) This is what happened when I drove my Mercedes to pick up food stamps – the experience of life in poverty after dropping down from $125k to $25k/year in two months due to childbirth, real estate market crash, and loss of a job. “Using the coupons was even worse. The stares, the faux concern, the pity, the outrage — I hated it. [..] That’s the funny thing about being poor. Everyone has an opinion on it, and everyone feels entitled to share. [..] Poverty is a circumstance, not a value judgment. I still have to remind myself sometimes that I was my harshest critic. That the judgment of the disadvantaged comes not just from conservative politicians and Internet trolls. It came from me, even as I was living it.“
- Isomorphic Clojure[Script], part I – enjoying all the benefits of Single-Page Apps while avoiding their drawbacks (SEO, slower page load, accessibility etc.) – a SPA that can be pre-rendered by the server. Using Om/React, JDK8 with the Nashorn JS engine, core.async, Sente (bi-dirrectional HTTP/WS communication over core.async) and Clojure in the JVM, ClojureScript in Nashorn in the JVM, and ClojureScript in the browser. Example app: Omelette.
- clj-crud: a relatively feature-complete example of a Clojure web (4/2014; GitHub) – using Component, Liberator (REST), Datascript + Quiescent (=> React.js), Enlive, Friend etc. including couple of unit-test and ui-test libraries
- Conclujon: Acceptance testing tool (α), Clojure reimplementation of Concordion, a beautifully simple ADD tool
- dynalint: human-friendly error messages during dev – Clojure typically provides little helpful and sometimes confusing error messages thrown from somewhere deep in the implementation, such as “Don’t know how to create ISeq from: java.lang.Long at clojure.lang.RT.seqFrom” while we want st. like “First argument to clojure.core/first must be seqable: 1 (instance of class java.lang.Long” – and that’s what Dynalint does. In the tradition of defensive programming, it adds checks and good error messages to Vars at runtime. You typically run it only during dev, triggering it from the REPL.
- Grimoire (Reid McKenzie) – a more up-to-date replacement for ClojureDocs
- Adam Bard’s Top Clojure Articles for beginners and intermediate Clojure devs – f.ex. Five Mistakes Clojure Newbies Make, Acceptable Error Handling in Clojure, Clojure Reducers for Mortals
- J. Wilk: Isolating External Dependencies in Clojure – a nice overview of the options and their pros and cons – with-redefs, alter-var-root, Midje (using alter-var-root in a more controlled manner), higher-order-functions (#1!) etc.
- philandstuff’s detailed notes from Euroclojure 2014
- NixOS (via @bodil) – a new interesting “purely functional” Linux distribution – system configuration is fully declarative (think of Puppet/Chef) and it is always trivial to roll back, you can have multiple versions of a package, users can install non-global SW
- InfluxDB – time series, metrics, and events DB that scales; contrary to Graphite it can store richer data than Graphite and its single value; additional highlights: authorization for individual data, roll-up/clean old data, https API. Written in Go.
Posted in General, Languages, Top links of month | Tagged: bigdata, clojure, ClojureScript, design, economics, human, linux, mobile, society, types | Comments Off
Posted by Jakub Holý on June 30, 2014
- The emperor’s new clothes were built with Node.js – I know sadly little about Node.js but this goes against the hype and is thus interesting. So what does Node.js give us? Performance 1-5x slower than Java [like Clojure] according to the Benchmarks Game (contrary to other benchmarks with the opposite result as mentioned in the comments), use of a single CPU/core on our multi-cpu, multi-core machines, callback hell. At the same time, there are good non-blocking servers available in other languages (Clojure’s http-kit, Vert.x, etc.) (Update: From the comments it seems that f.ex. the “callback hell” situation is geting better with 0.11, fibers and other things I do not know anything about. Also Sandro has a nice anti-comment (No. 36).)
The Node.js Is Bad Ass Rock Star Tech 5 min video is a nice companion :)
- The Expert (Short Comedy Sketch) (7 min) – you’ve certainly seen this one but I had to put it here; a young engineer is hammered into being an “Of course I can do it, I am an expert” ‘expert/consultant’ during a business meeting. Maybe you too have experienced a dialog with the business where your true expert opinion was crushed by the business people’s insistence on their absurd requirements?
- Reset The Net – Privacy Pack – privacy-enhancing apps for PC/mobile
- The Dyslexic Programmer (via Kent Beck) – interesting read about quite a different way to percieve and think about code, the advantages of IDEs.
- It’s Here: Docker 1.0 => more stable from now on
- Kent Beck: Learning About TDD: The Purpose of #isTDDDead – what is the purpose and value of TDD? Where are the limits of its value? “I recognize that TDD loses value as tests take longer to run, as the number of possible faults per test failure increases, as tests become coupled to the implementation, and as tests lose fidelity with the production environment.“
- Failure & Cake: A Guide to Spotify’s Psychology of Success – want to be innovative and successfull? Learn to embrace failure, nurture the “growth mindset” (failure as opportunity to improve) rather than the “fixed mindset” (I do not learn and every failure shows I have no value). Read this if you want your org to be a better place to work!
- LSD — The Problem-Solving Psychedelic – I never knew that drugs could be used to something positive, with an incredible effect. Are you stuck with a tech/design/art problem? Try LSD! :-)
- The French are right: tear up public debt – most of it is illegitimate anyway – “Debt audits show that austerity is politically motivated to favour social elites. [..] 60% of French public debt is illegitimate” – not improving the lives of people but thos at power/rich. Time to reconsider this debt business and ways to make our system better?
- Forbes: Why Financialization Has Run Amok – Wall Street is the kind and companies do everything to look better in its eyes – including giving up on opportunities. The might of the finance sector is destructive to our economy and distorts it, away from producing more value to making financial institutions richer, away from (value) creative activities to distributive ones. The article describes the problem and proposes a solution including limiting the size and leverage of banks, taxing financial transactions etc. Example of the effects: “[..] a cabal of senior IBM executives and the managers of some big investment firms got together and devised a five-year scheme—IBM’s Roadmap 2015—for increasing IBM’s earnings per share—and their own compensation—through measures that are not only increasing earnings per share but also steadily crippling IBM’s ability to innovate and compete [..]“
- Why Can’t We All Just Get Along? The Uncertain Biological Basis of Morality – very interesting criticism of “morality” that is mostly based on emotions and thus contradictory, a good argument for utilitarian morality [not that it hasn't its own challenges]. According to the author, many conflicts are nor primarily due to divergent values but due to different interpretation of the reality and history (such as “who has right to this land?”). People suffer “[..] from a deep bias—a tendency to overestimate their team’s virtue, magnify their grievances, and do the reverse with their rivals.” “This is the way the brain works: you forget your sins (or never recognize them in the first place) and remember your grievances. [..] As a result, the antagonisms confronting you may seem mysterious, and you may be tempted to attribute them to an alien value system.” This leads to partial judgements that play very badly with another psychological feature – “Namely: the sense of justice—the intuition that good deeds should be rewarded and bad deeds should be punished.” “When you combine judgment that’s naturally biased with the belief that wrongdoers deserve to suffer, you wind up with situations like two people sharing the conviction that the other one deserves to suffer. Or two groups sharing that conviction. And the rest is history.” And “The most common explosive additive is the perception that relations between the groups are zero-sum—that one group’s win is the other group’s loss.” => “So maybe the first step toward salvation is to become more self-aware.“
“When you’re in zero-sum mode and derogating your rival group, any of its values that seem different from yours may share in the derogation. Meanwhile, you’ll point to your own tribe’s distinctive, and clearly superior, values as a way of shoring up its solidarity. So outsiders may assume there’s a big argument over values. But that doesn’t mean values are the root of the problem.“
Those who choose not to act in the trolley dilemma “[..] are just choosing to cause five deaths they won’t be blamed for rather than one death they would be blamed for. Not a profile in moral courage!“
- The Case for Clojure (video, 5 min) – a short video arguing for Clojure as a good solution language based on its simplicity, power, and fun factor. There are many claims and few facts (as dictated by the short length) but it might be interesting for somebody.
- CrossClj.info – cross-reference of many OSS Clojure projects – find all uses of a fn across the projects, all fns with a given name, all projects using ring, … . Search by fn, macro, var, ns, prj.
- The Weird and Wonderful Characters of Clojure – ‘A reference collection of characters used in Clojure that are difficult to “google”.’
Posted in General, Languages, Tools, Top links of month | Tagged: android, clojure, economics, fun, human, nodejs, privacy, psychology, workplace | Comments Off
Posted by Jakub Holý on June 26, 2014
Pack Publishing has asked me to review their new book, Clojure for Machine Learning (4/2014) by Akhil Wali. Interested both in Clojure and M.L., I have taken the challenge and want to share my impressions from the first chapters. Regarding my qualification, I am a medium-experienced Clojure developer and have briefly encountered some M.L. (regression etc. for quantitive sociological research and neural networks) at the university a decade ago, together with the related, now mostly forgotten, math such as matrices and derivation.
In short, the book provides a good bird-eye view of the intersection of Clojure and Machine Learning, useful for people coming from both sides. It introduces a number of important methods and shows how to implement/use them in Clojure but does not – and cannot – provide deep understanding. If you are new to M.L. and really like to understand things like me, you want to get a proper textbook(s) to learn more about the methods and the math behind them and read it in parallel. If you know M.L. but are relatively new to Clojure, you want to skip all the M.L. parts you know and study the code examples and the tools used in them. To read it, you need only elementary knowledge of Clojure and need to be comfortable with math (if you haven’t worked with matrices, statistics, or derivation and equations scare you, you will have a hard time with some of the methods). You will learn how to implement some M.L. methods using Clojure – but without deep understanding and without knowledge of their limitations and issues and without a good overview of alternatives and the ability to pick the best one for a particular case.
Read the rest of this entry »
Posted in Languages | Tagged: BI, book, clojure, review | Comments Off
Posted by Jakub Holý on May 31, 2014
- Monolith – from The Codeless Code – fables and koans for the SW engineer – the Monad monolth #Haskell #fun
- http2 explained (pdf, 27 pages) – cons of http 1 (huge spec / no full impl., wasteful use of TCP <=> latency [x spriting, inlining, concatenation, sharding]) => make it less latency sensitive, fix pipelining (issue a req before previous one finished), stop the need for ever increasing # connections, remove/reduce optional parts of http. Http2 is binary; multiple “streams” over 1 connection => much less conns, faster data delivery; header/data compression; [predictive] resource pushing; . Inspired by SPDY. Chrome and Mozilla will only support it over TLS, yay! (see also Is TLS Fast Yet? [yes, it is]) Promise: faster, more responsive web pages & deprecation of http/1 workarounds => simplified web dev.
- exercism.io – crowd-sourced good code mentorship – get an exercise, implement it in any of the supported language(s), submit and get feedback, repeat; when finished, you too can comment the same excercise submitted by others while working on your next assignment. Languages include Clojure, JS, Scala, Python, Haskell, Go, Elixir, Java, and more.
Podcasts (FP & related)
- Cognicast (also @ iTunes) – Clojure, FP, etc.
- Functional Geekery (@ iTunes) – A podcast on Functional Programming, covering topics across multiple languages.
- Mostly λazy…a Clojure podcast by Chas Emerick
- Giant Robots Smashing into other Giant Robots – “a weekly technical podcast discussing development, design, and the business of software development”
- Software Engineering Radio (@ iTunes) – “The goal is to be a lasting educational resource, not a newscast. Every two to four weeks, a new episode is published that covers all topics software engineering. Episodes are either tutorials on a specific topic, or an interview with a well-known expert from the software engineering world.”
- EngineerVsDesigner – design insight (@ iTunes) – product design podcast – the latest digital design news, tips & tricks, Q&A, and an industry special guest
- core.async walkthrough for practicioners (12/2013; original title “Core.Async”) – Tim Baldrige 40m talk from Conj is a must-watch for anybody that wants to understand and use core.async. Examples from and beyond the talk are at GitHub. Highlights: While take! takes a callback, <!! wraps that into a promise so that it blocks and returns the value. Thread is similar to future, running the code asynchronously, but returns a channel instead of a promise. So does go, only it does not use real threads but simulated light-weight ones via a state machine and parking. Tim shows the different buffers (normal, dropping = earliest values kept, sliding = latest valus kept). Other topics: alts!!, …
Related vids by Tim: Core.Async Channel Internals, Core Async Go Macro Internals – Part I, Core Async Go Macros – Part II
- Clojure, Leiningen and Functional Programming for Java developers- implementing a queue in a functional way
- ownCloud – your own Dropbox/Google Drive, run on your server – sharing files between devices / PCs / web, syncing calendar and contacts, collaborative editing of documents (ODF)
- Mailpile – “A modern, fast web-mail client with user-friendly encryption and privacy features.”, to be self-hosted on a PC, RaspberryPI, USB stick
- Blackhole – role-based ssh proxy – an app that enables you to manage what users can ssh to what server as a particular user, from users’ point of view this is a ssh proxy; useful if many people need access to many servers but you do not want to add them all as users on those servers.
- Wuala – Secure Cloud Storage – Backup. Sync. Share. Access Everywhere. – Dropbox alternative, secure by default
- fb-flo – Facebook’s live-coding tool
- owncloud.org – self-hosted Dropbox-like service with calendar and contact sync and more
Posted in General, Languages, Tools, Top links of month | Tagged: clojure, cloud, DevOps, e-mail, haskell, mentoring, podcast, privacy, security, sharing, ssh | Comments Off
Posted by Jakub Holý on May 19, 2014
The other day I got this little helpful exception from Clojure:
(cond (>= nil 1) :unreachable)
;=> NullPointerException [trace missing]
- no line number or anything to troubleshoot it.
It turns out it is not Clojure’s failure but a HotSpot optimization that can apply to
ClassCastException. The remedy is to run the JVM with
From Oralce JDK release notes:
The compiler in the server VM now provides correct stack backtraces for all “cold” built-in exceptions. For performance purposes, when such an exception is thrown a few times, the method may be recompiled. After recompilation, the compiler may choose a faster tactic using preallocated exceptions that do not provide a stack trace. To disable completely the use of preallocated exceptions, use this new flag:
Many thanks to Ivan Kozik for the info!
Posted in Languages | Tagged: clojure, java | Comments Off
Posted by Jakub Holý on April 30, 2014
- The economics of reuse – developing code for reuse costs much more than for one need – it might cost 300% more to develop and save you 75% of work when (re)using it instead of developing from scratch (if one of the factors goes down, the other one typically goes down too). Summary: “That means that to get any value from your reused component, you better have five or more reusers or you have to find a way to substantially improve the [reuse value factor] or [reusability cost factor]. Very smart people have failed to do this.“
- Book in making: Reactive Design Patterns (1st ch free)
Sharing data on the web
- 8th Light: Combining Clojure and ClojureScript Libraries (3/2014) – really good and detailed article / tutorial using CLJX and platform-specific platform.clj[s] files to share code between Clojure and ClojureScript. It also recommends a file structure (src/(clj|cljs)/), demonstrates testing, discusses macro development, shows how to pack both into one jar.
Posted in General, Languages, Top links of month | Tagged: clojure, ClojureScript, reuse, seo, web | Comments Off
Posted by Jakub Holý on April 30, 2014
What my Clojure code is doing most of the time is transforming data. Yet I cannot see the shape of data being transformed – I have to know what the data looks like on the input and hold a mental model of how they change at each step. But I make mistakes. I make mistakes in my code so that the data does not correspond anymore to the model it should follow. And I make mistakes in my mental model of what the data currently looks like, leading likely to a code error later on. The end result is the same – a little helpful exception at some later step regarding wrong shape of data. There are two problems here: The error typically provides too little useful information and it usually manifests later than where the code/model mistake actually is. I therefore easily spend an hour or more troubleshooting these mistakes. In addition to that, it is also hard to read such code because a reader lacks the writer’s mental model of the data and has to derive it herself – which is quite hard especially if the shape of the input data is not clear in the first place.
I should mention that I of course write tests and experiment in the REPL but I still hit these problems so it is not enough for me. Tests cannot protect me from having a wrong model of the input data (since I write the [unit] tests based on the same assumptions as the code and only discover the error when I integrate all the bits) and even if they help to discover an error, it is still time-consuming the root cause.
Can I do better? I believe I can.
Read the rest of this entry »
Posted in Languages | Tagged: clojure | 8 Comments »
Posted by Jakub Holý on March 31, 2014
- Timo Mihaljov’s Pimp My REPL (3/2014)- really great tips – user.clj, :dev profile, user-wide config in .lein/profiles.clj, tools.namespace, making funs available everywhere & more via Vinyasa, form println with Spyscope, debug-repl, difform, clj-ns-browser
- clj-ds – Clojure immutable datastructures extracted from Clojure and made easier for use directly in Java
Posted in General, Top links of month | Tagged: clojure | Comments Off
Posted by Jakub Holý on February 28, 2014
- Nathan Marz: Principles of Software Engineering, Part 1 – Nathan has worked with Big Data at Twitter and other places and really knows the perils or large, distributed, real-time systems and this post contains plenty of valuable advice for making robust, reliable SW. Main message: “there’s a lot of uncertainty in software engineering“; every SW operates correctly only for a certain range of inputs (including volume, HW it runs on, …) and you never control all of them so there always is an opportunity for failure; you can’t predict what inputs you will encounter in the wild. “[..] while software is deterministic, you can’t treat it as deterministic in any sort of practical sense if you want to build robust software.” “Making software robust is an iterative process: you build and test it as best you can, but inevitably in production you’ll discover new areas of the input space that lead to failure. Like rockets, it’s crucial to have excellent monitoring in place so that these issues can be diagnosed.“. From the content: Sources of uncertainty (bugs, humans, requirements, inputs, ..), Engineering for uncertainty (minimize dependencies, lessen % of cascading failure [JH: -> Hystrix], measure and monitor)
- Suffering-oriented programming is certainly also worth reading (summary: do not start with great designs; only start generalizing and creating libs when you have suffered enough from doing things more manually and thus learned the domain; make it possible > make it beautiful > make it fast, repeat)
- ThoughtWorks open-sources Go, continuous delivery platform – good bye, Jenkins! – better support for pipelines etc., see features and elementary concepts
- Cloud Design Patterns: Prescriptive Architecture Guidance for Cloud Applications (recommended by @markusbk so it must be good); Patterns: Cache-aside, Circuit Breaker, Compensating Transaction, Competing Consumers, Compute Resource Consolidation, Command and Query Responsibility Segregation (CQRS), Event Sourcing, External Configuration Store, Federated Identity, Gatekeeper, Health Endpoint Monitoring, Index Table, Leader Election, Materialized View, Pipes and Filters, Priority Queue, Queue-based Load Leveling, Retry, Runtime Reconfiguration, Scheduler Agent Supervisor, (data) Sharding, Static Content Hosting (-> CDN), Throttling, Valet Key.
Guidance topics: Asynchronous Messaging Primer, Autoscaling, Caching, Compute Partitioning, Data Consistency Primer, Data Partitioning, Data Replication and Synchronization, Instrumentation and Telemetry, Multiple Datacenter Deployment, Service Metering
- MOOC course Functional programming with Clojure at Uni of Helsinki – to get started you need, I suppose, follow the “Material and course content” – essentially read the text for each chapter, clone its repo, submit pull requests to get your work graded
- Jez Humble: The Case for Continuous Delivery – read to persuade manager about CD: “Still, many managers and executives remain unconvinced as to the benefits [of CD], and would like to know more about the economic drivers behind CD.” CD reduces waste: “[..]online controlled experiments (A/B tests) at Amazon. This approach created hundreds of millions of dollars of value[..],” reduces risks: “[..] Etsy, has a great presentation which describes how deploying more frequently improves the stability of web services.” CD makes development cheaper by reducing the cost of non-value-adding activities such as integration and testing. F.ex. HP got dev. costs down by 40%, dev cost/program by 78%
- Request Quest (via @jraregris) – entertaining and educational intractive quiz regarding what does (not) trigger a request in browsers and differences between them (and deviances from the standard) – img, script, css, etc.
- The REST Statelessness Constraint – a nice post about statelessness in REST if you, like me, don’t know REST so much in depth; highlights: Statelesness (and thus the requirement for clients to send their state with every request) is a trade-off crucial for web-scale and partially balanced by caching – while typical enterprise apps have different needs (more state, less scale) so REST isn’t a perfect match. Distinguish application (client-side) and server (resources) state. Using a DB to hold the state still violates the requirement. Use links to transfer some state (e.g. contain a link to fetch the next page of records in the response).
- CodeMesh 2013 presentations – good stuff! F.ex. Refactoring Functional Programs: Past and Future, Distribution, Scale and Flexibility with ZeroMQ, Deepak Giridharagopal on Puppet, Immutable Deployments, Analyzing Systems with PuppetDB, Francesco Cesarini and Viktor Klang on the Reactive Manifesto and more
- Cognitive Biases in Times of Uncertainty – people under pressure/stress start to focus on risks over gains and (very) short-term rather than long-term and thus also adopt 0-some mindset (i.e. if sb. else wins, I loose) => polarization into we x them and focus on getting as big piece of the cake possible at any price, now, dismissal of collaboration. With accelerating rate of change in the society due to technology, this is exactly what is happening. How to counter it? Create more positive narratives than the threat-based ones (views of the world), support them via short-term gains. Bottom line: each of us must work on spreading a more positive attitude to save us from bleak future.
- Book – Nathan Marz: Big Data – I dislike the big data hype (and, with passion, Hadoop) but would love to read this book; it presents a fresh look at big data processing, heavily inspired by functional programming. Nathan has plenty of experiences from Twitter and creating Storm and Cascalog (both in Clojure, btw.). Read ch 1: A new paradigm for big data.
- Facebook Engineering: The Mature Optimization Handbook (or go directly to the pdf, ePub, Mobi). If you get bored, jump directly to ch 5. Instrumentation.
Posted by Jakub Holý on December 31, 2013
- HBR: Want to Build Resilience? Kill the Complexity – a highly interesting, thought provoking article relevant both to technology in particular and the society in general; f.ex.: more security features are bad for they make us behave less safely (risk compensation) and are more fragile w.r.t. unexpected events. “Complexity is a clear and present danger to both firms and the global financial system: it makes both much harder to manage, govern, audit, regulate and support effectively in times of crisis. [..] Combine complex, Robust-Yet-Fragile systems, risk-compensating human psyches, and risk-homeostatic organizational cultures, and you inevitably get catastrophes of all kinds: meltdowns, economic crises, and the like.” The solution to future financial crisis is primarily not more regulation but simplification of the system – to make it easier to police, tougher to game. We also need to decrease interconnectednes (of banks etc.), one of the primary sources of complexity. Also a great example of US Army combatting complex, high-risk situations by employing “devil’s advocates / professional skeptics” trained to help “avoid the perils of overconfidence, strategic brittleness, and groupthink. The goal is to respectfully help leaders in complex situations unearth untested assumptions, consider alternative interpretations and “think like the other”“.
- The Dark Side of Technology – technologies provide great opportunities – but also risks we should be aware of – they create a world of mounting performance pressure for all of us (individuals, companies, states), accelerate the rate of change, increasing uncertanity (=> risk of Taleb’s black swans). “All of this mounting pressure has an understandable but very dangerous consequence. It draws out and intensifies certain cognitive biases [..]” – magnify our perception of risk, shrink our time horizons, foster a more and more reactive approach to the world, the “if you win, I will lose” view, erode our ability to trust anyone – and “combined effect of these cognitive biases increases the temptation to use these new digital infrastructures in a dysfunctional way: surveillance and control in all aspects of our economic, social and political life.” => “significantly increase[d] the likelihood of an economic, social and political backlash, driven by an unholy alliance between those who have power today and those who have achieved some modest degree of income and success.“
Complexity theory: the more connected a system is, the more vulnerable it becomes to cascades of disruptive information/action.
- What Do Government Agencies Have Against 23andMe, Uber, and Airbnb? – innovative startups do not fit into established rules and thus bureaucrats do not know how to handle them and resort to their favourite weapon: saying no, i.e. enforcing rules that harm them (f.ex. France recently passed a law that requires Uber etc. drivers to wait 15 min before picking up a customer so that established taxi services have it easier; wot?!)
- Nonviolent communication in action – wonderful stories about NVC being applied in difficult situations with a great success
- Quora: Michael Wolfe’s answer to Engineering Management: Why are software development task estimations regularly off by a factor of 2-3? – a wonderful story explaining to a layman why estimation is hard, on the example of a hike from SF to LA
- Johannes Brodwall: Why I stopped using Spring [IoC] – worth to read criticism of Spring by a respected and experienced architect and developer; summary – dependency injection is good bug “magical” frameworks decrease understandability and encourage unnecessarily complex code => smaller code, , easier to navigate and understand and easier to test
- Misunderstanding technical debt – a brief discussion of the various forms of tech. debt (crappy code x misaligned design and problem domain x competence debt)
- Tension and Flaws Before Health Website Crash – surprising lack of understanding and tensions between the government and contractors on HealthCare.gov – “a huge gap between the administration’s grand hopes and the practicalities of building a website that could function on opening day” – also terribly decision making, shifting requirements (what news!), management’s lack of decision power, CGI’s blame-shifting. A nice horror story. The former head knew that they should “greatly simplify the site’s functions” – but the current head wasn’t able to “talk them out of it”.
- The Log: What every software engineer should know about real-time data’s unifying abstraction – logs are everywhere and especially important in distributed apps – DB logs, append-only logs, transaction logs – “You can’t fully understand databases, NoSQL stores, key value stores, replication, paxos, hadoop, version control, or almost any software system without understanding logs” – I have only read a small part but it looks useful
- What I Wish I Knew When Learning Haskell tl;dr
- Better Than Unit Tests – a good overview of testing approaches beyond unit tests – including “Automated Contract Testing” (ability to define a contract for a web service, use it to test it and to simulate it; see Internet of Strings for more info), Property-based Testing (test generic properties using random data/calls as with Quickcheck), Fault Injection (run on multiple VMs, simulate network failures), Simulation Testing as with Simulant.
- Use #NoEstimates to create options and deliver value reliably – a brief post with an example of an estimation-based vs. no-estimates project (i.e. more focus on delivering early, discovery)
- How Google Sold Its Engineers on Management – managers may be useful after all :-); a report about Google’s research into management and subsequent (sometimes radical) improvements in management style/skills and people satisfaction; I love that Google hasn’t HR but “people ops”
- Roy Osherove: Technical Disobedience – take nothing for granted, don’t let the system/process stop you, be creative about finding ways to improve your team’s productivity; there always is a way. Nice examples.
- Uncle Bob: Extreme Programming, a Reflection – a reflection on changes in the past ~ 14 years since XP that have seen many of the “extreme” practices becoming mainstream
- The Anti-Meeting Manifesto – essentially a checklist and tips for limitting meetings to minimum
- Ethics Daily – a freuently published collection of ethics-related links, articles, talks etc.
- British Library uploads one million public domain images to the net for remix and reuse – from 17th-19th century books, available at Flicker; it asks for help categorizing and documenting them, metadata of the images at GitHub (with links to Flicker); great project, interesting pics
- The Software Engineers’ Oath – lets bring ethics back to our daily (work) lives – respect the knowledge of others, use technology for good (!!!), keep learning, writing code for people, not ashamed to admit lack of knowledge, respect for privacy, obligation to make lifes of humans better, …
- David Pollak: Some musings on Scala and Clojure by a long time Scala dude (46 min) – a subjective but balanced comparison of Scala and Clojure and their strengths/weaknesses by the author of the Scala Lift framework (doing Scala since 2006, Clojure since 2013)
- Apache Sirona – a new monitoring tool in the Apache incubator – “a simple but extensible monitoring solution for Java applications” with support for HTTP, JDBC, JAX-RS, CDI, ehcache, with data published e.g. to Graphite or Square Cube. It is still very new.
- GenieJS – Ctrl-Space to popup a command-prompt for your web page, inspired by Alfred (type ‘ to see all possible commands)
A good #agile team considers their backlog inaccurate. It is merely a list of assumptions that must be tested & refined by shipping product
- @mick maguire 12/10
Ada Lovelace (1st program), Grace Hopper (1st compiler), Adele Goldberg (1st OO language), why would anyone think women aren’t in computing?
– @Dan North 12/11
There will always be a shortage of talented, self-motivated creative professionals who will unquestioningly follow orders.
– @Thomas K Nilsson 12/7
Estimation paradox = If something unpredictable happens, predict how long it will take to fix it
– me 12/7
IT systems can be inspired by AK-47 a.k.a. Kalashnikov. The rifle was purposefully designed to be simple and to be tolerant to imperfections in most parts; as a result, it required essentially no maintenance and was extremely reliable.
– summarized from Roman Pichlík’s Odkaz Michaila Kalašnikova softwarovému vývoji