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Most interesting links of December ’13

Posted by Jakub Holý on December 31, 2013

Recommended Readings

Society

  • 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

Tech

  • D. Nolen: The Future of JavaScript MVC Frameworks – highly recommended thought food – about React.js, disadvantages of event-based UI, benefits of immutability, performance, the ClojureScript React wrapper Om  – “I simply don’t believe in event oriented MVC systems – the flame graph above says it all. […] Hopefully this gives fans of the current crop of JS MVCs and even people who believe in just using plain JavaScript and jQuery some food for thought. I’ve shown that a compile to JavaScript language that uses slower data structures ends up faster than a reasonably fast competitor for rich user interfaces. To top it off Om TodoMVC with the same bells and whistles as everyone else weighs in at ~260 lines of code
  • 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
  • Style Guide for JavaScript/Node.js by Felix Geisendörfer, recommended by a respectable web dev; nothing groudn breaking I suppose but great start for a team’s standards
  • 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

Other

Talks

  • Pete Hunt: React: Rethinking best practices (JSConf 2013, 30 min) – one of the most interesting talks about frontend development, design, and performance I have heard this year, highly recommended. Facebook’s React JavaScript framework  is a fresh and innovative challenger in the MVC field. It is worthwile to learn why they parted ways with the popular approach of templates (spoiler: concern separation, cohesion x coupling, performance). Their approach with virtual DOM enables some cool things (run in Node, provide HTML5-like events in any browser with consistent behavior, …). Key: templates are actually tightly coupled to display logic (controllers) via the model view tailored for them (i.e. Controller must know what specific data & in what form View needs) => follow cohesion and keep them together componets, separate from other components and back-end code. Also, state changing over time at many places is hard => re-render the whole app rather than in-place updates. Also, the ClojureScript Om wrapper enables even more performance optimizations thanks to immutable data structures etc.
  • 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)

Clojure Corner

Tools/Libs

  • 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)

Favourite Quotes

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

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Most interesting links of September ’12

Posted by Jakub Holý on September 30, 2012

Recommended Readings

  • Johannes Brodwall: This dependency injection madness must end! – it’s very valuable to hear well-founded arguments against any popular belief and Dependency Injection is one of these. “I have started disliking the consequence of this strategy very much: All coupling in my system becomes implicit and harder to understand. I have instead reverted to using design patterns like the Singleton pattern, but with a slight twist.”
  • Computer Programmers Learn Tough Lesson in Sharing – WSJ.com – A balanced presentation of pair-programming including both benefits and issues. A key point: It is a skill that must be learned (to respect the other one, give her space, be aware of how your behavior is perceived by her, …).
  • Kent Beck: Functional TDD: A Clash of Cultures – TDD has been developed for object-oriented languages and applying it to a functional language with strong type brings interesting challenges. Also a good summary of the benefits of TDD: double checking of the logic (by the implementation and the, preferably quite different, test), solution decomposition (focus on part of the problem, once solve be sure it stays solved),  automatic checking of correctness, outside in design (API first, implementation after that). Plus the pleasant experience of the continuous cycle of tension (failing test) – relief (green).
  • Paul Callaghan: Thinking Functionally with Haskell: Types? Tests? We Need a New Word – Powerful type systems eliminate possibility of defects thus venturing into the domain of testing – what can they offer and where the new border and symbiosis between types and tests will be?
  • Tales from the Ops Side: Black Friday – an interesting and exciting view into the life of operations engineers one day when all went wrong. Key learnings: Many interdependant components are difficult to reason about; good monitoring and communication are crucial. The post refers to an interesting concept of Recovery-Oriented Computing, i.e. failures are inevitable and their prediction is nearly impossible thus we must focus on making the systems able to survive failures (e.g. vi damage containment, automatic fault detection, component-level restartability).
  • Groovy: The road map for the popular JVM language – why was Groovy created (as Java companion focused on productivity), key changes in Groovy 2.0 (more suport for static typing, Java 7, modularity with speed as a side-effect) and in the future Groovy 3.0 (invokedynamic everywhere, more Groovy written in itself).
  • Martin Fowler: Key Points from NoSQL Distilled – an overview of why NoSQL, data models, distribution models, consistency, map-reduce, polyglot persistence, criteries for choosing a database.
  • You’re a Top Developer! – a surprising hypothesis that “90% of all developers never read a programming blog, never have any side projects to learn something new, and never spend any time or effort outside work hours to improve”. However I haven’t seen any data to back that up (the author only quotes  Peopleware) and the author doesn’t propose any explanation for the fact. I’d really like to know if it is true and why it is so.

Business & Agile

  • Experimentation Is The New Planning – “You have no idea what’s going to happen to your industry. That’s why you build your organization into an engine of possibility.” We need “to  continually develop options and explore possibilities” to survive in the ever-changing conditions. Successful strategies emerge from the many ongoing experiments. However, “For emergent strategy to be successful, there must be enough autonomy, freedom, and slack in the system for people and resources to connect in a peer-to-peer way”.
  • The Buy-vs-Build Shift (part 1) – Buy to reduce risk of failure (however true agile development – with frequent deliveries and feedback-driven direction – may be cheaper and more importantly can tailor the product to the actual needs) and to avoid inefficiecy of development (but it doesn’t need to be so with agile). “[..] in projects with long cycle times (years) there is a tendency for the business to be somewhat speculative and request all functionality that they can think of [..] With prioritised iterative delivery the business can halt a project when all features that are actually needed have been completed. [..] it does reduce the amount of features that are implemented, and based on my experience, quite substantially so.” Today’s development with e.g. TDD, powerful IDEs supporting automated refactoring, powerful development/production machine, the all-knowing Internet may be much more efficient.
  • European entrepreneurs – Les misérables – A good analysis of why it is much more difficult to be an entrepreneur in Europe than in USA (the strong negative impact of a business failure, lack of local investors, cost of firing people) and the decline of European entrepreneurship since 19th century/WW1.
  • U.S. Government Accountability Office: Effective Practices and Federal Challenges in Applying Agile Methods – US government considers agile effective; description of the useful practices and of challenges

Tools

Clojure Corner

  • 10-minute Emacs for Clojure – getting started with Emacs for Clojure – install & config & basic usage for Emacs newbies (though no REPL integration yet)
  • Keep IT Simply Simple: First month @Runa Inc. – Clojure shop in Silicon Valley – brief post about using Clojure in the wild. Some points: TDD works splendidly; frameworks are not necessary; Clojure can be really fast (<= type hinting, memoziation, performant data structures + occasional Java code)
  • Blackstag: Why Clojure? The author describes the set of reasons that have led him to Clojure – and those that actually made him stick with it. “[..] what I like the most about Clojure is that it brings together the best of what many languages have to offer while not forcing it all upon me and, in doing so, has provided a good balance between power and flexibility.” “With Clojure I accomplish more and have found a greater sense of happiness with the work I am doing.”

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What Is CDI, How Does It Relate to @EJB And Spring?

Posted by Jakub Holý on November 9, 2011

A brief overview of dependency injection in Java EE, the difference between @Resource/@EJB and @Inject, and how does that all relate to Spring – mostly in the form of links.

Context Dependency Injection (CDI, JSR 299) is a part of Java EE 6 Web Profile and itself builds on Dependency Injection for Java (JSR 330), which introduces @Inject, @Named etc. While JSR 330 is for DI only and is implemented e.g. by Guice and Spring, CDI adds various EE stuff such as @RequestScoped, interceptors/decorators, producers, eventing and a base for integration with JSF, EJBs etc. Java EE components such as EJBs have been redefined to build on top of CDI (=> @Stateless is now a CDI managed bean with additional services).

A key part of CDI aside of its DI capabilities is its awarness of bean contexts and the management of bean lifecycle and dependencies within those contexts (such as @RequestScoped or @ConversationScoped).

CDI is extensible – you can define new context scopes, drop-in interceptors and decorators, make other beans (e.g. from Spring) available for CDI,… .

Resources to check: Read the rest of this entry »

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Most interesting links of October

Posted by Jakub Holý on October 31, 2011

Recommended Readings

  • Steve Yegge’s Execution in the Kingdom of Nouns – I guess you’ve already read this one but if not – it is a well-written and amusing post about why not having functions as first class citizens in Java causes developers to suffer. Highly recommended.
  • Reply to Comparing Java Web Frameworks – a very nice and objective response to a recent blog summarizing a JavaOne presentation about the “top 4″ web frameworks. The author argues that based on number of resources such as job trends, StackOverflow questions etc. (however data from each of them on its own is biased in a way) JSF is a very popular framework – and rightly so for even though JSF 1 sucked, JSF 2 is really good (and still improving). Interesting links too (such as What’s new in JSF 2.2?). Corresponds to my belief that GWT and JSF are some of the best frameworks available.
  • Using @Nullable – use javax.annotation.Nullable with Guava’s checkNotNull to fail fast when an unexpected null appeares in method arguments
  • JavaOne 2011: Migrating Spring Applications to Java EE 6 (slides) – nice (and visually attractive) comparison of JavaEE and Spring and proposal of a migration path. It’s fun and worthy to see.
  • xUnitPatterns – one of the elementary sources that anybody interested in testing should read through. Not only it explains all the basic concepts (mocks, stubs, fakes,…) but also many pitfalls to avoid (various test smells such as fragile tests due to Data Sensitivity, Behavior Sensitivity, Overspecified Software [due to mocks] etc.), various strategies (such as for fixture setup), and general testing principles. The materials on the site were turned into the book xUnit Test Patterns: Refactoring Test Code (2007), which is more up-to-date and thus a better source.
  • Eclipse tip: Automatically insert at correct position: Semicolon, Braces – in “while(|)” type “true {” to get “while(true) {|” i.e. the ‘{‘ is moved to the end where it belongs, the same works for ‘;’
  • Google Test Analytics – Now in Open Source – introduces Google’s Attributes-Components-Capabilities (ACC) application intended to replace laborous and write&forget test plans with something much more usable and quicker to set up, it’s both a methodology for determining what needs to be tested and a tool for doing so and tracking the progress and high-risk areas (based not just on estimates but also actual data such as test coverage and bug count). The article is a good and brief introduction, you may also want to check a live hosted version and a little more detailed explanation on the project’s wiki.
  • JSF and Facelets: build-time vs. render-time (component) tags (2007) – avoid mixing them incorrectly
  • StackOverflow: What are the main disadvantages of Java Server Faces 2.0? Answer: The negative image of JSF comes from 1.x, JSF 2 is very good (and 2.2 is expected to be just perfect :-)). Nice summary and JSF history review.
  • Ola Bini: JavaScript in the small – best practices for projects using partly JavaScript – the module pattern (code in the body of an immediately executed function not to polute the global var namespace), handling module dependencies with st. like RequireJS, keeping JS out of HTML, functions generating functions for more readable code, use of many anonymous functions e.g. as a kind of named parameters, testing, open questions.

Talks

  • Kent Beck’s JavaZone talk Software G Forces: The Effects of Acceleration is absolutely worth the 1h time. Kent describes how the development process, practices and partly the whole organization have to change as you go from annual to monthly to weekly, daily, hourly deployments. What is a best practice for one of these speeds becomes an impediment for another one – so know where you are. You can get an older version of the slides and there is also a detailed summary of the talk from another event.
  • Rich Hickey: Simple Made Easy - Rich, the author of Clojure, argues very well that we should primarily care for our tools, constructs and artifacts to be “simple”, i.e. with minimal complexity, rather than “easy” i.e. not far from our current understanding and skill set. Simple means minimal interleaving – one concept, one task, one role, minimal mixing of who, what, how, when, where, why. While easy tools may make us start faster, only simplicity will make it possible to keep going fast because (growing) comlexity is the main cause of slowness.  And simplicity is a choice – we can create the same programs we do today with the tools of complexity with drastically simpler tools. Rich of course explains what, according to him, are complex tools and their simple(r) alternatives – see below. The start of the 1h talk is little slow but it is worth the time. I agree with him that we should much more thing about the simplicity/complexity of the things we use and create rather than easiness (think ORM).
    Read also Uncle Bob’s affirmative reaction (“All too often we do what’s easy, at the expense of what’s simple. And so we make a mess. […] doing what is simple as opposed to what is easy is one of the defining characteristics of a software craftsman.”).

Random Notes from Rich’s Simple Made Easy Talk:

There are also better notes by Alex Baranosky and you may want to check a follow-up discussion with some Rich’s answers.

The complex vs. simple toolkit (around 0:31):

COMPLEXITY                             SIMPLICITY
State, objects                            Values
Methods                                   Functions, namespaces
vars                                          Managed refs
Inheritance, switch, matching  Polymorphism a la carte
Syntax                                      Data
Imperative loops, fold              Set functions
Actors                                      Queues
ORM                                         Declarative data manipulation
Conditionals                             Rules
Inconsistency                            Consistency

What each of the complexity constructs mixes (complects) together

CONSTRUCT                        COMPLECTS (MIXES)
State, objects – everything that touches it (for state complects time and value)
Methods – function and state, namespaces (2 classes, same m. name)
Syntax – Meaning, order
Inheritance – Types (ancestors, child)
Switch/matching – Multiple who/what pairs (1.decide who, 2.do what ?)
var(iable)s – Value, time
Imperative loops, fold – what/how (fold – order)
Actors – what/who
ORM – OMG :-)
Conditionals – Why, rest of program (rules what program does are intertw. with the structure and order of the program, distributed all over it)

HE SIMPLICITY TOOLKIT (around 0:44)
CONSTRUCT            GET IT IVA…
Values – Final, persistent collections
Functions – a.k.a. stateless methods
Namespaces – Language support
Data – Maps, arrays, sets, XML, JSON etc.
Polymorphism a la carte – Protocols, Haskell type classes
Managed refs – Clojure/Haskell refs (compose time and value , not mix)
Set functions – Libraries
Queues – Libraries
Declarative data manipulation – SQL/LINQ/Datalog
Rules – Libraries, Prolog
Consistency – Transactions, values

True abstraction isn’t hiding complexity but drawing things away – along one of the dimensions of who, what, when, where, why [policy&rules of the app.], how.
Abstraction => there are things I don’t need – and don’t want – to know.
Why – do explore rules and declarative logic systems.
When, where – when obj. A communicates with obj. B. => put a queue in between them so that A doesn’t need to know where B is; you should use Qs extensively.

Links to Keep

  • Incredibly Useful CSS Snippets –  “a list of CSS snippets that will help you minimize headaches, frustration and save your time while writing css” – few float resets, targetting specific browsers & browser hacks, cross-rowser transparency/min height/drop shadow, Google Font API, link styled by file type,

DevOps: Tools and libraries for system monitoring and (time series) data plotting

  • Hyperic SIGAR API – open-source library that unifies collection of system-related metrics such as memory, CPU load, processes, file system metrics across most common operating systems
  • rrd4j – Java clone of the famous RRDTool, which stores, aggregates and plots time-series data (RRD = round-robin database, i.e. keeps only a given number of samples and thus has a fixed size)
  • JRDS “is performance collector, much like cacti or munins”, uses rrd4j. The documentation could be better and it seems to be just a one man project but it might be interesting to look at it.

Clojure Corner

  • Alex Miller: Real world Clojure – a summary of experiences with using Clojure in enterprise data integration and analytics products at Revelytix, since early 2011 with a team of 5-10 devs. Some observations: Clojure code is 1-2 order of magnitude smaller than Java. It might take more time to learn than Java but not much. Clojure tooling is acceptable, Emacs is still the best. Debugging tools are unsurprisingly quite inferior to those for Java. Java profiling tools work but it may be hard to interpret the results. “[..]  I’ve come to appreciate the data-centric approach to building software.” Performance has been generally good so far.
  • Article series Real World Clojure at World Singles – the series focuses on various aspects of using Clojure and how it was used to solve particular problems at a large dating site that starting to migrate to it in 2010. Very interesting. F. ex. XML generation, multi-environment configuration, tooling (“If Eclipse is your drug of choice, CCW [Counter ClockWise] will be a good way to work with Clojure.”, “Clojure tooling is still pretty young [..]  – but given how much simpler Clojure is than most languages, you may not miss various features as much as you might expect!”)
  • StackOverflow: Comparing Clojure books – Programming Clojure, Clojure in Action, The Joy of Clojure, Practical Clojure – which one to pick? A pretty good comparison.
  • Clojure is a Get Stuff Done Language – experience report – “For all that people think of Clojure as a “hard” “propeller-head” language, it’s actually designed right from the start not for intellectual purity, but developer productivity.”

Posted in eclipse, General, j2ee, Languages, Testing, Top links of month | Tagged: , , , , , , , , , , | 3 Comments »

Spring: Make an Externally Created Object Available to Beans in applicationContext.xml

Posted by Jakub Holý on October 11, 2011

If your Spring beans need access to an object that is not created by Spring itself, you can “inject” it into the context by using a static parent context and registering the object with it. Beans can then reference it just as if it was defined in the application context file.

Java: Configure ApplicationContext with an Injected Bean

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.context.support.StaticApplicationContext;

Object externalyDefinedBean = ...;
GenericApplicationContext parentContext = new StaticApplicationContext();
parentContext.getBeanFactory().registerSingleton("injectedBean", externalyDefinedBean);
parentContext.refresh();   // seems to be required sometimes

ApplicationContext context = new FileSystemXmlApplicationContext(springConfigs, parentContext);

Xml: Make Use of It

<bean id="springBean" class="your.SpringBeanType">
   <!-- Note: The injectedBean is defined outside of Spring config -->
   <property name="someProperty" ref="injectedBean" />
</bean>

Voila!

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Most interesting links of November

Posted by Jakub Holý on November 30, 2010

This month has been quite interesting, among others I ‘ve picked up several blogs by Adam Bien. I really like his brief, practical and insightful posts :-)

Java, Jave EE, architecture etc.

  • EJB 3.1 + Hessian = (Almost) Perfect Binary Remoting – “With hessian it is very easy to expose existing Java-interfaces with almost no overhead. Hessian is also extremely (better than IIOP and far better than SOAP) fast and scalable.” See also the discussion regarding a “DynamicHessianServlet” (which would be more comfortable then creating a new servlet for each service).
  • Binary XML – Fast Infoset performance results – FI is the name of a standard for binary XML encoding and also of its OSS implementation; according to these measurements (with default settings, compared to Xerces 2.7.1), on average: The FI SAX parser  is about 5 times faster than the Xerces SAX parser, the FI DOM serializer (using default settings) is 25% to 30% faster than the Xerces DOM XMLSerializer, and FI documents are 40% to 60% smaller than XML documents (i.e. it can provide modest to good compression). And: “The use of external vocabularies can be a very effective way to increase the efficiency of parsing, serializing and size at the expense of the fast infoset documents no longer being self-describing … .”
    For the interested ones: FI is built on ASN.1, a standard for describing data structures in a way that is independent of machine architecture and implementation language, it also includes a selection on different binary encoding rules, e.g. DER (triplets tag id – length – value).
  • EJB 3.1 And REST – The Lightweight Hybrid – Why to use @Stateless – there have been recently discussion about Spring vs. EJB and whether @Stateless is of any use. According to this article, the added value of EJB (though some are provided also by Spring) include injection capabilities, transactions, single threading model (for why that is good see #2 on Why I like EJB 3.0/3.1), visibility in JMX, concurrency restriction via thread/bean pools.
  • Why Service Isn’t A ServiceFacade, But ServiceFacade Is Sometimes A Service…
  • Experiences from migrating Hyperic 4.5 from EJB/JBoss to Spring/Tomcat, what good has it brought – simplified unit and integration tests, simplified code thanks to Jdbc/JmsTemplate, … (My comment: EJB 3.1 would certainly bring at least some of the advantages too.)

Performance – large JVM heaps are very much feasible

  • Tuning the IBM JVM for large heaps – tuning 64b IBM JVM 6 with 100GB heap to have acceptable GC times (~ 1/2s as opposed to 25s with the default settings)
  • BigMemory: Heap Envy – there have been recently a lot of fuss about Terracotta’s new BigMemory, a  GC-resistent many GB cache space (using NIO byte buffer). This post discusses it’s disadvantages and compares it with a solution based on ConcurrentHashMap, comming to the conclusion that the old good ConcurrentHashMap outperforms BigMemory considerably.

Other

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Most interesting links of September

Posted by Jakub Holý on September 30, 2010

The most interesting articles and other IT resources I’ve encountered the previous month, delayed a bit due to my holiday in Andalusia. In no particular order. Included some performance stuff, few tools and few general SW engineering things.

  • The Open-Closed Principle , i.e. open to extension, closed to modification – one of the basic principles in OOP underlying many best practices such as “make all member variables private” nicely explained, with code samples with and without O/CP applied.  Noteworthy: The principle is implemented with abstractions (abstract classes defining the constant part with subclasses being the extensions). You can’t “close” your design against all changes and must thus choose the ones that are more likely, i.e. create a “strategic closure”.
  • Java EE 6 xor Spring by A. Bien – the main difference is in the philosophy behind – Java EE is based on Convention over Configuration. The decision factor is usually the support policy, though. Also the tc Server is certainly better than a “custom” Tomcat with Spring.
  • ThoughtWorks Technology Radar – to help decision-makers from CIOs to developers understand emerging technologies and trends that affect the market today; though their assignment of GWT under hold is disputable (http://www.dzone.com/links/r/thoughtworks_radar_demystified_gwt.html); TW answers: “As it turned out the conciseness of the text didn’t allow us to adequately make our points so that they were not misunderstood. We are interested in a discussion but our opinion about the suitability and usability of GWT has still not changed.”
    • JavaScript as a 1st-class language w/ the same best practices (unit t., refact.,…); functional languages (Clojure > Scala)
    • WS-* beyond the basic profile, GWT, RIA on hold
  • “Agile Business” for a startup with “Virtual Assistants”: outsource (to an “Virtual Assistant”) what you can, only do what’s necessary at the time even if that means doing manually (outsourced) st. that could be automated; this helped to decrease time from 160 MH to 10 MH.
    “The lesson is that before you launch your product, think about the processes you can avoid automating. How about reminder emails? How about monthly billing? Could a human being run a report once a month and send emails or charge credit cards?” , “Every hour spent writing code is wasted time if that code could be replaced by a human being doing the same task until your product proves itself.”
  • InMemProfiler: Identifying Memory Allocators – tool to track memory allocation capable of attributing it to the classes (i.e. packages) of interest without blurring the results with char[] and all the java.lang.* classes
  • Easy Performance Analysis with AppDynamics Lite – I’m fond of performance troubleshooting tools and AppDynamics Lite looks really cool. The post includes two very short yet very informative and nice screencast showing its installation and usage. App. D. automatically discovers Struts actions, JDBC calls, webservices etc. and captures slow operations with the necessary details; this is quite similar to what the open-source Glassbox.com does. The monitoring web UI is very nice and user friendly. See the white box on the right side at http://www.appdynamics.com/lite.php to see what JVMs, ASs and frameworks it supports. Check also the comparison of the lite and standard versions (max 30 transactions, max 2 hours if diagnostics data, …).
  • Google Relaunches Instantiations Developer Tools – Now Available for Free – incl. the static code analysis tool (Eclipse plugin) CodePro AnalytiX
  • A blog about Terracota’s new BigMemory (commercial) claims that 64b JVM with heap over few GB may be a nightmare – “… not all people know about 64-bit JVMs and the nightmare these things can cause. Contrary to what other vendors are claiming, most shops such as Unibet, PartyPoker, Expedia, Sabre Holdings, Intercontinental Hotels Group, JP Morgan, Goldman, and more will tell you a 64-bit JVM pauses unpredictably and for minutes at a time. even when a 64 bit JVM is small (<2GB) it takes 30+% more RAM than a 32-bit equivalent JVM running under the same app.
  • Presentation Real Software Engineering by Glenn Vanderburg  – the talk is pretty interesting and I recommend it. Few, subjectively selected and interpreted points:
    The SW engineering as taught in universities doesn’t work, it’s actually a caricature of “engineering” (that is, established practices that work). The reason is that SwE is unreasonably fascinated by (ideally mathematical) modeling and precise, repeatable processes. This is not how real SW development can or does work. Given the complexity and uncertainty, an empirical process, based on frequent feedback and continual adjustment, is much more suitable. Also we don’t need complex models because prototyping and testing is nearly “free”, compared e.g. to spacecraft engineering. And with BDD and tools like RSpec and FitNesse we may have both readable and executable specifications – the code becomes the model.
  • Monte Carlo Analysis of the Zero Defect Mentality of TDD – conclusion: TDD pays off in the long run even though being slower [learning curve; 0-value bringing defect fixing] Fow short life time, TDD may be not worth it. Don’t argue, simulate :-)

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Exposing a POJO as a JMX MBean easily with Spring

Posted by Jakub Holý on September 16, 2010

JMX is a great way to check or change state variables or invoke a method in a (remote) running application via a management GUI such as JConsole. And Spring makes it trivial to expose any POJO as a JMX MBean with only little configuration in a few minutes. The Spring JMX documentation is very good, however there are few points that I struggled with for a while and would therefore like to record here the right solutions.

I needed to monitor a command-line java application using Spring 2.5 on IBM JVM 1.4 1.5 running on a server with a jconsole on Sun JVM 1.6 as the JMX client on my PC.

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