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Spring Naming Sucks

Javalobby Syndicated Feed - Tue, 31-May-16 02:31

Recently, I've been working on a new project using Spring. It's been a great chance to try out new things, gather all the best practices and see what comes out of it. One of the things that struck me was how confusing Spring naming is when trying to go the right way.

Let's say I want a class responsible for creating instances of my business classes. Something like:

Categories: Java

Build and Clean Selected Files in Eclipse CDT

Javalobby Syndicated Feed - Mon, 30-May-16 23:01

Sometimes it is very useful to clean or build a selected set of files. For this I select the file(s) in the Eclipse Project Explorer and use the context menu:

Build Selected Files

Categories: Java

How Dependency Injection (DI) Works In Spring Java Application Development

Javalobby Syndicated Feed - Mon, 30-May-16 05:16

This article explains the concept of Dependency Injection (DI) and how it works in Spring Java application development. You will learn about the advantages, disadvantages, and basics of DI with examples. Look further for more information.

Advantages of Dependency Injection

  • DI allows a client the flexibility of being configurable. Only client's behavior is fixed.

Categories: Java

Go and Quasar: A Comparison of Style and Performance

Javalobby Syndicated Feed - Mon, 30-May-16 04:31

A user recently made us aware of the Skynet benchmark, a microbenchmark for “extreme” multithreading (1M threads). We are generally wary of such microbenchmarks because they are often tailored to measure a specific strength of a particular platform, without taking into account how relevant that strength is for real applications. For example, a platform with a 1000x faster implementation of sqrt would be hard pressed to yield even a 0.01% improvement in performance when running real applications. With threads the situation is a bit different: when many threads are active (say, over 10K) processing transactions in short bursts, the kernel thread scheduling overhead might become onerous and your application may then spend a significant portion of its time waiting for the kernel to schedule your code. Lightweight thread (AKA fibers) implementations, like those provided by Go, Erlang, and, on the JVM, Quasar (and Kilim), can reduce this overhead by two orders of magnitude. This may be the difference between your server application being able to handle 500 or 5000 requests per second (some benchmarks can be found here and here).

However, once the threading overhead is reasonably low – say, less than 1% of the total time – differences in a particular implementation matter less and less: if there’s no overhead at all, the performance improvement will be only 1%. Because the JVM does not yet have built-in fibers, Quasar is required to implement them in a way that adds more overhead than platforms with native implementations. This is why in a microbenchmark that tests scheduling overhead alone, a generally slow runtime like Erlang’s BEAM may outperform a very fast runtime like HotSpot, even though once there’s any actual workload, the JVM quickly makes up the difference and then some (and then a lot, really). To further confuse the picture, some classical scheduling benchmarks like the ring benchmark actually reward schedulers that are only good at single-core scheduling and penalize schedulers that are good at sharing load among many cores.

Categories: Java

How React Makes Web Development Scalable

codecentric Blog - Mon, 30-May-16 02:33

This is an evaluation on how the React toolset works as part of a modern web development project and why it is particularly suitable for scalability.
React is currently unique because it originated, and is used successfully, by the biggest social network in the world, Facebook. Nothing comes close in terms of size and complexity, back in 2012 they had 700 developers and a huge number working on their frontend.

Everybody uses these very dynamic and well designed webpages. This is why users and designers expect this level of sophistication today and developers have to keep up.
While server and client side frameworks became very good at managing complexity behind the scenes, this does not apply to the view layer. Traditional HTML is very efficient, but limited to its native elements. Every custom tag needs to be built in a static and verbose way and then, in a second step, made dynamic by JavaScript. This breaks the development flow, because templating engines work very differently than regular code.
One alternative is to only use code and skip templating by operating directly on the DOM, but it is verbose and feels unnatural because in the end we create HTML without any abstraction in place.
To improve this, approaches like Angular and Web Components provide APIs for custom tags to encapsulate behaviour in a single component. But those just hide a lower level of templating and are also often unnecessarily complex.

Wouldn’t it be nice to compose components like functions while keeping the expressiveness of HTML?

React does that with a virtual DOM and JSX.
While preprocessing JavaScript is normal for every modern workflow, you can work with React through an extended JavaScript called JSX. There you have a very clean, simple xml-like syntax that is integrated into the Language, so code that manipulates the UI and the markup can be combined into a single file. This way there is no context switching and you can often see what’s going on immediately.

Now to protect you from the real terrifying DOM, React has its own virtual one in memory and every delta is checked first and then applied to the parsed HTML via direct DOM references. This is an extremely efficient way to apply changes and also adds a layer that can be virtualized on the server for testing and HTML rendering.

We got rid of the DOM and can further look at how the the React library supports scalable development.
Components encourage a unidirectional data flow and make state explicit. Data can only be entered into JSX elements through descriptive properties and nothing else, so every component forces the creator to think about his interface. Inside the component you usually access the properties (or child JSX elements for more powerful components) and they are immutable. If you want some complex logic or just change the UI, you can use the state attribute, but this information has no effect on the parent elements.

Let’s look at an example with a simple component that has one property:

React rendering of CombinedComponents:

Hello Imported
Hello Class loop: i=1 i=2 i=3
Hello Function
Hello Variable

This is a very basic example that displays the different kinds of components: Class, function and one just being imported.
Please note that JSX elements are just a part of regular code, so all the existing helper methods like map can be reused. They also can have descriptive variable names and organised for readability.

Since it is pure JavaScript, we can rely on traditional ways to organise code to make it robust and scalable. Thanks to the tree-like structure, it’s easy to find issues by going one component deeper. The attributes provide a descriptive API and as long as they don’t change there is no regression if the component is changed.
This perfectly encapsulates the underlying functionality, so this way you can easily have a big number of developers working “behind” one component without being affected.

Maybe this gives you some insight into why React is so popular, it’s very comfortable even for a low number of developers to work with it and build robust and maintainable software.
Today many companies use React and a growing ecosystem make it a safe bet for your stack.

The post How React Makes Web Development Scalable appeared first on codecentric Blog.

Categories: Agile, Java, TDD & BDD

Read YAML in Java with Jackson

Javalobby Syndicated Feed - Mon, 30-May-16 02:31

In this post, we will see how we can use Jackson’s YamlFactory to read YAML files into Java Beans.

What is YAML?

YAML is a human friendly data serialization
standard for all programming languages.

Categories: Java

Try and Catch in Golang

Javalobby Syndicated Feed - Sun, 29-May-16 23:01

Golang (as opposed to Java) does not have exceptions such as try/catch/finally blocks. It has strict error handling with functions called panic and recover and a statement named defer. It is a totally different approach. Is this a better approach than Java takes? (Sorry that I keep comparing it to Java. I am coming from the Java world.)

When we handle exceptions in Java we enclose the commands into a ‘try’ block denoting that something may happen that we want to handle later in a ‘catch’ block. Then we have the ‘finally’ block that contains all the things that are to be executed no matter what. The problem with this approach is that it separates the commands that belong to the same concern.

Categories: Java

Thank you

Dan North's Blog - Sun, 29-May-16 12:08

tl;dr: Thank you to some lovely people for translating or graphic recording some of my work.

One of the nicest compliments you can receive as a writer is someone choosing to translate your work to make it available to a new audience. I am enormously grateful to the people who have translated my articles and blog posts over the years, most recently Julia Kadauke, who translated What’s In A Story into German.

However nothing prepared me for the email from Denis Oleynik, CTO of 1service.ru, telling me he had translated no fewer than eight posts and articles into Russian!

They are:
Introducing Deliberate Discovery [Russian]
Are You Ready for the Truth? [Russian]
Continuous Build is not Continuous Integration [Russian]
Blink Estimation [Russian]
The Art of Misdirection [Russian]
The Perils of Estimation [Russian]
What’s in a Story? [Russian]
A Classic Introduction to SOA [Russian]

All these links appear on the respective posts as well. Introducing BDD is now available in seven languages and What’s in a Story? is up to five!

While I am thanking people, I had the privilege of giving the opening talk earlier this month at Craft conference in Budapest. The talk is about Embracing Uncertainty and two graphic artists, Dóra Matyus and Márti Frigyik, recorded it in the following images:

Embracing Uncertainty 1/3 Embracing Uncertainty 2/3 Embracing Uncertainty 3/3

I first encountered graphic recording via ImageThink and quite apart from the wonderful experience of having your ideas rendered as images, it is a great way to learn what someone heard from your talk rather than what you think you said.

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To-Do Lists with Eclipse Tasks View

Javalobby Syndicated Feed - Sun, 29-May-16 02:31

Eclipse has a cool feature which might not be known to everyone: the "To-Do" (or Tasks) List which keeps track of what I have to do:

Tasks View

Categories: Java

Builder in C#

Javalobby Syndicated Feed - Sat, 28-May-16 23:01

C# has in many ways inherited its relationship with Builder from Java, where it was usually called by the more degenerative term “Factory” or “Factory pattern”. (Technically, what Java calls a “Factory pattern” is typically one of Builder, Factory Method, or Abstract Factory, depending on what precisely looks to be varied and/or encapsulated.) C#, however, never fell quite as deeply in love with the “Factory pattern” as the Java development crowd did, and as such it wasn’t as widely used.

We start with the target Product:

Categories: Java

MuleSoft: Method Entry Point Resolver

Javalobby Syndicated Feed - Sat, 28-May-16 02:31

The Anypoint platform provides various components and built-in functions for integration purposes. Most of our needs in a project can be fulfilled easily, especially when we use the Enterprise Edition. Not only does this include the availability of ready-to-use connectors, but also a quick response from MuleSoft support.

Let's say we have to develop integration project using Community Edition. Obviously, with limited support from them. Although we can rely on the community forum with tons of ideas and discussions, sometimes we face a common impediment from our internal developers. In particular, they resist adopting the Anypoint platform and still engage with their preferred programming language. For example, they do not want to use MEL or expression component, but prefer to write a Java class.

Categories: Java

Builder in Java

Javalobby Syndicated Feed - Sat, 28-May-16 02:31

Java has long had a relationship with Builder, usually calling it by the more degenerative term “Factory” or “Factory pattern.” (Technically, what Java calls a “Factory pattern” is typically one of Builder, Factory Method, or Abstract Factory, depending on what precisely looks to be varied and/or encapsulated.)

We start with the target Product:

Categories: Java

7 Options for Capturing Thread Dumps

Javalobby Syndicated Feed - Fri, 27-May-16 23:01

Thread dumps are vital artifacts to diagnose CPU spikes, deadlocks, memory problems, unresponsive applications, poor response times, and other system problems. There are great online thread dump analysis tools such as http://fastthread.io/ that can analyze and spot problems. But to those tools you need provide proper thread dumps as input. Thus in this article, I have documented 7 different options to capture thread dumps.

1. jstack

‘jstack’ is an effective command line tool to capture thread dumps. The jstack tool is shipped in JDK_HOME\bin folder. Here is the command that you need to issue to capture thread dump:

Categories: Java

Java EE 8, Current Status: Case Study for Completed Work Since Late 2015

Javalobby Syndicated Feed - Fri, 27-May-16 11:13

For anyone who pays close attention to Java EE, it has become clear in the past six months that there has been a decline of activity...especially in those JSRs for which Oracle maintains the lead.  What's the deal?  There has been a lot of conversation in the Java EE community in this regard lately, and I think it is important that the developer community be given a fair timeline of what we can expect for the future of Java EE.  The uncertainty is becoming long in the tooth, and the community is becoming more concerned with the future of Java SE and Java EE as time goes on.

Let me give you a bit of background.  I'm an expert group member on a couple of JSRs targeted for Java EE 8, those being JSR 372 (JavaServer Faces 2.3), and JSR 378 (Portlet 3.0 Bridge for JavaServer Faces 2.2).  At the beginning of 2016, I had noticed that since October 2015 the number of emails on the Expert Group list for JSR 372 had really slowed down.   In fact, in the final quarter of 2015, the activity on JSR 372 had slowed down to a near halt, whereas it should be picking up momentum as time moves forward closer to the eventual final release.  In late January, I was contacted by a couple of members of the Java EE community, indicating that they also had seen a slowdown of activity and were very concerned.  I was then asked to join a community of concerned Java EE advocates on a Slack community...and when I joined and read the backlog of messages I could clearly see that it looked as though Oracle had stopped activity in just about every area of Java EE, specifically work on all of the JSRs that were Oracle-led.

Categories: Java

Oracle vs Google: Where are the Oracle Supporters?

Javalobby Syndicated Feed - Fri, 27-May-16 10:10

The verdict is in once again on the Oracle vs Google lawsuit regarding Google's use of Java in Android, and no sooner was Google declared the winner than Oracle announced their intent to appeal (at least) once more. The reaction to the verdict has been widespread in technology circles as one would expect, although the reaction is fairly one-sided (see thread examples here and here).

In reading some of the reaction on a range of site, I'm not seeing much (any?) sympathy for Oracle's loss, which might seem odd in a case like this. If you think about high-profile copyright/patent cases or questions of ownership in other industries, the public sympathy tends to be with the owner/creator. Remember Ice Ice Baby? (I'm trying to forget). The public was happy to see Vanilla Ice paying Queen royalties for using their song. Human nature in these types of cases would make one inclined to be behind Oracle, but this is a different case.

Categories: Java

Arrays: Disarray or Datarray?

Javalobby Syndicated Feed - Fri, 27-May-16 04:31


This is the first in the data structure reviews and likely the simplest: the humble array. The first issue is the term Array; its term differs depending on who uses it but we will get to that a bit later.

Generally, I think of an array like this:

Categories: Java

Code Smells—Part II

Javalobby Syndicated Feed - Fri, 27-May-16 02:31

In the last post, Code Smells - Part I, I talked about the bloaters: they are code smells that can be identified as Long Methods, Large Classes, Primitive Obsessions, Long Parameter List and Data Clumps. In this one, I would like to dig into the Object-Orientation Abusers and the Change Preventers.

Object-Orientation Abusers

This type of code smell usually happens when object-oriented principles are incomplete or incorrectly applied.

Categories: Java

Thoughts on JSRs, TCKs, and Open Source

Javalobby Syndicated Feed - Fri, 27-May-16 01:16

In the Java EE umbrella every piece of technology is standardized under a JSR (Java Specification Request). The Expert Groups of the JSRs have to deliver the specification, a Reference Implementation, and a TCK (Technology Compatibility Kit). For most of the JSRs, the TCK is licensed as closed-source software and is not available for the public.

That has the implication that any vendor who wants to implement a specific technology has to explicitly apply/ask for/buy the TCK in order to test their implementation and get officially certified. The problem with this situation is clearly that it raises the barrier for potential vendors. Or, in other words, it would be a benefit for vendors to more easily join in the game. Having that said it would then also be more favorable for users of Java EE to have more competition among implementations.

Categories: Java

Build Configurations in Eclipse

Javalobby Syndicated Feed - Fri, 27-May-16 01:01

Eclipse-based IDE’s have a powerful feature to make ‘variants’ of the same projects: Build Configurations. Build configurations are a powerful thing in Eclipse: they allow me to make ‘variants’ of a project. The project will share the common things, and I can simply tweak things one way or the other for example to produce a ‘release’ or a ‘debug’ binary of my application without duplicate the project.

Build configurations are managed through either the context menu on the project or with the top menu:

Categories: Java

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