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From the Trenches of the Enterprise Software

Yakov Fain

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Top Stories by Yakov Fain

In this article I’ll introduce the switchMap() operator. The previous articles in this series include: 1. Basic Terms 2. Operators map, filter, and reduce 3. Using Observable.create() 4. Using RxJS Subject 5. The flatMap operator While flatMap() unwraps and merges all the data from the outer observable values, the switchMap() operator handles the data from the outer observable but cancels the inner subscription being processed if the outer observable emits a new value. The switchMap() operator is easier to explain with the help of its marble diagram shown next. The outer observable emits the red circle, and switchMap() emits the item from the inner observable (red diamond and square) into the output stream. The red circle was processed without any interruptions because the green circle was emitted after the inner observable finished processing. The situation is diffe... (more)

RxJS essentials. Part 4: Using Subject

In this article I’ll introduce an RxJS Subject. The previous articles in this series include: 1. Basic Terms 2. Operators map, filter, and reduce 3. Using Observable.create() An RxJS Subject is an object that contains the observable and observer(s). This means that you can push the data to its observer(s) using next() as well as subscribe to it. A Subject can have multiple observers, which makes it useful when you need to implement for multi-casting – emit a value to multiple subscribers. Say, you have an instance of a Subject and two subscribers. If you push a value to the sub... (more)

How Do You Deploy Patches in Your Rich Internet Application?

OK, your Flex application is already deployed in production. How are you planning to deploy patches to your code? I mean bug fixes or enhancements to specific MXML components or ActionScript classes? Of course, you can recompile the entire application with hundreds of classes just to deploy a new version of the class MyGreatCreation.as. Let’s see if there is a way to deploy just MyGreatCreation leaving the rest of your application intact. In Java world, the solution to this issue is pretty simple. A typical Java application consists of a number of .jar files (think librarie... (more)

Secrets Of The Masters: Core Java Job Interview Questions

JDJ's Enterprise Editor, Yakov Fain (pictured) writes: If you are planning to hit the job market,  you may need to refresh some of the Java basic terms and techniques to prepare yourself for a technical interview. Let me offer you some of the core Java questions that you might expect during the interviews.  For  most questions  I’ve provided only  short  answers to encourage further research.  I have included only  questions for mid (*) and senior level (**) Java developers. These sample questions could also become handy for people who need to interview Java developers (see also ... (more)

Android: Who Hates Google Over the Phone?

After Google’s Android announcement , at least four big guys should be irritated:Sun Microsystems, Apple, Adobe and Microsoft. Google approaches telephony from the open source side – Linux-based platform uses Java but does not care about sticking to Java ME – they are planning to use fast OpenGL libraries and are not afraid to be hardware-specific.  Check out the Youtube videos at the android site. Performance-wise that device looks pretty impressive.  Google has created an alliance of more than thirty parties – phone manufacturers and service providers.  Google knows how to do t... (more)