Cassandra

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Cassandra are non-relational/NoSQL is a highly scalable, high-performance distributed database designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure. Cassandra used by giants like NetFlix, eBay, Twitter and Reddit. Snitches  Determines how Cassandra can tell the topology of the infrastructure. In layman’s term how nodes would […]

Redux

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Redux Notes: Redux is in charge of the whole application state NOT component state All Reducers are matched in combineReducers method Action Creator are in charge of changing application state Store Action Creator – returns an object action, which automatically sent to all reducers reducer_data – is your data Some Imports to note import {connect} […]

Docker Mastery

Posted on Posted in Java, Technologies

Below are more detailed notes on various aspects of Docker, and somewhat more advanced topics with dealing with container/image management. Docker commands are now separated into main modules. previously when you wanted to run a command, you would do docker <command> In the newer version you can say: docker <module> <module_command> Modules config – Manage […]

Future Posts

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This contains a list of articles I plan to write on: linux.conf actor system protocol buffers google cache Algorithms default local variables constructor this or super static block inheritance garbage collection overloading vs overriding initializing final variable polymorphism – changing behavior during run time abstract vs encapsulation interface Unchecked exception vs checked exception Throwable base […]

Akka Ask

Posted on Leave a commentPosted in Akka, Java

On all our previous example we have been using Tell method to send messages to actors, in Akka this is known as fire-and-forget. Which means you send a message and there is no blocking, Actors, handle a separate thread to handle the actual work. But what happens when you need a return value? you pass a […]

Akka Immutable Messages

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By default Akka does not make your variables immutables, so if you are passing around message/objects with mutable variables there is still a case where you can experience a deadlock. That is why it is highly recommended to use immutable messages when integrating with Akka Actors. What are immutable messages? Basically these are variables that […]

Actor Hierarchy

Posted on Leave a commentPosted in Architect, Java

Akka Architecture by default supports parent-child Actor structures. On startup Akka already creates several actors for you: http://doc.akka.io/docs/akka/current/java/guide/tutorial_1.html Root guardian – to handle all the actors System guardian – Akka System guardian User guardian – user in this case is you, user guardian manages all the actors created by the developer. Usually you can only […]

Akka Actor Model

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Akka Actor Model  Dealing with highconcurrency, highly scalable applications. Again, just want to emphasize this site does not aim to give a complete comprehension of given topic, but rather an overview, or review of certain topics. It is still recommended to do a reading on the actual documentation. Recommended Reading: http://doc.akka.io/docs/akka/current/java/guide/tutorial_1.html What is Actor Architecture? In […]

Static vs Instance variables

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Static vs Instance variables When you declare a variable static, there is only one copy of that variable per class. Consider the following example (bad encapsulation code do not copy): when we use static, there is only one copy per class, so no matter how many Humans objects we have, there is only one PLANET, […]

Java Basics

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Here we discuss basic concepts surrounding Java, they are terms and principles that surround java as a language. JDK vs JRE JRE – Java Runtime Environment – environment to enable java applications to run. JDK – Java Development Toolkit – everything need to develop a java application, which in turns includes a runtime environment (JRE) […]