Remote config in MicroServices

We are in a world of microservices, an application typically uses one or more infrastructure and 3rd party services. Examples of infrastructure services include: multiple environments, cloud configurations, a message broker and a database server.Examples of 3rd party services include: payment processing, email and messaging, etc.Although every microservice instance is an independent unit, it is recommended an approach to externalized their configurations management from one central service/location.

The concept of using configuration server inside microservices architecture is visualized on my design below.It is based on basic Spring boot implementation, further, different layers and orchestration can be added to enhance it.

Feel free to contact me if you want to discuss this in detail.



Love of Python : My first Python script

Every next day my love of Python and Scala is getting stronger, Hence I thought to post one python script here which is a sample script to perform some common configurations that we need in application deployment on production, test or automation servers. I am going to use this script (updated version of it) in my project to reduce an overtake of approximately 15-20 mins of manual configuration works of service deployment.

This python script performs following tasks
(1) Add new configuration
(2) Update configurations
(3) Run Unix commands (native OS) on server and few other tasks

You can customize this script as per your project requirement. The script is available at my gitlab repository. I would love to improvise any of my reader’s recommendations for any specific change/requirement over this script.

PS: This script is in the initial draft form, I will update it with more useful commands and comments to make it more user-friendly.



How to achieve parallel code execution without user Threads

What comes to your mind when you have to run a piece of code in parallel? you will create some threads to do it, correct! But this is not only a way to achieve it. Recently I came across one interesting requirement where I had to run a piece of code of an API for three parallel calls (without Threads).My approach is not something new, many of you might be doing it already and others might have not noticed this approach while maintaining the legacy code 🙂 .

Well, so this approach is nothing but a combination of Bean loading in Spring container and corresponding mapped Java class execution, and hooking a API to support parallelism. when spring container loads a annotated/configured Bean it executes Java method associated with it. using this concept we can define and load the same bean with three different ids to execute the method ( the same code runnable implementation ) code rather than doing it through Three different threads.

<beans profile="cluster">
<bean id="mongoQueryServList" class="com.skilledminds.thirdPartyService.configure.db.connectionProvider.cacheQueryProcessor"/>
<beans profile="cluster">
<bean id="cassandraQueryServList" class="com.skilledminds.thirdPartyService.configure.db.connectionProvider.cacheQueryProcessor"/>
<beans profile="no_cluster">
<bean id="graphQueryServList" class="com.skilledminds.thirdPartyService.configure.db.connectionProvider.cacheQueryProcessor"/>

Above piece of code is just a replacement of Three threads for  "cacheQueryProcessor" task, now to achieve parallelism/conditional task execution this method should be designed properly to meet the requirement. For more details on parallelism/conditional task execution please refer Spring-Batch Scaling and Parallel Processing or Java executor framework ( which is a base of every Parallelism implementation).

Still you want to take a deep dive of similar implementation then take a look at ongoing Spring Jira

PS: For an experienced java professional this may look very simple to do but considering this in a bigger picture gives the insight of an option to design an utility tool/Jar without heavy Spring batch or similar APIs.

Handling dynamic/unknown Datasource in Application

Let’s see how we can deal with a requirement when server-side input configuration or data source is not constant in your application and furthermore memory footprint of application should be also very low ( i.g a mobile Product ).

Once for a big data ( web crawler based ) product we had one requirement where input datasource was not fixed, based on customer choice datasource was configurable. Since product was a mobile application so we wanted to keep application’s memory footprint as low as possible, so we did not use Spring / Hibernate / Gauva etc…. framework for creating and maintaining configuration container on Fly.

Here is one basic design approach that I had prepared which later I improved to meet exact requirement. Contact me if you need further details on such implementations. I will upload this design in SkilledMind’s ( gitlab.

PS: Due to an agreement I have not added exact design.

Data Access layer Design



who will dance with Nancy ? Find in below code !

My new post is going to take little more time so thought of to post solution of this long pending problem posted by me on November 1, 2014

public class DecideDancePair {

DecideDancePair ddp1;
StringBuffer ddp2 = new StringBuffer();

public static void main(String[] args) {

new Thread(new Runnable() {

public void run() {
synchronized (DecideDancePair.class) {
System.out.println("Its weekend .... Hey Guys !! this is Nancy , who will dance with me? ");


new Thread(new Runnable() {

public void run() {

synchronized (new DecideDancePair().ddp1) {
System.out.println("Hey Nancy !! this is Peter , I will dance with you.");


new Thread(new Runnable() {

public void run() {
synchronized (new DecideDancePair().ddp2) {
System.out.println("Hey Nancy !! this is Rozer , I will dance with you.");





Soln :

Nancy will always go for dance because she having Lock over a object which is not NULL. same with Rozer , he is also having a non-NULL lock. while poor Peter is caught with NULL object Lock so that piece of code will throw below exception and Hence Nancy and Rozer will be in dance 🙂 !!!

Code execution will looks like :

Its weekend .... Hey Guys !! this is Nancy , who will dance with me?
Exception in thread "Thread-1" Hey Nancy !! this is Rozer , I will dance with you.
	at BasicConcepts.DecideDancePair$

An Introduction to REST and a High Level Design of a REST API

What is REST and Why is it called Representational State Transfer?

REpresentational State Transfer (REST) is a style of software architecture for distributed systems such as the World Wide Web. REST has emerged as a predominant Web service design model.
The Web is comprised of resources. A resource is any item of interest. For example, the Jet Aircraft Corp may define a 747 resource. Clients may access that resource with this URL:
A representation of the resource is returned (e.g., Jet747.html). The representation places the client application in a state. The result of the client traversing a hyperlink in Jet747.html is another resource is accessed. The new representation places the client application into yet another state. Thus, the client application changes (transfers) state with each resource representation –> Representational State Transfer!

Below is one sample high level REST API design that I had designed some year back. REST’s new learner can take reference of it.

Sample search REST API High level design

SparkJava multipart/form-data fileUpload

Spark Framework is a simple and lightweight Java web framework built for rapid development. With Spark it’s possible to start a REST web server with a few lines of code.It is the Java porting of Sinatra: famous micro-framework written in Ruby.The purpose of this post is to explain how to work with Spark  for multipart/form-data fileUpload requirement.In different dev community I have seen people searching fix of fileUpload failure of SparkJava framework, so I thought to share the fix that I have encountered and fixed recently."/files/upload/:userName", "multipart/form-data", new Route() {
			public Object handle(Request request, Response response) {
				// process request
				String userID = request.params("userName");
				if (isValidUser(userID)) {
// These two lines work as fix.
MultipartConfigElement multipartConfigElement = new MultipartConfigElement("data/tmp");
request.raw().setAttribute("org.eclipse.jetty.multipartConfig", multipartConfigElement);

					Collection<Part> parts = null;
					try {
						parts = request.raw().getParts();
					} catch (IOException | ServletException e2) {
						// TODO Auto-generated catch block
					for (Part part : parts) {
						System.out.println("Name:" + part.getName());
						System.out.println("Size: " + part.getSize());
						System.out.println("Filename:" + part.getSubmittedFileName());
					String fName = null;
					Part file = null;
					try {
						file = request.raw().getPart("fileToBeUploaded");
						fName = request.raw().getPart("fileToBeUploaded").getSubmittedFileName();
					} catch (IOException | ServletException e1) {