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How many of you are currently using Java 21 in production, or are you planning to update? Worldwide, there are numerous legacy applications that pose significant challenges when upgrading to a new version due to the complexity of business logic within the application. Essentially, maintaining them becomes a trial-and-error process for new developers.

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Are you afraid of writing programming code?
This is based on my personal experience.Everyone might have different level of experience.

Suggestions to beginner ,do not afraid to write programing code.here are few tips .

Once I was also afraid to write code ,I used to think it is most difficult task .But later I found it’s normal. But,Still I have to keep myself up to date with technology.

I am beginner to programming ,where shall I start ?
Read books ,do not jump on short Tutorial or Courses.

Why should I read books ,it takes times, I want to be expert within few months or within year ?
If you really want to survive in this industry for decades keeping yourself competitive to sell your skills in International Competitive market your programming base must be strong.

In my experience reading book makes your base of programming strong.

Actually how many months or year it takes to get expertise in programming ?
It depends on how many lines of code you write. Writing code daily will atomically boost your skills ,you will experience it within 1 year.

Here are few categories of technology used by Java based product.

1 Use of JSF / Prime faces /JSP /Servlets
These category of technology product are running for long time in production. These technology are creating risk for company to innovate their products with new technology.
Their major revenue is gone for maintaining these application where there are less manpower in market & takes very longer time to make few changes in application. These are very legacy application.

2 Spring Framework with JSP
These category of technology product uses Spring framework where configuration are xml driven .MVC pattern is being used using Spring MVC.

Xml driven JPA is used .Architecture is monolithic application.

Deployment is done on Tomcat /Jetty . Still company is facing difficulty to maintain & support these applications due to large base of monolithic code & also these technology are becoming legacy which is replaced with spring boot.

3 Spring Framework With Rest
Product is developed using service based architecture & API are fully Rest.Still there is issue of maintaining application due to large no of configuration & monolithic code.

4 Spring Boot
Application is developed with features provided by Spring boot.Easy to maintain & develop.

5 Spring Boot with micro service based Architecture.

Do you know actually how Java works?
Here is short explanation of how it works .
For this explanation I assume there is already User.java program created.
Source Code Compilation:When you write java program first of all it need to be compiled .For example if you wrote User.java class then compiler will compile it to User.class .That means when you write User.java class now its part of compiler to compile it.
Loading Class into JVM:When Java program is successfully compiled it is run on JVM.That means this compiled class need to be loaded to JVM.For example we have compiled our User.java it will be converted to User.class ,now this User.class which is byte code is loaded on JVM when we run our program.
Ex*****on of byte code: After byte code is loaded on JVM ,then it is executed by JVM.Java is interpreted language therefore JVM execute it being interpreted.This means JVM will execute byte code line by line into underlying hardware machine instruction one after another.

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Here are possible design options for Micro service architecture for Authentication & Authorization.

Option 1 : Authentication & Authorization on Each Service

This design will keep API Gateway lightweight ,using API Gateway just for Routing.

Suppose say we have 2 different services as User Service ,Password Service then API Gateway will route to respective service based on request URI.
On Each service based on configuration of security setting user Authorization & Authentication takes place on that respective service.

Option 2 : Authentication & Authorization as separate service

This design will also keep API Gateway lightweight .In this type of design there will be separate service that will take care of Authentication & Authorization.

Suppose if request is made to user service then gateway will route this request to user service.User service will call centerlized authentication & Authorization for request validation.

If user is not already authenticated then authenticated will takes place & return response with token.If user is already authenticated then validation of token takes place.

I would recommend Keeping API Gateway light weight, keeping it simple & used for just Routing. Let me know if there is other better approach in comment section.

Different types of Garbage collectors in Java.
There are 5 types of Garbage collection In Java.
Serial Garbage Collector
Parallel Garbage Collector
CMS Garbage Collector
G1 Garbage Collector
Z Garbage Collector

But from Java 9 CMS is deprecated. For new versions of Java G1 Garbage Collector is default.

Why we need JVM tuning for your product Backend written In Java?
May be this topic is kept as low priority if new Product BE is developed using Java programming. If its new product & number of users using application are low then we do not encounter this situation often.

But ,if product BE is running for long period in production & no of users using application is increasing gradaully JVM tuning is one of the areas we can consider for tuning your application.

One of the scenario is when running application pauses for definite time & end up with Out of memory exception, this scenario comes when Garbage collection goes for Full GC .
To over come this situation we need to consider JVM Optimization , JVM Tuning, profiling & troubleshooting for better performance , Throughput, Latency of application.

How often have faced situation of JVM tuning ,profiling & troubleshooting? Let me know in comment section.

Looking over current market scenario of AI revolution, it seems Big companies invest lots of money in research and development but they lose innovation. For startup they have freedom to move towards innovation driven by passion.Hope this new technology advancement motivate startup to develop more innovative products.

7 things every developer must not forget while estimating their tasks.

- Time for task grooming :You have properly groomed your tasks with your team mates & have done sufficient research for your tasks.You are clear for your tasks ,there is proper UI & you have communicated well for product owner about feature.
- Time for Development.
- Time for unit testing & integration testing.
- Time for code review & feedback implementation.
- Time for own self testing.
- Time for Own raised bugs fixing.
- Time for communication.

How can we make ML prediction more human readable & adapt ChatGPT inspirations to integrate on products ?

Those we are working on Data industry ChatGPT has clearly given path of showing result in human readable format.

For businesses they have their data stored in different formats but to get insight of data in human readable format is still struggle if we are leveraging ML for decision making.

For example if I we have data sets stored on database & have ML model ready to being train on that.

If that model is trained with training data fetched from database with all data conversion done for training.

When we have real data to be tested for ML model deployed on production & we have result given by ML for real data.

But sometimes ML give some anamology answers to business questions then in this case often data analyst manually has to check data why there is anamology in result.

If we can solve this problem by presenting result in human readable format with more advance informations like why ,where ,how by integrating technique & architecture followed by ChatGPT then in BI Analytics industry can get significant benefits from it.

May be sooner we have open source community to leverage same like ChatGPT to integrate for their Proprietary data.

When your product goes into market in product life cycle many challenges start to pop up, here are few challenges every product company face on their product life cycle when it starts to gain customers.

- Technology could not scale up & this becomes one of the problem ,again development cost increases to rewrite application to make it scalable.

-Technology that was used for developing product is sooner becoming legacy ,which need to be replaced with new technology.

- Tech debts keep in increasing to solve problems using work around approach to solve raising problems.

- Tech support from technology implementor stops i.e we are using some version of framework & that framework is deprecated with support ending soon.

- New features rolling & maintenance would be extreme difficult when code written in old version is difficult to understand and expertise in market for older technology is hard to find.

These are some common problems every tech company are facing ,they want to move forward with new technology but due to fear of loosing business with implementation of new technology code written once is non touchable.
If there are other complexity you are facing let me know in comment section.

How class loader works in JVM?
There are 4 types of class loader
Bootstrap class loader
Extension class loader
Application class loader
Custom class loader

Bootstrap class loader:It loads class from rt.jar. This jar contains core library.

Extension class loader:It loads classes from jre/lib/ext directory.

Application class loader:It loads classes from application current class path.

Custom class loader:If we want to load classes from different locations rather than rt.jar or jre/lib/ext directory or current class path in this case we use custom class loader.

Suppose say we are creating new object inside main method as
User user=new User() then class loading mechanism will be as described below.

1 When ex*****on of java program starts from main method it does not load all classes eagerly which we have imported in our program.First of all it tries to load core classes from Bootstrap class loader.

2 If inside main method we creating new object ,suppose say we are creating object of User class, then in this case first of all class loader tries to find User class in bootstrap class loader

3 If it is found in bootstrap class loader it will be loaded from bootstrap class loader ,otherwise it tries to load from Extension class loader .If it is not found in Extension class loader then it tries to load from Application class loader.
This is general class loading mechanism in JVM.

Do you know actually how Java works?
Here is short explanation of how it works .

For this explanation I assume there is already User.java program created.

Source Code Compilation:When you write java program first of all it need to be compiled .For example if you wrote User.java class then compiler will compile it to User.class .That means when you write User.java class now its part of compiler to compile it.

Loading Class into JVM:When Java program is successfully compiled it is run on JVM.That means this compiled class need to be loaded to JVM.For example we have compiled our User.java it will be converted to User.class ,now this User.class which is byte code is loaded on JVM when we run our program.

Ex*****on of byte code: After byte code is loaded on JVM ,then it is executed by JVM.Java is interpreted language therefore JVM execute it being interpreted.This means JVM will execute byte code line by line into underlying hardware machine instruction one after another.

Why startup can not understand complexity of implementing micro service architecture?

Every one wants their product to be bullet proof from beginning.If its new product & development need to be done from scratch then company wants to implement with best standards, architecture followed by large product companies.

This is obvious reason every one wants their product to be scalable with respect to time & does not want their product to be legacy soon as they are investing large sum of their money on their product.Finally ,they ended up with going micro service architecture.

But ,when when development kick starts ,sooner development takes more time than expected, infrastructure keep on growing ,developer ,QA testing time keep on growing.This will push more pressure to team to complete within development timeline which will eventually team will be task oriented ,no unit testing ,no integration testing ,no code review & quality of code keep on decreasing which means more bugs ,more time to fix which again add more time to release product to market.

This is just one use case for related development. There are others drawbacks related to infrastructure management ,production supports, new feature update & maintenance which will eventually increase the cost of Project.
If you are starting to develop product & making decision to go for micro service architecture first understand your budget & its complexity. Besides micro service architecture also there are other options we can choose for startup.

How to define definition of done for your task in Software development?
Here are few items we need to consider
* You have completed development for your task.

* You have written a unit test & integration test for your task.

* You have completed code review for your task
.
* You have documented your task.

* You have completed a self test for your task in the dev environment.