Tag Archives: hands-on

Things everyone should know about responsive images and srcset

The aim of responsive images is to deliver the same image in mobile and desktop view without disturbing the viewport size that is the image should look alike in every device .

Therefore this problem of responsive images can be solved by using srcset attribute in image tag or using media queries.

Both are suitable to deal with this situation but prefer to use srcset instead of media queries because media queries will take time to write but srcset does the same thing in small time and space .
The information below will explain all about srcset .

srcset
The srcset attribute is listing different resolutions of the same image from which the browser chooses the best fitting image source before loading it.
Example: srcset="ninja-1000w.jpg 1000w, ninja-500w.jpg 500w, ..."
To calculate this, the browser assumes the image fills up the full viewport width (100vw) by default, which means it uses the full width of the browser.

In short, Srcset is a new attribute which allows you to specify different kind of images for different screen-sizes/orientation/display-types.
The usage is really simple, you just provide a lot of different images separating them with a comma like this:

<img src="image.jpg" alt="image" srcset="<img> <descriptor>, ..., <img_n> <descriptor_n>">.

Here is an example:

srcset="image.jpg 160w, image2.jpg 320w, image3.jpg 2x"

Descriptors are just a way to show what kind of image is coming from the resource. There are various kinds of descriptors:

  1. density descriptor–> srcset=”image.jpg, image-2X.jpg 2x” The display density values—the 1x, 2x, etc. are referred to as display density descriptors. If a display density descriptor isn’t provided, it is assumed to be 1x.
  2. width descriptor –> srcset=”image-240.jpg 240w, image-640.jpg 640w”.
    When using the w-descriptor we have to specify the default explicitly by adding a second srcset image option, with its own w-descriptor, and separating them with a comma.
  3. size descriptor–> It only makes sense if you use width descriptor.
    srcset=”image-160.jpg 160w, image-320.jpg 320w, image-640.jpg 640w, image-1280.jpg 1280w” sizes=”(max-width: 480px) 100vw, (max-width: 900px) 33vw, 254px”>.
    The instructions for the browser would look like this: (max-width: 480px) 100vw — if the viewport is 480 pixels wide or smaller, the image will be 100% of the viewport width.So it is like using media queries in html which looks a lot easier as compared to media queries written in css .

Pros–>
1.much easier than media query
2.saves time

Cons–>
1.Browser should be updated to see the effect
2.Not all browsers support this.
At present, Edge, Safari, and iOS Safari only support a subset of the srcset specification. Firefox, Chrome, Opera, Android Browser, and the forthcoming versions of Safari and iOS Safari fully support it.

Demo can be seen on my github link

pershantgoel.github.io/imgsrcset

Test Driven Development with SpringBoot+Junit

 

Test-driven development(TDD) in the Spring framework.

TDD  helps me speed up my software release cycles, and ensure that I end up with a high-quality product. Spring makes Java enterprise development much easy.  Spring Boot, which we will use in this blog, is a project that does this task with excellence.

Follows are the steps to configure your spring boot framework with the Junit and Maven.

Step-1)Set up Spring boot with J-Unit testing Approach

After Set your maven dependencies , for spring-boot add following dependency for testing Approach.

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.4</version>
<scope>test</scope>
</dependency>

<dependency>
<groupId>org.springframework.restdocs</groupId>
<artifactId>spring-restdocs-mockmvc</artifactId>
<scope>test</scope>
</dependency>

Step-2)Create test Package and in that ,create DemoApplicationTests Class.

Step-3)Inject controller using @InjectMocks, Inject repository using @Mock Annotations.

Let us take some J-Unit Annotations used in java class :

@Before:@Before annotation are executed before each test.

@After:It executes after each test.

@BeforeClass: It executes common operation before each test,So it executes  only once before running all tests.

@AfterClass: It executes common operation after each test, So it executes only once after running all tests.

@Test:The Test annotation tells JUnit that the public void method to which it is attached can be run as a test case.

In JUnit 5, the tags @BeforeEach and @BeforeAll are the equivalents of @Before and @BeforeClass in JUnit 4.

Configure Java File and Select Run as Junit and Test the file.

 

Congratulations!!!you are done with your TDD approach.

Eclipse not auto-configuring/auto-importing a Git mavenized project

I was trying to setup a maven project in eclipse via GIT. I had hoped, it will auto import the project into eclipse, but for some reason that did not happen.

 

This is what was done as a workaround:

Step:1 Checkout your repository in your system

File->import->Git->Project from Git->Clone URI->Enter Git Repository Details

Select Destination where you wanted to store your Git Repository

Step:2 Import your Project into Eclipse

File->import->maven->install or deploy an artifact to a Maven Repository

Once these steps are done, The project is browsable in eclipse!

Some Helpful Git Commands for the commandline:

git init — Initialize your directory with git.

git add FILE and git checkout — FILE To stage/unstage a file

git commit— To save your changes. This commit will be local

git stash and git stash pop — Stashes are back

git reset HEAD –hard Revert all your local changes

git log— Access all the history in the repository

git rebase –You can squash all the commits! (one should be carefull with this one)

git branch –You can create local branches,But keep the history linear

Hope this workaround and the commands are useful to a new user.

The IoT AI Manifesto

With the recent sloppiness in implementation of software & hardware and synergizing them into so called the being called IoT  The time is appropriate that a defacto manifesto be brought in place for the artificial species called IoT.

I assume most of us are aware of the Three Laws by Isaac Asimov.

What I propose is build for the interacting robotics with lesser-minded-human-kind!

  1. An equipment if called IoT should abide by:
    1. It should be considered a legal offspring of the last hand-off human entity.
    2. It should have an IDENTU  mode that should let it spill out its purpose/identity/owners.
    3. It should have safe mode where any voice may command it to stop the current action.(something like a STATUE/RESUME mode)

Pretty simple! Very much make-possible!

Thoughts?

What Elon Musk can learn from Java App/Cloud Deployments!

I had an unproductive day yesterday!

I did nothing, but slept through most of the day. And then late night this next challenge of deploying the hush-hush java app over the cloud started to bother me.(afterall it was not a totally unproductive day, thinking wise!)

And then, flash back to a few days, where comparisons were made, what I am doing (javascript ehew!) and what one of the current top living inspiration in the current world Elon Musk is doing, and then I went into sad slumber!

Then yesterday happened, and then it clicked:: we Java devs(web ones, not hard core jdk ones) are orchestrating everything in lifecycle of what Elon Musk is trying to do!

Here is the analogy(it can be extended wonderfully!):

  1. The WAR(Web ARchieve)(sorry, I am old fashioned) is like the unmanned space ship.
  2. The dev JVM is like simulated Mars environment.
  3. The cloud is the SPACE where the bits travel to-and-fro in form of data/packets.
  4. The machine IP Address is like the lat/long of where you want to deploy.

So my current app is in its final integraton phase(hush-hush…) and I am trying to accomplish Slide Driven Development.(nice term!).

Slice Driven Development :: A development approach where a feature/flow is shipped to staging environment as soon as it becomes usable.

Currently I(with @explorer) are trying to integrate all features/flow of the hush-hush app, While I am totally unsure/unaware how it will behave when deployed on staging/production environment. Therefore, I had come up with this approach :: The momemt a feature becomes bug-discoverable, it ought be shipped so that:

  1. Move to the next flow..
  2. Bugs can be quashed..
  3. (most imp)Our path of going from dev–>staging–>production for any feature should be seamless and smooth like  skating on butter!

And then, a Eureka moment happened!! And this blog post came about!

Your Takeaway: If you are on a team working with Elon Musk(or anyone trying to transport stuff from place X to place Y, in an unsure environment), you can leverage from the experience of thousand if not millions of deployments of web java developers trying to deploy WAR file formats from local dev JVM to production JVM.

We know the nuances of this lifecycle!

It might save you some time! 🙂

The Slow Moving Manifesto!

If you are being tailgated, we recommend you follow this approach to come out of that situation!

Go Absolutely Slow!

YES, surprisingly it works out just fine!

Purpose: To know who is tail-gating you AND Why?

How it works?

  • If the vehicle following you sees you slowing down, they will have no choice to speed up (which means they were not following you) or look-you-in-the-eye. (either ways, the problem is solved!)

Benefits of slowing down

  1. By slowing down, you opened an opportunity to talk.. Human Connect!
  2. By slowing down, maybe you can have a running conversation, you are driving + talking(giving direction who knows). Saves time!
  3. By slowing down, you saved lifes! No stats but still true!
  4. By slowing down, You enjoy the road-side scenary. (remember enjoy the journey not just the destination!)
  5. By slowing down, You literally look the problem in the eye than running away from it.

There goes, we have the Slow Moving Manifesto!

Credits: Smita, Rachit + (KennyG played in our neighbouring park @ 1000 hrs) 🙂

Java Lookout — Java Language and Platform Futures @Devoxx, Belgium.

Feedback on watching the Java lookout!

1/Bad humour. Meh!

2/If you cannot commit anything to the language, why broadcast it? Are you scared of a features popularity? Rant on a similar thing in JavaEE

3/Spineless Humour!  https://youtu.be/oGll155-vuQ?t=564

4/Listen carefully :: “You may have to use type args more with lambda’s” https://youtu.be/oGll155-vuQ?t=721 So your principle of bringing least disruptive change FAILED!

5/Freeze the screen :: Which code is still less readable? https://youtu.be/oGll155-vuQ?t=830 Come on! Stop pushing #JEP286 #DieJEP286 IT DOES NOT MAKE SENSE. Simple!

6/Sadly the current Java architects are trying to add features to reduce developers time to build a feature. There are already players to do this: Spring et al. You should be focused to create the playground, and not the rules. Why can’t they understand this simple fact? Look at the earlier Java architects… Did they focus delivering a CS concept or ease of developer writing the code? Don’t outsmart Spring, Don’t outsmart IDE’s outsmart CS concepts and implement them in Java.

7/Improved Switch design is being talked about, this is a brainstorming topic, it does not make sense to show-off it *conceptually* here!

8/Value Types — Only needed if you are pixel developer or probably a compiler writer. A lot of people writing Java are Enterprise users. We have custom wrappers, and would *not* need Value Types. But nonetheless its a welcome feature!

9/Project Valhalla — Get a basic version out, build on it later. Do not try to deliver a 5 story building in one go. Deliver one layer per version.

10/The decision for priority of a feature should have been *complexity* and if some feature is wanted and do-able, IT SHOULD BE DONE AND NOT POSTPONED.

I have gone a lot rusty with Java! :-/

 

 

When the internet was crippled to a halt! ~ The dDos attack – A Post Mortem

The Problem

Couple of days back, 21-October-2016 everyone connected on the web experienced sluggishness in connecting to the normal sites and saw obstruction in their regular works.

The scenario can be visually described as follows:

DDOS Attack Explained
DDOS Attack Explained

Incase you might be wondering why this attack happened now, the internet is way mature, why can’t it protect itself from such attacks?

Well, then do read on…

The Players

From an ideal perspective the players in the attack are listed:

  1. Users of the web (us) (attackers and victims)
  2. ISP’s (medium through which attack was carried out)
  3. Device Manufacturers (Things, which got compromised — zombies)
  4. Regulatory Organizations (They are mostly sleeping or doing other important silly stuff, lets leave them out of this discussion)

The Premise

Let us look at those questions asked earlier and more:

What is dDos?

It stands for distributed Denial of Service. Consider your regular pesky thing that you have to do and can’t live without?(siblings,kids,neighbours.. anyhuman thing). They come nagging to you, you can handle it but maybe 10 requests in a day a max! The 11th request from that pesky thing will get a denial of service response!(simply a No!)

Now,Imagine yourself at a play house. And you are already having a minor headache(it was Friday, everyone was in the mood to relax). Multiply your single pesky thing with say 10, you are bombarded with pesky request from everywhere, what will happen to you? You might handle say 20 requests at that moment, looking at the situation, but a time will come soon where you will get exhausted and simply stop responding to important requests of like : open the door, and you are standing still!

You just got dDos’ed 🙂

Can you explain it in layman’s terms?

Here is the wikipedia entry.

I still did not get it..

See this:

Why this attack happened now?

It was waiting to happen, its like too many cooks, spoil the broth kinda scenario. Lot of unpatched/sloppy devices connected to the internet working for you and they all had a common zombie entry point, that simply got activated!

The internet is way mature, why can’t it protect itself from such attacks?

I am sure there are some orgn that were actually fighting this menace! Imagine a hospital unable to get reports of a patient in critical condition!So I am pretty sure what got reported and what actually got fixed and treated is somewhat different. So the internet is not at all mature, we are still not ready to have our life depend on it, our livelihood might depend on it but not life!So some orgn might be involved (even now) preventing many such attacks to keep the internet working, and some sleeping regulations might have also protected and saved us from a much more severe attack!

The rules are pretty simple, everyone is united on this matter and no one likes a dDos attack to happen! It actually interrupts normal/perceived flow of life on a day-to-day basis.

So basically its the attackers who (misued?) a compromised device and affected the network. Its pretty clear, there is something that needs to be fixed/controlled in the wild. And its not impossible..

Onto the solution then, shall we proceed?

The Solution

Two parts solution can be proposed:

  1. Regulation. In an ideal world, regulation is already in place and device manufacturers are supposed to follow them and hence they are able to sell their products. So something stronger needs to be put in place for regulation. Say if a device is an IoT kinda device, then as per regulation it should be allowed to use 5% of the bandwidth. If its a phone or a computer, then it will not have such a restriction, or maybe it can have!
  2. ISP Level Quota Software. ISP’s would want to pitch in this idea, where a custom configuration software would be installed at per user site and there based on the MAC address the bandwidth quotas can be defined. Say you got a new IoT device for your home, you will get to configure and set a max bandwidth that device is allowed to consume on your home network.

Thoughts?

Talking to mysql on Bitnami google-cloud Tomcat instance

The Java deployment world is plagued with infra issues! Things we need to take care of:

  • Apache
  • Tomcat
  • RDBMS
  • Firewall/Ports
  • Shell accesses
  • Security/Encryption/Keys
  • File System Storage
  • Indexes corrupting and the list goes on…

So after my failed attempt to understand/decipher CORS issues on the AWS platform, I fortunately stumbled on google-cloud! And it is one hell of a bouquet of services for us petty and dev-ops-complaining Java folks!

So churn out a bitnami tomcat instance and you get the feel of the aws thing. For over a month now my google cloud app was(still is) talking to the mysql instance on aws, before that starts to drain my mini wallet, time to configure a mysql instance on google-cloud. And here are the steps:

  1. Have access to the SSH into your google cloud instance working
  2. Create following script (/home/bitnami/mysql-init):
  3.  UPDATE mysql.user SET Password=PASSWORD('NEW_PASSWORD') WHERE User='root';
     FLUSH PRIVILEGES;
    
  4. sudo /opt/bitnami/ctlscript.sh stop mysql
    
  5. sudo /opt/bitnami/mysql/bin/mysqld_safe --defaults-file=/opt/bitnami/mysql/my.cnf --pid-file=/opt/bitnami/mysql/data/mysqld.pid --init-file=/home/bitnami/mysql-init 2> /dev/null &
    
  6. sudo /opt/bitnami/ctlscript.sh restart mysql
  7. Remove the script in step 2.

So it turns out to get mysql talking on your bitnami instance you only need to reset the password.

Further to enable remote access do this in

/opt/bitnami/mysql/my.cnf:

  •  #bind-address=127.0.0.1
    

Next to enable remote mysql access via workbench you need to enable firewall ports to allow connections for tcp 3306 for a specific ip on your google cloud instance.

And there you go, you have a lot powerful config, much like aws ready to be used, backed by google!!

 

 

Sculptor’s Log

There was once a log, ready to have a meeting with the Sculptor, getting ready for the grind!
Casually it approached the scene, not knowing what is to happen to it next,
Waiting to see who/what is the Sculptor is and what can he do for it?
Seeing a couple of wasted logs around the scene, it could not resist but ask their state!
They said in chorus – “One word, Do as the sculptor says” as they were tossed out of the view.
“Ahh, What could the Sculptor ask me to do” was the only thought pacing up and down the log’s mind!

Log being chiseled!

And the moment of the log’s meeting arrived…
Placed in the hands of the Sculptor, the log could not giggle profusely!
And then.. Bam! Sculptor’s chisel tore apart a big chunk from the log.
And the log screamed to the Sculptor, “What are you doing, please stop”
The Sculptor stopped, and asked whether the this log did not have a chatter with other logs?
The log said, “They said only-to listen to you,they did not tell you’ll make me undergo this chisel”
The Sculptor looked clueless, and the log asked itself to be excused.

After some time of pondering…
The log thought of going through the process as one strike a day…
And the deal was made…
Days,Weeks,Months passed and the log took the blow daily and frowned and complained..
And then one fine day, the Sculptor said to the log, I’m done with you.
And then the sculpted-log was moved to a different place — not knowing where and for what, it cooperated!

Being sculpted

A few days later…
The log was placed at a higher platform, and then by chance it got to see itself in a mirror!
And it could not believe what it could see — A beautiful deity crossed its sight.
Not believing that was It, the log waited for another such day and then the belief was confirmed.

Outcome of fore-bearing the chiseling

The log had a good after thought..
All the suffering, the chiseling, was given to it for its shaping.
Had it complained and not gone through the grind, it might have become another wasted log…
Thanking the Sculptor, (and the wasted logs for the advice), for his efforts, it just smiled.

(This post is inspired from a story over-heard — all images are googled, no claim on ownership)