DeVeloper sHoulD kNow

Saturday, 20 June 2020

Setting Environment for Angular

source: different websites n following these work for me

Must have : user account with `sudo` privileges

you must familiar with these two commands refresh our local package

sudo apt-get update

sudo apt-get upgrade

sudo apt-get update
Then you probably want to make sure that your system is up to date:

sudo apt-get upgrade
It will list the packages wants to install, tell you how much space it needs for the download, and then get on with it when you tell it to. When you want to install some new software

Trying toinstall angular oops...

Mayank:~$ npm install -g @angular/cli
Command 'npm' not found, but can be installed with:

First need to install npm packages...

Angular, the Angular CLI, and Angular apps depend on features and functionality provided by libraries that are available as npm packages

Mayank:~$ npm - v
Command 'npm' not found, but can be installed with:Mayank:~$ sudo apt install npm

Mayank:~$ node -v
Command 'node' not found, but can be installed with:Mayank:~$ sudo apt install nodejs
Mayank:~$ node -v


Output
v8.10.0

Mayank:~$ npm - v


Output
5.6.0

The Angular CLI requires a minimum Node.js version of either v10.13 or v12.0.

Please update your Node.js version or visit https://nodejs.org/ for additional instructions.

To update Node.js to 12 & NPM on Ubuntu 19.04

Mayank:~$ sudo curl -sL https://deb.nodesource.com/setup_12.x | sudo -E bash -
Mayank:~$ sudo apt-get install -y nodejs  
Mayank:~$ npm install -g @angular/cli

Mayank:~$ ng new my-angular-app

Mayank:/opt/angularws$  ng new my-angular-app 
? Would you like to add Angular routing? Yes
? Which stylesheet format would you like to use? CSS
CREATE my-angular-app/README.md (1029 bytes)
CREATE my-angular-app/.editorconfig (274 bytes)
CREATE my-angular-app/.gitignore (631 bytes)
CREATE my-angular-app/angular.json (3630 bytes)
CREATE my-angular-app/package.json (1256 bytes)
CREATE my-angular-app/tsconfig.json (489 bytes)
CREATE my-angular-app/tslint.json (3125 bytes)
CREATE my-angular-app/browserslist (429 bytes)
CREATE my-angular-app/karma.conf.js (1026 bytes)
CREATE my-angular-app/tsconfig.app.json (210 bytes)
CREATE my-angular-app/tsconfig.spec.json (270 bytes)
CREATE my-angular-app/src/favicon.ico (948 bytes)
CREATE my-angular-app/src/index.html (298 bytes)
CREATE my-angular-app/src/main.ts (372 bytes)
CREATE my-angular-app/src/polyfills.ts (2835 bytes)
CREATE my-angular-app/src/styles.css (80 bytes)
CREATE my-angular-app/src/test.ts (753 bytes)
CREATE my-angular-app/src/assets/.gitkeep (0 bytes)
CREATE my-angular-app/src/environments/environment.prod.ts (51 bytes)
CREATE my-angular-app/src/environments/environment.ts (662 bytes)
CREATE my-angular-app/src/app/app-routing.module.ts (246 bytes)
CREATE my-angular-app/src/app/app.module.ts (393 bytes)
CREATE my-angular-app/src/app/app.component.css (0 bytes)
CREATE my-angular-app/src/app/app.component.html (25757 bytes)
CREATE my-angular-app/src/app/app.component.spec.ts (1083 bytes)
CREATE my-angular-app/src/app/app.component.ts (218 bytes)
CREATE my-angular-app/e2e/protractor.conf.js (808 bytes)
CREATE my-angular-app/e2e/tsconfig.json (214 bytes)
CREATE my-angular-app/e2e/src/app.e2e-spec.ts (647 bytes)
CREATE my-angular-app/e2e/src/app.po.ts (301 bytes)
✔ Packages installed successfully.

Mayank:/opt/angularws$ cd my-angular-app
Mayank:/opt/angularws/my-angular-app$ ng serve --open

Tuesday, 21 April 2020

Docker Part 0.1 (Source stackoverflow n docker.com)

Docker

There are three different setups that providing a stack to run an application on (This will help us to recognize what a container is and what makes it so much powerful than other solutions):

1) Traditional Servers(bare metal)
2) Virtual machines (VMs)
3) Containers

1) Traditional server stack consist of a physical server that runs an operating system and your application.
Advantages:

Utilization of raw resources
Isolation

Disadvantages:

Very slow deployment time
Expensive
Wasted resources
Difficult to scale
Difficult to migrate
Complex configuration

2) The VM stack consist of a physical server which runs an operating system and a hypervisor that manages your virtual machine, shared resources, and networking interface. Each Vm runs a Guest Operating System, an application or set of applications.
Advantages:

Good use of resources
Easy to scale
Easy to backup and migrate
Cost efficiency
Flexibility

Disadvantages:

Resource allocation is problematic
Vendor lockin
Complex configuration

3) The Container Setup, the key difference with other stack is container-based virtualization uses the kernel of the host OS to rum multiple isolated guest instances. These guest instances are called as containers. The host can be either a physical server or VM.
Advantages:

Isolation
Lightweight
Resource effective
Easy to migrate
Security
Low overhead
Mirror production and development environment

Disadvantages:

Same Architecture
Resource heavy apps
Networking and security issues.

- A platform for (a)developing,(b)shipping & (c)running application
- Container based over virtualization technology
- Container management service Since March 2013
- Especially for AGILE methodology both development and testing activities are concurrent

Docker encapsulates an application with all its dependencies.

Adv:
Ability to reduce size.
Seamlessly working across different platforms.
Deploy container any where physical machine virtual machine and even in cloud platform
scalable light weight

1. Lightweight

This is probably the first impression for many docker learners.
First, docker images are usually smaller than VM images, makes it easy to build, copy, share.
Second, Docker containers can start in several milliseconds, while VM starts in seconds.

2. Layered File System

This is another key feature of Docker. Images have layers, and different images can share layers, make it even more space-saving and faster to build.
If all containers use Ubuntu as their base images, not every image has its own file system, but share the same underline ubuntu files, and only differs in their own application data.

3. Shared OS Kernel

Think of containers as processes!
All containers running on a host is indeed a bunch of processes with different file systems. They share the same OS kernel, only encapsulates system library and dependencies.
This is good for most cases(no extra OS kernel maintains) but can be a problem if strict isolations are necessary between containers.

Docker, basically containers, supports OS virtualization i.e. your application feels that it has a complete instance of an OS whereas VM supports hardware virtualization. You feel like it is a physical machine in which you can boot any OS.

Tuesday, 12 September 2017

JAVA Begins...

Features in JDK 1.1

JDBC (Java Database Connectivity)

Inner Classes

Java Beans

RMI (Remote Method Invocation)

Reflection (introspection only)

Features in J2SE 1.2

Code named Playground and released on December 8, 1998.

Collections framework.

Java String memory map for constants.

Just In Time (JIT) compiler.

Jar Signer for signing Java ARchive (JAR) files.

Policy Tool for granting access to system resources.

Java Foundation Classes (JFC) which consists of Swing 1.0, Drag and Drop, and Java 2D class libraries.

Java Plug-in

Scrollable result sets, BLOB, CLOB, batch update, user-defined types in JDBC.

Audio support in Applets.

Features in J2SE 1.3

Code named Kestrel and released on May 8, 2000.

Java Sound
Jar Indexing
A huge list of enhancements in almost all the java area.

Features in J2SE 1.4

Code named Merlin and released on February 6, 2002 (first release under JCP).

XML Processing

Java Print Service

Logging API

Java Web Start

JDBC 3.0 API

Assertions()

Preferences API

Chained Exception

Internet protocol version 6 ( IPv6) Support

Regular Expressions

Image I/O API

Features in J2SE 5.0

Code named Tiger and released on September 30, 2004.

Generics

Enhanced for Loop

Autoboxing/Unboxing

Typesafe Enums

Varargs

Static Import

Metadata (Annotations)

Instrumentation

Features in Java SE 6

Code named Mustang and released on December 11, 2006.

Scripting Language Support

JDBC 4.0 API

Java Compiler API

Pluggable Annotations

Native PKI, Java GSS, Kerberos and LDAP support.

Integrated Web Services.

Lot more enhancements.

Features in Java SE 7

Code named Dolphin and released on July 28, 2011.

Strings in switch Statement

Type Inference for Generic Instance Creation

Multiple Exception Handling

Support for Dynamic Languages

Try with Resources

Java nio Package

Binary Literals, underscore in literals

Diamond Syntax

Automatic null Handling

Features in Java SE 8

Java 8 was released on 18 March 2014. The code name culture is dropped with Java 8 and so no official code name going forward from Java 8.

Lambda Expressions

Pipelines and Streams

Date and Time API

Default Methods

Type Annotations

Nashhorn JavaScript Engine

Concurrent Accumulators

Parallel operations

PermGen Error Removed

TLS SNI