Java Application Building

1. Java Application as a Black Box: codebase management, building, troubleshooting and running. 30hrs.

Training Objectives

• Understanding Java platform architecture and its typical defects
• Hands-on skill of managing Java codebase with version control tool
• Understanding core Java application structure for fast localization focus
• Hands-on skill of building and autotesting complex Java Application
• Understanding core Java syntax to localize and report compile-time errors
• Hands-on skill of running and debugging complex Java Application
• Understanding core Application architecture for fast localization focus

Prerequisites

Hardware

• RAM ≥ 8Гб
• Wi-Fi with Internet access

Software

• git
• JDK8
• IDEA (trial Ultimate)
• Maven
• Tomcat
• Chrome standalone offline installer
• Docker for Windows or Docker for Mac

Network Access

• github.org :443 :80
• repo1.maven.org :443 :80
• jcenter.bintray.com :443 :80
• hub.docker.com :443 :80

Agenda

Training introducing and focusing (1 hrs)

• Schedule
• Trainer
• Training overview
• Rules

Hands-on: teams and their demand

• Pairs forming and introduction
• Topics focus demand from attendees
• Additional topics demand form attendees

Intro to Java Platform (2)

Java platform

• Java Platform definition
• Java Platform goals and constrains
• Brief history and versioning
• Basic terms: JVM, JRE, JDK
• Sourcepath and Classpath

Demo

• Two-classes Java application manual build and run cycle
• Run-time parametrization: JVM parameters, application properties, program arguments

Hands-on

• Two-classes Java application manual build and run cycle with run-time parametrization

javac
java
javadoc

Java Application structure (2)

Application structure

• Class and its responsibility
• Method and its intention
• Package and its cohesion
• JAR and executable JARs

Typical development errors

• Compiler warnings
• Compiler errors (CNFE, typing)
• Run-time errors (CNDFE, Exceptions and Errors)

Demo

• Compiling milti-class packaged application from sources
• Compiling milti-class packaged application from sources and raw comiled classes
• Compiling milti-class packaged application from sources and JARed comiled classes
• Making and running executable JAR

Hands-on

• Making and running executable JAR from packaged sources and JARed comiled classes

Git DVCS overview (1)

Local versioning workflow

• Local repo
• Commit
• Log
• Tag
• Branch

Remote versioing workflow

• Remote repo
• Clone
• Push
• Pull

Demo

• Make group custom branch
• Local and remote workflow with IDE tool

Hands-on

• Fork this repo with your account
• Add pair as collborator
• Clone fork locally

git clone --branch master --depth 1 https://github.com/ACCOUNT/java-application-building

• Open project with IDE
• Make identyfing change and push

Intro to configuration management patterns (1)

Repo patterns

• Distributed
• Centralized

Branching patterns

• Team branch
• Relese branch
• Git Flow: feature branches + dev branch
• Trunk-based development + Feature toggling

Demo

• Making pull-request: code review + merge

Hands-on

• Make change
• Make pull-request for code review and merge
• Make reverse pull-request to get trainers changes

Maven Overview (1)

Maven build lifecycle

• Build lifecycles
• Lifecycles phases
• Plugins
• Managing plugins with pom.xml

Dependency management

• Dependecy artifacts: JARed classes, sources, javadocs
• Artifact repositories
• Artifact identifying
• Artifact versioning: stable and snapshots
• Dependency management with pom.xml
• Typical issues: dependency hell

Demo

• Unit vs Integration tests pattern
• Partial application build with IDE
• Uber-jar pattern
• Full application build with IDE
• Build results analysing

Hands-on

• Full application build with IDE
• Errors analysing
• Compile errors fixing
• Build without tests ran

IDE tooling overview (1)

Demo

• Project settings and structure: modules, sourcepath + classpath
• Main and Test sources
• Workspace
• Views and hotkey switching
• Editing sources and foreground compilation
• Debugging methods
• Running tests from IDE
• Running application with run configuration and hotkey shortcut
• Full application building from Maven view
• Hotkey shortcuts for git workflow operations
• Main hotkey

Hands-on

• Edit: fix test defects localized
• Debug
• Run tests
• Full Maven build
• Build results analysing
• Commit and push

Memory structure and errors (2)

Memory structure

• Methods and Call Stack
• Objects and Heap Object Space
• Classes and Perm/Meta Space
• References in all scopes and GC

Errors

• Class locading errors: compilation and run-time
• Static context access
• NPE
• OOME: object heap space leak
• OOME: perm/meta space leak
• GC overhelming and stop-the-world

Demo

• Application profiling with VisualGC plugin and Heap profiling
• Heap dump

Hand-on

• Application profiling with VisualGC plugin and Heap profiling

Error handling architecture (2)

Exception definition

• Type
• Object
• Handling
• Stack trace

Exception types

• Built-in
• Errors vs Exceptions
• Checked vs Unchecked

Handling architecture

• Where to handle: system architecture layering aspect
• How to handle: patterns

Try-with-resources

• TRW
• Stateful vs Stateless components

Demo

• Business exception design and handling
• Exception suppression demo

Hands-on

• Business exception design and handling

Multithreading architecture (2)

Threads overview

• Thread concept
• Scheduler
• Scheduler overhead issue
• Data race issue
• Thread-safety design and documetation
• Threads syncronization: why
• Deadlock issue

Demo

• Data race issue demo
• Application profiling with threads states and stack dump

Hands-on

• Application profiling with threads states and stack dump

Web application architecture (2)

HTTP protocol

• HTTP as a transport layer
• Methods
• Payload
• Errors

Web container

• JavaEE/JakartaEE standart
• Tomcat overview
• Web application layout
• Webapp building
• Webapp deploying
• Webapp running
• Webapp undeploying

Web application architectures

• Components: servlets, jsp, filters, listeners
• UI webapp architecture
• REST- and Web-services architecture

Demo

• Simple UI webapp building and deploying to Tomcat
• HTTP layer sniffing with Chrome

Hands-on

• Simple UI webapp building and deploying to Tomcat
• HTTP layer sniffing with Chrome

Frameworked Webapp architecture (2)

Framework concept

• Framework definintion
• Typical application architecture: layers
• Typical responsibilities
• Application configuration: why and what
• Why not JavaEE

Spring

• Responsibilities
• Application configuration ways
• Context definition
• Profiles definition
• Typical issues with context components

Spring MVC

• Responsibilities for REST and SOAP API
• Typical issues with Controllers

Spring Boot

• Responsibilities
• Typical issues with Boot modules

Demo

• REST API overview
• Structure of Boot application for API
• Building and running

Hands-on

• Building and running Boot REST API application
• Manual tesing

Data storage architecture (2)

Data storage types

• Plain files
• RDBMS
• NoSQL/NewSQL
• Pros and Cons

RDBMS access types

• JDBC API: db schema constrains, type mapping, transactions
• JPA API: entities and constrains, caching, transactions
• Spring Boot Data generated repositores

Data Validation API

• Configuring constraints

Typical issues

• Db schema constrains
• Entities constraints
• Validation API constraints
• JDBC transactions and isolation, db deadlocks
• JPA transactions and optimistic exceptions

DB versioning

• Why

Demo

• DB versioning with Liquibase and access with Boot Data repositories

Hands-on

• Add entity field with Validation API constraints
• Add Liquibase change
• Build and run application
• Manual testing

Autotests architecture (2)

Autotests definintion

• Testing scopes mapped to application architecture
• Test structure
• Test doublers
• Reporting: test run and coverage
• Test error types

Demo

• Attendees choose their typical scope for demo
• Unit test: plain service + manual doubling
• Unit test: service + spring context doubling
• Integration test: controller + serivce
• Integration test: controller + service + repository
• Integration test: HTTP layer + controller + service + repository
• Integration test: HTTP layer + controller + service + remote REST service + repository

UI testing

• HTML overview
• Selenium API overview
• Selenide library
• Driver manager library

Demo

• UI Selenide test with Chrome headless mode off

Hands-on

• Choose testing scope
• Implement autotest
• Run from IDE
• Run full Maven build
• Analyse reports

Logging and Monitoring architecture (2)

Local logging

• Logging libraries hell overview
• SLF4J API
• Logback configuration
• Profiles
• Production issues

Remote logging

• Centralized remote logging architecture
• ELK stack for implementation

Demo

• Remote ELK overview
• Application logs to Logstash
• Log stream with Kibana
• Log searching and filtering with Kibana
• Business events filtering
• Kibana dashboards for business events

Monitoring with ELK

• What to monitor?
• Gathering system metrics with Beats
• Kibana dashboards

Monitoring with JMX

• What to monitor?
• JMX MBeans
• MBeans implementations: JVM, container, framework, application
• Remote monitoring with JVisualVM

Hands-on

• Customize logging level
• Analyse logs
• Local monitoring with JVVM

DevOps Pipeline architecture* (2)

DevOps culture

• Production process overview
• Bottlenecks
• Communications as a key
• DevOps culture

DevOps pipeline tooling

• Source management
• Artifact management
• CI
• Autotesting
• Stage provisioing and IaaC concept
• Stage virtualization and containerization
• CD
• DB versioning
• Feature toggling
• Deployment patterns
• Production logging and monitoring

QA value

• Where is QA adds value?

Demo

• CD pipeline demo

Hands-on

• Push feature change full-auto to prod environment

Test containerization architecture* (1)

Containerization concept

• Containerization goals
• Containerization vs virtualization
• QA use-cases and value

Docker implementation overview

• Docker images
• Docker container
• Docker Hub
• Image provisioning

Demo

• Application dockeriaztion
• Container run

Environment management

• Docker Compose
• Docker Swarm
• k8s

Buffer (2)

• Daily retrospectives