Modern web application development with java ee 7

Software Development Done Right

Modern Web Applica0on Development with

Java EE 7

By Shekhar Gula0

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Who am I – Shekhar Gula0

•  Currently working @ Xebia •  Polyglot programmer •  Previously OpenShiG Evangelist @ Red Hat •  Author of OpenShiG Cookbook •  TwiLer handle @ shekhargula0

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Agenda

•  Showcase miles2run •  Defining modern web applica0on •  How we built this applica0on using Java EE 7

– GeOng started with Java EE 7 – Technology Stack – Cloud deployment op0ons –  Java EE 7 limita0ons and challenges

•  Going polyglot persistence

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How it all started?

•  A cool Java EE 7 demo applica0on •  A Java EE 7 app that would allow users to store their running ac0vi0es

•  It should run on OpenShiG •  It should use modern technologies •  It should look and feel modern •  It should be open source

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PetStore or CargoTracker are not modern real applica0ons

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Software Development Done Right 6

https://github.com/miles2run/miles2run


Modern Java Web Application



What makes a modern web applica0on?

•  Exposes REST JSON web services •  Embraces HTML 5 •  Single page web applica0on •  Stateless so that you can scale horizontally •  Uses Oauth •  Embraces Polyglot Persistence •  Responsive •  Cloud aware •  Social


Some op0ons in Java world

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Building Miles2Run – Ini0al Requirements

•  Applica0on that can store daily running ac0vi0es

•  Authen0ca0on using TwiLer •  Responsive web applica0on •  Each user should have a public profile

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Technology Stack

•  Java EE 7 with JDK 7 –  JPA, EJB, CDI, JAX-‐RS

•  SLF4J •  MySQL •  AngularJS •  TwiLer Bootstrap •  WildFly on OpenShiG

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Java EE 7

•  Standards based development •  Portability across applica0on servers •  Lightweight deployment •  Easy to get started •  Java EE API provides a good star0ng point

– CDI, JAX-‐RS, JPA are at the heart of any modern web applica0on

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Java EE 7

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LOOK AT FEW JAVA EE API

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CDI 1.1-‐-‐ Context and Dependency Injec0on •  Allows you to use dependency injec0on in Java EE

environment without third party libraries. •  Don’t call us. We will call you. •  CDI container manages the life cycle of components. •  CDI brings dependency injec0on, context and scopes,

interceptors, loose coupling and strong typing. •  Injected bean lifecycle depends on the target bean.

•  Turns nearly every Java class into CDI bean •  It is not a non sta0c inner class •  It is a concrete class or annotated with decorators •  Has default constructor with no parameters or declares a constructor with @Inject


CDI 1.1: What’s new in Java EE 7?

•  Finer scanning control in beans.xml •  bean-‐discovery-‐mode aLribute – all, none, annotated

•  @Vetoed annota0on to veto processing of a package or class.

•  You can use @Transac0onal with CDI beans. •  You can get away from EJBs.


JPA •  Describes the management of rela0onal data in applica0ons. •  JPA implementa0ons provide ORM framework •  JPA provides an API to perform CRUD and find opera0ons on

en00es. •  An en0ty is a POJO, whose state is mapped to a rela0onal

database table. •  JPA also provides a query language to make queries against

en00es stored in rela0onal database.


JPA 2.1 – What’s new in Java EE 7?

•  Schema genera0on using standard proper0es.

•  Use @Index to define addi0onal indexes in schema genera0on.

•  New En0tyGraph API available in En0tyManager.


Storing data in UTC

•  Store all the dates in the UTC format and then depending on the client 0mezone show it to the user

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Bean Valida0on

•  Specifies common valida0on concept for JavaBeans.

•  Allow you to put constraints on data to make sure it is valid.

•  Annota0on based constraints •  Use constraint in any layer


Bean Valida0on Example

public class Status{ @NotNull @Size(max = 140) private String message; @NotNull @Past private final Date postedAt; @UniqueUrl private String url; public Status() {} }


Bean Valida0on 1.1 – What’s new in Java EE 7?

•  Approaches Programming by Contract •  Can inject with CDI into Validator implementa0ons •  Integra0on with JAX-‐RS

@Path(“/statuses”) public class StatusService { @POST @Produces(“application/json”) public @NotNull Status postStatus(@Valid @NotNull Status status) { // persist in database return status; } }


JAX-‐RS

•  Java API for RESTful web services •  Annota0on driven API that aims to help developers build RESTful web services in Java

•  POJO based Resource classes •  HTTP centric

– Maps HTTP requests to Java method invoca0ons

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JAX-‐RS Resource

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What’s new in Java EE 7?

•  Client API •  Asynchronous JAX-‐RS services •  Filters and interceptors

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SLF4J

•  Abstrac0on or façade on top of different logging API

•  SLF4J with Logback provides a faster logging implementa0on

•  SLF4J has great paLern subs0tu0on support. logger.debug("Calcula0ng Goal-‐{} progress between {} and {}", goalId, startDate, endDate);

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AngularJS

•  Extends HTML to add dynamic nature so that we can build modern web applica0ons with ease

•  Declara0ve approach •  Eliminates DOM manipula0on by two way data binding

•  Ideal for building single page web applica0ons

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AngularJS in Ac0on

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OpenShift is

PaaS by Red Hat

Multi-language, Auto-Scaling, Self-service,

Elastic, Cloud Application Platform


CLOUD COMPUTING 101

COMPUTE RESOURCES (CPU, RAM, NETWORK, DISK)

VIRTUAL GUEST IMAGES

OPERATING SYSTEM

APPLICATION PLATFORM (App Server, Middleware, Languages)

APPLICATION

Automated and Managed by the Cloud Provider

Provided and Controlled by Cloud Consumer

IaaS PaaS SaaS

Increased Control

Increased Automation

DEVELOPER TOOLING (IDE, Source Control, Build Tools, CI)


Why OpenShiZ?

l  Focus on code, not on configura0on l  Speeds up deployment l  Scales your app l  Efficient l  Embraces polyglot programming and persistence.


Bringing everything together

•  Start by crea0ng WildFly app on OpenShiG •  OpenShiG will create a Maven app •  Clone the app Git repo on your local machine •  Import the app in your favorite IDE •  Write domain model •  Write EJB services that uses JPA en0ty manager •  Expose REST API •  Commit the code to local repo and push changes to remote Git repository

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Challenges

•  Rendering HTML 5 pages from JAX-‐RS •  Use JAX-‐RS as MVC framework •  Servlet containers do not create sessions when you render HTML 5 pages

•  Your whole applica0on is not a single SPA •  Java EE has no support for OAuth providers like TwiLer

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To overcome some of these challenges

I wrote a small framework called JUG hLps://github.com/miles2run/jug It allows me to render HTML 5 pages using Thymeleaf template engine Provides basic security check Enables sessions for HTML 5 pages

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JUG Example

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Why Thymeleaf?

•  Thymeleaf documents are valid HTML 5 documents so you can work with them offline

•  Extends HTML by a tag library •  All thymeleaf documents are valid HTML 5 documents

•  Allows designers and developers to work together

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createProfile.html


Make app social – new requirements

•  Ability to follow other users •  View their ac0vi0es on my home page

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Redis to rescue

•  REmote DIc0onary Server •  Redis is an in-‐memory key value data store •  Supports persistence •  Supports rich set of data types

– List, Set, Sorted Set, Hash

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Redis Set for storing follower and following

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Redis update 0meline with follower 0meline

41 TimelineRepository.java


Redis – Storing Ac0vi0es

42 TimelineRepository.java


Other use case of Redis

•  Maintaining applica0on counters •  Latest ac0vi0es on user home page •  Caching ac0vi0es

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Sugges0ng users – another requirement

•  Sugges0ng users based on loca0on

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MongoDB to rescue

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Storing GeoSpa0al data

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Querying data

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Loca0onBasedUserSuggester

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Adding beau0ful graphs

•  C3.js for crea0ng graphs •  Provides API to write D3 based charts •  No need to work with D3 API •  Examples hLp://c3js.org/examples.html

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Genera0ng a Donut chart

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Configuring error pages

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THANKS Q & A

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