Rock GWT UI's with Polymer Elements

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The new polymer ecosystem makes really easy to share UI components between developers. Let's GWT take advantage of the JS ecosystem to create amazing UIs.

GWTcon Florence 2015

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Rock GWT UI's with Polymer Elements

  1. 1. ROCK GWT UI'S WITH POLYMER ELEMENTS
  2. 2. 1. Motivations 2. What are web components 3. What’s polymer 4. JsInterop 5. GWT consuming web components 6. introducing gwt-polymer-elements 7. Demo: full-stack gwt app using polymer and rest services. Agenda
  3. 3. Motivations public void onScrollMove(ScrollMoveEvent event) { int y = scrollPanel.getY(); if (header != null) { if (y > header.getStateSwitchPosition() && headerState != PullState.PULLED) { headerState = PullState.PULLED; scrollPanel.setMinScrollY(0); if (headerPullhandler != null) headerPullhandler.onPullStateChanged(header, headerState); } else { if (y <= header.getStateSwitchPosition() && headerState != PullState.NORMAL) { headerState = PullState.NORMAL; scrollPanel.setMinScrollY(-header.getHeight()); if (headerPullhandler != null) headerPullhandler.onPullStateChanged(header, headerState); } } header.onScroll(y); } int y_off = y; if (footer != null && y < -footer.getHeight()) { if (footerState == PullState.PULLED) { y_off = y_off - footer.getHeight(); } if (footerState == PullState.NORMAL) { y_off = y_off + footer.getHeight(); } if (y_off < (scrollPanel.getMaxScrollY() - footer.getStateSwitchPosition()) && footerState != PullState.PULLED) { footerState = PullState.PULLED; scrollPanel.setMaxScrollY(scrollPanel.getMaxScrollY() - footer.getHeight()); if (footerPullhandler != null) { footerPullhandler.onPullStateChanged(footer, footerState); } } else { if (y_off > (scrollPanel.getMaxScrollY() - footer.getStateSwitchPosition()) && footerState != PullState.NORMAL) { footerState = PullState.NORMAL; scrollPanel.setMaxScrollY(scrollPanel.getMaxScrollY() + footer.getHeight()); if (footerPullhandler != null) { footerPullhandler.onPullStateChanged(footer, footerState); } } } footer.onScroll(y_off - scrollPanel.getMaxScrollY()); } } Former Gwt Ui Development - Verbose code - Slow Debug & Test - Difficult to share - Ugly widgetset & no mobile Gwt + Web Components - Standard specs. - Ready to use elements - Designers friendly - Active Development - Google - Vaadin
  4. 4. gwt-classic vs gwt-polymer 6.500 LOC http://gwt-mobilewebapp.appspot.com/ 750 LOC http://manolo.github.io/gwt-polymer-chat-app/demo/
  5. 5. Vaadin vision of Web Components
  6. 6. What are Web Components?
  7. 7. Problem: DOM unique tree body { background-color: white; }
  8. 8. Solution: Shadow DOM body { background-color: white; }
  9. 9. Encapsulation
  10. 10. Composition
  11. 11. Community
  12. 12. Web Components State of the art
  13. 13. Browser support
  14. 14. Polyfill
  15. 15. Activity
  16. 16. What’s Polymer
  17. 17. Polymer - Polymer makes it easier and faster to create anything from a button to a complete application across desktop, mobile, and beyond. - Polymer ecosystem enables sharing UI components between developers. - JS estable API & polyfills - Production ready reusable components - Documentation system - Let's GWT take advantage of the JS ecosystem to create amazing UIs.
  18. 18. Catalog - Iron Elements - Paper Elements -> Material Design - Neon Elements - Platinum Elements - Google Elements - Vaadin Elements
  19. 19. JsInterop
  20. 20. 1. Why JsInterop a. Nowadays most GWT big projects interact with JS libs. b. JSNI is a bad option for complex scenarios 2. JsInterop magic allows interact natively with Js. No JSNI anymore! a. @JsType b. @JsProperty @JsConstructor @JsMethod @JsFunction c. Issues ? : experimental, does not extend JSO 3. Elemental-2.0 Interfaces for all HTML a. Window, Document, Element, Style, Events, … b. Issue: not available yet 2.8.x ? 4. Code generation a. Let’s explore ways to create java boilerplate code GWT JsInterop
  21. 21. GWT: Consuming Web Components
  22. 22. 1. Code Interfaces for Native Objects (Elemental-2) 2. Code methods for interacting with Web Components Spec (create, import ...). 3. Define an annotated Java Interface per component, event or behavior. - Extends HTMLElement or Event 4. Optionally Wrap each Interface in a Widget class for classic GWT apps. Steps to consume WC in Java
  23. 23. Interfaces for native JS objects @JsType public interface HTMLElement extends Element { } @JsType public interface Element extends Node { @JsProperty String getInnerHTML(); @JsProperty DOMTokenList getClassList(); void setAttribute(String name, String value); String getAttribute(String name); void removeAttribute(String name); } @JsType public interface Node extends EventTarget { } @JsType public interface EventTarget { void addEventListener(String type, EventListener listener); } Elemental-2 (gwt-2.8.1)
  24. 24. Utility methods public class Polymer { ... // Ensures that the tagName has been registered, otherwise injects // the appropriate <import> tag in the document header public static void ensureHTMLImport(String tagName) { if ( !registered(tagName)) { String href = GWT.getModuleBaseForStaticFiles() + "bower_components/" + tagName + "/" + tagName + ".html"; Polymer.Base.importHref(href); } } // Returns a new instance of the Element. It loads the webcomponent // if not loaded yet. public static <T> T createElement(String tagName) { ensureHTMLImport(tagName); return (T)Document.get().createElement(tagName); } ... }
  25. 25. The WebComponentElement.java @JsType public interface PaperButton extends HTMLElement { @JsProperty PaperButton setLabel(String val); @JsProperty String getLabel(); @JsProperty PaperButton setRaisedButton(boolean val); @JsProperty boolean getRaisedButton(); @JsProperty PaperButton setIcon(String val); @JsProperty String getIcon(); }
  26. 26. Consuming WC in Java (Element API) // Create a new instance of PaperButton PaperButtonElement button = Polymer.create(PaperButtonElement.TAG); // Set some properties button.icon("polymer"); button.label("Polymer"); button.raisedButton(false); // Add event listeners button.addEventListener("click", e -> { }); // Append to the document document.get().ppendChild(button);
  27. 27. The WebComponentWidget.java public class PaperButton extends PolymerWidget { //Default Constructor. public PaperButton() { this(""); } //Constructor used by UIBinder public PaperButton(String html) { this(PaperButtonElement.TAG, html); } // Used when this element is extended by another. protected PaperButton(String tag, String html) { super(tag, html); } // Gets a handle to the Polymer object's underlying DOM element. public PaperButtonElement getPolymerElement() { return (PaperButtonElement) getElement(); } public boolean isRaised() { return getPolymerElement().isRaised(); } } public class PolymerWidget extends HTMLPanel { public PolymerWidget(String tag, String src, String html) { super(tag, html); Polymer.ensureCustomElement(getElement(), src); } ... }
  28. 28. Consuming WC in Java (Widget API) // Widgets allow consume WC using the GWT classic way. PaperButton button = new PaperButton(); button.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { // ... } }); RootPanel.get().add(button);
  29. 29. Consuming WC in UIBinder <ui:UiBinder xmlns:ui='urn:ui:com.google.gwt.uibinder' xmlns:g='urn:import:com.google.gwt.user.client.ui' xmlns:p='urn:import:com.vaadin.components.gwt.polymer.client.widget'> <ui:style> .container paper-button.colored { background: #4285f4; color: #fff; } </ui:style> <g:HTMLPanel> <!-- to use widgets we don’t need to import webcomponents by hand --> <p:PaperButton toggle="" raised="" active="" addStyleNames="{style.colored}">active</p:PaperButton> <!-- to use elements it’s mandatory to import webcomponents previously --> <paper-button raised="" noink="">Click me</paper-button> </g:HTMLPanel>
  30. 30. Introducing Vaadin gwt-polymer
  31. 31. Two Projects 1. gwt-api-generator: It’s a code generator to produce GWT wrappers for JS components a. Scrapes source documentation b. Right now polymer, but considering other sources. c. Uses standard JS libraries to parse components. - node.js, npm, bower, gulp - hydrolysis parser + lodash.template 2. gwt-polymer-elements: a ready-to-use library for using polymer elements in gwt (iron, paper, neon, vaadin) a. Version 1.2.1.0.alpha1 (polymer 1.2.1) b. Still under definition, expect package name changes, etc
  32. 32. gwt-polymer-elements GWT PaperButtonWidget PolymerWidget HTMLElement PaperButtonElement Polymer paper-button.html polimer.js JsInterop Vaadin gwt-api-generator
  33. 33. 1. Add java dependency to your project. - vaadin-gwt-polymer-elements-1.2.1.0-alpha1.jar 2. Inherit it in your GWT module - <inherits name="com.vaadin.polymer.Elements"/> 3. Use new Widgets or Elements as usual - Document.get().createElement("PaperSliderElement") 4. Run mvn clean install to produce your package .jar 5. Everything is contained in the artefact - polyfill, components, java code. gwt-polymer-elements (bundle)
  34. 34. 1. Install the generator - sudo npm install gwt-api-generator -g 2. Install all the components you need for your project. - bower install my-github-account/my-custom-polymer-element 3. Run the script to generate .java classes - gwt-api-generator [--pom --groupId=xx --artifactId=xx] 4. Run mvn clean install to produce your gwt-package .jar gwt-api-generator (custom elements)
  35. 35. gwt-api-generator goals 1. Very little code to maintain. a. 1500 LOC / 100 KB 2. But it produces a lot of java code a. 50000 LOC (paper & core elements) 3. It uses native JS parsers for JS code. a. The same tools that polymer developers use b. No GWT generators nor APT processors. 4. Standard tools for web developers. a. They can deliver gwt libraries without knowing any java
  36. 36. Demo: Building a full stack app
  37. 37. Demo Application GWT Polymer PouchDB CouchDB - Responsive - Material Design - Online/Offline - Real Time
  38. 38. Demo Components - GWT + Polymer - CouchDB is a database that completely embraces the web. - Store your data with JSON documents - Access your data via HTTP - Serve pages directly - PouchDB is database inspired by Apache CouchDB that is designed to run well within the browser.
  39. 39. Demo http://manolo.github.io/gwt-polymer-chat-app/demo/ https://github.com/manolo/gwt-polymer-chat-app
  40. 40. Thanks +ManuelCarrascoMonino manolo@vaadin.com @dodotis

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