ADDING GEOSPATIAL FEATURES TO A JAVA WEB APP CODEONE 2018

Transcription

1 ADDING GEOSPATIAL FEATURES TO A JAVA WEB APP CODEONE 2018

2 Matti Tahvonen OS S A DVO CAT E Web pages from 1994 Web apps from 1996 (JavaScript, Perl, PHP ) Java web apps from 2006 (Vaadin R&D + helping our customers) Since 2014, mostly DevRel/marketing as daily job, but in Vaadin that means that IDE is open all the time :-) Orienteering, sailing, hiking, mountain biking,

3 WHY AM I HERE? Started orienteering (endurance sport) I got interested about WWW Joined a Java company as our first JS developer OpenLayers wrapper for Vaadin (Java) I can still do JS & browser magic, but prefer Java & JVM

4 TODAY - You ll realise how easy it is to add small (but professional) GIS features to your existing business apps. - Full stack Sailing Course Planner example (Open Source) - Introduction to a set of handy GIS libraries and some alternatives

5 SCP - SAILING COURSE PLANNER OSS APP TO PLAN AND SET UP SAILING COMPETITIONS

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7 ARCHITECTURE

8 ARCHITECTURE OVERVIEW Desktop/Tablet optimised web app for course design PosgreSQL PostGIS JVM Spring Boot, JTS, Hibernate (spatial), Geotools, Vaadin, Leaflet Mobile web app for course set-up

9 Persistency Sailing Course Planner architecture PostgreSQL + PostGIS Open Source Excellent support for spatial indexes and functions Alternatives: Oracle, MS SQL, MySQL/MariaSQL, GeoDB (H2 db extension) Many NoSQL databases, like also support spatial indexes and queries Do you need spatial aware persistency solution at all?

10 Persistency Sailing Course Planner architecture Database with spatial extensions? With large datasets JVM can t handle all in memory. Select entities in this viewport only, Select entities overlapping given polygon etc Datatypes, geospatial functions/operators and indexes. Support for somewhat standard SQL extensions varies a lot among databases. For some use cases, you don t need one. Just store features as blobs, or points in lat/lon columns.

11 CREATE EXTENSION postgis; CREATE TABLE geometries (name varchar, geom geometry); INSERT INTO geometries VALUES ('Point', 'POINT(0 0)'), ('Linestring', 'LINESTRING(0 0, 1 1, 2 1, 2 2)'), ('Polygon', 'POLYGON((0 0, 1 0, 1 1, 0 1, 0 0))'), ('PolygonWithHole', 'POLYGON((0 0, 10 0, 10 10, 0 10, 0 ('Collection', 'GEOMETRYCOLLECTION(POINT(2 0),POLYGON(( SELECT name, ST_AsText(geom) FROM geometries; name st_astext Point POINT(0 0) Linestring LINESTRING(0 0,1 1,2 1,2 2) Polygon POLYGON((0 0,1 0,1 1,0 1,0 0)) PolygonWithHole POLYGON((0 0,10 0,10 10,0 10,0 Collection GEOMETRYCOLLECTION(POINT(2 0), (5 rows) SELECT name, ST_AsText(geom) FROM geometries WHERE ST_Contains( ST_GeomFromText('POLYGON((-1-1,1-1,1 1,-1 1,-1-1))'), geom ); name st_astext Point POINT(0 0) Polygon POLYGON((0 0,1 0,1 1,0 1,0 0)) (2 rows) Example derived from the PostGIS tutorial

12 JVM Sailing Course Planner architecture JVM libraries in use Spring Boot - application framework JTS Java Topology Suite - datatypes for domain model and basic planar math Spring Data JPA/Hibernate (spatial)- object relational mapping and database connectivity Geotools - tools to handle geospatial data in Java JSR 363, Units of Measurement - conversion of distances to weird units Vaadin - the plain Java UI library for web apps Leaflet - a slippy map web component

13 Spring Boot Sailing Course Planner architecture Spring Boot An application framework, makes easy to develop and deploy web apps. Alternatives Plain servlet application, Java EE

14 @SpringBootApplication public class DemoApplication { public static void main(string[] args) { SpringApplication.run(DemoApplication.class, args); } public static class MainView extends VerticalLayout { public MainView() { add(new Span("Hello World!")); } }

15 JTS Sailing Course Planner architecture JTS aka Java Topology Suite The most commonly used library in Java apps handling geographical information. Object model (Point, LineString, Polygon ) for planar linear geometry and a set of fundamental geometric functions. C++ port (GEOM) powers PostGIS, QGIS, Google Earth etc.. Moving to Eclipse (LocationTech project) Alternatives Geolatte, Apache SIS, Spatial4j

16 GeometryFactory geometryfactory = new GeometryFactory(); Point point = geometryfactory.createpoint( ); new Coordinate(1, 1) LinearRing linearring = geometryfactory.createlinearring( new Coordinate[]{ new Coordinate(0, 0), new Coordinate(0, 2), new Coordinate(2, 2), new Coordinate(2, 0), new Coordinate(0, 0) } ); boolean contains = linearring.contains(point); // true

17 JPA Sailing Course Planner architecture Hibernate (spatial) Hibernate 5 introduced an extension for geographic types (JTS and Geolatte) Previously a community extension Provides also some spatial functions to HQL and criteria API. Alternatives QueryDSL has a spatial extension EclipseLink (JPA implementation) contains some custom support for Oracle databases Plain JDBC (data comes in/out as WKT)

18 @Entity public class SpatialEvent extends AbstractEntity { } private String private Date date; //@Column(columnDefinition = "POINT") // this type is known by = "geometry") private Point location; = "POLYGON") // this type is known by = "geometry") private LineString route; // //Select only entities within current viewport Polygon viewport = geometryfactory.createpolygon( coordinates ); SpatialEvent event = entitymanager.createquery( "select e " + "from SpatialEvent e " + "where within(e.location, :viewport) = true", SpatialEvent.class).setParameter("window", viewport).getsingleresult(); }

19 JPA Sailing Course Planner architecture Spring Data JPA Repository pattern for JPA No special support for geometries, but one can define SQL/JPQL/HQL explicitly. Alternatives DeltaSpike Data (CDI)

20 public interface SailingCourseRepository extends JpaRepository<SailingCourse,Long> { } // findall, count, save, delete, findby(example example) etc via super = {"mainbuoys", "helperbuoys", "coursepoints", "admin s"}) public SailingCourse findonewithdetailsbyid(long = {"mainbuoys", "helperbuoys", "coursepoints", "admin s"}) public SailingCourse findbyuuid(string DISTINCT s FROM SailingCourse s JOIN s.admin s e WHERE e = : ") public List<SailingCourse> retrieveby (@param( ") String );

21 Geotools Sailing Course Planner architecture Geotools: tools for Java GIS apps Geometry support provided by Java Topology Suite (JTS) Read/write many raster and vector formats Tools for more complex analyses, like geodetic calculations Swing components Alternatives Spatial4j, Geolatte, Apache SIS

22 Why Geotools? Transformation of WSG84 coordinates using JTS double angle = 2 * Math.PI * degrees / 360; Point centroid = getcentroid(); AffineTransformation at = new AffineTransformation().setToRotation(angle, centroid.getx(), centroid.gety()); for (MainBuoy mb : getmainbuoys()) { Geometry transformed = at.transform(mb.getlocation()); mb.setlocation((point) transformed); } for (HelperBuoy mb : gethelperbuoys()) { Geometry transformed = at.transform(mb.getlocation()); mb.setlocation((point) transformed); } Don t do this with geodesic coordinates!

23 gc = new GeodeticCalculator() gc.setstartinggeographicpoint( lastknownpoint.getlon(), lastknownpoint.getlat() ); gc.setdestinationposition( JTS.toDirectPosition( targetbuoy.getlocation().getcoordinate(), crs) ); int azimuth = (int) gc.getazimuth(); if (azimuth < 0) { // convert to "compass angle" azimuth = azimuth + 360; } double orthodromicdistance = gc.getorthodromicdistance();

24 COUNTRIES NOT USING METRIC SYSTEM

25 JSR 363 UOM Sailing Course Planner architecture Units of Measurement API A new standard Java API for presenting and handling units of measurement. Libraries by default use SI units Not that tightly related to geospatial features, but you quite often need custom presentation for that one nation (and sailors). Alternatives Dig constants from wikipedia and build your own conversion methods

26 public static String formatdistance(double meters) { LengthAmount l = new LengthAmount(meters, SI.METRE); Quantity to = l.to(nonsi.nautical_mile); return String.format("%d m, %.2f nm", (int) meters, to.getvalue()); }

27 Vaadin Vaadin - Java UI framework to build modern web apps Sailing Course Planner architecture Creates XHR/WebSocket powered SPAa even with plain Java code, without web expertise. For both desktop and mobile devices. Extensible and has 700+ community extensions. Has good slippy map widgets based on Leaflet, OpenLayers and Google Maps Alternatives JSF, Wicket, React (JS), Angular (JS), Vue (JS)

28 new VerticalLayout( new Button("I'm a button"), new DatePicker("Select a date"), new ComboBox <>("Select an option"), new Span("I'm a <span>") );

29 Leaflet Sailing Course Planner architecture Slim OSS alternative to Google Maps Small well performing core Good support for different base maps Excellent for both desktop and mobile devices Extensible, lot of community extensions Alternatives OpenLayers, Google Maps (license!!), Mapbox GL JS (License)

30 var map = L.map( map ).setview([-122.3, 37.7], 13); L.tileLayer(' { attribution: ' <a href=" contributors' }).addto(map); L.marker([-122.3, 37.7]).addTo(map);

31 v-leaflet Sailing Course Planner architecture Java/Vaadin API for LeafletJS Wraps LeafletJS with Java API Trivial to integrate to other JVM technologies, no REST APIs or data conversions needed Contains Vaadin fields to directly edit JTS data types -> developer productivity Extension for editing, heat map, marker cluster Alternatives Vaadin OpenLayers integration, JSF integrations, REST API + client side JS code (additional complexity, but access to all low level details)

32 LMap map = new LMap(); map.addlayer(new LOpenStreetMapLayer()); map.addlayer(new LMarker(-122.3, 37.7)); private private private private TextField title = new TextField(); DateField date = new DateField(); PointField location = new PointField(); LineStringField route = new LineStringField(); public void bindentitytoform(spatialevent entity) { layout.add(title, date, location, route); // naming based binding to properties in SpatialEvent BeanValidationBinder<SpatialEvent> binder = new BeanValidationBinder<>(SpatialEvent.class); binder.bindinstancefields(this); binder.setbean(entity); }

33 KEY TAKEAWAYS ADDING GEOSPATIAL FEATURES TO A JAVA WEB APP

34 DEVELOPING BASIC GEOSPATIAL FEATURES IS EASIER THAN YOU THINK

35 JAVA ECOSYSTEM HAS A LOT OF HANDY LIBRARIES FOR GIS

36 VAADIN + LEAFLET IS PROBABLY THE EASIEST SOLUTION FOR JAVA DEVELOPER TO BUILD UI

37 Vaadin BOF session today 20:30 BOF5640 in room 2010, today 08:30 PM Vaadin booth in expo area I ll be there for more questions today & tomorrow. github.com/mstahv/scp Source code for the Sailing Course Planner example vaadin.com/forum A good place for Vaadin (+ geospatial) related questions

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39 QUESTIONS? ADDING GEOSPATIAL FEATURES TO A JAVA WEB APP