8.10. GeoMesa Scala Console

The GeoMesa tools have a scala-console command that starts a Scala REPL configured for use with GeoMesa. The command will place the GeoMesa classpath and configuration for that distribution on the REPL’s classpath. Additionally it will preload commonly used imports. The command also comes with tooling that will provide the option to download and run the appropriate version Scala if it is not available. This is a portable install and will not alter the machine’s current configuration.

8.10.1. Example Usage

The following example was performed against the FileSystem data store generated by the GeoMesa FileSystem Quick Start. It shows how to use the scala-console command to connect to a FileSystem Datastore, discover the feature type names, get the schema and query for data.

Note

This code is running against the output of the FileSystem Datastore. To reproduce this code exactly you must run the FileSystem Datastore Quickstart first.

First we run the command, this starts up the Scala REPL with all of the resources we need.

$ bin/geomesa-fs scala-console

We see it import commonly used libraries and present us with the REPL prompt.

Loading /tmp/geomesa-fs_2.11-2.0.0-SNAPSHOT/conf/.scala_repl_init...
import org.geotools.data._
import org.geotools.filter.text.ecql.ECQL
import org.opengis.feature.simple._
import org.locationtech.geomesa.utils.geotools.SimpleFeatureTypes
import org.locationtech.geomesa.features.ScalaSimpleFeature
import org.locationtech.geomesa.utils.collection.SelfClosingIterator
import scala.collection.JavaConverters._

Welcome to Scala 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_101).
Type in expressions for evaluation. Or try :help.

scala>

Next we get a connection to the FileSystem Datastore.

scala> val dsParams = Map("fs.path" -> "file:///tmp/fsds/", "fs.encoding" -> "parquet")
dsParams: scala.collection.immutable.Map[String,String] = Map(fs.path -> file:///tmp/fsds/, fs.encoding -> parquet)

scala> val ds = DataStoreFinder.getDataStore(dsParams.asJava)
ds: org.geotools.data.DataStore = org.locationtech.geomesa.fs.FileSystemDataStore@27a7ef08

Now we do some example discovery to see what feature types and schemas are stored in the database.

scala> ds.getTypeNames()
res0: Array[String] = Array(gdelt-quickstart)

scala> val sft = ds.getSchema("gdelt-quickstart")
sft: org.opengis.feature.simple.SimpleFeatureType = SimpleFeatureTypeImpl gdelt-quickstart identified extends Feature(GLOBALEVENTID:GLOBALEVENTID,Actor1Name:Actor1Name,Actor1CountryCode:Actor1CountryCode,Actor2Name:Actor2Name,Actor2CountryCode:Actor2CountryCode,EventCode:EventCode,NumMentions:NumMentions,NumSources:NumSources,NumArticles:NumArticles,ActionGeo_Type:ActionGeo_Type,ActionGeo_FullName:ActionGeo_FullName,ActionGeo_CountryCode:ActionGeo_CountryCode,dtg:dtg,geom:geom)

In order to sample the data we create a Query and a FeatureReader and then run the query.

scala> val query = new Query(sft.getName.toString())
query: org.geotools.data.Query =
Query:
   feature type: gdelt-quickstart
   filter: Filter.INCLUDE
   [properties:  ALL ]

scala> val reader = ds.getFeatureReader(query, Transaction.AUTO_COMMIT)
reader: org.geotools.data.FeatureReader[org.opengis.feature.simple.SimpleFeatureType,org.opengis.feature.simple.SimpleFeature] = org.geotools.data.simple.DelegateSimpleFeatureReader@7bd96822

Next, we consume the FeatureReader, printing out the results.

scala> while (reader.hasNext()) { println(reader.next().toString()) }
ScalaSimpleFeature:719024956:719024956|||GANG||120|6|1|6|1|Brazil|BR|Sun Dec 31 19:00:00 EST 2017|POINT (-55 -10)
ScalaSimpleFeature:719024898:719024898|||SYDNEY|AUS|010|14|2|14|4|Sydney, New South Wales, Australia|AS|Sun Dec 31 19:00:00 EST 2017|POINT (151.217 -33.8833)
ScalaSimpleFeature:719024882:719024882|SECURITY COUNCIL||PYONGYANG|PRK|163|2|1|2|1|Russia|RS|Sun Dec 24 19:00:00 EST 2017|POINT (100 60)
ScalaSimpleFeature:719024881:719024881|||RUSSIA|RUS|042|2|1|2|3|Allegheny County, Pennsylvania, United States|US|Sun Dec 24 19:00:00 EST 2017|POINT (-80.1251 40.6253)
ScalaSimpleFeature:719025149:719025149|ARGENTINE|ARG|DIOCESE||010|1|1|1|4|Corrientes, Corrientes, Argentina|AR|Sun Dec 31 19:00:00 EST 2017|POINT (-58.8341 -27.4806)
...

Finally, we cleanup our connections.

scala> reader.close()

scala> ds.dispose()