This release allows reading metadata from CKAN and performing searches.

Getting started

With Maven: If you use Maven as build system, put this in the dependencies section of your pom.xml:

    <dependency>
        <groupId>eu.trentorise.opendata</groupId>
        <artifactId>jackan</artifactId>
        <version>0.3.3</version>
    </dependency>

Without Maven: you can download Jackan jar and its dependencies from here, then copy the jars to your project classpath.

In case updates are available, version numbers follow semantic versioning rules.

Usage examples

Get the dataset list of dati.trentino.it:

Test code can be found in TestApp.java

    import eu.trentorise.opendata.jackan.JackanException;
    import eu.trentorise.opendata.jackan.ckan.CkanClient;

    public class App {
        public static void main( String[] args )
        {        
            CkanClient cc = new CkanClient("http://dati.trentino.it");        
            System.out.println(cc.getDatasetList());               
        }
    }

Get list of first 10 datasets of dati.trentino.it and print their resources:

    import eu.trentorise.opendata.jackan.ckan.CkanClient;
    import eu.trentorise.opendata.jackan.ckan.CkanDataset;
    import eu.trentorise.opendata.jackan.ckan.CkanResource;
    import java.util.List;

    public class App 
    {
        public static void main( String[] args )
        {

            CkanClient cc = new CkanClient("http://dati.trentino.it");

            List<String> ds = cc.getDatasetList(10, 0);

            for (String s : ds){
                System.out.println();
                System.out.println("DATASET: " + s);
                CkanDataset d = cc.getDataset(s);            
                System.out.println("  RESOURCES:");
                for (CkanResource r : d.getResources()){                
                    System.out.println("    " + r.getName());
                    System.out.println("    FORMAT: " + r.getFormat());
                    System.out.println("       URL: " + r.getUrl());
                }
            }
        }
    }

Should give something like this:

    DATASET: abitazioni
      RESOURCES:
        abitazioni
        FORMAT: JSON
           URL: http://www.statweb.provincia.tn.it/INDICATORISTRUTTURALISubPro/exp.aspx?idind=133&info=d&fmt=json
        abitazioni
        FORMAT: CSV
           URL: http://dati.trentino.it/storage/f/2013-06-16T113651/_lcmGkp.csv
        numero-di-abitazioni
        FORMAT: JSON
           URL: http://www.statweb.provincia.tn.it/INDICATORISTRUTTURALISubPro/exp.aspx?ntab=Sub_Numero_Abitazioni&info=d&fmt=json
        numero-di-abitazioni
        FORMAT: CSV
           URL: http://dati.trentino.it/storage/f/2013-06-16T113652/_yWBmJG.csv

    DATASET: abitazioni-occupate
      RESOURCES:
        abitazioni-occupate
        FORMAT: JSON
           URL: http://www.statweb.provincia.tn.it/INDICATORISTRUTTURALISubPro/exp.aspx?idind=134&info=d&fmt=json
        abitazioni-occupate
        FORMAT: CSV
           URL: http://dati.trentino.it/storage/f/2013-06-16T113653/_iaMMc2.csv
        numero-di-abitazioni-occupate
        FORMAT: JSON
           URL: http://www.statweb.provincia.tn.it/INDICATORISTRUTTURALISubPro/exp.aspx?ntab=Sub_Numero_Abitazioni_Occupate&info=d&fmt=json
        numero-di-abitazioni-occupate
        FORMAT: CSV
           URL: http://dati.trentino.it/storage/f/2013-06-16T113654/__lLACk.csv

    ...

Search datasets filtering by tags and groups:

    import eu.trentorise.opendata.jackan.ckan.CkanClient;
    import eu.trentorise.opendata.jackan.ckan.CkanDataset;
    import eu.trentorise.opendata.jackan.ckan.CkanQuery;

    public class TestApp 
    {

        public static void main( String[] args )
        {
            CkanQuery query = CkanQuery.filter().byTagNames("settori economici", "agricoltura").byGroupNames("conoscenza");

            List<CkanDataset> filteredDatasets = cc.searchDatasets(query, 10, 0).getResults();

            for (CkanDataset d : filteredDatasets){
                System.out.println();
                System.out.println("DATASET: " + d.getName());           
            } 
        }
    }

Should give something like this:

    DATASET: produzione-di-mele

    DATASET: produzione-di-uva-da-vino

    DATASET: produzione-lorda-vendibile-frutticoltura

    DATASET: produzione-lorda-vendibile-viticoltura

    DATASET: produzione-lorda-vendibile-zootecnia

    DATASET: produzione-lorda-vendibile-silvicoltura

Serialization

For serialization Jackson library annotations are used. Notice that although field names of Java objects are camelcase (like authorEmail), serialized fields follows CKAN API stlye and use underscores (like author_email).

If you want to serialize to json a Java object obj fetched by Jackan, you can call

    String json = CkanClient.getObjectMapperClone().writeValueAsString(obj);

Logging

Jackan uses native Java logging system (JUL). If you also use JUL in your application and want to see Jackan logs, you can take inspiration from jackan test logging properties. If you have an application which uses SLF4J logging system, you can route logging with JUL to SLF4J bridge, just remember to programmatically install it first.