How to extend OSM2PO with ferry durations?

Question

I would like to have the ferry duration [1] taken into account, when transforming OSM files to SQL.

But I'm not sure if I need to write my own waytagresolver, or it is possible to simply add it to the osm_meta tag by adding a parameter or by config? I'm hoping for the latter, as this of cause is the simples by far :)

[1] http://wiki.openstreetmap.org/wiki/Tag:route%3Dferry

Answer 1

I have succeded in creating a WayTagResolver that parses the duration and puts it into the osm_meta column. I therefore share the solution here, for others to use this or deveelop futher on it.

1. Download osm2po
2. In the plugins folder, extract osm2po-plugins-4.7.7-src.zip
3. Enter the extracted folder, and STAY there :)
4. Create a java file for storing the WayTagResolver in e.g. de/cm/osm2po/samples/FerryDurationResolver.java - code for this file will be shown below.
5. Compile the Java file: javac -d . -classpath ../../osm2po-core-4.7.7-signed.jar de/cm/osm2po/samples/FerryDurationResolver.java
6. Create a new Jar file: jar cf ../osm2po-plugins-4.7.7_custom.jar *
7. in your osm2po.config file, add wayTagResolver.class=de.cm.osm2po.samples.FerryDurationResolver
8. When running osm2po (back to main folder), remember to include the newly created jar file in your classpath. I personally execute: java -Xmx 4g -classpath osm2po-core-4.7.7-signed.jar:osm2po-plugins/osm2po-plugins-4.7.7_custom.jar:de.cm.osm2po.Main cmd=tjsp prefix=some_name "url"

And here is the code for my FerryDurationResolver.java: package de.cm.osm2po.samples; import de.cm.osm2po.converter.DefaultWayTagResolver;

public class FerryDurationResolver extends DefaultWayTagResolver  {

    private String metadata;

    @Override
    public void onTags(long entityId) {
        this.metadata = null;
        super.onTags(entityId);
    }

    @Override
    public void onTag(String key, String value) {
        if ("duration".equals(key)){
            String[] durations = value.split(":");
            if (durations.length == 2){
                this.metadata = new Integer(Integer.parseInt(durations[0])*60+Integer.parseInt(durations[1])).toString();
            }
        }
        super.onTag(key, value);
    }

    @Override
    public String getMeta() {
        return this.metadata;
    }

}

What the code does is to read the duration tag and translate the hh:mm into minutes only. Please be aware, that duration MIGHT take other formats: http://wiki.openstreetmap.org/wiki/Key:duration

I hope I haven't missed anything, and this could be useful for others, if they want to import duration (or other variables) into the osm_meta field of the SQL output.

Answer 2

The FerryDurationResolver is absolutely correct. Good work! But you can make things easier. I assume you are using Eclipse. Then just create a new project. Add osm2po.jar as library and create a new Run-Config. Develop the FerryDurationResolver as usual. Debugging is possible.

When everything works as expected, just create a jar-file using Eclipse's "Export Jar-File" option. Finally copy the created jar into the plugins-folder and modify the config to wayTagResolver.class=de.cm.osm2po.samples.FerryDurationResolver. Alternatively you can even set this parameter on the command line where it overrides the default.

Answer 3

Theoretically it is possible to let osm2po handle timetables, even for ferries. Everything is prepared for it. Nevertheless, you need some basic understanding of the Java-API. The default config is shipped with a very pragmatic approach. Namely, givin a ferry the same impact as e.g. an ordinary street in shape of its maxSpeed. The duration, your are asking for is sth. very dynamic. It may be assigned to a way as well as to a relation. The latter may make things very complicated. But as I said before, almost everything is possible. Please ask me via mail.