Getting error while fetching Category and keywords as xml using core-service in java

Question

I have tried the following code to get xml.

void getListXml(ICoreService endpoint, String myUri) throws Exception {
        TaxonomiesFilterData filter = new TaxonomiesFilterData();
        Element listXml = (Element) endpoint.getListXml(myUri, filter).getAny();

        NodeList items = listXml.getElementsByTagName("tcm:Item");
        System.out.println("xml element is : " + listXml);
        for (int i = 0; i < items.getLength(); i++) {
            Element itemXml = (Element) items.item(i);
            System.out.println(itemXml.getAttribute("Title"));
        }
    }

but i am getting error with message

com.sdltridion.contentmanager.coreservice.ICoreServiceGetListXmlCoreServiceFaultFaultFaultMessage: Unexpected item type: Category.

it would be helpful if get some input on this.

EDIT : I have Changed the implementation to TaxonomiesOwlFilter

        TaxonomiesOwlFilterData taxonomyFilter = new TaxonomiesOwlFilterData();
        ArrayOfLinkToCategoryData arrayOfLinkToCategoryData = new ArrayOfLinkToCategoryData(){
            @Override
            public List<LinkToCategoryData> getLinkToCategoryData() {
                List<LinkToCategoryData> linkToCategoryDatas = new ArrayList<>();
                LinkToCategoryData linkToCategoryData = new LinkToCategoryData();
                linkToCategoryData.setIdRef(new JAXBElement<String>(new QName("http://www.sdltridion.com/ContentManager/R6","IdRef"), String.class, categoryId));
                return linkToCategoryDatas;
            }
        };

        taxonomyFilter.setRootCategories(new JAXBElement<ArrayOfLinkToCategoryData>(new QName("http://www.sdltridion.com/ContentManager/R6","RootCategories"),ArrayOfLinkToCategoryData.class,arrayOfLinkToCategoryData));
        GetListXmlResult getListXmlResult  = endpoint.getListXml(publicationId, taxonomyFilter);
        System.out.println(getListXmlResult.getAny());

then i am getting output as :

[rdf:RDF: null]

Answer 1

If you use GetListXml with TaxonomiesFilterData, you should pass in a Publication ID as id parameter: it returns a list of all Taxonomies within the given Publication.

In case you intended to get the Taxonomy XML/OWL for a single Taxonomy: use TaxonomiesOwlFilterData for that purpose. You will still have to specify a Publication ID as id parameter, but you can also specify one or more Category IDs in TaxonomiesOwlFilterData.RootCategories.