Adding links to REST Responses

Question

I have REST services that respond with unmarshalled domain entities. For example:

Request:
GET http://someAddress.com/customer/001

Response:
<customer>
    <id>001</id>
    <name>Some Guy</name>
    ...
</customer>

I would like to add some links to the response for discovering services. For example:

<customer>
    <id>001</id>
    <name>Some Guy</name>
    ...
    <link xml:link="delete" href="http://someAddress.com/customer/001"/>
</customer>

The concern I have is if this will cause marshalling problems. I want the links discoverable, but I want consumers to use the domain schema easily, which does not contain elements for links.

Is it better to put the links elsewhere in the reply? If so, where?

Either update the schema to contain links or make a separate controller to retrieve the links. — Johan Sjöberg, Mar 08 '11 at 17:24
A separate controller? Do you mean adding a separate xml island to the response (e.g. ......)? — TERACytE, Mar 08 '11 at 17:33

score 1 · Answer 1 · answered Mar 08 '11 at 17:38

Assuming you are using JAXB for the object-to-XML layer you could do something like the following with an XmlAdapter, but instead of a String you will need an object for Link:

import java.net.HttpURLConnection;
import java.net.URL;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.annotation.adapters.XmlAdapter;

public class CustomerAdapter  extends XmlAdapter<String, Customer>{

    private JAXBContext jaxbContext;

    public CustomerAdapter() {
        try {
            jaxbContext = JAXBContext.newInstance(Customer.class);
        } catch(JAXBException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public String marshal(Customer v) throws Exception {
        if(null == v) {
            return null;
        }
        return "http://someAddress.com/customer/" + v.getId();
    }

    @Override
    public Customer unmarshal(String v) throws Exception {
        if(null == v) {
            return null;
        }

        URL url = new URL(v);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");
        connection.setRequestProperty("Accept", "application/xml");

        Customer customer = (Customer) jaxbContext.createUnmarshaller().unmarshal(connection.getInputStream());
        connection.disconnect();
        return product;
    }

}

For more information on XmlAdapter see:

http://bdoughan.blogspot.com/2010/07/xmladapter-jaxbs-secret-weapon.html

score 0 · Accepted Answer · edited Oct 07 '21 at 06:31

0

If you really don't want to change your schemas to support the link element then you could use Link headers. https://www.rfc-editor.org/rfc/rfc5988

edited Oct 07 '21 at 06:31

Community

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answered Mar 08 '11 at 19:10

Darrel Miller

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Adding links to REST Responses

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