Issue with serializing ReportTO as it has an interface ReportletConf

[Christian Schneider <ch...@die-schneider.net>]

I have an issue serializing and unserializing ReportTO using jaxb.

The problem is at the ReportletConf list:
    public List<ReportletConf> getReportletConfs() {
        return reportletConfs;
    }

As ReportletConf is an interface JAXB can not handle it. So we get an
IllegalAnnotationException or similar and JAXB does not even initialize.

So I introduced the annotation below. This allowed the serialization to run.
    @XmlElement(type=AbstractReportletConf.class)

The problem now is that the result of the serialization is not complete
and can not be deserialized into the actual classes.
This is how it looks (in an example I did with simplified classes:
<?xml version="1.0" encoding="UTF-8"
standalone="yes"?><report><reportletConfs><name>test</name><description>desc</description></reportletConfs></report>

As you can see there is not enough information to detect the real class.

So I tried to change the signature to use the abstract class and not use
the annotation:
public List<AbstractReportletConf> getReportletConfs()

This works:
<?xml version="1.0" encoding="UTF-8"
standalone="yes"?><report><reportletConfs
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:type="staticReportletConf"><name>test</name><description>desc</description></reportletConfs></report>

>From the xsi:type jaxb knows the class to instantiate.

So there are the following questions:

- Is there a better way to achieve correct serialization of interfaces ?
- Would it be ok if I change ReportletTO to use the abstract class?
- I would like to avoid the xsi:type and instead have elements for each
class extending AbstractReportletConf. Is that possible?

Best regards

Christian

-- 
Christian Schneider
http://www.liquid-reality.de

Open Source Architect
http://www.talend.com

Re: Issue with serializing ReportTO as it has an interface ReportletConf

[Francesco Chicchiriccò <il...@apache.org>]

On 29/01/2013 13:09, Christian Schneider wrote:
> I have an issue serializing and unserializing ReportTO using jaxb.
>
> The problem is at the ReportletConf list:
>      public List<ReportletConf> getReportletConfs() {
>          return reportletConfs;
>      }
>
> As ReportletConf is an interface JAXB can not handle it. So we get an
> IllegalAnnotationException or similar and JAXB does not even initialize.
>
> So I introduced the annotation below. This allowed the serialization to run.
>      @XmlElement(type=AbstractReportletConf.class)
>
> The problem now is that the result of the serialization is not complete
> and can not be deserialized into the actual classes.
> This is how it looks (in an example I did with simplified classes:
> <?xml version="1.0" encoding="UTF-8"
> standalone="yes"?><report><reportletConfs><name>test</name><description>desc</description></reportletConfs></report>
>
> As you can see there is not enough information to detect the real class.
>
> So I tried to change the signature to use the abstract class and not use
> the annotation:
> public List<AbstractReportletConf> getReportletConfs()
>
> This works:
> <?xml version="1.0" encoding="UTF-8"
> standalone="yes"?><report><reportletConfs
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> xsi:type="staticReportletConf"><name>test</name><description>desc</description></reportletConfs></report>
>
>  From the xsi:type jaxb knows the class to instantiate.
>
> So there are the following questions:
>
> - Is there a better way to achieve correct serialization of interfaces ?

I am not an expert at all of JAXB, passing this question.

> - Would it be ok if I change ReportletTO to use the abstract class?

Not good, but still acceptable IMHO.

> - I would like to avoid the xsi:type and instead have elements for each
> class extending AbstractReportletConf. Is that possible?

Same as above; we will have to remember this when we will finally write 
a wiki page about how to create custom reports via reportlets.

Regards.

-- 
Francesco Chicchiriccò

ASF Member, Apache Syncope PMC chair, Apache Cocoon PMC Member
http://people.apache.org/~ilgrosso/