[ovirt-devel] Some ideas on oVirt Java SDK
Hi guys,
since the initial (small, working & well-tested) version of oVirtJS
JavaScript SDK is finished [*], I've started working on GWT wrapper
for oVirtJS.
While analyzing/reverse-engineering oVirt Java SDK, some thoughts
came to my mind, and I wanted to share them with you.
[*] TODO(vszocs) upload new patchset with all recent changes
First, the way XJC (JAXB binding compiler that generates Java beans
out of REST XSD schema) is invoked looks a bit weird to me, as Java
SDK's XsdCodegen does this:
Runtime.getRuntime().exec(command)
Why not simply use existing Maven plugins to invoke XJC?
- either: https://github.com/highsource/maven-jaxb2-plugin
- or: http://mojo.codehaus.org/jaxb2-maven-plugin/
Second, and most importantly, what's the point of having "group"
entities? I'll give an example - api.xsd contains this:
<xs:complexType name="DataCenters">
<xs:complexContent>
<xs:extension base="BaseResources">
<xs:sequence>
<xs:annotation>
<xs:appinfo>
<jaxb:property name="DataCenters"/>
</xs:appinfo>
</xs:annotation>
<xs:element ref="data_center" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
(Same as above for Hosts, Clusters, VMs, etc.)
This results in following (IMHO rather meaningless) Java class
being generated by XJC:
public class DataCenters extends BaseResources {
@XmlElement(name = "data_center")
protected List<DataCenter> dataCenters;
public List<DataCenter> getDataCenters() {
if (dataCenters == null) {
dataCenters = new ArrayList<DataCenter>();
}
return this.dataCenters;
}
public boolean isSetDataCenters() {
return ((this.dataCenters!= null)&&(!this.dataCenters.isEmpty()));
}
public void unsetDataCenters() {
this.dataCenters = null;
}
}
Instead, we could use @XmlElementWrapper as described in [1]
to avoid generating "group" entities altogether.
[1] https://github.com/dmak/jaxb-xew-plugin
The fact that Java SDK provides decorator for each specific
resource collection (like DataCenters), instead of having ONE
resource collection type, greatly complicates overall design
and code-gen aspect.
In oVirtJS GWT wrapper, we'll avoid above complication through
single resource collection type (having common methods like
get(id), list() etc) for all resources.
Regards,
Vojtech