Retrieve a Property from a Specified Managed Object

This procedure shows how to use the PropertyCollector to retrieve a property from a VirtualMachine object with the RetrieveProperiesEx method. The example retrieves a managed object reference to the parent object of a VirtualMachine object in the inventory hierarchy.

To retrieve a reference to the parent object of a specific virtual machine, you must:

Prepare a PropertySpec to specify the parent property and the parentVApp property of the VirtualMachine class. A virtual machine can have only one parent, but the parent can be either a Folder object or a VirualApp object. This example collects both properties, one of which will be null.
Prepare an ObjectSpec to identify the starting object, which is the specified VirtualMachine. There is no need for a TraversalSpec because the property belongs to the starting object itself. However, the ObjectSpec.skip property is set to false; a value of true would cause the PropertyCollector not to collect properties from the starting object.
Assemble a PropertyFilterSpec from the prepared data.
Invoke the RetrievePropertiesEx method.

Prerequisites

For this task you need:

A virtual machine managed object reference in a variable named vmRef.
An authenticated Web Services session with the vSphere server that manages the virtual machine.
A VimPort binding provider referenced by the variable methods, which is attached to the vSphere server connection context.
A PropertyCollector instance referenced by the variable pCollector.

Note: This procedure shows only how to use the PropertyCollector. For a description of server connection and getting a reference to the PropertyCollector, see Build a Simple vSphere Client Application for the Web Services SDK.

Procedure

Declare a function that accepts a virtual machine MOref and returns a MOref to its parent object.in a key-value pair.
```
  private static DynamicProperty getVMParentProperty(ManagedObjectReference vmRef)
  throws Exception {
```
Specify the properties for retrieval (VirtualMachine.parent and VirtualMachine.parentVApp).
Because the VirtualMachine has two mutually exclusive parent properties, depending on the parent type, this code collects both properties.
```
    PropertySpec pSpec = new PropertySpec();
    pSpec.setType("VirtualMachine");
    pSpec.getPathSet().add("parent");
    pSpec.getPathSet().add("parentVApp");
```
Create an ObjectSpec to define the property collection.
Use the setObj method to specify that the vmRef is the starting object for this property collection. Set the skip property to false to indicate that you want to collect properties from the starting object. Omit the selectSet property because the property collection does not need to traverse away from the starting object.
```
    ObjectSpec oSpec = new ObjectSpec();
    oSpec.setObj(vmRef);
    oSpec.setSkip(false);
```

Create a PropertyFilterSpec and add the object and property specs to it.

    PropertyFilterSpec fSpec = new PropertyFilterSpec();
    fSpec.getObjectSet().add(oSpec);
    fSpec.getPropSet().add(pSpec);

Create a list for the filters and add the property filter spec to it.

    List<PropertyFilterSpec> fSpecList = new ArrayList<PropertyFilterSpec>();
    fSpecList.add(fSpec);

Use the filter spec to retrieve the property collection from the server.

    RetrieveOptions ro = new RetrieveOptions();
    RetrieveResult props = methods.retrievePropertiesEx(pCollector,fSpecList,ro);

Unwrap the parent property.

    if (props != null) {
      for (ObjectContent oc : props.getObjects()) {
        List<DynamicProperty> dps = oc.getPropSet();
        if (dps != null) {
          for (DynamicProperty dp : dps) {
            if (dp.getName().equals("parent") || dp.getName().equals("parentVApp")) {
              return dp;
            }
          }
        }
      }
    }
    System.out.println("Parent not found.");
    throw new Exception();
  }

Results

The method returns a key-value pair, name and val, indicating the name of the parent property and a managed object reference to the parent object.

What to do next

  DynamicProperty parent = getVMParentProperty( vmRef );
  if (parent.getName().equals("parentVApp")) {
    System.out.format("VApp MOref: %s", parent.getVal());
  } else {
    System.out.format("Folder MOref: %s", parent.getVal());
  }