Here is the link describing how to configure application RIB: https://wiki.opendaylight.org/view/BGP_LS_PCEP:User_Guide#BGP_Application_Peer

When the data is added to 41-example-bgp.xml config file, module is created correctly. But if restconf PUT is used to create (or update) the module, using the following command:
curl -v -X PUT -H "Content-Type:application/xml" -d '<module xmlns="urn:opendaylight:params:xml:ns:yang:controller:config">
<type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">prefix:bgp-application-peer</type>
<name>example-bgp-peer-app</name>
<bgp-peer-id xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">22.22.22.22</bgp-peer-id>
<target-rib xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">
<type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">prefix:rib-instance</type>
<name>example-bgp-rib</name>
</target-rib>
<application-rib-id xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">example-app-rib</application-rib-id>
<data-broker xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">
<type xmlns:sal="urn:opendaylight:params:xml:ns:yang:controller:md:sal:dom">sal:dom-async-data-broker</type>
<name>pingpong-broker</name>
</data-broker>
</module>' 127.0.0.1:8181/restconf/config/network-topology:network-topology/topology/topology-netconf/node/controller-config/yang-ext:mount/config:modules/module/odl-bgp-rib-impl-cfg:bgp-application-peer/example-bgp-peer-app

it returns http status 500. Here is segment of karaf.log:

2015-06-11 13:39:39,719 | WARN | oupCloseable-6-1 | NetconfDeviceCommunicator | 240 - org.opendaylight.controller.sal-netconf-connector - 1.2.0.SNAPSHOT | RemoteDevice

: Error reply from remote device, request: <rpc message-id="m-2" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<edit-config>
<target>
<candidate/>
</target>
<default-operation>none</default-operation>
<config>
<modules xmlns="urn:opendaylight:params:xml:ns:yang:controller:config">
<module xmlns:a="urn:ietf:params:xml:ns:netconf:base:1.0" a:operation="replace">
<type xmlns:x="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">x:bgp-application-peer</type>
<name>example-bgp-peer-app</name>
<application-rib-id xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">example-app-rib</application-rib-id>
<data-broker xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">
<type xmlns:x="urn:opendaylight:params:xml:ns:yang:controller:md:sal:dom">x:dom-async-data-broker</type>
<name>pingpong-broker</name>
</data-broker>
<bgp-peer-id xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">22.22.22.22</bgp-peer-id>
<target-rib xmlns="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">
<type>rib-instance</type>
<name>example-bgp-rib</name>
</target-rib>
</module>
</modules>
</config>
</edit-config>
</rpc>
, response: <rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" message-id="m-2">
<rpc-error>
<error-type>application</error-type>
<error-tag>operation-failed</error-tag>
<error-severity>error</error-severity>
<error-message>Unexpected error</error-message>
<error-info>
<error>java.lang.IllegalStateException: Service type value not prefixed with namespace</error>
</error-info>
</rpc-error>
</rpc-reply>

The log shows <type>rib-instance</type>, which would explain which value was not prefixed, but the curl command did have prefix there: <type xmlns:prefix="urn:opendaylight:params:xml:ns:yang:controller:bgp:rib:impl">prefix:rib-instance</type>
It seems the prefix was dropped somewhere in restconf (maybe because target-rib has the same prefix?) but netconf (or config) subsystem still requires it.