Issue 12499: Clarify usage of KeyHash                                                                                                                                                                                (dds-interop-rtf)
Source: Real-Time Innovations (Mr. Kenneth Brophy, ken@rti.com ken.brophy@rti.com)
Nature: Uncategorized Issue
Severity: 
Summary: Usage of keyHash is currently underspecified.  It is not clear whether its presence in the message is mandatory and how it should be processed.
Resolution:
Expanded descriptions of the intended usage of keyHash parameter are added.
Revised Text:
Insert new Section 8.7.8

8.7.8 "Key Hash"

The Key Hash provides a hint for the key that uniquely identifies the data-object that is being changed within the set of objects that have been registered by the RTPS Writer.

Nominally the key is part of the serialized data of a data submessage.  Using the key hash benefits implementations providing a faster alternative than deserializing the full key from the received data-object.

When the key hash is not received by a DataReader, it should be computed from the data itself. If there is no data in the submessage, then a default zero-valued key hash should be used by the DataReader   

If there is a KeyHash, if present, shall be computed as described in Section 9.6.3.3

Resolution: Expanded descriptions of the intended usage of keyHash parameter are added
Revised Text: Insert new Section 8.7.8 after Section 8.7.7 (Original Writer Info)

8.7.8 "Key Hash"

The Key Hash provides a hint for the key that uniquely identifies the data-object that is being changed within the set of objects that have been registered by the RTPS Writer.

Nominally the key is part of the serialized data of a data submessage.  Using the key hash benefits implementations providing a faster alternative than deserializing the full key from the received data-object.

When the key hash is not received by a DataReader, it should be computed from the data itself. If there is no data in the submessage, then a default zero-valued key hash should be used by the DataReader 

The KeyHash, if present, shall be computed as described in Section 9.6.3.3.

Actions taken:
May 20, 2008: received issue
Discussion: 

End of Annotations:=====
s is issue # 12499

Clarify usage of KeyHash

Usage of keyHash is currently underspecified.  It is not clear whether its presence in the message is mandatory and how it should be processed.
Resolution:
Expanded descriptions of the intended usage of keyHash parameter are added.
Revised Text:
Insert new Section 8.7.8

8.7.8 "Key Hash"

The Key Hash provides a hint for the key that uniquely identifies the data-object that is being changed within the set of objects that have been registered by the RTPS Writer.

Nominally the key is part of the serialized data of a data submessage.  Using the key hash benefits implementations providing a faster alternative than deserializing the full key from the received data-object.

When the key hash is not received by a DataReader, it should be computed from the data itself. If there is no data in the submessage, then a default zero-valued key hash should be used by the DataReader   

If there is a KeyHash, if present, shall be computed as described in Section 9.6.3.3