actionType metadata: delete support

[fgalan]

Upon completion of #1494, the actionType with value delete must be supported.

Once this issue gets implemented, the following needs to be removed inthe implementation notes:

actionType metadata

From NGSIv2 specification section "Special metadata in notifications", regarding actionType metadata:

Its value depend on the request operation type: update for updates, append for creation and delete for deletion. Its type is always Text.

Current Orion implementation supports "update" and "append". The "delete" case will be supported upon completion of this issue.

Implementation notes:

Have a look to the skip field in ContextAttribute class and how it is used to mark an attribute as deleted in the entity memory image that is keep during the update process. It may be useful at actionType metadata generation time in order to see which attribute were deleted.

static void deleteAttrInNotifyCer
(
  ContextElementResponse* notifyCerP,
  ContextAttribute*       targetAttr
)
{  
  for (unsigned int ix = 0; ix < notifyCerP->contextElement.contextAttributeVector.size(); ix++)
  {
    ContextAttribute* caP = notifyCerP->contextElement.contextAttributeVector[ix];
    if (caP->name == targetAttr->name)
    {
      caP->skip = true;
    }
  }
}

[Anjali-NEC]

Hi @fgalan sir,

I would like to work on this issue, please let me know this issue still need to be fix or not?
Thanks

[fgalan]

Yes, the issue is still valid. After the recent completion of #1494 it is a good moment to address it.

Thanks for your willingness to work on it!

[Anjali-NEC]

@fgalan

As per my understanding we need to support delete actionType in Special metadata in notifications
Currently actionType support only on the request operation type: update and append

So, we need to add actionType delete for delete operation in the notifications for providing more information about the deleted attribute.

I am referring the below document for same:

fiware-orion/doc/apiary/v2/fiware-ngsiv2-rc-2016_10_31.apib

Line 881 in 0dc7718

## Special metadata in notifications

Please confirm my understanding.

[fgalan]

doc/manuals/orion-api.md section ## actionType metadata should be removed upon completing this issue.

[fgalan]

@fgalan

As per my understanding we need to support delete actionType in Special metadata in notifications Currently actionType support only on the request operation type: update and append

So, we need to add actionType delete for delete operation in the notifications for providing more information about the deleted attribute.

I am referring the below document for same:

fiware-orion/doc/apiary/v2/fiware-ngsiv2-rc-2016_10_31.apib

Line 881 in 0dc7718

## Special metadata in notifications

Please confirm my understanding.

I think your understanding is correct. Thanks!