Announcement ResourcesARC-2014-1255-Announcement_Issues

Group Name: WG2Source: Barbara Pareglio, NECMeeting Date: 2014-04-07Agenda Item: Input Contribution

Problem statement

• Missing a clear description of what is the reason of having “announced resource”

• Incomplete information for the reader on how to handle these announced resources

• Not clear how the resources looks like and what to do.

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Current state

• A resource can be announced to one or more remote CESs to inform them of the existence of the original resource

• Not clearly stated in the TS but the hypothesis is that by means of announcing resources the discovery of a resource is optimized.

• The announced resource has a limited set of attributes though, and a limited set of child resources from the original resource

• The announced-resource has a link to the original resource at the resource hosting-CSE, thereby allowing access to the attributes that are not available at the announced-resources

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Section 9Observations:

1. not specified when a resource is eligible to be announced2. Each annc resource shall be of a new resourceType, the term

“corresponding” doesn’t indicate what it should be. The notation of such of such resource is “originalRecourceType”+Annc. (Once a resourceType is assigned it is clear that it belongs only to that specific resource Type.)

9.1.1 Resource Announcement

The following are the resource specification guidelines for the resource announcement:

Some resource types are announce-able, while others are not. For the announce-able resource type, an additional column shall be specified following the resource template in the section 9.5.1.

For an announce-able resource type, suffix "Annc" to the original resource type shall be used to indicate its corresponding announced resource type. For example, resource <containerAnnc> shall indicate the announced resource type for resource <container>; <groupAnnc> shall indicate announced resource type for resource <group>, etc.

Section 9

Child Resource Name of

<resourceType>

Child Resource Type

Multiplicity 

Description<resourceTypeAnnc>

Child Resource

<Fill in the name of Child Resource1 if a fixed name is required or [variable] if no fixed name is required>

<Fill in the type of Child Resource1>

<Fill in Multiplicity>

See clause <XRef <clause> where the type of this child resource is described.

<Fill the child resource type for the announced resource. It can be none or <crTypeAnnc>; where the <crType> is the child resource type in the second column>

<Fill in the name of Child ResourceN if a fixed name is required or [variable] if no fixed name is required>

<Fill in the type of Child ResourceN>

<Fill in Multiplicity>

See clause <XRef <clause> where the type of this child resource is described.

<Fill the child resource type for the announced resource. It can be none or <crTypeAnnc>; where the <crType> is the child resource type in the second column>

The child resource table for the announce-able <resourceType> resource shall include an additional column titled '<resourceTypeAnnc> Child Resource', indicating that resource <resourceType> is announce-able. See the section 9.6.22 for further details.

Table 9.5.1.1-1: Child Resources of <resourceType>

Observations: 3. An annc resource seems to have children and these children MUST

be the announced child resources of the original

Section 9

Attribute Name of <resourceType>

Multiplicity

RW/RO/WO

Description<resourceTypeAnnc>

(MP/OP/NP)

<Fill in name of Common Attribute1>

<Fill in Multiplicity>

<Fill in RW or RO or WO>

Provide description of this attribute…to be moved later to a common attribute section.

<Fill in MP or OP or NP>

<Fill in name of Common AttributeN>

<Fill in Multiplicity>

<Fill in RW or RO or WO>

Provide description of this attribute…to be moved later to a common attribute section.

<Fill in MP or OP or NP>

<Fill in name of Resource Specific Attribute1>

<Fill in Multiplicity>

<Fill in RW or RO or WO>

Provide description of this attribute .. to be moved later to a central attribute table that also defines the type of the attribute, allowed ranges etc.

<Fill in MP or OP or NP>

<Fill in name of Resource-Specific AttributeN>

<Fill in Multiplicity>

<Fill in RW or RO or WO>

Provide description of this attribute .. .. to be moved later to a central attribute table that also defines the type of the attribute, allowed ranges etc.

<Fill in MP or OP or NP>

The attributes table for the announce-able <resourceType> resource shall include an additional column titled 'Attribute for <resourceTypeAnnc>', indicating that resource <resourceType> is announce-able. See the section 9.6.22 for further details.

Table 9.5.1.1-2: Attributes of <resourceType>

Observations: 4. An annc resource seems to have a subset of the attributes of the

original resource5. The description only speaks about the presence of the attribute but

not the content.

The attributes for <resourceTypeAnnc> in the attribute table can have the following set of values:

MP (Mandatory Present): This attributes in the original resource shall be present in the announced resources.

OP (Optional Present): This attributes in the original resource may or may not be present in the announced resources depending on the contents of the announcedAttribute attribute of the original resource.

NP (Not Present): This attribute shall not be present in the announced resource.

Section 9: common attributesObservations:

4. An annc resource shall have the “link” mandatory for Annc resources5. Original resource MAY have the announceTo and the announceAttribute

optional for normal resources (cannot be mandatory since announcement is an optional feature)

link (ln) This attribute shall be present only for the announced resource. This attribute shall provide the URI to the original resource.

announceTo (aT) This attributes shall be present for the announceable original resource only. This attribute maintains the list of URIs to the announced resources. Updates on this attribute will trigger new resource announcement or de-announcement. In case of new resource announcement, either the exact URI to the announced resource that is to be created can be provided, or the CSE-ID of the remote CSE can be provided. This means the original resource-hosting CSE will decide the exact location of the announced resource in the remote CSE identified by the CSE-ID.

announcedAttribute (aA) This attributes shall be present for the announceable original resource only. This attribute maintains the list of the announced attributes in the original resource. Updates on this attribute will trigger new attribute announcement if a new attribute is added or de-announcement if the existing attribute is removed.

Example from the TS

Child Resource Name of

<accessControlPolicy>

Child Resource Type

Multiplicity Description<accessControlPolic

yAnnc> Child Resource Type

[variable] <subscription> 0..n See clause 9.6.8 <subscriptionAnnc>

Table 9.6.2-1: Child resources of <accessControlPolicy> resource

What this means?If the AccessControlPolicy resource is announced, do we also need to announce the subresources? What is the reason for doing that?

Example from the TS

Table 9.6.2-2: Attributes of <accessControlPolicy> resource

It just indicate that is mandatory, not present or optional but it gives no information about the actual meaning and value

Section 10• The following clauses are defined:

– 10.2.18.1 Procedure for AE and CSE to initiate the creation or deletion of the Announced Resource

• CREATE and UPDATE request for an “Annc resource”, over Mca. Response missing

– 10.2.18.2 Procedure for original resource hosting CSE to Announce Resource• The hosting CSE CREATing the real Annc resource only acting on announceTo, over Mcc

– 10.2.18.3 Procedure for original resource hosting CSE to delete the Announced Resource• Hosting CSE DELETing the real Annc resource based on removal of some announceTo, over Mcc

– 10.2.18.4 Procedure for AE and CSE to initiate the creation or deletion of the Announced Attribute

• Originator UPDATE the content announceAttribute for requesting announcing attribute, over Mca. Response missing.

– 10.2.18.5 Procedure for original resource hosting CSE to Announce Attribute• The hosting CSE CREATing the real Annc attribute only acting on announceAttribute, over Mcc

– 10.2.18.6 Procedure for original resource hosting CSE to delete the Announced Attribute• Hosting CSE DELETing the real Annc attribute based on removal of some announceAttribute, over

Mcc

RETRIEVE &Discovery

• There is no procedure for reading the announced resource, what is the returned value?

• What is the result of the discovery procedure for Announced Resource?– There is no description about that– Shall the annc resource be returned of the original

resource?

Issues from section 9• Define what is the purpose of announcing a resource clearly, there is only

some text in section 9.6.34 but it should be said early on the definition of such type of resources.

• More clarification is needed for:1. Which resource can be announced, what are the criteria, if any2. Adding a column on the table for the attribute and resource does not say

what the value should be and it creates confusion with the original resource3. Common attributes needs clarification:

• Link: contains the URI of the original resource, this is clear• announceTo: list of the announced resource. it is confusing the value that can be

given in the request and the value that should be provided in the response.• announceAttribute: list of announce attributes. Why do we need to announce

the resource and also more attributes that are not discoverable directly? Announced resources are not a copy of the original resources and they are not a cache.

Issues on attributes• According to 9.6.34 only labels attribute is synchronized with the original resource. • Clearly the link attribute is needed and it points to the original resource• It is not clear what is intended for the other attributes that are not clearly

indicated in the same section.• The text on child resource is conflicting with the normal announce procedure. If we

take the example in slide 8 the Originator could request to announce the child <subscription> resource without announcing the <accessControlPolicy> and if later the latter is announced there might not be a relation between the 2 resources since the Receiver will choose the location of the “annc” resources. This will have a different effect if the Originator has chosen to announce the <accessControlPolicy> resource first.

• Right now “annc” resource cannot contain any “regular” resources as child resource. Is that intentional?

Proposal for the way forward

Proposal• Proposal is to define these set of attributes for announce resource:

– resourceType: mandatory but not the same of the original resource– parentID: mandatory but it is not the same of the original– expirationTime: mandatory but not the same as the original– accessControlPolicyID: mandatory and the same as the original resource– Labels: mandatory and the same as original– creationTime: mandatory not the same as original– lastModifiedTime: mandatory not the same as original

• There are 2 type of attributes:– Real attributes with content and not synchronized with the original resource– Synchronized with the original resource: labels and accessControlPolicyID

• This means that a “annc” resourceType has a very specific set of attributes therefore it would be beneficial to have these attributes described separately in clause 9.6.34 and not in the “original resource”

Proposal• Do not announce any of the specific resource attribute. Announcing such

attributes just complicate the announce procedure for a non specified benefit.

• Announce child resources independently and not as part of the parent resource. The request over Mca may ask to also announce the child resource, but each resource needs to be created independently over Mcc.

• Make clear that the attribute “announceTo” may either contains CSE-ID list or the actual location of the new “annc” resource on the request. The attribute however always contains URIs of the actual “annc” resources in the resource representation which will be the only value returned.

– Handled the error scenario in case of request with a specific URI that cannot be accepted.

Proposal• Describe the procedure in clause 10.2.18 clearly as 2 procedures one

potential over Mca (if requested by AE) and one over Mcc. These procedures are correlated, so also the handling of response and error need to be very clear. Right now only who knows how the procedure works can understand how the Originator is informed of successful request. (No clear indication of error cases)

• Make clear if announced resource cannot have any regular resource as child resources or it can.

Proposal• Remove procedures on specific attribute (10.2.18.4, 10.2.18.5,

10.2.18.6)• Describe how RETRIEVE and discovery works for the announced resource.

The proposal is to:– Provide the original as default– Use rc request parameter to specify if the AnncResource or the the

link shall be received.

There are actual CR already proposed in ARC#10 for fixing some of the issues listed