Resource subscription using DDS in oneM2M Group Name: ARC#29 Source: Sarah, Huawei, changhongna@huawei.com Echo, Huawei, echo.xubei@huawei.com Meeting Date: 2017-05-22

Summary of DDS Features The Data Distribution Service (DDS) is a middleware protocol for data-centric connectivity, providing many-to-many communication, extreme reliability, and a scalable architecture. 2

Applications DDS is used by many industries developing mission and business-critical smart applications, for example, transportation, industrial automation, military & aerospace, and so on. 3

Combined Scenario The application wants to subscribe to the temperature resource of device A and device B. Device A, device B and the application in oneM2M system support DDS protocol. Device A, device B and the application register to MN A, MN B, and MN C respectively.

Comparison of Resource Discovery and Subscription between DDS and oneM2M The process of subscription in oneM2M The process of dynamic discovery in DDS In oneM2M system, the implement of resource discovery and subscription depending on the application and the application needs to be preconfigured information about subscribed resources, which leads to inflexible network deployment. The establishment of communication entirely depends on the dynamic discovery mechanism, which leads to the unauthorized devices could access to the oneM2M network .

Overview of DDS Solution Architecture General Flow The DDS repository function can discovery the resources which can be permitted to be subscribe to for the subscriber and identify the communication list for the publishers (AEs and CSEs) according to the resource matching and other information (e.g. group information , ACP policy). DDS repository can be contained inside the MN-CSE or/and IN-CSE. The solution consists of 4 steps: registration, topic report, resource matching, resource subscription.

Solution – Topic Report Step 1: The topics defined by the DDS middleware can be considered a new resource type named <topicDirectory>. An AE/CSE can create this new resource to the remote CSE of its registrar CSE. Step 2: After creating the new resource, the registrar CSE adds its identifier to the new resource. If the registrar CSE has registered to another CSE and hasn’t the DDS Repository function, the registrar CSE shall send a CREATE request of the new resource to its Registrar CSE. Topic Report The name of the topics defined by the DDS. Represent that the topic can be published or subscribed. Represents the addresses to be used by other CSEs to connect to this CSE (e.g. IP address, Globally Unique Identifier (GUID defined by DDS). Records the IDs of the AE/CSEs which are included in topic report path Represents a list of addresses of remote CSEs/AEs which subscribe to this resource. The <topicDirectory> resource type

Solution – Resource Matching The CSE which contains the DDS repository function can match the resources received from oneM2M parties. Topic name match pubsubAttribute match Conform to configured rules(e.g.ACP) PUBLISHER SUBSCRIBER

Solution – Resource Subscription Step-1: The DDS repository creates the address list of matching parties and updates the peerList attribute of the <topicDirectory> resource. Then, DDS repository sends the UPDATE request to the resource publisher. Step-2: After receiving the UPDATE request, the MN CSE updates the peerList attribute of the <topicDirectory> resource. Then, the MN CSE sends the UPDATE request to the resource publisher. Step-3: The originator updates the peerList attribute of the <topicList> resource and configures the DDS middleware configuration according to the peerList attribute. Step-4: Then trigger the dynamic discovery procedure. Step-5: the device A sends the notification message to the APP directly.

The Advantages of Solution Dynamic discovery of resources No need to preconfigure information of peer nodes, which enables the network topology flexible and extensible. Data exchange directly Use dynamic discovery mechanism to establish pub-sub relationship to exchange data directly. The central control of resource discovery and subscription ensures the network more secure.

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