Dear OSWG Members & Iotivity Maintainers,
Before I deep dive into topic, let me explain what default interface is in short. When a client queries server for a resource without any "if" value, it is default interface who guides the resource to send appropriate response. There is ongoing discussion regarding how to inform default interface of a resource to client. OIC Spec defines 1st interface in order for value of "if" property in payload should be considered as default interface. OIC Spec also allows a resource to override spec defined default interface. There has been multiple views regarding what default interface should do & how it should be handled. Following are few options with their pros and cons as given below. [Option 3 is from Spec while 1 & 2 are just opinion I heard during discussion for this topic] Option 1 - Default interface is clearly defined for each resource. Overriding interface type is not allowed. Pros - No surprises for a client due to prior knowledge of default interface for each resource. Cons - Higher memory footprint due to storage of default interface information for every resource. Spec to become bulky as on new resources are added. Spec lose the flexibility advantage to let a resource decide its own default interface. Option 2 - Single or Common default interface for all resources. Overriding interface type is not allowed. Pros - Fixed memory footprint and easy to maintain. No surprises for client due to only 1 interface type to be handled for all resources. Cons - Constraint devices & network to have trouble if selected interface sends more than required data. Spec becomes bounded and no scope of extension when new resources or verticals are added. Option 3 - Default interface is defined in general or specifically depending on resource. Overriding the interface type is allowed. 1st interface listed in "if" property value is default interface. Pros - No need of prior knowledge. Smart way to identify the default interface. Small memory footprint. Spec gains flexibility advantage and will be lighter even if more resources are added. Cons - Need strong safe guarding mechanism to make sure there are no surprises. Software maintenance becomes tricky as on more resources are added. Thoughts please? Regards Dwarka ---------------------------------------------------------------------------- ------ Software R&D Center | Software Platform Team | IoT Lab Open Interconnect Consortium - Open Source Work Group Member Iotivity Steering Group - Advisory Committee -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.iotivity.org/pipermail/iotivity-dev/attachments/20160202/c252bfb2/attachment.html>
