Post on 28-Jan-2021
Pervasive Systems
Ioannis Chatzigiannakis
Sapienza University of RomeDepartment of Computer, Control, and Management Engineering (DIAG)
Lecture 9:CoAP
The Web and REST
Web Naming URL Resolution
An HTTP Request Web Paradigms
A REST Request CoAP Design Requirements
The CoAP Architecture The CoAP ProtocolI A very efficient RESTful protocolI Ideal for constrained devices and networksI Specialized for M2M applicationsI Easy to proxy to/from HTTPI Does not replace HTTPI Is not a cut-down HTTP versionI Not just for resource-constrained networks
CoAP FeaturesI Embedded web transfer protocol (coap://)I Asynchronous transaction modelI UDP binding with reliability and multicast supportI GET, POST, PUT, DELETE methodsI URI supportI Small, simple 4 byte headerI DTLS based PSK, RPK and Certificate securityI Subset of MIME types and HTTP response codesI Built-in discoveryI Optional observation and block transfer
Request Example
Dealing with Packet Loss Separate Response
Proxying and caching Observation
Block transfer