See: https://datatracker.ietf.org/doc/rfc7252/
This implementation currently supports the main protocol according to RFC 7252 (without SSL) plus
- the core link format (see https://datatracker.ietf.org/doc/rfc6690/) and
- the observe extension (draft 14) (see http://tools.ietf.org/html/draft-ietf-core-observe-14).
The nCoAP project is organized in several maven modules, i.e.,
<groupId>de.uniluebeck.itm</groupId>
<artifactId>ncoap-core</artifactId>
for the raw protocol implementation. For CoAP application development this is probably what you want. To use the latest protocol implementation release add the following to your pom.xml
<repositories>
...
<repository>
<id>itm-maven-repository-releases</id>
<name>ITM Maven Releases Repository</name>
<url>https://maven.itm.uni-luebeck.de/content/repositories/releases</url>
</repository>
...
</repositories>
...
<dependencies>
...
<dependency>
<groupId>de.uniluebeck.itm</groupId>
<artifactId>ncoap-core</artifactId>
<version>1.8.2</version>
</dependency>
...
</dependencies>
The other models, i.e.,
<groupId>de.uniluebeck.itm</groupId>
<artifactId>ncoap-simple-client</artifactId>
and
<groupId>de.uniluebeck.itm</groupId>
<artifactId>ncoap-simple-server</artifactId>
provide simple CoAP applications for both, client and server. There intention is to highlight, how easy it is to write such applications using ncoap.
The documentation is available at http://media.itm.uni-luebeck.de/people/kleine/maven/ncoap-complete/1.8.2