* Auto-instrumentation mechanism, **no need to CHANGE any application source code**. [Supported middlewares, frameworks and libraries](https://github.com/wu-sheng/sky-walking/wiki/3.0-supported-list).
* Auto-instrumentation mechanism, **no need to CHANGE any application source code**. [Supported middlewares, frameworks and libraries](https://github.com/wu-sheng/sky-walking/wiki/3.1-supported-list).
* Explicit-instrumentation, as an [OpenTracing supported tracer](http://opentracing.io/documentation/pages/supported-tracers).
* Explicit-instrumentation, as an [OpenTracing supported tracer](http://opentracing.io/documentation/pages/supported-tracers).
* Pure Java server implementation, with RESTful Web service.
* Pure Java server implementation, with RESTful Web service.