Evaluation of CoAP Implementations for Live Streaming using CoAP-Observe

CoAP (Constrained Application Protocol) enables embedded devices to offer RESTful Web Services and exchange small binary message headers. Next to the transmission of sensor data and control information between smart home devices, there is an application field of streaming data using CoAP. There are CoAP implementations available in Java, that allow an execution on heterogeneous devices and operating systems due to the Java Virtual Machine and Java Runtime Environment. Because of the timing demands of live streaming applications in terms of low latency communication at application layer, we evaluate two different CoAP Java implementations. We compare the timing fluctuations of the packet processing with a CoAP C implementation. As a conclusion we identify the Java Garbage Collector to cause large fluctuations of the packet processing, which results in bad suitability for a live streaming scenario. Furthermore, we recommend the usage of native code applications because of better timing results.