说明：  定向扩散（Directed Diffusion, DD）协议在omnet++模拟器上的实现。原理：Sink 向所有传感器节点发送兴趣(兴趣是通过分配不同的属性值来表示不同任务的描述符) , 每个传感器节点在收到兴趣后将其保存在各自的 CACHE 中。每个兴趣项包含一个时间标签域和若干个梯度域。当一个兴趣传遍整个网络后, 从 Source 到 Sink 之间的梯度就建立起来了，梯度反映了网络中节点对匹配请求条件的数据源的近似判断。一旦Source 采集到兴趣所需的数据, 那么它将沿着该兴趣的梯度路径传输数据到汇集点或基站。
(Directional proliferation (Directed Diffusion, DD) agreement omnet++ Realize simulator. Principle: Sink to all sensor nodes send interest (interest is through the distribution of different attribute values to express a different mission descriptors), each sensor node after the receipt of interest in the preservation of their respective CACHE. Interest of each tag contains a time domain and a number of gradient domain. When an interest throughout the network, from the Source to Sink gradient between the built up, the gradient reflects the network node on the request of the conditions of matching the data source to determine approximate. Once the Source of interest collected the required data, it would be interested in the gradient along the path to transmit data to the focal point or base station.)