Whatever the case, the type of interaction you will be modeling determines the first (and left-most) element in the sequence diagram.
无论是哪种情况，将要建模的交互类型决定了序列图中的第一个(最左边的)元素。
2
The interface is still the most important element for technical interaction with the service but now SOA service is defined by the Service Description.
这些接口仍然是与服务进行交互的最重要技术元素。 但是，现在SOA服务是由服务描述来定义的。
3
A service contract is binding on all participants in the interaction, including the service itself and the element that provides it for the particular interaction in question.