Each service may only provide a small part of the overall business transaction, with results of one operation feeding into the processing of another (such as order fulfillment and billing).
每个服务只提供整个业务事务的一小部分，结果是一个操作进入另一个的处理中（例如订单执行和记账）。
2
So a blocked worker thread, because it's waiting on a response from some remote service, can't proceed with the current transaction and can't start processing a new transaction either.
The coordination service controls the activity completion processing for the registered Web services using the selected coordination protocol (defined in WS-Transaction).