If performance is important, you can access the EJBs via their local interface (call-by-reference), unless your topology requires remote access.
如果性能很重要，可以通过EJB的本地接口访问它们(按引用调用)，除非拓扑要求进行远程访问。
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The enable-call-by-reference element is generally used to pass parameters by reference rather than by value, which requires making a copy of the parameters.
Modelers should make no assumptions about the location of the data, call-by-value or call-by-reference semantics, nor any implicit concurrency management facilities.