java - EJB限制: compromise component distributability

Question

似乎禁止从 EJB 读取文件，如此链接中所述:

http://java.sun.com/blueprints/qanda/ejb_tier/restrictions.html#file_access

Enterprise beans aren't allowed to access files primarily because files are not transactional resources. Allowing EJBs to access files or directories in the filesystem, or to use file descriptors, would compromise component distributability, and would be a security hazard.

什么是“损害组件的可分发性”？？？

Answer 1

摘自How to Be Distributable来自 Enterprise Servlet 和 J2EE:

An EJB may be distributed across a number of backend machines and may be moved between machines at the container's discretion. To enable this distribution model, EJB must follow a strict specification-defined ruleset for what they can and cannot do.

文件系统可能因机器而异，文件描述符肯定是不同的。使用它们可以防止 EJB 迁移和/或钝化。

另请参阅

• How to access the file system from an EJB 3?
• Java EE, EJBs File handling