An Arbortext PE 應用程式 does not need to be thread-safe. An Arbortext PE 子流程 only handles one request at a time; therefore, it can only run one Arbortext PE 應用程式 at a time. However, an Arbortext PE 應用程式 does need to be safe for multi-processing, because the Arbortext PE Request Manager could ask two or more Arbortext PE 子流程 to run the same Arbortext PE 應用程式 at the same time.

For example, if an Arbortext PE 應用程式 attempts to write temporary data using an absolute path and file name (e:\tempdata\tempdatafile.txt), two instances of the Arbortext PE 應用程式 might run at the same time and overwrite each other’s file. If an Arbortext PE 應用程式 stores data to the Windows clipboard, two instances of the operation might run simultaneously and interfere with each other.

Every Arbortext PE 應用程式 needs to be serially reusable. An Arbortext PE 應用程式 should not attempt to maintain any state from one call to the next. The Arbortext PE Request Manager could ask a particular Arbortext PE 子流程 to execute any Arbortext PE 應用程式 repeatedly, so the Arbortext PE 應用程式 must not assume any prior state each time it is invoked. If a particular client submits several Arbortext PE 應用程式 requests to an Arbortext PE 伺服器, the Arbortext PE Request Manager might allocate a different Arbortext PE 子流程 to serve each request. If the second request expects to find information left behind by the first request (for example, a value stored in a global variable), the application would only work if the Arbortext PE Request Manager happened to allocate the same Arbortext PE 子流程 to serve both requests.