An Arbortext PE アプリケーション does not need to be thread-safe. An Arbortext PE サブプロセス only handles one request at a time; therefore, it can only run one Arbortext PE アプリケーション at a time. However, an Arbortext PE アプリケーション does need to be safe for multi-processing, because the Arbortext PE Request Manager could ask two or more Arbortext PE サブプロセス to run the same Arbortext PE アプリケーション at the same time.

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

Every Arbortext PE アプリケーション needs to be serially reusable. An Arbortext PE アプリケーション should not attempt to maintain any state from one call to the next. The Arbortext PE Request Manager could ask a particular Arbortext PE サブプロセス to execute any Arbortext PE アプリケーション repeatedly, so the Arbortext PE アプリケーション must not assume any prior state each time it is invoked. If a particular client submits several Arbortext PE アプリケーション requests to an Arbortext PE サーバー, the Arbortext PE Request Manager might allocate a different Arbortext PE サブプロセス 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 サブプロセス to serve both requests.