谷歌应用程序引擎PHP ebay搜索API返回null

我正在做一个eBay搜索API调用findItemsByKeywords在谷歌应用程序引擎的php。它在本地工作，而不是在GAE上。这是我如何呼叫的

$resp = simplexml_load_file($apicall);

我检查了主机提供已启用PHP打开url作为文件ini_get('allow_url_fopen')返回1.

只有在GAE上运行时，我才在$resp中获得空值。

编辑:

下面是GAE错误日志中的内容。

2014-06-12 16:21:50 Running command: "['C:''Python27''pythonw.exe', 'C:''google-cloud-sdk''bin''dev_appserver.py', '--skip_sdk_update_check=yes', '--port=10080', '--admin_port=8002', 'C:''app_engine''invApp']"
INFO     2014-06-12 16:21:53,055 devappserver2.py:716] Skipping SDK update check.
WARNING  2014-06-12 16:21:53,076 api_server.py:378] Could not initialize images API; you are likely missing the Python "PIL" module.
INFO     2014-06-12 16:21:53,099 api_server.py:171] Starting API server at: http://localhost:16086
INFO     2014-06-12 16:21:53,107 dispatcher.py:182] Starting module "default" running at: http://localhost:10080
INFO     2014-06-12 16:21:53,111 admin_server.py:117] Starting admin server at: http://localhost:8002
INFO     2014-06-12 16:22:01,536 module.py:639] default: "GET / HTTP/1.1" 200 1637
INFO     2014-06-12 16:22:01,566 module.py:639] default: "GET /static/main.css HTTP/1.1" 200 206
INFO     2014-06-12 16:22:01,568 module.py:639] default: "GET /static/script.js HTTP/1.1" 304 -
ERROR    2014-06-12 16:22:01,566 module.py:714] Request to '/static/main.css' failed
Traceback (most recent call last):
  File "C:'google-cloud-sdk'platform'google_appengine'google'appengine'tools'devappserver2'module.py", line 710, in _handle_request
    return handler.handle(match, environ, wrapped_start_response)
  File "C:'google-cloud-sdk'platform'google_appengine'google'appengine'tools'devappserver2'static_files_handler.py", line 369, in handle
    return self._handle_path(full_path, environ, start_response)
  File "C:'google-cloud-sdk'platform'google_appengine'google'appengine'tools'devappserver2'static_files_handler.py", line 182, in _handle_path
    start_response('200 OK', headers)
  File "C:'google-cloud-sdk'platform'google_appengine'google'appengine'tools'devappserver2'module.py", line 640, in wrapped_start_response
    return start_response(status, response_headers, exc_info)
  File "C:'google-cloud-sdk'platform'google_appengine'lib'cherrypy'cherrypy'wsgiserver'wsgiserver2.py", line 2155, in start_response
    raise TypeError("WSGI response header value %r is not of type str." % v)
TypeError: WSGI response header value u'text/css' is not of type str.
INFO     2014-06-12 16:22:01,571 module.py:639] default: "GET /static/main.css HTTP/1.1" 500 -
INFO     2014-06-12 16:22:11,984 module.py:639] default: "GET /api.php?target=ebay&searchClause=cake|3|4|true HTTP/1.1" 200 940

编辑:

我找到了解决办法。我必须使用file_get_contents，然后如果成功，使用simplexml_load_string。由于某些原因，GAE不允许我使用simplexml_load_file。

这是有效的代码。

$resp = file_get_contents($apicall);
if($resp){
    $result = simplexml_load_string($resp);       
}
exit(json_encode($result));