E:\> cd e:\appengine-java-sdk

E:\appengine-java-sdk> bin\appcfg.cmd update hydrogen-tweet-1.0/web
——————到这里是我输入的部分，以下是系统回复

Reading application configuration data...
2012-4-29 23:52:58 com.google.apphosting.utils.config.AppEngineWebXmlReader read
AppEngineWebXml
信息: Successfully processed hydrogen-tweet-1.0/web\WEB-INF/appengine-web.xml
2012-4-29 23:52:58 com.google.apphosting.utils.config.AppEngineWebXmlReader read
AppEngineWebXml
严重: Received exception processing hydrogen-tweet-1.0/web\WEB-INF/appengine-web
.xml
com.google.apphosting.utils.config.AppEngineConfigException: appengine-web.xml d
oes not contain a element.
See http://code.google.com/appengine/docs/java/config/appconfig.html#Using_Concu
rrent_Requests for more information.
You probably want to enable concurrent requests.
at com.google.apphosting.utils.config.AppEngineWebXmlReader.readAppEngin
eWebXml(AppEngineWebXmlReader.java:79)
at com.google.appengine.tools.admin.Application.(Application.java:
139)
at com.google.appengine.tools.admin.Application.readApplication(Applicat
ion.java:225)
at com.google.appengine.tools.admin.AppCfg.(AppCfg.java:145)
at com.google.appengine.tools.admin.AppCfg.(AppCfg.java:69)
at com.google.appengine.tools.admin.AppCfg.main(AppCfg.java:65)
Bad configuration: appengine-web.xml does not contain a element.
See http://code.google.com/appengine/docs/java/config/appconfig.html#Using_Concu
rrent_Requests for more information.
You probably want to enable concurrent requests.
Please see the logs [D:\DOCUME~1\Owner\LOCALS~1\Temp\appcfg7139122775966785817.l
og] for further information.

E:\> cd e:\appengine-java-sdk

接下来就不知道怎么办了，我猜You probably want to enable concurrent requests.这句话有可能提示了解决错误的办法，但是理解不能，求指教，谢谢