Upload App Engine Endpoint project

Step 1: create the project at Google Developer Console and copy the project id for later usage.

Step 2: import the app engine project into Eclipse (follow this link on how to do this: http://czcodezone.blogspot.sg/2014/09/import-and-run-app-engine-endpoint.html). Expand the project directory in the "project explorer" of Eclipse to the folder "[project_folder]->main->webapp->WEB-INF" and double-click to open "appengine-web.xml". Change the text element in the xml element "<application>"
to the project id copied earlier in step 1.

Step 3: Right-click the project in the "project explorer" of Eclipse and select "Run As->Run Configuration". In the run configuration dialog, right-click "Maven Build" and select "New". enter the configuration name (e.g. "training-upload") and select the base directory using the "Browse Workspace" button. Next enter "appengine:update" into the "Goals" and click "Apply". Now click "Run" button.

Step 4: To reupload, simply right-click the project in the "project explorer" and select "Run As->Maven Build" and select the earlier created configuration (e.g. the "training-upload" specified earlier in Step 3).