a python server responses every URL request which contains 'shortestpath'. It returns a Json file shows the shortest path from source to target in a weighted graph G.
- call initDataset() as long as the server running
- after data is ready, call do_GET() function when receives an URL request.
- In do_GET() function, the main idea is: extract source pid and target pid, then call Handler.calP(source,target) to get path list of pid, then call Handler.writejson(path) to generate json file. BaseHTTPRequestHandler.wfile.write(json file) to show result on browser.