twistedTCPServer.py

#File: twistedTCPServer.py
#Querying database asynchronously with Twisted
 
from twisted.web import resource, server
from twisted.internet import reactor
from twisted.enterprise import adbapi
 
class BlobLoads(resource.Resource):
    def __init__(self, dbconn):
        self.dbconn = dbconn
        resource.Resource.__init__(self)
    def _getBlobs(self, txn, query):
        txn.execute(query)
        return txn.fetchall()
    def render_GET(self, request):
        query = "select id, blobdoc from blob_tab"
        self.dbconn.runInteraction(self._getBlobs, query).addCallback(
            self._writeBlobs, request).addErrback(
            self._exception, request)
        return server.NOT_DONE_YET
    def _writeBlobs(self, results, request):
        request.write("""
       
       
       
         

Writing BLOBs from the database to your disk

         """)
        for id, blobdoc in results:
          request.write("/tmp/picture%s.bmp
" % id)
          blob = blobdoc.read()
          output = open("/tmp/picture%s.bmp" % id, 'wb')
          output.write(blob)
          output.close()
   
        request.write("""
       

Operation completed

       
       
        """)
        request.finish( )
    def _exception(self, error, request):
        request.write("Error obtaining BLOBs: %s" % error.getErrorMessage())
        request.write("""
       

Could not complete operation

       
       
        """)
        request.finish( )
 
class SiteResource(resource.Resource):
    def __init__(self, dbconn):
        resource.Resource.__init__(self)
        self.putChild('', BlobLoads(dbconn))
 
if __name__ == "__main__":
    dbconn = adbapi.ConnectionPool('cx_Oracle', user='usr', password ='pswd', dsn='127.0.0.1/XE')
    site = server.Site(SiteResource(dbconn))
    print "Listening on port 8000"
    reactor.listenTCP(8000, site)
    reactor.run()