webserver ↔ service call convention

A request to a serveice:

getSomethingFromService( SelectionDict, SortDict, StartItem, MaxItems )

Where:
SelectionDict - { 'key1' : [ 'value1', 'value2'] }
SortList - [ ['key1', 'value1'],['key2', 'value2'],... ]
StartItem - integer
MaxItems - integer

A service response is:

{'Value':' { 'ParameterNames':['Name1', 'Name2'], 'Records':[[v1,v2],[v1,v2]], 'TotalRecords':int, 'Extras':{whatever} } '}

Where:
ParameterNames - list of parameters
Records - list of lists with values corresponding to parameters
TotalRecords - integer
Extras - all additional info goes here and it could be whatever you like (i.e. list of dict or single integer)