A traveling salesperson (TSP) route request must have at least three locations. Unlike simple multi-address route requests, the <start_location> element is optional.
TSP route requests are multi-address requests that have the optimize_route attribute present and set to TRUE. TSP route requests attempt to reorder the unfixed locations in the request to optimize the overall route.
All the locations in a TSP request are classified as unfixed or fixed:
Unfixed ___location: If a ___location is specified with the <___location> element, it is considered an unfixed ___location and is subject to reordering during route computation.
Fixed ___location: If the ___location is specified with a <start_location> or <end_location> element, it is considered a fixed ___location and is not subject to reordering during route computation.
If intermediate locations need to be fixed, a simple multi-address route request should be used instead of a TSP route request.
TSP route requests use the route_type attribute to classify the route as an open or closed tour.:
Open tour: The route does not return to the start ___location.
Closed tour: The route returns to the start ___location.
If a TSP closed tour route is requested, the <start_location> element must be specified. This start ___location is also used as the end ___location during route computation. If an <end_location> element is specified in a TSP closed tour route request, an error is returned. By definition, TSP closed tour routes use a single fixed start and end ___location but the intermediate locations are still subject to reordering.
Example: TSP Open Tour Route Request
To drive from your workplace, visiting customers A, B, and C:
The route has the workplace as a fixed start ___location.
The route has customers A, B, and C as unfixed intermediate locations. These locations are reordered to optimize the overall route.
The returned route is an optimized open tour route from the workplace to the first reordered ___location, through the second reordered ___location, to the final ___location.
Example: TSP Closed Tour Route Request
To drive from your workplace, visiting customers A, B, and C, and then returning to your workplace:
The route has the workplace as a fixed start ___location. The workplace is also used as a fixed end ___location. An <end_location> element should not be specified in the route request. The routing engine adds the subroute from last unfixed ___location to the workplace automatically when it sees a request for a closed tour.
The route has customers A, B, and C as unfixed intermediate locations. These locations are reordered to optimize the overall route.
The returned route is an optimized closed tour route from the workplace to the first reordered ___location, through the second and third reordered locations, and finally back to the start ___location.
TSP route requests can contain several attributes specific to each subroute. These attributes include return_subroutes, return_subroute_edge_ids, and return_subroute_geometry. These attributes are explained in Route Request XML Schema Definition.