On Mon, Dec 26, 2011 at 6:50 AM, Ben Niven-Jenkins
<[email protected]> wrote:
> Haibin,
>
> On 26 Dec 2011, at 09:42, Songhaibin wrote:
>
>> The current ALTO protocol document describes the dependency of the cost map 
>> and network map, and only network map version tag is used for consistence 
>> check. But the cost map might be changed without the change of network map, 
>> I think we should allow the ALTO client to only update its cost map if the 
>> network map has not been changed.
>
> This seems an unnecessary restriction as if the Network Map changes in many 
> cases the resulting Cost Map will have to change and in addition there will 
> be cases where the Cost map changes when the Network Map stays the same.
>
>> Shall we add a version tag for the cost map?
>
> My preference would be that ALTO Servers & Clients make use of HTTP Etags so 
> that clients can do IfNoneMatch type operations to check if the Cost Map has 
> changed without having to first obtain the entire unchanged map again and 
> check for a costmap-version field embedded in the map itself.
>

Agreed. We only needed a version tag for consistency between network
map and cost map because they are two separate HTTP resources and we
need a way to cross-reference them.  Asking for updates to single
resource can be done using the standard tools in HTTP.

Rich

> Ben
>
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