hi Sebastian OK...I got it....I was thinking I could use it for an online scenario...... Thank you
Angelo 2014-03-26 14:52 GMT+01:00 Sebastian Schelter <s...@apache.org>: > Hi Angelo, > > It very much depends on your use case. Do you want to precompute paths > offline in batch or are you looking for a system that answers online? > Giraph has been built for the first scenario. > > --sebastian > > > On 03/26/2014 02:48 PM, Angelo Immediata wrote: > >> hi Claudio >> >> so, if I understood correctly, it has no sense to use Giraph for shortest >> path calculation in my scenario >> >> Am I right? >> >> >> 2014-03-26 13:27 GMT+01:00 Claudio Martella <claudio.marte...@gmail.com>: >> >> It looks like you're expecting to use Giraph in an online fashion, such >>> as >>> you would use a database to answer queries within milliseconds or >>> seconds. >>> Giraph is an offline batch processing system. >>> >>> >>> On Wed, Mar 26, 2014 at 11:11 AM, Angelo Immediata <angelo...@gmail.com >>> >wrote: >>> >>> Hi there >>>> >>>> In my project I have to implement a routing system with good >>>> performance; >>>> at the beginning this system should be able in giving routes information >>>> only for one italian region (Lombardia) but it could be used for the >>>> whole >>>> Italy (or world....) >>>> Let's stop to the Lombardia for now. By reading OSM files I can create >>>> my >>>> own graph in the best format i can use it; then I need to use Dijkstra >>>> (or >>>> any other algorithm) in order to propose to the user K possible paths >>>> from >>>> point A to point B (K becouse i need to show to the customer also the >>>> alternatives). I can't use Contraction Herarchy algorithm becouse I >>>> need to >>>> take care of external events that can modify the weights on my built >>>> graph >>>> and this implies that I should create the "contracted" graph once again >>>> and >>>> this can be a very onerous operation >>>> >>>> By my experimentations, I saw that by reading the Lombardia OSM file I >>>> should create a graph with around 1 million of vertexes and 6 million of >>>> edges and I was thinking to use Giraph to solve my issue (I saw this >>>> link >>>> http://giraph.apache.org/intro.html where you talked about >>>> shortestpaths >>>> problem >>>> I have a couple of question for you giraph/hadoop gurus >>>> >>>> - does it make sense to use giraph for my scenario? >>>> - must i respect some graph format to pass to the giraph algorithm >>>> in >>>> >>>> order to have K shortest paths from point A to point B? If >>>> so....which >>>> format should I respect? >>>> - what would be perfomance by using giraph? I know that Dijstra >>>> >>>> algorithm problem is that it is slow.....by using giraph will I be >>>> able in >>>> improving its performances on very large graph? >>>> >>>> I know these can seem very basic questions, but I'm pretty new to giraph >>>> and I'm trying to understand it >>>> >>>> Thank you >>>> Angelo >>>> >>>> >>> >>> >>> -- >>> Claudio Martella >>> >>> >>> >> >
