I am trying to produce a routing functionality in a web-GIS that, given a start and an end point, will retrieve the least cost path taking into account points along edges representing major costs, thus avoiding them. I would like to ask what I could do to start producing this function. I have a graph with edges and nodes, I have points representing costs along edges, I have quite a good knowledge of Python and I was thinking to use PostGIS to store my data. I had a look at the pgRouting extension of PostGIS and it seems to be the solution I am looking for. Anyway I would like to ask someone more experienced to provide advice on what I need, what I need to know and how to get started.