[OpenLayers-Dev] Making BBOX strategy smarter - part2

Ivan Grcic ivan.grcic at geofoto.hr
Wed Nov 12 17:20:00 EST 2008

This post continues on previous discussion opened under name "bbox
strategy and zooming"

OK, I made a little mess here :) Im pretty new with this, so I still
dont know really well how things function.

> Tim says
> Keep in mind that the cluster strategy doesn't know anything about bbox, and vice-versa.
So what  bbox does, is fetching the data, and cluster is then, well
clustering that data? (without getting any new data, cuz thats bbox'es
So on layer pan/zoom, first bbox is activated to fetch, and then
cluster to process. Did i get it right?

Well knowing that, then thers not so much to say about Cluster
strategy. Its allready doing its job pretty well.

Its only about making bbox more efficient, cuz of reasons that
Tim/Christopher said:

Tim said:
> I want to have maxfeatures, and more aggressive invalidation because of it.

Christopher said (thats my case btw)
> Someone else might have a specific need to make the strategy more
> aggressive because the server returns more detailed data based on the
> extent of the request (I don't know, just making things up here).

I would also say that bbox should be more efficient to serve cluster
strategy better, by giving it less number of features to process.
Because, its not only important how many features will cluster render,
but also how many of them it has to calculate with.
(we can only have 10 points on our screen, but if they represent few
hundred features, it will take some time to process them, so its
crucial to keep that number as small as possible)

Its all about what Tim said before:

>The bbox strategy is about determining when the
>previous data bounds become invalid, determining which existing features
>no longer belong on the layer, and deciding how to handle the results of
>a new request (based on a previous response).

...and how to implement that... well I think you guys will  have more
ideas about it.

I hope that the sitation is more clear now :)

Ivan Grcic

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