Increasing Maxlayers limit - anyone have spare Windows binaries? :)

[Bonnie Stewart]

Hi all,
 
I'm working on a way to make a large amount of our vector and raster data available via WMS and WFS, and I've come up against the MAXLAYERS setting (200 in our install I think).
 
I'm already trying to get around the need for having so many layers in a single mapfile by reducing the granularity available as you get to mapfiles which cover a larger time period - let me see if I can explain what I mean without rambling on too much.
 
At the lowest level of granularity, we're providing access to raster and vector files which are derived from satellite passes - and there may be 10-40 passes per day, depending on the product. I've already set up a process to automatically generate a mapfile containing the last 5 days worth of data, using the GROUP parameter to group them according to the day. This is jolly nifty for those customers who need to look at the recent info on a pass by pass basis.
 
However, if I try to give people access to the entire archive (several years worth, and 10-15 different products, at 10-40 passes per day) on a pass by pass basis, the number of layers involved will be horrendous, so I'm trying to reduce the granularity at which archival data is available.
 
My current plan is to (programmatically) create a series of weekly mapfiles, structured in the same way as mentioned above, with individual satellite passes grouped by day. I would have 52 of those for each year, and then to wrap them up so that people could have an overview of what's available, I'm planning to create some mapfiles (either yearly or monthly, maybe both), which connect to these weekly mapfiles via WMS, and pull in each daily group from the 52 weekly mapfiles, and define them as a single layer.
 
So I think I would end up with a mapfile for each year, with a group for each week, and under each group, 7 individual layers - one for each day. Hopefully then there are two options:
1) People's clients are able to pull apart the vector data, and maybe do a query (for instance) to only display the lightning data from one particular satellite pass - although having used ArcMap and ArcExplorer for testing I'm not too hopeful about this;
2) Specific file naming conventions could allow users to find the week they're interested in in the yearly mapfile, and then work out what the mapfile name/URL for that week's lower level mapfile would be.
 
So, now I'm finally going to get to my point - even using this structure, a MAXLAYERS setting of 200 is too low for me - I can do about 5 or 6 days of satellite passes in 200 layers, but to get to a whole week I would need to increase the MAXLAYERS parameter. To have a layer for each day in my yearly mapfile, I'd need a MAXLAYERS of around 370.
 
I gather it's relatively easy to change the parameter and recompile Mapserver, but as I have very little experience in this area (and I've seen so many emails on this list seeking help with compiling mapserver!) I was hoping somebody might possibly have already done this, and might have Windows binaries compiled with a higher MAXLAYERS that they would be willing to share.
 
Alternatively, if the structure I described above sounds silly or you can think of something more effective, please let me know :) We do have another approach in mind for the vector data, which is to produce an ongoing concatenated shapefile which contains all the features for that product (for instance, as a new pass's worth of lightning data becomes available, it is automatically added in to one big Lightning shapefile), and then to use classes to colour them up a bit according to the time that each event occurred. It's a nice theory for the vector info, but I'd still need to do something about the raster info.
 
 
Any advice (or binaries!) would be very much appreciated :)
 
 
Thanks,
 
 
Bonnie
 
__________________________________
Bonnie Stewart
Research Officer
Satellite Remote Sensing Services
Information Access Division
Department of Land Information
65 Brockway Road, FLOREAT WA 6014
Ph. (08) 9387 0342 | Fx. (08) 9383 7142
bonnie.stewart at dli.wa.gov.au
www.dli.wa.gov.au


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