1. To Be Safe For Now: Keep your shapefiles simple
Remove unneeded attributes
“Simplify” spatial data
Pyramids are coming soon
Only allow “info boxes” on points
Allows the user to drag everywhere else

2. Web Development Web development never ends:
Find out what the stakeholders need (sponsors, users, etc.)
Investigate available technology
Plan the project
Build/update the web site
Test functionality in all browsers
Release the site
Monitor and maintain
Go to 1.

3. Technical Issues Keeping a web site available Maintaining a server
Getting “hacked”
Performance problems

4. Bottom Line
If your web site is not available:
You don’t exist!

5. What is a web server? Has a “hard IP”. Runs “web server” software
An IP address that never changes
Runs “web server” software
Typically IIS or Apache
Typically:
Is in a “rack” in a protected space that is:
Is environmentally controlled (air conditioned)
Has “conditioned” power (a UPS)
Has redundant components

6. Maintaining a server You can “rent” space on a server
DropBox offers a “Public” folder
A server costs from $500 to $100,000
Don’t listen to what the manufacturers tell you what you need! Talk to other developers.
It costs $100 to $200 per month to have someone “host” your server.
In theory, you could have a server at your house but it is not recommended

7. Software Keep the server as simple as possible Limit access
Complexity = more failures
Limit access
Do required updates
There are web site that will monitor your server and you if it goes down

8. Getting Hacked Common Types: These can cause: SQL Injection
“Stealing Bandwidth”
Web Server breach
Uploading viruses
Denial of service errors
These can cause:
404 Errors (web page unavaialble)
Web pages being replaced
Getting billed $1000s of dollars!
Information being stolen?

10. SQL Injection In a query string, enter: Can also steal info from DB
“Query; DELETE FROM ‘<table>’”
Deletes the entire contents of the table
Can also steal info from DB
Easy to protect from:
Check for single quotes and replace them with two single quotes
Don’t allow “delete from” in a query
Don’t allow sensitive information in your database

11. Stealing Bandwidth
Someone breaks into your server and puts a bunch of data there. Then, they make you their download site
Causes a massive spike in bandwidth which you have to pay for!
Preventing:
Don’t have FTP sites
Keep web software up to date
Make sure your ISP monitors for them

12. Web Server Breach
An HTML steam that breaks your web server and then takes over your server.
Used to steal band width and corrupt your server’s contents
Preventing:
These are rare and can only be prevented by the web server software provider
Keep web server software up to date

13. Uploading Viruses
User’s upload a file that than runs a program or “sleeps” until users download it to their computer
Allows others to get you to distributed viruses!
Don’t allow “scripts” to be uploaded. This includes:
“xls”, “doc”, “ppt” files!

14. Denial of Server
A web service is written that calls your web site over and over again to “bring it down”.
IIS can crash with these
Preventing:
Don’t attract attention
If you do, get a lot of servers
Block abusive users
Only allow reasonable web service calls

15. Reality Getting hacked today is rare
Twice in last 10 years (never in last 7)
Keep the OS and web software up to date
Don’t let a lot of folks edit the contents of your server
Keep an eye on it
Other problems (like performance) will be bigger.

16. GIS Web Sites GIS web sites “go bad” because of: New issues:
Poor user design
Poor performance
New issues:
Scripting performance
Database performance
Geospatial data access

17. Scripting Performance
Load information on demand
Make sure there is minimal recursion
Functions calling functions, etc.
Loops in loops, etc.
Find the “bottlenecks” and fix them
Evaluate each library carefully and be ready to reject one and replace it

18. Database Performance Don’t use MS-Access Use indexes (search trees)
Use MySQL with small, simple data
Use indexes (search trees)
Minimize string searches
Index if needed
Minimize hierarchical queries
Do performance analysis on key queries and add redundant data if needed
I’m evaluating a “NoSQL” database
MongoDB

19. Geospatial Issues Pixels .vs geographic systems Large datasets:
Pyramids of tiles
Transfer speeds
The Internet is not getting any faster!

20. -180
180 90
Height in
Pixels
-90
Width in Pixels

21. 10,000,000 meters
UTM, Zone 10
6,600,000 meters

22. Pixels
Geospatial Coordinates
0,0
Easting, Northing
Positive X
Positive X
Positive Y
Negative Y

23. Raster Pyramids Problem: Analysis: Solution: Rasters can be huge!
The Internet is slow
Analysis:
Users can only view about 1000 x 1000 pixels at time
Options:
Large area at low resolution
Small area at high resolution
Solution:
Create a “pyramid” of tiles and only transfer the tiles that are needed

24. Raster Pyramid

25. Zoom Level 1
0,0
256,256

26. Zoom Level 2
Columns 1
0,0
Rows 1
512,512

27. Zoom Level 3
Columns 1
0,0
Rows 1
512,512

28. Zoom Level 4
Columns 1
0,0 1
Rows
512,512

29. Zoom Level
Pixel Width
Num Columns
Size (Pixels)
Num Tiles 1
256
65536 2
512
262144 4 3
1024 16
2048 8 64 5
4096 6
8192 32 7
16384
32768
128 9 10
131072 11 12
524288
E+11 13
E+12 14
E+12 15
E+13
E+13 17
1.7E+07
E+14 18
3.4E+07
1.1259E+15 19
6.7E+07
4.5036E+15
Sum:
6.0048E+15

30. Vector Pyramids Vector data is getting larger
Millions of points
Complex, global polygons
Detailed polyline networks (rivers, roads)
CanvasMap now has Vector Pyramids!
But they are really new so expected issues.