1. 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.

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

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

4. 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

5. 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

6. 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

7. 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?

9. 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

10. 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

11. 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

12. 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!

13. 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
Education and only allow reasonable web service calls

14. Reality Getting hacked today is rare
Twice in last 8 years (never in last 6)
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.

15. 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

16. Scripting Performance
Use a “modern” language
Make sure there is minimal recursion
Functions calling functions
Scripts calling scripts
Including files that include the same files
Find the “bottlenecks” and fix them
Don’t use ArcGIS (you’re not allowed to in a server environment anyway).

17. Database Performance Don’t use MS-Access or MySQL
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

18. Geospatial Issues Pixels .vs geographic systems Cartesian vs. tiles
Tiled data
Transfer speeds

19. -180
180 90
Height in
Pixels
-90
Width in Pixels

20. 10,000,000 meters
UTM, Zone 10
6,600,000 meters

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

22. 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

23. Raster Pyramid

24. 0,0
Zoom Level 0
256,256

25. Columns 1
0,0
Zoom Level 1
Rows 1
512,512

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

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

28. 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

29. Vector Pyramids Vector data is getting later
Millions of points
Complex, global polygons
Vector Pyramids are coming
Each tile contains GeoJSON data for that tile