When building geospatial editing web applications one needs to plan, or don't, for the fact that two people may edit SDE data at the same time. If you aren't and your application isn't used frequently then it is probably not an issue, yet. But you may start to see this error and not know what to do.

The version has been redefined to reference a new database state. [sde.DEFAULT] What happens is more than one edit session starts and one finishes before the rest. This redefines the SDE states table which causes the subsequent save edit operations to fail.  

Our strategy was to put the editing operation in a do while loop. Basically, do the edit operation while SDE did not kick out a version mismatch error. In the code we check if the version has been redefined, if it has refresh it and try again.

A possible better approach would be to create a unique version per edit operation and reconcile that version or lock the thread that has started the edit operation and queue subsequent requests until the lock has been removed.

What are your strategies for overcoming database concurrency?

This VBA script is designed to derive the location for mileposts routes in a polylineM feature class that has already been created.

In addition to an x and y coordinate, a polylineM routes contain a measure (m) coordinate with the milepost coordinate for every vertex. In some cases, information exists to calibrate the route at endpoints but the locations for mileposts are unknown.

The code works for single and multipart route features. It interates through the routes and writes a record to an output .csv file for each milepost expected along the parts that make up a route. If a route starts at 0 goes to 3.777 then records will be created for 0,1,2 abd 3 mileposts. X and Y coordinates are also written for each route-milepost record.

The next step is easy. Add the resulting .csv file to ArcMap, right click on it and select the 'Display XY Data' context menu item.

A set of milepost approximate locations has been created for Utah and they are now loaded into an SGID layer named SGID93.TRANSPORTATION.UDOTMilepost_Approx.

A recent Government Technology magazine article (Gov 2.0 Summit: GIS the Big Winner in Push for Open Government) discusses the role of GIS can play as part of open government directives being considered at many levels of government.

According to Government Technology editor Tod Newcombe, GIS is the key component in that effort, and thus, the winner.

"The math is simple. According to the U.S. Office of Management and Budget's Federal Enterprise Architecture framework, 74 percent of government data is location based. At the state and local level, the number is even higher: 80 percent, according to several organizations and publications".

The article goes on to discuss  an important role that govenment can take on with repect to technology platforms and the benefits that can be realized in both sectors with public-private partnership:

"The summit's program co-chair, Tim O'Reilly, founder and CEO of O'Reilly Media Inc., gives two major reasons why government must be viewed as a platform: The public sector built two of the most important digital infrastructures: the Internet and GPS. "The government built these platforms and the private sector ran with them," he concluded. Just as important is the fact that government has also become a major beneficiary of both platforms." 

Mike Mahaffie, NSGIC's state representative from Delaware writes on the NSGIC blog that,

"Recognition of the importance of GIS in Government 2.0 is great; but it's up to us as GIS practitioners, to make sure that the work we do meets the needs of an open policy."

Regsitered users of the Utah GIS Portal site can now elect to join the mailing list for the Utah Valley GIS Users Group.

To join the list:

1. login to the portal using the Login panel on the left side of the site's main page
2. Click on Your User Page
3. Click on the Edit button on your user page and select update Profile
4. Click the Interests tab, look for Coordination Interests and check the box for Local User Group - Utah Valley
5. Click Update at the bottom of the page