Case Studies

The case is that we have tables with GB's of data. This tables are updated regularly by different users and applications. Mapserver is used for WMS and is connected to Oracle.

We can not change all the applications to use postgresSQL and we can not except all user's to switch from Oracle to postgresSQL overnight.

One place to start would be to use mapserver against Postgis. To do this we only need to make a copy of the data from Oracle to PostgreSQL. The Oracle database will master and PostgreSQL the slave.

In some cases it's easy to copy data from Oracle to PostgreSQL. For instance if we have small tables and non frequent changes.

But it this case we have big tables (More 10 GB and millions of rows pr table) and some of them changes many times a week.

In our case we need a simple program that can find all the differences and transfer this changes to PostgresSQL while both databases are in use.

We have made such program that handles this case. We want describe the algorithm behind this program and the code.

Key words here are :

• Split in small chunks by using grids.
• Keep track of neighbors
• Remove all equals rows from work mem.
• Push update, delete and read in single SQL transaction using Hibernate Spatial.

Various software can style maps and generate a proper SLD document for OGC compliant WMS like GeoServer to use. However, in most occasions, the styling allowed by the graphical tools is pretty limited and not good enough to achieve good looking, readable and efficient cartographic output.

The presentation aims to provide the attendees with enough information to master SLD documents allowing him to produce amazingly looking maps on his own. SLD will no longer be cartographer's enemy.

Topics that will be covered are as follows:

• making scales that show different data at different scales, and that change its cartographic rendering as well, by means of multi scale rules
• using GeoServer extensions to build common hatch patterns and how to control the patterns appears using advanced stroke control over the basic marks
• line styling beyond the basics, such as cased lines, repeating symbols and hatch patterns
• leveraging TTF symbol fonts and SVGs to generate good looking point thematic maps, line and fill patterns
• use the full power of GeoServer label lay-outing tools to build pleasant, informative maps on both point, polygon and line layers, including adding road plates to your map
• leverage the labelling subsystem conflict resolution engine to avoid overlaps in stand alone point symbology
• blending charts into a map
• dynamically transform data during rendering to get more explicative maps without the need to pre-process a large amount of views, such as on the fly extraction of contours, range polygons and wind maps from raster data
• perform cross layer filtering and parametrize it to generate a generic “paint all points of interest close to the main road” style in which the client can dynamically change the distance.