Filter Encoding Standard 1.1 and the curious case of the missing ‘IN’ operator
I was working with the Filter Encoding (FE) 1.1 standard recently and was surprised to find that it did not have an equivalent to the ‘IN’ operator. The FE 1.1 standard currently supports the following comparison operator.
That was a big bummer for me since when I tried to use multiple “PropertyIsEqualTo” comparison operator coupled with the logical “OR” operator the performance was VERY bad. I am using ArcGIS server 9.3 like always.
The OGC support in ArcGIS Server is really great in case your are wondering. ArcGIS Server 9.3 supports the Filter Encoding 1.1, Styled Layer Descriptor 1.0 and other OGC standards as listed here http://www.esri.com/software/standards/standards_tables.html. Support for Styled Layer Descriptor 1.1 is not there yet but may happen in the future versions.
The FE 1.1 standard does include support for the ‘GmlObjectId’ object identifiers way of querying data. This can serve as the ‘IN’ operator if you are querying by the object identifiers. Unfortunately, I wasn’t. The Filter Encoding does include support for ‘Functions’ where custom filters can be supported by the GIS Server. And since, the ‘IN’ comparison operator is missing, it can be implemented as a custom ‘Function’ by GIS Servers to serve clients who desperately that functionality…