[Geomoose-users] unifying select.php, query.php and identify.php

[Andrew Sheppard]

Hi all,

I would like to propose unifying some common features in select, query, and identify into a shared module to facilitate feature re-use and simplify maintenance.  For example, identify could benefit from the highlighting provided in select, and query could benefit from select's buffering and (potential) vector interaction capabilities*.  This refactoring will also simplify any long-term transition to another scripting language (e.g. Python.)

At some point, the entire service workflow could be abstracted into a fully generalized "Service" class.  However, for now I am only interested in unifying the output loop in each of the three services - leaving the input parsing and query processing unique to each service.  In spite of the similarities, each of the services has a slightly different way of producing output:

*identify* produces a list of results and centroid coordinates.  No geometries are provided for highlighting or buffering.

*query* produces a list of results with full feature coordinates for zooming, as well as an on-the-fly geometry layer for highlighting results.  The layer is not saved on the server, to avoid filling up the disk with large query result sets.  This means buffering is not readily available.

*select* produces a list of results, and a semi-persistent geometry layer that can be used by the server for follow-up requests (e.g. buffering).  As I mentioned previously, it was relatively straightforward to add WFS support to this layer to support full vector interactivity on the client.

I would like to move the output routines from query and select into a separate "output.php", so that all three services can take advantage of one of two output modes:
 - a query-style in-memory highlight layer, or
 - a select-style semi-permanent layer with support for buffering and vector interaction

Are there any important caveats I should keep in mind?

(* See http://osgeo-org.1560.n6.nabble.com/Geomoose-users-utilize-wfs-for-select-service-tt4984390.html)

S. Andrew Sheppard
GIS/Web Developer
Houston Engineering, Inc.