MapGuide RFC 38 - GETDYNAMICMAPOVERLAYIMAGE Enhancements for Selection

This page contains an change request (RFC) for the MapGuide Open Source project. More MapGuide RFCs can be found on the RFCs page.

Status

RFC Template Version	(1.0)
Submission Date	Oct 2 15:40:00 2007
Last Modified	Trevor Wekel Timestamp
Author	Trevor Wekel
RFC Status	draft
Implementation Status	pending
Proposed Milestone	2.0
Assigned PSC guide(s)
Voting History	Oct 9, 2007
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Overview

Enhance the GETDYNAMICMAPOVERLAYIMAGE HTTP API to allow the selection and overlay images to be rendered as separate images.

Motivation

Currently, MapGuide renders the selection and the overlay image as a single image. This requires all untiled layers to be redrawn whenever the selection is changed. This is an inefficient use of server-side rendering resources and it reduces multi-user performance for untiled maps.

Proposed Solution

Add an additional parameter BEHAVIOR to the existing GETDYNAMICMAPOVERLAYIMAGE. Increase the VERSION to 2.0.0 and deprecate the existing KEEPSELECTION parameter for the new version of the API. BEHAVIOR is a bitmask with the following values:

  RenderSelection = 1
  RenderLayers = 2
  KeepSelection = 4

Add an additional signature for MgRenderingService.RenderDynamicMapOverlay that includes the behavior parameter:

  MgByteReader* RenderDynamicOverlay(MgMap* map, MgSelection* selection, CREFSTRING format, INT32 behavior);

Update the existing WebLayout based ajax viewer to use the new API while maintaining the existing functionality. A new "selection" layer will not be added to the WebLayout based viewer.

Implications

Since this is a new version of the HTTP request and a new signature for RenderDynamicMapOverlay, compatibility with existing clients/scripts is maintained. The behavior parameter encapsulates the current "keepSelection" functionality so the existing RenderDynamicOverlay methods could be deprecated in a future release.

Test Plan

Ensure that existing clients continue to function as expected. Verify that the new HTTP API renders only the selection or layers, or both depending on the behavior setting.

Funding/Resources

Autodesk will provide resources to implement the enhanced HTTP request. Time permitting, DM Solutions will update the new "Fusion" based viewer to include a new "selection" layer.