Changes between Version 2 and Version 3 of MapGuideRfc130

Timestamp:

Jan 3, 2013, 2:34:14 AM (11 years ago)

Author:

jng

Comment:

--

MapGuideRfc130

@@ -9 +9 @@
 ||RFC Template Version||(1.0)||
 ||Submission Date||18 Dec 2012||
-||Last Modified||||
+||Last Modified||3 Jan 2013||
 ||Author||Jackie Ng||
 ||RFC Status||draft||
@@ -24 +24 @@
 == Overview ==
 
-This RFC proposes to add support for streaming feature/aggregate/SQL query results over the HTTP mapagent.
+This RFC proposes to add support for streaming feature/aggregate/SQL query results over the HTTP mapagent in a memory-efficient manner.
 
 == Motivation ==
@@ -35 +35 @@
  * JSON: 1.5GB (!!!)
 
-And this is just for one request. If we want MapGuide to be a useful '''data''' platform, one that can support [http://osgeo-org.1560.n6.nabble.com/OpenLayers-SVG-MapGuide-Vector-Viewer-td4210812.html a theoretical map viewer that does full client-side rendering], our methods of querying data from it must be efficient. What we currently have in place is not acceptable.
+And this is just for one request. If we want MapGuide to be a useful '''data''' platform, one that can support [http://osgeo-org.1560.n6.nabble.com/OpenLayers-SVG-MapGuide-Vector-Viewer-td4210812.html a theoretical map viewer that does full client-side rendering], our methods of querying data from it must be efficient in both performance '''and memory use'''. What we currently have in place is not acceptable.
 
 == Proposed Solution ==
@@ -132 +132 @@
 }}}
 
-The proxy versions of these readers (MgProxyFeatureReader/MgProxyDataReader/MgProxySqlDataReader) provides implementations of these methods to return the various XML fragments that compose the default XML response. 
+The proxy versions of these readers (MgProxyFeatureReader/MgProxyDataReader/MgProxySqlDataReader) provides implementations of these methods to return the various XML fragments that compose the default XML response. Server implementations will never have these methods called, so they will throw an exception if invoked.
 
 To explain what these new internal APIs are supposed to do, here's the current implementation of MgProxyDataReader::ToXml()
@@ -273 +273 @@
  * WFS GetFeature responses
 
-KML rendering internally buffers KML content at the Renderer/Stylization level. To facilitate true '''streamed''' KML content would require refactoring of the KmlRenderer and/or the Rendering/Stylization architecture. Supporting streamed KML responses would have to be the scope of another separate RFC.
-
-WFS GetFeature responses is handled by MapGuide's OGC templating engine. This templating engine suffers from the same problem of internally buffering the full WFS GetFeature response up-front. What's worse is that this internal buffering is backed by the MgByte class that has a hard-coded limit of 64MB. Although rare, WFS queries that result in over 64MB of buffered data will be truncated (see #1070). Supporting streamed WFS GetFeature responses is a monumental task in itself due to the design and use of the templating engine and would have to be the scope of a separate RFC.
+KML rendering internally buffers KML content at the Renderer/Stylization level. To facilitate true '''streamed''' KML content would require refactoring of the KmlRenderer and/or the Rendering/Stylization architecture. Supporting streamed KML responses would have to be the scope of another separate RFC if we want to go down this path.
+
+WFS GetFeature responses is handled by MapGuide's OGC templating engine. This templating engine suffers from the same problem of internally buffering the full WFS GetFeature response up-front. What's worse is that this internal buffering is backed by the MgByte class that has a hard-coded limit of 64MB. Although rare, WFS queries that result in over 64MB of buffered data will be truncated (see #1070). Supporting streamed WFS GetFeature responses is a monumental task in itself due to the design and use of the templating engine and would have to be the scope of a separate RFC if we ever want to go down this path.
 
 == Test Plan ==
 
-Exercise the affected operations against the Apache/ISAPI/CGI agents. Verify the XML/JSON content is the same for all 3 agents and is the matches the content as it was before this RFC.
+Exercise the affected operations against the Apache/ISAPI/CGI agents. Verify the XML/JSON content is the same for all 3 agents and matches the content as it was before this RFC.
 
 == Funding / Resources ==