Add some information about how/why this dissector is (partially) machine-generated and what that means to Wireshark maintainers.

svn path=/trunk/; revision=32577

1 files changed, 33 insertions, 2 deletions

diff --git a/plugins/opcua/README b/plugins/opcua/README
index df58cd5108..07068d77d0 100644
--- a/plugins/opcua/README
+++ b/plugins/opcua/README
@@ -50,6 +50,37 @@ For more information see http://www.opcfoundation.org
 Known limitations:
 ==================
 
-* Only the security policy http://opcfoundation.org/UA/SecurityPolicy#None is supported,
-  which means the encryption and signing is turned off.
+* Only the security policy http://opcfoundation.org/UA/SecurityPolicy#None is
+  supported, which means the encryption and signing is turned off.
   
+Machine-generated dissector:
+============================
+Parts of the OpcUa dissector are machine generated.  Several of the files are
+marked "DON'T MODIFY THIS FILE!" for this reason.
+
+However, the code to create this dissector is not part of the Wireshark source
+source code distribution.  This was discussed prior to the plugin's inclusion.
+From http://www.wireshark.org/lists/wireshark-dev/200704/msg00025.html :
+
+~~~
+> a lot of the code seems to be autogenerated (as the comments suggest)
+> It might make sense to include the sources and the build process instead 
+> of the intermediate files (if the amount of code/tools to build the 
+> files seems reasonable). The reason: When people start to hack your code 
+> (e.g. to remove warnings on a compiler you don't even think about), 
+> you'll might get into annoying trouble with merging code the next time 
+> you've update the upcua files.
+>
+>   
+I'm sorry, but I cannot give you the sources of the code generator,
+because they are owned by the OPC Foundation.
+I only extended the existing code generator to produce also wireshark code.
+It's .Net based so I guess you don't want to have it anyway ;-)
+~~~
+
+So, if changes must be made to the machine-generated files, it just means the
+upstream source will have to be modified before pushing any updates back to
+Wireshark.
+
+Of course it also means that care must be taken when applying patches from
+upstream to ensure local changes aren't reversed.