This post describes a series of Python scripts to convert FGDC XML metadata for WMS and WFS services to ISO 19139 service metadata via GeoNetwork's OGC harvest service. Here are the steps:

1. Extract WMS and WFS GetCapabilities URLs from FGDC XML metadata and write them to a file.
2. Create a GeoNetwork Harvest Node from extracted GetCapabilities URLs and let GeoNetwork's OGC WMS/WFS harvester create ISO 19139 metadata from GetCapabilities response. Note: the resulting ISO 19139 metadata is only as good as the one in the GetCapabilities response. In addition, GetCapabilities responses do not include all fields necessary for minimum ISO 19139 metadata.
3. Copy some FGDC metadata entries (Title, Abstract, etc.) to newly created ISO 19139 metadata.

Our goal is to have working WMS and WFS metadata records in our CSW catalog that can be used to add the described services to analytical software such as ESRI's C-SW Client for ArcGIS Desktop. Following are the reasons why I am currently choosing this convoluted process instead of a direct FGDC to ISO 19139 metadata conversion:

Files: 

MultipartPostHandler.py_.txt

Following are authoritative FGDC Content Standard for Digital Geospatial Metadata (CSDGM) XML schema document (XSD) and document type definition (DTD) URLs for FGDC-STD-001-1998. These documents are used to validate a FGDC XML metadata file.

• http://www.fgdc.gov/metadata/fgdc-std-001-1998.dtd - Usage:
  

  <?xml version="1.0" encoding="ISO-8859-1"?>
  <!DOCTYPE metadata SYSTEM "http://www.fgdc.gov/metadata/fgdc-std-001-1998.dtd">

• http://www.fgdc.gov/metadata/fgdc-std-001-1998.xsd - Usage:
  

  <metadata 
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
       xsi:noNamespaceSchemaLocation="http://www.fgdc.gov/metadata/fgdc-std-001-1998.xsd">

There are also annotated and modified FGDC-STD-001-1998 schema available for download:

I am working on transforming FGDC XML metadata records to the USGIN 1.1 version of ISO 19139 metadata and having a hard time finding formal FGDC schema, name spaces, and schema locations. This is what I found so far: