*.obf and *.pbf are compressed binary file extensions of OSM data.
I want to open these in GIS software like ArcGIS.
How is the conversion possible?
Is there any automated tool?
A GDAL/OGR driver on reading PBF is currently under development. Active testing is underway. You can use this driver to convert OSM's PBF file to any other vector data supported by GDAL/OGR.
Not entirely a PBF solution, but the original OSM format (*.osm) can be opened by ArcGIS's OSM Editor.
SpatiaLite now supports opening ProtoBuf encoded OSM files (via the new readosm library). You can use that to import the files into SpatiaLite tools and then you can use tools like QGIS to do any work required. See the documentation for SpatiaLite OSM tools for specific details on the import and which tools to use for what purpose.
I tried using GDAL, but this is difficult for non-programmers.
This option is way more efficient and easy: http://wiki.openstreetmap.org/wiki/Osmconvert
You can convert the file to an .osm, which can be opened through the ArcGIS for OSM tool. You get a large file though (file size x 20).