[mkgmap-dev] Binary OSM file support?From Scott Crosby scrosby at cs.rice.edu on Mon Sep 13 17:55:00 BST 2010
On Mon, Sep 13, 2010 at 6:06 AM, Steve Ratcliffe <steve at parabola.me.uk> wrote: > Hi Scott > > I am adding support for your binary format to mkgmap itself (not the > splitter). Excellent! Thank you. > > Now I've done enough refactoring of the XML reader to allow me to > start I have a few questions. > > 1. Is there an final name for the format and the jar file? Not yet. There are too many 'osm binary formats'. I asked for suggestions on osm-dev yesterday and got 'protobuf binary format'. Do you have any ideas? > > 2. Is there an 'offical' download location for a pre-built jar file? > No. > 3. How do I recognise a file in your format. Is there a conventional > file extension for it? Those are good questions; I wish someone had asked them earlier. I have not put in error checking to detect illegal/wrong inputs. I have fixes in my local tree that throw exceptions on very ill-formed inputs. They will be out in my next RC. I have not thought about how one might detect the format. How important is this? For now, try feeding the data to the parser and see if there is an exception? I can add a more robust check with magic at the start of the file, but I won't have time to implement it for a while. I designed a concatenable and streamable format. Magic at the start of a file needs to also be a legal fileblock. I can specify and define such a magic, as the static serialized contents of a '__Magic' fileblock but implementing this may take a little while. I have used *.bin as an extension, but I am open to suggestions. > Are the OSMHeader and OSMData blocks required file block types? > I am not sure what you are asking, but yes, both are required. OSMHeader contains HeaderBlock::required_features, which must be examined to confirm that your implementation can parse the file. You may also want the contents of HeaderBlock::bbox. > 4. Does the osmosis conversion from XML to binary keep the order of > the elements the same as they were in the XML file? Yes. Absolutely. Scott
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