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A C++ implementation of the OpenStreetMap API map call.
C++ Ruby Shell

README.md

CGImap

Overview

CGImap is a C++ implementation of some parts of the OpenStreetMap API as an FCGI process. The rails implementation of the "map" call had a few problems with memory - it uses a lot of it and there is a leak which makes it annoying to use in long-running environments, like the main OSM server.

CGImap attempts to address these memory problems and makes it easier to optimise the queries, something which is also a bit of a pain to do in Rails.

Currently, CGImap implements:

  • the "map" API call,
  • single node, way and relation fetches,
  • multiple node, way and relation fetches and
  • the "full" way and relation calls.

Requirements

CGImap depends on the following libraries. Versions used during development are in brackets. Other versions may work, but YMMV.

  • libxml2 (2.9.1+dfsg1-3ubuntu4.4)
  • libpqxx3 (3.1.1-0ubuntu4)
  • libfcgi (2.4.0-8.1ubuntu5)
  • libboost (1.54.0-4ubuntu3.1)

If you're running a Debian or Ubuntu system these can be installed using the following command:

sudo apt-get install libxml2-dev libpqxx3-dev libfcgi-dev \
  libboost-dev libboost-regex-dev libboost-program-options-dev \
  libboost-date-time-dev libboost-system-dev libmemcached-dev

The build system used is GNU Make, using pkg-config to provide some of the flags.

Note that the full set of packages needed from a fresh install (tested with Ubuntu 14.04.1) - you may already have many or all of these - is:

sudo apt-get install git build-essential automake autoconf

To build the system from scratch, first check out the source code (skip this step if you've already got the source):

git clone git://github.com/zerebubuth/openstreetmap-cgimap.git

Then change to the source code directory to configure and build:

cd openstreetmap-cgimap/
./autogen.sh
./configure --with-fcgi=/usr
make

You should now have a "./map" executable in the current directory.

Setup

A sample lighttpd.conf file is provided, which can be used to test. To test CGImap with lighttpd use the supplied config file with lighttpd and run cgimap on the command line with a command like

./map --port 54321 --backend apidb --dbname openstreetmap

You can then access the running instance at http://localhost:31337/api/0.6/map?bbox=...

The api.osm.org instance runs CGImap as a daemon and Apache with mod_fastcgi_handler. An init.d script to run CGImap as a daemon is supplied in scripts/cgimap.init. To use it modify the paths and environment variables to suit your installation, copy it to /etc/init.d/cgibin and change the mode to 755, and owner:group to root:root.

An example of this can be found in OSM Chef.

Typically you will need to modify the database connection parameters and path to the executable. See ./map --help for a list of options. To convert a command line option to an environment variable append CGIMAP_ to the option and capatalize it. For example, the option --dbname becomes the environment variable CGIMAP_DBNAME.

Fcgi programs can be deployed with Apache using mod_fastcgi_handler, mod_fcgid, mod_fastcgi, and on recent versions mod_proxy_fcgi. A sample Apache configuration file that will work in conjunction with CGImap as a daemon is supplied in scripts/cgibin.conf. To use this on a Ubuntu-based system you need to copy the cofiguration to where Apache will read it and create an api directory:

sudo cp scripts/cgimap.conf /etc/apache2/sites-available/cgimap
sudo chmod 644 /etc/apache2/sites-available/cgimap
sudo chown root:root /etc/apache2/sites-available/cgimap
sudo mkdir /var/www/api
sudo a2ensite cgimap
sudo service apache2 restart

The apache modules mod_proxy and mod_fastcgi_handler must also be enabled.

Database Permissions

The apidb backend requires permissions to SELECT and CREATE TEMPORARY on the Postgres server. For situations where temporary tables cannot be created there is the --readonly option.

The pgsnapshot backend requires permissions to SELECT and CREATE TEMPORARY on the Postgres server, but will not work in situations where temporary tables cannot be created.

In both cases it is recommended that a separate account is created for CGImap to avoid any possibility of data corruption. Care has been taken programming CGImap but, as with most C++ applications, there is the chance of an exploitable flaw leading to complete pwnage.

Testing

To run the test suite using make check you will need additional packages installed:

sudo apt-get install postgresql postgresql-contrib postgis \
  ruby libxml-ruby ruby-pg

And you will need to be able to create databases as your user:

sudo -u postgres createuser -s $USER

Acknowledgements

CGImap contains code from and is partly based on the following:

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