# Revision history [back]

The map_server simply allows you to read a map or create a new one.

• It publishes only one time the map you ask him to. You can check by yourself using rosrun map_server map_server your_map.yaml, you will see that the map_server reads the informations of the map and publishes on the topics /map and /map_metadata only one time.
• The map isn't stored by the map_server, it reads a map file. You can store a map when creating one (with gmapping for example) you can save it to yaml and a pgm files using map_saver. In this case, instead of publishing on the /map topic it subscribes to it. But if you don't use map_saver, nothing will be stored.
• The map isn't updated. You create one when using map_saver but it will only listen to the topic /map once to generate the map files and then the node ends itself.
• Cf previous answer : Yes, if you run rosrun map_serer map_saver multiple times.
• Unless you directly change the pgm file the map isn't updated.

• It publishes only one time the map you ask him to. You can check by yourself using rosrun map_server map_server your_map.yaml, you will see that the map_server reads the informations of the map and publishes on the topics /map and /map_metadata only one time.
• The map isn't stored by the map_server, it reads a map file. You can store a map when creating one (with gmapping for example) you can save it to yaml and a pgm files using map_saver. In this case, instead of publishing on the /map topic it subscribes to it. But if you don't use map_saver, nothing will be stored.
• The map isn't updated. You create one when using map_saver but it will only listen to the topic /map once to generate the map files and then the node ends itself.
• Cf previous answer : Yes, if you run rosrun map_serer map_saver multiple times.
• Unless you directly change the pgm file the map isn't updated.