I am new with neo4j, i will use the community version.
I want to know how can i request the database within a java application, i don't want to create nodes/relationships (the database is created in another project ) but i want to connect to the db and add a label for a node (my graph represents a VM's and their relationships, when there is a problem with a VM, i want to add a label for example :alert for this node which implicate changing the color + size of this node).
How can i do this? Is there several manner to do it?
you could integrate the official neo4j java bolt driver in your project. (Get started - Neo4j Driver Manual)
When you have this driver and can create a session you could simply write a query that matches the node you'd like to update based on an id (for performance reasons you should index that id) and then set the label on the node
HashMap<String, Object> params = new HashMap<>();
params.put('id', some_id)
session.run("MATCH (vm:VM {id:$id}) SET vm:ALERT",params)"
The code above shows how you could go about this, putting the id in the run parameters allows for query caching and speedup. Here i construct a java map with the arguments and then run the query with the map added. For additional information look towards to documentation.