does neo4j embedded driver lock the db files?

Question

I have a general question about the embedded driver for neo4j. What exactly does it mean to be embedded, besides it being lower level and higher performance. Is it an actual instance of the database service or just a driver for connecting to an existing database process or service. For instance

• Does using the embedded driver libraries acquire an exclusive lock on the database files?
• Can multiple clients use the embedded driver to use the same database at the same time?
• Can it run against a database that already has a database service(along with the REST api) running? Initial tests seem to indicate no since it throws a file lock exception.
• Does the embedded driver have to be on the same machine or process as the database service? For instance if the db data files are on a shared SAN that multiple machines can access, and there is another server that is running the REST api and the neo4j service. The configuration on the driver seems to point to the data files directly rather than a service or port.

Answer 1

I am using embedded Neo4j in a project.

Embedded Neo4j is a Neo4j server started and shutdown by your application. So it is not just a driver used to connect to some standalone server. For a standalone server you would use Neo4j over Rest (locally or remotely).

Because of it's implementation embedded neo4j can be used by only one application - the application that started the embedded instance. It retrieves a lock on the graph files, and you can't use any other application (e.g. neo4j-sh) to access those files as long the embedded server is running.