Migrating from 1.7 to 4.0

This page is for users who would like to migrate their 1.7 driver to 4.0. The following sections serve as a quick look at what have been added and/or changed in 4.0 .NET driver.

What's New

• Upcoming version is now named as 4.0.0 instead of 2.0.0 to better align with server versions.
• Bolt V4.0 is implemented in the 4.0.0 driver.
• Reactive API is available under namespace Neo4j.Driver.Reactive when using together with Neo4j 4.0 databases.
• Multi-databases support is added. Database can be selected for each session on creation with SessionConfig#ForDatabase.
• A new feature detection method IDriver#SupportsMultiDbAsync is added for querying if the remote database supports multi-databases.
• A new IDriver#VerifyConnectivityAsync method is introduced for verify the availability of remote DBMS.

Breaking Changes

• Encrypted is turned off by default. When encryption is explicitly enabled, the default trust mode is to trust the certificates that are trusted by underlying operating system, and hostname verification is enforced by default.
• v1 is removed from drivers' package name. All public APIs are under the namespace Neo4j.Driver instead of the old Neo4j.Driver.V1.
• The Neo4j.Driver package contains only the asynchronous API. Synchronous session API has been moved to the namespace Neo4j.Driver.Simple.
• A new neo4j scheme is added and designed to work with all possible 4.0 server deployments. bolt scheme is still available for explicit direct connections with a single instance and/or a single member in a cluster. For 3.x servers, neo4j replaces bolt+routing.
• Asynchronous methods have been extracted out and put in interfaces prefixed with IAsync, whereas synchronous methods are kept under the old interface but live in package Neo4j.Driver.Simple. This change ensures that blocking and no-blocking APIs can never be mixed together.
• IDriver#Session methods now make use of a session option builder rather than method arguments.
• Bookmark has changed from a string and/or a list of strings to a Bookmark object.
• ITransaction#Success is replaced with ITransaction#Commit. However unlike ITransaction#Success which only marks the transaction to be successful and then waits for ITransaction#Dispose to actually perform the real commit, ITransaction#Commit commits the transaction immediately. Similarly, ITransaction#Failure is replaced with ITransaction#Rollback. A transaction in 4.0 can only be committed OR rolled back once. If a transaction is not committed explicitly using ITransaction#Commit, ITransaction#Dispose will roll back the transaction.
• Statement has been renamed to Query. IStatementResult has been simplified to IResult. Similarly, IStatementResultCursor has been renamed to IResultCursor.
• A result can only be consumed once. A result is consumed if either the query result has been discarded by invoking IResult#Consume and/or the outer scope where the result is created, such as a transaction or a session, has been closed. Attempts to access consumed results will be responded with a ResultConsumedException.
• LoadBalancingStrategy is removed from Config class and the drivers always default to LeastConnectedStrategy.
• The IDriverLogger has been renamed to ILogger.
• TrustStrategy is replaced with TrustManager.