Fixes #558: Check for neo4j version being compatible with neo version

core/src/main/java/apoc/RegisterComponentFactory.java

@@ -1,6 +1,6 @@
 package apoc;
 
-import apoc.trigger.TriggerHandler;
+import org.neo4j.annotations.service.ServiceProvider;
 import org.neo4j.kernel.api.procedure.GlobalProcedures;
 import org.neo4j.kernel.extension.ExtensionFactory;
 import org.neo4j.kernel.extension.ExtensionType;
@@ -17,14 +17,14 @@
 /**
  * NOTE: this is a GLOBAL component, so only once per DBMS
  */
+@ServiceProvider
 public class RegisterComponentFactory extends ExtensionFactory<RegisterComponentFactory.Dependencies> {
 
     private Log log;
     private GlobalProcedures globalProceduresRegistry;
 
     public RegisterComponentFactory() {
-        super(ExtensionType.GLOBAL,
-                "ApocRegisterComponent");
+        super(ExtensionType.GLOBAL, "ApocRegisterComponent");
     }
 
     @Override

core/src/main/java/apoc/cypher/CypherInitializer.java

@@ -2,8 +2,10 @@
 
 import apoc.ApocConfig;
 import apoc.util.Util;
+import apoc.version.Version;
 import org.apache.commons.configuration2.Configuration;
 import org.neo4j.common.DependencyResolver;
+import org.neo4j.configuration.Config;
 import org.neo4j.configuration.GraphDatabaseSettings;
 import org.neo4j.internal.helpers.collection.Iterators;
 import org.neo4j.kernel.api.procedure.GlobalProcedures;
@@ -15,6 +17,7 @@
 import java.util.Collections;
 
 import java.util.ConcurrentModificationException;
+import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
 
@@ -24,6 +27,7 @@ public class CypherInitializer implements AvailabilityListener {
     private final Log userLog;
     private final GlobalProcedures procs;
     private final DependencyResolver dependencyResolver;
+    private final String defaultDb;
 
     /**
      * indicates the status of the initializer, to be used for tests to ensure initializer operations are already done
@@ -35,6 +39,7 @@ public CypherInitializer(GraphDatabaseAPI db, Log userLog) {
         this.userLog = userLog;
         this.dependencyResolver = db.getDependencyResolver();
         this.procs = dependencyResolver.resolveDependency(GlobalProcedures.class);
+        this.defaultDb = dependencyResolver.resolveDependency(Config.class).get(GraphDatabaseSettings.default_database);
     }
 
     public boolean isFinished() {
@@ -57,6 +62,17 @@ public void available() {
                 if (!isSystemDatabase) {
                     awaitApocProceduresRegistered();
                 }
+
+                if (defaultDb.equals(db.databaseName())) {
+                    final List<String> versions = db.executeTransactionally("CALL dbms.components", Collections.emptyMap(),
+                            r -> (List<String>) r.next().get("versions"));
+                    final String apocFullVersion = Version.class.getPackage().getImplementationVersion();
+                    if (isVersionDifferent(versions, apocFullVersion)) {
+                        userLog.warn("The apoc version (%s) and the Neo4j DBMS versions %s are incompatible. \n" +
+                                        "See the compatibility matrix in https://neo4j.com/labs/apoc/4.4/installation/ to see the correct version",
+                                apocFullVersion, versions.toString());
+                    }
+                }
                 Configuration config = dependencyResolver.resolveDependency(ApocConfig.class).getConfig();
 
                 for (String query : collectInitializers(isSystemDatabase, config)) {
@@ -75,6 +91,11 @@ public void available() {
         }).start();
     }
 
+    // only for testing purpose
+    public static boolean isVersionDifferent(List<String> versions, String apocFullVersion) {
+        return versions.stream().noneMatch(apocFullVersion::startsWith);
+    }
+
     private Collection<String> collectInitializers(boolean isSystemDatabase, Configuration config) {
         Map<String, String> initializers = new TreeMap<>();
 

core/src/test/java/apoc/cypher/CypherIsVersionDifferentTest.java

@@ -0,0 +1,20 @@
+package apoc.cypher;
+
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class CypherIsVersionDifferentTest {
+
+    @Test
+    public void shouldReturnFalseOnlyWithCompatibleVersion() {
+        assertTrue(CypherInitializer.isVersionDifferent(List.of("3.5"), "4.4.0.2"));
+        assertTrue(CypherInitializer.isVersionDifferent(List.of("5_0"), "4.4.0.2"));
+
+        // we expect that APOC versioning is always consistent to Neo4j versioning
+        assertFalse(CypherInitializer.isVersionDifferent(List.of("5_0"), "5_0_0_1"));
+    }
+}

docs/asciidoc/modules/ROOT/pages/installation/index.adoc

@@ -58,6 +58,12 @@ The version compatibility matrix explains the mapping between Neo4j and APOC ver
 
 // end::version-matrix[]
 
+If by mistake a jar not compatible with the neo4j version is inserted, a `log.warn` like this will appear in `neo4j.log`:
+```
+The apoc version (<APOC_VERSION>) and the Neo4j DBMS versions [NEO4J_VERSION] are incompatible. 
+See the compatibility matrix in https://neo4j.com/labs/apoc/4.4/installation/ to see the correct version
+```
+
 [[docker]]
 == Docker