BREAKING CHANGE(server): disable legacy backends include MySQL/PG/c*(.etc)

.github/workflows/server-ci.yml

@@ -27,7 +27,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        BACKEND: [ memory, rocksdb, hbase, cassandra, mysql, postgresql, scylladb ]
+        BACKEND: [ memory, rocksdb, hbase ]
         JAVA_VERSION: [ '11' ]
 
     steps:

README.md

@@ -26,8 +26,9 @@ achieved through the powerful [Gremlin](https://tinkerpop.apache.org/gremlin.htm
 - Compliant to [Apache TinkerPop 3](https://tinkerpop.apache.org/), supports [Gremlin](https://tinkerpop.apache.org/gremlin.html) & [Cypher](https://en.wikipedia.org/wiki/Cypher) language
 - Schema Metadata Management, including VertexLabel, EdgeLabel, PropertyKey and IndexLabel
 - Multi-type Indexes, supporting exact query, range query and complex conditions combination query
-- Plug-in Backend Store Driver Framework, support `RocksDB`/`HStore`, `HBase`, `Cassandra/ScyllaDB`, and `MySQL/Postgre` now and easy to add another backend store driver if needed
+- Plug-in Backend Store Framework, mainly support `RocksDB`/`HStore` + `HBase` for now and you could choose other backends in the [legacy version](https://hugegraph.apache.org/docs/download/download/) ≤ `1.5.0` (like `MySQL/PG`/`Cassandra` ...)
 - Integration with `Flink/Spark/HDFS`, and friendly to connect other big data platforms
+- Complete graph ecosystem (including both in/out-memory `Graph Computing` + `Graph Visualization & Tools` + `Graph Learning & AI`, see [here](#3-build-from-source))
 
 
 ## Quick Start

hugegraph-cluster-test/hugegraph-clustertest-dist/src/assembly/static/conf/hugegraph.properties.template

@@ -39,6 +39,7 @@ edge.cache_type=l2
 backend=hstore
 serializer=binary
 
+# graph name
 store=hugegraph
 
 # pd config
@@ -50,48 +51,16 @@ task.schedule_period=10
 task.retry=0
 task.wait_timeout=10
 
-# raft config
-raft.mode=false
-raft.path=./raft-log
-raft.safe_read=true
-raft.use_replicator_pipeline=true
-raft.election_timeout=10000
-raft.snapshot_interval=3600
-raft.backend_threads=48
-raft.read_index_threads=8
-raft.snapshot_threads=4
-raft.snapshot_parallel_compress=false
-raft.snapshot_compress_threads=4
-raft.snapshot_decompress_threads=4
-raft.read_strategy=ReadOnlyLeaseBased
-raft.queue_size=16384
-raft.queue_publish_timeout=60
-raft.apply_batch=1
-raft.rpc_threads=80
-raft.rpc_connect_timeout=5000
-raft.rpc_timeout=60
-raft.install_snapshot_rpc_timeout=36000
-
 # search config
 search.text_analyzer=jieba
 search.text_analyzer_mode=INDEX
 
-# rocksdb backend config
+### RocksDB backend config
 #rocksdb.data_path=/path/to/disk
 #rocksdb.wal_path=/path/to/disk
 
 
-# cassandra backend config
-cassandra.host=localhost
-cassandra.port=9042
-cassandra.username=
-cassandra.password=
-#cassandra.connect_timeout=5
-#cassandra.read_timeout=20
-#cassandra.keyspace.strategy=SimpleStrategy
-#cassandra.keyspace.replication=3
-
-# hbase backend config
+### HBase backend config
 #hbase.hosts=localhost
 #hbase.port=2181
 #hbase.znode_parent=/hbase
@@ -102,25 +71,3 @@ cassandra.password=
 #hbase.enable_partition=true
 #hbase.vertex_partitions=10
 #hbase.edge_partitions=30
-
-# mysql backend config
-#jdbc.driver=com.mysql.jdbc.Driver
-#jdbc.url=jdbc:mysql://127.0.0.1:3306
-#jdbc.username=root
-#jdbc.password=
-#jdbc.reconnect_max_times=3
-#jdbc.reconnect_interval=3
-#jdbc.ssl_mode=false
-
-# postgresql & cockroachdb backend config
-#jdbc.driver=org.postgresql.Driver
-#jdbc.url=jdbc:postgresql://localhost:5432/
-#jdbc.username=postgres
-#jdbc.password=
-#jdbc.postgresql.connect_database=template1
-
-# palo backend config
-#palo.host=127.0.0.1
-#palo.poll_interval=10
-#palo.temp_dir=./palo-data
-#palo.file_limit_size=32

hugegraph-server/README.md

@@ -8,4 +8,4 @@ HugeGraph Server consists of two layers of functionality: the graph engine layer
   - Backend Interface: Implements the storage of graph data to the backend.
 
 - Storage Layer:
-  - Storage Backend: Supports multiple built-in storage backends (RocksDB/MySQL/HBase/...) and allows users to extend custom backends without modifying the existing source code.
+  - Storage Backend: Supports multiple built-in storage backends (RocksDB/Memory/HStore/HBase/...) and allows users to extend custom backends without modifying the existing source code.

hugegraph-server/hugegraph-core/src/main/java/org/apache/hugegraph/backend/store/BackendProviderFactory.java

@@ -17,6 +17,7 @@
 
 package org.apache.hugegraph.backend.store;
 
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
@@ -26,14 +27,24 @@
 import org.apache.hugegraph.backend.store.raft.RaftBackendStoreProvider;
 import org.apache.hugegraph.config.CoreOptions;
 import org.apache.hugegraph.config.HugeConfig;
+import org.apache.hugegraph.util.E;
 import org.apache.hugegraph.util.Log;
 import org.slf4j.Logger;
 
+/**
+ * BREAKING CHANGE:
+ * since 1.7.0, only "hstore, rocksdb, hbase, memory" are supported for backend.
+ * if you want to use cassandra, mysql, postgresql, cockroachdb or palo as backend,
+ * please find a version before 1.7.0 of apache hugegraph for your application.
+ */
 public class BackendProviderFactory {
 
     private static final Logger LOG = Log.logger(BackendProviderFactory.class);
 
-    private static Map<String, Class<? extends BackendStoreProvider>> providers;
+    private static final Map<String, Class<? extends BackendStoreProvider>> providers;
+
+    private static final List<String> ALLOWED_BACKENDS = List.of("memory", "rocksdb", "hbase",
+                                                                 "hstore");
 
     static {
         providers = new ConcurrentHashMap<>();
@@ -47,8 +58,7 @@ public static BackendStoreProvider open(HugeGraphParams params) {
 
         BackendStoreProvider provider = newProvider(config);
         if (raftMode) {
-            LOG.info("Opening backend store '{}' in raft mode for graph '{}'",
-                     backend, graph);
+            LOG.info("Opening backend store '{}' in raft mode for graph '{}'", backend, graph);
             provider = new RaftBackendStoreProvider(params, provider);
         }
         provider.open(graph);
@@ -57,8 +67,10 @@ public static BackendStoreProvider open(HugeGraphParams params) {
 
     private static BackendStoreProvider newProvider(HugeConfig config) {
         String backend = config.get(CoreOptions.BACKEND).toLowerCase();
-        String graph = config.get(CoreOptions.STORE);
+        E.checkState(ALLOWED_BACKENDS.contains(backend.toLowerCase()),
+                     "backend is illegal: %s", backend);
 
+        String graph = config.get(CoreOptions.STORE);
         if (InMemoryDBStoreProvider.matchType(backend)) {
             return InMemoryDBStoreProvider.instance(graph);
         }
@@ -68,24 +80,23 @@ private static BackendStoreProvider newProvider(HugeConfig config) {
                                "Not exists BackendStoreProvider: %s", backend);
 
         assert BackendStoreProvider.class.isAssignableFrom(clazz);
-        BackendStoreProvider instance = null;
+        BackendStoreProvider instance;
         try {
-            instance = clazz.newInstance();
+            instance = clazz.getDeclaredConstructor().newInstance();
         } catch (Exception e) {
             throw new BackendException(e);
         }
 
         BackendException.check(backend.equals(instance.type()),
                                "BackendStoreProvider with type '%s' " +
-                               "can't be opened by key '%s'",
-                               instance.type(), backend);
+                               "can't be opened by key '%s'", instance.type(), backend);
         return instance;
     }
 
     @SuppressWarnings({"rawtypes", "unchecked"})
     public static void register(String name, String classPath) {
         ClassLoader classLoader = BackendProviderFactory.class.getClassLoader();
-        Class<?> clazz = null;
+        Class<?> clazz;
         try {
             clazz = classLoader.loadClass(classPath);
         } catch (Exception e) {

hugegraph-server/hugegraph-dist/docker/scripts/detect-storage.groovy

@@ -21,11 +21,6 @@ import org.apache.hugegraph.dist.RegisterUtil
 // register all the backend to avoid changes if needs to support other backend
 RegisterUtil.registerPlugins()
 RegisterUtil.registerRocksDB()
-RegisterUtil.registerCassandra()
-RegisterUtil.registerScyllaDB()
 RegisterUtil.registerHBase()
-RegisterUtil.registerMysql()
-RegisterUtil.registerPalo()
-RegisterUtil.registerPostgresql()
 
 graph = HugeFactory.open('./conf/graphs/hugegraph.properties')