[3.0][cdc-common] Introduce DataSource related APIs for Flink CDC 3.0

This closes #2625.

flink-cdc-common/src/main/java/com/ververica/cdc/common/source/DataSource.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2023 Ververica Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.ververica.cdc.common.source;
+
+import org.apache.flink.annotation.PublicEvolving;
+
+/**
+ * {@code DataSource} is used to access metadata and read change data from external systems. It can
+ * read data from multiple tables simultaneously.
+ */
+@PublicEvolving
+public interface DataSource {
+
+    /** Get the {@link EventSourceProvider} for reading events from external systems. */
+    EventSourceProvider getEventSourceProvider();
+
+    /** Get the {@link MetadataAccessor} for accessing metadata from external systems. */
+    MetadataAccessor getMetadataAccessor();
+}

flink-cdc-common/src/main/java/com/ververica/cdc/common/source/EventSourceProvider.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2023 Ververica Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.ververica.cdc.common.source;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.api.connector.source.Source;
+import org.apache.flink.streaming.api.functions.source.SourceFunction;
+
+/**
+ * A marker interface used to provide an event source for reading events from external systems. We
+ * can reuse exiting Flink {@link Source} and Flink {@link SourceFunction} implementation, and we
+ * can support our own {@code EventSource} implementation in the future.
+ */
+@PublicEvolving
+public interface EventSourceProvider {}

flink-cdc-common/src/main/java/com/ververica/cdc/common/source/FlinkSourceFunctionProvider.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2023 Ververica Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.ververica.cdc.common.source;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.streaming.api.functions.source.SourceFunction;
+
+import com.ververica.cdc.common.event.Event;
+
+/**
+ * {@code FlinkSourceFunctionProvider} is used to provide a Flink {@link SourceFunction} for reading
+ * events from external systems.
+ */
+@PublicEvolving
+public interface FlinkSourceFunctionProvider extends EventSourceProvider {
+
+    /** Get the {@link SourceFunction} for reading events from external systems. */
+    SourceFunction<Event> getSourceFunction();
+
+    /** Create a {@link FlinkSourceFunctionProvider} from a {@link SourceFunction}. */
+    static FlinkSourceFunctionProvider of(SourceFunction<Event> sourceFunction) {
+        return () -> sourceFunction;
+    }
+}

flink-cdc-common/src/main/java/com/ververica/cdc/common/source/FlinkSourceProvider.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2023 Ververica Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.ververica.cdc.common.source;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.api.connector.source.Source;
+
+import com.ververica.cdc.common.event.Event;
+
+/**
+ * {@code FlinkSourceProvider} is used to provide a Flink {@link Source} for reading events from
+ * external systems.
+ */
+@PublicEvolving
+public interface FlinkSourceProvider extends EventSourceProvider {
+
+    /** Get the {@link Source} for reading events from external systems. */
+    Source<Event, ?, ?> getSource();
+
+    /** Create a {@link FlinkSourceProvider} from a {@link Source}. */
+    static FlinkSourceProvider of(Source<Event, ?, ?> source) {
+        return () -> source;
+    }
+}

flink-cdc-common/src/main/java/com/ververica/cdc/common/source/MetadataAccessor.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2023 Ververica Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.ververica.cdc.common.source;
+
+import org.apache.flink.annotation.PublicEvolving;
+
+import com.ververica.cdc.common.event.TableId;
+
+import javax.annotation.Nullable;
+
+import java.util.List;
+
+/**
+ * {@code MetadataAccessor} is used by {@link DataSource} to access the metadata from external
+ * systems.
+ */
+@PublicEvolving
+public interface MetadataAccessor {
+
+    /** List all namespaces from external systems. */
+    List<String> listNamespaces() throws UnsupportedOperationException;
+
+    /** List schemas by namespace from external systems. */
+    List<String> listSchemas(@Nullable String namespace) throws UnsupportedOperationException;
+
+    /** List tables by namespace and schema from external systems. */
+    List<TableId> listTables(@Nullable String namespace, @Nullable String schemaName);
+
+    // TODO: Schema getTableSchema(TableID tableId);
+}