add javadoc

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/PipePlugin.java

@@ -19,4 +19,41 @@
 
 package org.apache.iotdb.pipe.api;
 
+/**
+ * {@link PipePlugin}
+ *
+ * <p>{@link PipePlugin} represents a customizable component that can serve as a data extraction
+ * plugin, data processing plugin, or data sending plugin within a pipeline framework.
+ *
+ * <p>Developers can implement different plugin functionalities according to specific requirements,
+ * such as collecting data from various sources, transforming the data, or forwarding the data to
+ * external systems.
+ *
+ * <p>Usage Model:
+ *
+ * <ul>
+ *   <li>By default, a {@link PipePlugin} can operate under a tree model only, if no model
+ *       annotation under {@link org.apache.iotdb.pipe.api.annotation} is specified.
+ *   <li>To extend its applicability, a {@link PipePlugin} can be configured to support table model,
+ *       or both tree and table models concurrently.
+ * </ul>
+ *
+ * <p>Lifecycle:
+ *
+ * <ul>
+ *   <li>When the pipeline framework loads, the plugin's configuration is parsed and validated.
+ *   <li>As part of the setup, methods can be provided to prepare connections or resources required
+ *       by the plugin (e.g., reading external configurations, establishing data routes).
+ *   <li>During data processing, the plugin performs its core functionality (extraction,
+ *       transformation, or sending).
+ *   <li>When the pipeline is stopped or destroyed, any allocated resources must be released
+ *       accurately, and {@link #close()} will be invoked to ensure a clean shutdown.
+ * </ul>
+ *
+ * <p>Example: {@link org.apache.iotdb.CountPointProcessor}
+ *
+ * <p>Implementations of {@link PipePlugin} should follow best practices for resource management and
+ * gracefully handle exceptions, especially when running in long-lived or continuously operating
+ * environments.
+ */
 public interface PipePlugin extends AutoCloseable {}

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/annotation/TableModel.java

@@ -24,6 +24,16 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+/**
+ * Indicates that a plugin can be used in table model environments.
+ *
+ * <p>When implementing a custom {@link org.apache.iotdb.pipe.api.PipePlugin} that needs to operate
+ * under table model settings, declare this annotation on the plugin class. Through the {@code
+ * CREATE PIPEPLUGIN} statement, a plugin annotated with {@link TableModel} is valid for both tree
+ * model connections and table model connections.
+ *
+ * @since 2.0.0
+ */
 @Target(ElementType.TYPE)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface TableModel {}

iotdb-api/pipe-api/src/main/java/org/apache/iotdb/pipe/api/annotation/TreeModel.java

@@ -24,6 +24,16 @@
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+/**
+ * Indicates that a plugin can be used in tree model environments.
+ *
+ * <p>When implementing a custom {@link org.apache.iotdb.pipe.api.PipePlugin} that needs to operate
+ * under tree model settings, declare this annotation on the plugin class. Through the {@code CREATE
+ * PIPEPLUGIN} statement, a plugin annotated with {@link TreeModel} is valid for both tree model
+ * connections and tree model connections.
+ *
+ * @since 2.0.0
+ */
 @Target(ElementType.TYPE)
 @Retention(RetentionPolicy.RUNTIME)
 public @interface TreeModel {}