Java Native API

July 10, 2023About 12 min

Java Native API

Installation

Using IoTDB Java Native API with Maven

<dependencies>
    <dependency>
      <groupId>org.apache.iotdb</groupId>
      <artifactId>iotdb-session</artifactId>
      <version>1.0.0</version>
    </dependency>
</dependencies>

Syntax Convention

IoTDB-SQL interface: The input SQL parameter needs to conform to the syntax conventions and be escaped for JAVA strings. For example, you need to add a backslash before the double-quotes. (That is: after JAVA escaping, it is consistent with the SQL statement executed on the command line.)
Other interfaces:
- The node names in path or path prefix as parameter: The node names which should be escaped by backticks (`) in the SQL statement, escaping is required here.
- Identifiers (such as template names) as parameters: The identifiers which should be escaped by backticks (`) in the SQL statement, and escaping is not required here.
Code example for syntax convention could be found at: example/session/src/main/java/org/apache/iotdb/SyntaxConventionRelatedExample.java

Native APIs

Here we show the commonly used interfaces and their parameters in the Native API:

Session Management

Initialize a Session

// use default configuration
session = new Session.Builder.build();

// initialize with a single node
session =
    new Session.Builder()
        .host(String host)
        .port(int port)
        .build();

// initialize with multiple nodes
session =
    new Session.Builder()
        .nodeUrls(List<String> nodeUrls)
        .build();

// other configurations
session =
    new Session.Builder()
        .fetchSize(int fetchSize)
        .username(String username)
        .password(String password)
        .thriftDefaultBufferSize(int thriftDefaultBufferSize)
        .thriftMaxFrameSize(int thriftMaxFrameSize)
        .enableRedirection(boolean enableRedirection)
        .version(Version version)
        .build();

Version represents the SQL semantic version used by the client, which is used to be compatible with the SQL semantics of 0.12 when upgrading 0.13. The possible values are: V_0_12, V_0_13, V_1_0, etc.

Open a Session

void open()

Open a session, with a parameter to specify whether to enable RPC compression

void open(boolean enableRPCCompression)

Notice: this RPC compression status of client must comply with that of IoTDB server

Close a Session

void close()

SessionPool

We provide a connection pool (`SessionPool) for Native API.
Using the interface, you need to define the pool size.

If you can not get a session connection in 60 seconds, there is a warning log but the program will hang.

If a session has finished an operation, it will be put back to the pool automatically.
If a session connection is broken, the session will be removed automatically and the pool will try
to create a new session and redo the operation.
You can also specify an url list of multiple reachable nodes when creating a SessionPool, just as you would when creating a Session. To ensure high availability of clients in distributed cluster.

For query operations:

When using SessionPool to query data, the result set is SessionDataSetWrapper;
Given a SessionDataSetWrapper, if you have not scanned all the data in it and stop to use it,
you have to call SessionPool.closeResultSet(wrapper) manually;
When you call hasNext() and next() of a SessionDataSetWrapper and there is an exception, then
you have to call SessionPool.closeResultSet(wrapper) manually;
You can call getColumnNames() of SessionDataSetWrapper to get the column names of query result;

Examples: session/src/test/java/org/apache/iotdb/session/pool/SessionPoolTest.java

Or example/session/src/main/java/org/apache/iotdb/SessionPoolExample.java

Database & Timeseries Management API

Database Management

CREATE DATABASE

void setStorageGroup(String storageGroupId)

Delete one or several databases

void deleteStorageGroup(String storageGroup)
void deleteStorageGroups(List<String> storageGroups)

Timeseries Management

Create one or multiple timeseries

void createTimeseries(String path, TSDataType dataType,
      TSEncoding encoding, CompressionType compressor, Map<String, String> props,
      Map<String, String> tags, Map<String, String> attributes, String measurementAlias)

void createMultiTimeseries(List<String> paths, List<TSDataType> dataTypes,
      List<TSEncoding> encodings, List<CompressionType> compressors,
      List<Map<String, String>> propsList, List<Map<String, String>> tagsList,
      List<Map<String, String>> attributesList, List<String> measurementAliasList)

Create aligned timeseries

void createAlignedTimeseries(String prefixPath, List<String> measurements,
      List<TSDataType> dataTypes, List<TSEncoding> encodings,
      List <CompressionType> compressors, List<String> measurementAliasList);

Attention: Alias of measurements are not supported currently.

Delete one or several timeseries

void deleteTimeseries(String path)
void deleteTimeseries(List<String> paths)

Check whether the specific timeseries exists.

boolean checkTimeseriesExists(String path)

Schema Template

Create a schema template for massive identical devices will help to improve memory performance. You can use Template, InternalNode and MeasurementNode to depict the structure of the template, and use belowed interface to create it inside session.

public void createSchemaTemplate(Template template);

Class Template {
    private String name;
    private boolean directShareTime;
    Map<String, Node> children;
    public Template(String name, boolean isShareTime);

    public void addToTemplate(Node node);
    public void deleteFromTemplate(String name);
    public void setShareTime(boolean shareTime);
}

Abstract Class Node {
    private String name;
    public void addChild(Node node);
    public void deleteChild(Node node);
}

Class MeasurementNode extends Node {
    TSDataType dataType;
    TSEncoding encoding;
    CompressionType compressor;
    public MeasurementNode(String name,
                           TSDataType dataType,
                           TSEncoding encoding,
                          CompressionType compressor);
}

We strongly suggest you implement templates only with flat-measurement (like object 'flatTemplate' in belowed snippet), since tree-structured template may not be a long-term supported feature in further version of IoTDB.

A snippet of using above Method and Class：

MeasurementNode nodeX = new MeasurementNode("x", TSDataType.FLOAT, TSEncoding.RLE, CompressionType.SNAPPY);
MeasurementNode nodeY = new MeasurementNode("y", TSDataType.FLOAT, TSEncoding.RLE, CompressionType.SNAPPY);
MeasurementNode nodeSpeed = new MeasurementNode("speed", TSDataType.DOUBLE, TSEncoding.GORILLA, CompressionType.SNAPPY);

// This is the template we suggest to implement
Template flatTemplate = new Template("flatTemplate");
template.addToTemplate(nodeX);
template.addToTemplate(nodeY);
template.addToTemplate(nodeSpeed);

createSchemaTemplate(flatTemplate);

You can query measurement inside templates with these APIS:

// Return the amount of measurements inside a template
public int countMeasurementsInTemplate(String templateName);

// Return true if path points to a measurement, otherwise returne false
public boolean isMeasurementInTemplate(String templateName, String path);

// Return true if path exists in template, otherwise return false
public boolean isPathExistInTemplate(String templateName, String path);

// Return all measurements paths inside template
public List<String> showMeasurementsInTemplate(String templateName);

// Return all measurements paths under the designated patter inside template
public List<String> showMeasurementsInTemplate(String templateName, String pattern);

To implement schema template, you can set the measurement template named 'templateName' at path 'prefixPath'.

Please notice that, we strongly recommend not setting templates on the nodes above the database to accommodate future updates and collaboration between modules.

void setSchemaTemplate(String templateName, String prefixPath)

Before setting template, you should firstly create the template using

void createSchemaTemplate(Template template)

After setting template to a certain path, you can use the template to create timeseries on given device paths through the following interface, or you can write data directly to trigger timeseries auto creation using schema template under target devices.

void createTimeseriesUsingSchemaTemplate(List<String> devicePathList)

After setting template to a certain path, you can query for info about template using belowed interface in session:

/** @return All template names. */
public List<String> showAllTemplates();

/** @return All paths have been set to designated template. */
public List<String> showPathsTemplateSetOn(String templateName);

/** @return All paths are using designated template. */
public List<String> showPathsTemplateUsingOn(String templateName)

If you are ready to get rid of schema template, you can drop it with belowed interface. Make sure the template to drop has been unset from MTree.

void unsetSchemaTemplate(String prefixPath, String templateName);
public void dropSchemaTemplate(String templateName);

Unset the measurement template named 'templateName' from path 'prefixPath'. When you issue this interface, you should assure that there is a template named 'templateName' set at the path 'prefixPath'.

Attention: Unsetting the template named 'templateName' from node at path 'prefixPath' or descendant nodes which have already inserted records using template is not supported.

Data Manipulation Interface (DML Interface)

Data Insert API

It is recommended to use insertTablet to help improve write efficiency.

Insert a Tablet，which is multiple rows of a device, each row has the same measurements
- Better Write Performance
- Support batch write
- Support null values: fill the null value with any value, and then mark the null value via BitMap

void insertTablet(Tablet tablet)

public class Tablet {
  /** deviceId of this tablet */
  public String prefixPath;
  /** the list of measurement schemas for creating the tablet */
  private List<MeasurementSchema> schemas;
  /** timestamps in this tablet */
  public long[] timestamps;
  /** each object is a primitive type array, which represents values of one measurement */
  public Object[] values;
  /** each bitmap represents the existence of each value in the current column. */
  public BitMap[] bitMaps;
  /** the number of rows to include in this tablet */
  public int rowSize;
  /** the maximum number of rows for this tablet */
  private int maxRowNumber;
  /** whether this tablet store data of aligned timeseries or not */
  private boolean isAligned;
}

Insert multiple Tablets

void insertTablets(Map<String, Tablet> tablet)

Insert a Record, which contains multiple measurement value of a device at a timestamp. This method is equivalent to providing a common interface for multiple data types of values. Later, the value can be cast to the original type through TSDataType.
The correspondence between the Object type and the TSDataType type is shown in the following table.
TSDataType Object
BOOLEAN Boolean
INT32 Integer
DATE LocalDate
INT64 Long
TIMESTAMP Long
FLOAT Float
DOUBLE Double
TEXT String, Binary
STRING String, Binary
BLOB Binary

TSDataType	Object
BOOLEAN	Boolean
INT32	Integer
DATE	LocalDate
INT64	Long
TIMESTAMP	Long
FLOAT	Float
DOUBLE	Double
TEXT	String, Binary
STRING	String, Binary
BLOB	Binary

void insertRecord(String deviceId, long time, List<String> measurements,
   List<TSDataType> types, List<Object> values)

Insert multiple Records

void insertRecords(List<String> deviceIds, List<Long> times,
    List<List<String>> measurementsList, List<List<TSDataType>> typesList,
    List<List<Object>> valuesList)

Insert multiple Records that belong to the same device.
With type info the server has no need to do type inference, which leads a better performance

void insertRecordsOfOneDevice(String deviceId, List<Long> times,
    List<List<String>> measurementsList, List<List<TSDataType>> typesList,
    List<List<Object>> valuesList)

Insert with type inference

When the data is of String type, we can use the following interface to perform type inference based on the value of the value itself. For example, if value is "true" , it can be automatically inferred to be a boolean type. If value is "3.2" , it can be automatically inferred as a flout type. Without type information, server has to do type inference, which may cost some time.

Insert a Record, which contains multiple measurement value of a device at a timestamp

void insertRecord(String prefixPath, long time, List<String> measurements, List<String> values)

Insert multiple Records

void insertRecords(List<String> deviceIds, List<Long> times,
   List<List<String>> measurementsList, List<List<String>> valuesList)

Insert multiple Records that belong to the same device.

void insertStringRecordsOfOneDevice(String deviceId, List<Long> times,
        List<List<String>> measurementsList, List<List<String>> valuesList)

Insert of Aligned Timeseries

The Insert of aligned timeseries uses interfaces like insertAlignedXXX, and others are similar to the above interfaces:

insertAlignedRecord
insertAlignedRecords
insertAlignedRecordsOfOneDevice
insertAlignedStringRecordsOfOneDevice
insertAlignedTablet
insertAlignedTablets

Data Delete API

Delete data before or equal to a timestamp of one or several timeseries

void deleteData(String path, long time)
void deleteData(List<String> paths, long time)

Data Query API

Time-series raw data query with time range:
- The specified query time range is a left-closed right-open interval, including the start time but excluding the end time.

SessionDataSet executeRawDataQuery(List<String> paths, long startTime, long endTime);

Last query:
- Query the last data, whose timestamp is greater than or equal LastTime.
```
SessionDataSet executeLastDataQuery(List<String> paths, long LastTime);
```
- Query the latest point of the specified series of single device quickly, and support redirection;
  If you are sure that the query path is valid, set 'isLegalPathNodes' to true to avoid performance penalties from path verification.
```
SessionDataSet executeLastDataQueryForOneDevice(
    String db, String device, List<String> sensors, boolean isLegalPathNodes);
```
Aggregation query:
- Support specified query time range: The specified query time range is a left-closed right-open interval, including the start time but not the end time.
- Support GROUP BY TIME.

SessionDataSet executeAggregationQuery(List<String> paths, List<Aggregation> aggregations);

SessionDataSet executeAggregationQuery(
    List<String> paths, List<Aggregation> aggregations, long startTime, long endTime);

SessionDataSet executeAggregationQuery(
    List<String> paths,
    List<Aggregation> aggregations,
    long startTime,
    long endTime,
    long interval);

SessionDataSet executeAggregationQuery(
    List<String> paths,
    List<Aggregation> aggregations,
    long startTime,
    long endTime,
    long interval,
    long slidingStep);

Execute query statement

SessionDataSet executeQueryStatement(String sql)

Data Subscription

1 Topic Management

The SubscriptionSession class in the IoTDB subscription client provides interfaces for topic management. The status changes of topics are illustrated in the diagram below:

1.1 Create Topic

 void createTopicIfNotExists(String topicName, Properties properties) throws Exception;

Example:

try (final SubscriptionSession session = new SubscriptionSession(host, port)) {
  session.open();
  final Properties config = new Properties();
  config.put(TopicConstant.PATH_KEY, "root.db.**");
  session.createTopic(topicName, config);
}

1.2 Delete Topic

void dropTopicIfExists(String topicName) throws Exception;

1.3 View Topic

// Get all topics
Set<Topic> getTopics() throws Exception;

// Get a specific topic
Optional<Topic> getTopic(String topicName) throws Exception;

2 Check Subscription Status

The SubscriptionSession class in the IoTDB subscription client provides interfaces to check the subscription status:

Set<Subscription> getSubscriptions() throws Exception;
Set<Subscription> getSubscriptions(final String topicName) throws Exception;

3 Create Consumer

When creating a consumer using the JAVA native interface, you need to specify the parameters applied to the consumer.

For both SubscriptionPullConsumer and SubscriptionPushConsumer, the following common configurations are available:

key	required or optional with default	description
host	optional: 127.0.0.1	`String`: The RPC host of a certain DataNode in IoTDB
port	optional: 6667	Integer: The RPC port of a certain DataNode in IoTDB
node-urls	optional: 127.0.0.1:6667	`List<String>`: The RPC addresses of all DataNodes in IoTDB, can be multiple; either host:port or node-urls can be filled in. If both host:port and node-urls are filled in, the union of host:port and node-urls will be used to form a new node-urls application
username	optional: root	`String`: The username of a DataNode in IoTDB
password	optional: root	`String`: The password of a DataNode in IoTDB
groupId	optional	`String`: consumer group id, if not specified, a new consumer group will be randomly assigned, ensuring that different consumer groups have different consumer group ids
consumerId	optional	`String`: consumer client id, if not specified, it will be randomly assigned, ensuring that each consumer client id in the same consumer group is unique
heartbeatIntervalMs	optional: 30000 (min: 1000)	`Long`: The interval at which the consumer sends heartbeat requests to the IoTDB DataNode
endpointsSyncIntervalMs	optional: 120000 (min: 5000)	`Long`: The interval at which the consumer detects the expansion and contraction of IoTDB cluster nodes and adjusts the subscription connection
fileSaveDir	optional: Paths.get(System.getProperty("user.dir"), "iotdb-subscription").toString()	`String`: The temporary directory path where the TsFile files subscribed by the consumer are stored
fileSaveFsync	optional: false	`Boolean`: Whether the consumer actively calls fsync during the subscription of TsFile

3.1 SubscriptionPushConsumer

The following are special configurations for SubscriptionPushConsumer:

key	required or optional with default	description
ackStrategy	optional: `ACKStrategy.AFTER_CONSUME`	Consumption progress confirmation mechanism includes the following options: `ACKStrategy.BEFORE_CONSUME` (submit consumption progress immediately when the consumer receives data, before `onReceive`) `ACKStrategy.AFTER_CONSUME` (submit consumption progress after the consumer has consumed the data, after `onReceive`)
consumeListener	optional	Consumption data callback function, need to implement the `ConsumeListener` interface, define the consumption logic of `SessionDataSetsHandler` and `TsFileHandler` form data
autoPollIntervalMs	optional: 5000 (min: 500)	Long: The interval at which the consumer automatically pulls data, in ms
autoPollTimeoutMs	optional: 10000 (min: 1000)	Long: The timeout time for the consumer to pull data each time, in ms

Among them, the ConsumerListener interface is defined as follows:

@FunctionInterface
interface ConsumeListener {
  default ConsumeResult onReceive(Message message) {
    return ConsumeResult.SUCCESS;
  }
}

enum ConsumeResult {
  SUCCESS,
  FAILURE,
}

3.2 SubscriptionPullConsumer

The following are special configurations for SubscriptionPullConsumer :

key	required or optional with default	description
autoCommit	optional: true	Boolean: Whether to automatically commit consumption progress. If this parameter is set to false, the commit method must be called to manually `commit` consumption progress.
autoCommitInterval	optional: 5000 (min: 500)	Long: The interval at which consumption progress is automatically committed, in milliseconds. This only takes effect when the autoCommit parameter is true.

After creating a consumer, you need to manually call the consumer's open method:

void open() throws Exception;

At this point, the IoTDB subscription client will verify the correctness of the consumer's configuration. After a successful verification, the consumer will join the corresponding consumer group. That is, only after opening the consumer can you use the returned consumer object to subscribe to topics, consume data, and perform other operations.

Both SubscriptionPushConsumer and SubscriptionPullConsumer provide the following JAVA native interfaces for subscribing to topics:

// Subscribe to topics
void subscribe(String topic) throws Exception;
void subscribe(List<String> topics) throws Exception;

Before a consumer subscribes to a topic, the topic must have been created, otherwise, the subscription will fail.
If a consumer subscribes to a topic that it has already subscribed to, no error will occur.
If there are other consumers in the same consumer group that have subscribed to the same topics, the consumer will reuse the corresponding consumption progress.

5 Consume Data

For both push and pull mode consumers:

Only after explicitly subscribing to a topic will the consumer receive data for that topic.
If no topics are subscribed to after creation, the consumer will not be able to consume any data, even if other consumers in the same consumer group have subscribed to some topics.

5.1 SubscriptionPushConsumer

After SubscriptionPushConsumer subscribes to topics, there is no need to manually pull data.

The data consumption logic is within the consumeListener configuration specified when creating SubscriptionPushConsumer.

5.2 SubscriptionPullConsumer

After SubscriptionPullConsumer subscribes to topics, it needs to actively call the poll method to pull data:

List<SubscriptionMessage> poll(final Duration timeout) throws Exception;
List<SubscriptionMessage> poll(final long timeoutMs) throws Exception;
List<SubscriptionMessage> poll(final Set<String> topicNames, final Duration timeout) throws Exception;
List<SubscriptionMessage> poll(final Set<String> topicNames, final long timeoutMs) throws Exception;

In the poll method, you can specify the topic names to be pulled (if not specified, it defaults to pulling all topics that the consumer has subscribed to) and the timeout period.

When the SubscriptionPullConsumer is configured with the autoCommit parameter set to false, it is necessary to manually call the commitSync and commitAsync methods to synchronously or asynchronously commit the consumption progress of a batch of data:

void commitSync(final SubscriptionMessage message) throws Exception;
void commitSync(final Iterable<SubscriptionMessage> messages) throws Exception;

CompletableFuture<Void> commitAsync(final SubscriptionMessage message);
CompletableFuture<Void> commitAsync(final Iterable<SubscriptionMessage> messages);
void commitAsync(final SubscriptionMessage message, final AsyncCommitCallback callback);
void commitAsync(final Iterable<SubscriptionMessage> messages, final AsyncCommitCallback callback);

The AsyncCommitCallback class is defined as follows:

public interface AsyncCommitCallback {
  default void onComplete() {
    // Do nothing
  }

  default void onFailure(final Throwable e) {
    // Do nothing
  }
}

6 Unsubscribe

The SubscriptionPushConsumer and SubscriptionPullConsumer provide the following JAVA native interfaces for unsubscribing and closing the consumer:

// Unsubscribe from topics
void unsubscribe(String topic) throws Exception;
void unsubscribe(List<String> topics) throws Exception;

// Close consumer
void close();

If a consumer unsubscribes from a topic that it has not subscribed to, no error will occur.
When a consumer is closed, it will exit the corresponding consumer group and automatically unsubscribe from all topics it is currently subscribed to.
Once a consumer is closed, its lifecycle ends, and it cannot be reopened to subscribe to and consume data again.

7 Code Examples

7.1 Single Pull Consumer Consuming SessionDataSetsHandler Format Data

// Create topics
try (final SubscriptionSession session = new SubscriptionSession(HOST, PORT)) {
  session.open();
  final Properties config = new Properties();
  config.put(TopicConstant.PATH_KEY, "root.db.**");
  session.createTopic(TOPIC_1, config);
}

// Subscription: property-style ctor
final Properties config = new Properties();
config.put(ConsumerConstant.CONSUMER_ID_KEY, "c1");
config.put(ConsumerConstant.CONSUMER_GROUP_ID_KEY, "cg1");

final SubscriptionPullConsumer consumer1 = new SubscriptionPullConsumer(config);
consumer1.open();
consumer1.subscribe(TOPIC_1);
while (true) {
  LockSupport.parkNanos(SLEEP_NS); // wait some time
  final List<SubscriptionMessage> messages = consumer1.poll(POLL_TIMEOUT_MS);
  for (final SubscriptionMessage message : messages) {
    for (final SubscriptionSessionDataSet dataSet : message.getSessionDataSetsHandler()) {
      System.out.println(dataSet.getColumnNames());
      System.out.println(dataSet.getColumnTypes());
      while (dataSet.hasNext()) {
        System.out.println(dataSet.next());
      }
    }
  }
  // Auto commit
}

// Show topics and subscriptions
try (final SubscriptionSession session = new SubscriptionSession(HOST, PORT)) {
  session.open();
  session.getTopics().forEach((System.out::println));
  session.getSubscriptions().forEach((System.out::println));
}

consumer1.unsubscribe(TOPIC_1);
consumer1.close();

7.2 Multiple Push Consumers Consuming TsFileHandler Format Data

// Create topics
try (final SubscriptionSession subscriptionSession = new SubscriptionSession(HOST, PORT)) {
  subscriptionSession.open();
  final Properties config = new Properties();
  config.put(TopicConstant.FORMAT_KEY, TopicConstant.FORMAT_TS_FILE_HANDLER_VALUE);
  subscriptionSession.createTopic(TOPIC_2, config);
}

final List<Thread> threads = new ArrayList<>();
for (int i = 0; i < 8; ++i) {
  final int idx = i;
  final Thread thread =
      new Thread(
          () -> {
            // Subscription: builder-style ctor
            try (final SubscriptionPushConsumer consumer2 =
                new SubscriptionPushConsumer.Builder()
                    .consumerId("c" + idx)
                    .consumerGroupId("cg2")
                    .fileSaveDir(System.getProperty("java.io.tmpdir"))
                    .ackStrategy(AckStrategy.AFTER_CONSUME)
                    .consumeListener(
                        message -> {
                          doSomething(message.getTsFileHandler());
                          return ConsumeResult.SUCCESS;
                        })
                    .buildPushConsumer()) {
              consumer2.open();
              consumer2.subscribe(TOPIC_2);
              // block the consumer main thread
              Thread.sleep(Long.MAX_VALUE);
            } catch (final IOException | InterruptedException e) {
              throw new RuntimeException(e);
            }
          });
  thread.start();
  threads.add(thread);
}

for (final Thread thread : threads) {
  thread.join();
}

Other Modules (Execute SQL Directly)

Execute non query statement

void executeNonQueryStatement(String sql)

Write Test Interface (to profile network cost)

These methods don't insert data into database and server just return after accept the request.

Test the network and client cost of insertRecord

void testInsertRecord(String deviceId, long time, List<String> measurements, List<String> values)

void testInsertRecord(String deviceId, long time, List<String> measurements,
        List<TSDataType> types, List<Object> values)

Test the network and client cost of insertRecords

void testInsertRecords(List<String> deviceIds, List<Long> times,
        List<List<String>> measurementsList, List<List<String>> valuesList)

void testInsertRecords(List<String> deviceIds, List<Long> times,
        List<List<String>> measurementsList, List<List<TSDataType>> typesList
        List<List<Object>> valuesList)

Test the network and client cost of insertTablet

void testInsertTablet(Tablet tablet)

Test the network and client cost of insertTablets

void testInsertTablets(Map<String, Tablet> tablets)

Coding Examples

To get more information of the following interfaces, please view session/src/main/java/org/apache/iotdb/session/Session.java

The sample code of using these interfaces is in example/session/src/main/java/org/apache/iotdb/SessionExample.java，which provides an example of how to open an IoTDB session, execute a batch insertion.

For examples of aligned timeseries and measurement template, you can refer to example/session/src/main/java/org/apache/iotdb/AlignedTimeseriesSessionExample.java