Session Native API

February 23, 2023About 11 min

Session Native API

In the native API of IoTDB, the Session is the core interface for interacting with the database. It integrates a rich set of methods that support data writing, querying, and metadata operations. By instantiating a Session, you can establish a connection to the IoTDB server and perform various database operations within the environment constructed by this connection. The Session is not thread-safe and should not be called simultaneously by multiple threads.

SessionPool is a connection pool for Session, and it is recommended to use SessionPool for programming. In scenarios with multi-threaded concurrency, SessionPool can manage and allocate connection resources effectively, thereby improving system performance and resource utilization efficiency.

1 Overview of Steps

Create a Connection Pool Instance: Initialize a SessionPool object to manage multiple Session instances.
Perform Operations: Directly obtain a Session instance from the SessionPool and execute database operations, without the need to open and close connections each time.
Close Connection Pool Resources: When database operations are no longer needed, close the SessionPool to release all related resources.

2 Detailed Steps

This section provides an overview of the core development process and does not demonstrate all parameters and interfaces. For a complete list of functionalities and parameters, please refer to:Java Native API or check the: Source Code

2.1 Create a Maven Project

Create a Maven project and add the following dependencies to the pom.xml file (JDK >= 1.8, Maven >= 3.6):

<dependencies>
    <dependency>
      <groupId>org.apache.iotdb</groupId>
      <artifactId>iotdb-session</artifactId>
      <!-- The version number is the same as the database version number -->
      <version>${project.version}</version>
    </dependency>
</dependencies>

2.2 Creating a Connection Pool Instance

import java.util.ArrayList;
import java.util.List;
import org.apache.iotdb.session.pool.SessionPool;

public class IoTDBSessionPoolExample {
    private static SessionPool sessionPool;

    public static void main(String[] args) {
        // Using nodeUrls ensures that when one node goes down, other nodes are automatically connected to retry
        List<String> nodeUrls = new ArrayList<>();
        nodeUrls.add("127.0.0.1:6667");
        nodeUrls.add("127.0.0.1:6668");
        sessionPool =
                new SessionPool.Builder()
                        .nodeUrls(nodeUrls)
                        .user("root")
                        .password("root")
                        .maxSize(3)
                        .build();
    }
}

2.3 Performing Database Operations

2.3.1 Data Insertion

In industrial scenarios, data insertion can be categorized into the following types: inserting multiple rows of data, and inserting multiple rows of data for a single device. Below, we introduce the insertion interfaces for different scenarios.

Multi-Row Data Insertion Interface

Interface Description: Supports inserting multiple rows of data at once, where each row corresponds to multiple measurement values for a device at a specific timestamp.

Interface List:

Interface Name	Function Description
`insertRecords(List<String> deviceIds, List<Long> times, List<List<String>> measurementsList, List<List<TSDataType>> typesList, List<List<Object>> valuesList)`	Inserts multiple rows of data, suitable for scenarios where measurements are independently collected.

Code Example:

import java.util.ArrayList;
import java.util.List;
import org.apache.iotdb.rpc.IoTDBConnectionException;
import org.apache.iotdb.rpc.StatementExecutionException;
import org.apache.iotdb.session.pool.SessionPool;
import org.apache.tsfile.enums.TSDataType;

public class SessionPoolExample {
 private static SessionPool sessionPool;
     public static void main(String[] args) throws IoTDBConnectionException, StatementExecutionException {
          // 1. init SessionPool
        constructSessionPool();
          // 2. execute insert data
        insertRecordsExample();
          // 3. close SessionPool
        closeSessionPool();
  }

  private static void constructSessionPool() {
        // Using nodeUrls ensures that when one node goes down, other nodes are automatically connected to retry
        List<String> nodeUrls = new ArrayList<>();
        nodeUrls.add("127.0.0.1:6667");
        nodeUrls.add("127.0.0.1:6668");
        sessionPool =
                new SessionPool.Builder()
                        .nodeUrls(nodeUrls)
                        .user("root")
                        .password("root")
                        .maxSize(3)
                        .build();
    }

    public static void insertRecordsExample() throws IoTDBConnectionException, StatementExecutionException {
        String deviceId = "root.sg1.d1";
        List<String> measurements = new ArrayList<>();
        measurements.add("s1");
        measurements.add("s2");
        measurements.add("s3");
        List<String> deviceIds = new ArrayList<>();
        List<List<String>> measurementsList = new ArrayList<>();
        List<List<Object>> valuesList = new ArrayList<>();
        List<Long> timestamps = new ArrayList<>();
        List<List<TSDataType>> typesList = new ArrayList<>();

        for (long time = 0; time < 500; time++) {
            List<Object> values = new ArrayList<>();
            List<TSDataType> types = new ArrayList<>();
            values.add(1L);
            values.add(2L);
            values.add(3L);
            types.add(TSDataType.INT64);
            types.add(TSDataType.INT64);
            types.add(TSDataType.INT64);

            deviceIds.add(deviceId);
            measurementsList.add(measurements);
            valuesList.add(values);
            typesList.add(types);
            timestamps.add(time);
            if (time != 0 && time % 100 == 0) {
                try {
                    sessionPool.insertRecords(deviceIds, timestamps, measurementsList, typesList, valuesList);
                } catch (IoTDBConnectionException | StatementExecutionException e) {
                    // solve exception
                }
                deviceIds.clear();
                measurementsList.clear();
                valuesList.clear();
                typesList.clear();
                timestamps.clear();
            }
        }
        try {
            sessionPool.insertRecords(deviceIds, timestamps, measurementsList, typesList, valuesList);
        } catch (IoTDBConnectionException | StatementExecutionException e) {
            // solve exception
        }
    }
    
      public static void closeSessionPool(){
        sessionPool.close();
    }
}

Single-Device Multi-Row Data Insertion Interface

Interface Description: Supports inserting multiple rows of data for a single device at once, where each row corresponds to multiple measurement values for a specific timestamp.

Interface List：

Interface Name	Function Description
`insertTablet(Tablet tablet)`	Inserts multiple rows of data for a single device, suitable for scenarios where measurements are independently collected.

Code Example:

import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import org.apache.iotdb.rpc.IoTDBConnectionException;
import org.apache.iotdb.rpc.StatementExecutionException;
import org.apache.iotdb.session.pool.SessionPool;
import org.apache.tsfile.enums.TSDataType;
import org.apache.tsfile.write.record.Tablet;
import org.apache.tsfile.write.schema.MeasurementSchema;

public class SessionPoolExample {
      private static SessionPool sessionPool;
      public static void main(String[] args) throws IoTDBConnectionException, StatementExecutionException {
        // 1. init SessionPool
        constructSessionPool();
        // 2. execute insert data
        insertTabletExample();
        // 3. close SessionPool
        closeSessionPool();
          }

        private static void constructSessionPool() {
        // Using nodeUrls ensures that when one node goes down, other nodes are automatically connected to retry
        List<String> nodeUrls = new ArrayList<>();
        nodeUrls.add("127.0.0.1:6667");
        nodeUrls.add("127.0.0.1:6668");
        sessionPool =
                new SessionPool.Builder()
                        .nodeUrls(nodeUrls)
                        .user("root")
                        .password("root")
                        .maxSize(3)
                        .build();
    }

    private static void insertTabletExample() throws IoTDBConnectionException, StatementExecutionException {
        /*
         * A Tablet example:
         *      device1
         * time s1, s2, s3
         * 1,   1,  1,  1
         * 2,   2,  2,  2
         * 3,   3,  3,  3
         */
        // The schema of measurements of one device
        // only measurementId and data type in MeasurementSchema take effects in Tablet
        List<MeasurementSchema> schemaList = new ArrayList<>();
        schemaList.add(new MeasurementSchema("s1", TSDataType.INT64));
        schemaList.add(new MeasurementSchema("s2", TSDataType.INT64));
        schemaList.add(new MeasurementSchema("s3", TSDataType.INT64));

        Tablet tablet = new Tablet("root.sg.d1", schemaList, 100);

        // Method 1 to add tablet data
        long timestamp = System.currentTimeMillis();

        Random random = new Random();
        for (long row = 0; row < 100; row++) {
            int rowIndex = tablet.rowSize++;
            tablet.addTimestamp(rowIndex, timestamp);
            for (int s = 0; s < 3; s++) {
                long value = random.nextLong();
                tablet.addValue(schemaList.get(s).getMeasurementId(), rowIndex, value);
            }
            if (tablet.rowSize == tablet.getMaxRowNumber()) {
                sessionPool.insertTablet(tablet);
                tablet.reset();
            }
            timestamp++;
        }
        if (tablet.rowSize != 0) {
            sessionPool.insertTablet(tablet);
            tablet.reset();
        }
    }

    public static void closeSessionPool(){
        sessionPool.close();
    }
}

2.3.2 SQL Operations

SQL operations are divided into two categories: queries and non-queries. The corresponding interfaces are executeQuery and executeNonQuery. The difference between them is that the former executes specific query statements and returns a result set, while the latter performs insert, delete, and update operations and does not return a result set.

import java.util.ArrayList;
import java.util.List;
import org.apache.iotdb.isession.pool.SessionDataSetWrapper;
import org.apache.iotdb.rpc.IoTDBConnectionException;
import org.apache.iotdb.rpc.StatementExecutionException;
import org.apache.iotdb.session.pool.SessionPool;

public class SessionPoolExample {
  private static SessionPool sessionPool;
  public static void main(String[] args) throws IoTDBConnectionException, StatementExecutionException {
        // 1. init SessionPool
        constructSessionPool(); 
        // 2. executes a non-query SQL statement, such as a DDL or DML command.
        executeQueryExample();
        // 3. executes a query SQL statement and returns the result set.
        executeNonQueryExample();
        // 4. close SessionPool
        closeSessionPool();
    }

    private static void executeNonQueryExample() throws IoTDBConnectionException, StatementExecutionException {
        // 1. create a nonAligned time series
        sessionPool.executeNonQueryStatement("create timeseries root.test.d1.s1 with dataType = int32");
        // 2. set ttl
        sessionPool.executeNonQueryStatement("set TTL to root.test.** 10000");
        // 3. delete time series
        sessionPool.executeNonQueryStatement("delete timeseries root.test.d1.s1");
        private static void executeQueryExample() throws IoTDBConnectionException, StatementExecutionException {
        // 1. execute normal query
        try(SessionDataSetWrapper wrapper = sessionPool.executeQueryStatement("select s1 from root.sg1.d1 limit 10")) {
            while (wrapper.hasNext()) {
                System.out.println(wrapper.next());
            }
                }
        // 2. execute aggregate query
        try(SessionDataSetWrapper wrapper = sessionPool.executeQueryStatement("select count(s1) from root.sg1.d1 group by ([0, 40), 5ms) ")) {
            while (wrapper.hasNext()) {
                System.out.println(wrapper.next());
            }
        }
          }

        private static void constructSessionPool() {
        // Using nodeUrls ensures that when one node goes down, other nodes are automatically connected to retry
        List<String> nodeUrls = new ArrayList<>();
        nodeUrls.add("127.0.0.1:6667");
        nodeUrls.add("127.0.0.1:6668");
        sessionPool =
                new SessionPool.Builder()
                        .nodeUrls(nodeUrls)
                        .user("root")
                        .password("root")
                        .maxSize(3)
                        .build();
    }

    public static void closeSessionPool(){
        sessionPool.close();
    }
}

3 Native Interface Description

3.1 Parameter List

The Session class has the following fields, which can be set through the constructor or the Session.Builder method:

Field Name	Type	Description
`nodeUrls`	`List<String>`	List of URLs for database nodes, supporting multiple node connections
`username`	`String`	Username
`password`	`String`	Password
`fetchSize`	`int`	Default batch size for query results
`useSSL`	`boolean`	Whether to enable SSL
`trustStore`	`String`	Path to the trust store
`trustStorePwd`	`String`	Password for the trust store
`queryTimeoutInMs`	`long`	Query timeout in milliseconds
`enableRPCCompression`	`boolean`	Whether to enable RPC compression
`connectionTimeoutInMs`	`int`	Connection timeout in milliseconds
`zoneId`	`ZoneId`	Time zone setting for the session
`thriftDefaultBufferSize`	`int`	Default buffer size for Thrift Thrift
`thriftMaxFrameSize`	`int`	Maximum frame size for Thrift Thrift
`defaultEndPoint`	`TEndPoint`	Default database endpoint information
`defaultSessionConnection`	`SessionConnection`	Default session connection object
`isClosed`	`boolean`	Whether the current session is closed
`enableRedirection`	`boolean`	Whether to enable redirection
`enableRecordsAutoConvertTablet`	`boolean`	Whether to enable the function of recording the automatic transfer to Tablet
`deviceIdToEndpoint`	`Map<String, TEndPoint>`	Mapping of device IDs to database endpoints
`endPointToSessionConnection`	`Map<TEndPoint, SessionConnection>`	Mapping of database endpoints to session connections
`executorService`	`ScheduledExecutorService`	Thread pool for periodically updating the node list
`availableNodes`	`INodeSupplier`	Supplier of available nodes
`enableQueryRedirection`	`boolean`	Whether to enable query redirection
`version`	`Version`	Client version number, used for compatibility judgment with the server
`enableAutoFetch`	`boolean`	Whether to enable automatic fetching
`maxRetryCount`	`int`	Maximum number of retries
`retryIntervalInMs`	`long`	Retry interval in milliseconds

3.2 Interface list

3.2.1 Metadata Management

Method Name	Function Description	Parameter Explanation
`createDatabase(String database)`	Create a database	`database`: The name of the database to be created
`deleteDatabase(String database)`	Delete a specified database	`database`: The name of the database to be deleted
`deleteDatabases(List<String> databases)`	Batch delete databases	`databases`: A list of database names to be deleted
`createTimeseries(String path, TSDataType dataType, TSEncoding encoding, CompressionType compressor)`	Create a single time series	`path`: The path of the time series，`dataType`: The data type，`encoding`: The encoding type，`compressor`: The compression type
`createAlignedTimeseries(...)`	Create aligned time series	Device ID, list of measurement points, list of data types, list of encodings, list of compression types
`createMultiTimeseries(...)`	Batch create time series	Multiple paths, data types, encodings, compression types, properties, tags, aliases, etc.
`deleteTimeseries(String path)`	Delete a time series	`path`: The path of the time series to be deleted
`deleteTimeseries(List<String> paths)`	Batch delete time series	`paths`: A list of time series paths to be deleted
`setSchemaTemplate(String templateName, String prefixPath)`	Set a schema template	`templateName`: The name of template，`prefixPath`: The path where the template is applied
`createSchemaTemplate(Template template)`	Create a schema template	`template`: The template object
`dropSchemaTemplate(String templateName)`	Delete a schema template	`templateName`: The name of template to be deleted
`addAlignedMeasurementsInTemplate(...)`	Add aligned measurements to a template	Template name, list of measurement paths, data type, encoding type, compression type
`addUnalignedMeasurementsInTemplate(...)`	Add unaligned measurements to a template	Same as above
`deleteNodeInTemplate(String templateName, String path)`	Delete a node in a template	`templateName`: The name of template，`path`: The path to be deleted
`countMeasurementsInTemplate(String name)`	Count the number of measurements in a template	`name`: The name of template
`isMeasurementInTemplate(String templateName, String path)`	Check if a measurement exists in a template	`templateName`: The name of template，`path`: The path of the measurement
`isPathExistInTemplate(String templateName, String path)`	Check if a path exists in a template	same as above
`showMeasurementsInTemplate(String templateName)`	Show measurements in a template	`templateName`: The name of template
`showMeasurementsInTemplate(String templateName, String pattern)`	Show measurements in a template by pattern	`templateName`: The name of template，`pattern`: The matching pattern
`showAllTemplates()`	Show all templates	No parameters
`showPathsTemplateSetOn(String templateName)`	Show paths where a template is set	`templateName`: The name of the template
`showPathsTemplateUsingOn(String templateName)`	Show actual paths using a template	Same as above上
`unsetSchemaTemplate(String prefixPath, String templateName)`	Unset the template setting for a path	`prefixPath`: The path，`templateName`: The name of template

3.2.2 Data Insertion

Method Name	Function Description	Parameter Explanation
`insertRecord(String deviceId, long time, List<String> measurements, List<TSDataType> types, Object... values)`	Insert a single record	`deviceId`: Device ID，`time`: Timestamp，`measurements`: List of measurement points，`types`: List of data types，`values`: List of values
`insertRecord(String deviceId, long time, List<String> measurements, List<String> values)`	Insert a single record	`deviceId`: Device ID，`time`: Timestamp，`measurements`: List of measurement points，`values`: List of values
`insertRecords(List<String> deviceIds, List<Long> times, List<List<String>> measurementsList, List<List<Object>> valuesList)`	Insert multiple records	`deviceIds`: List of device IDs，`times`: List of timestamps，`measurementsList`: List of timestamps，`valuesList`: List of lists of values
`insertRecords(List<String> deviceIds, List<Long> times, List<List<String>> measurementsList, List<List<TSDataType>> typesList, List<List<Object>> valuesList)`	Insert multiple records	Same as above，plus `typesList`: List of lists of data types
`insertRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<TSDataType>> typesList, List<List<Object>> valuesList)`	Insert multiple records for a single device	`deviceId`: Device ID，`times`: List of timestamps，`measurementsList`: List of lists of measurement points，`typesList`: List of lists of types，`valuesList`: List of lists of values
`insertRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<TSDataType>> typesList, List<List<Object>> valuesList, boolean haveSorted)`	Insert sorted multiple records for a single device	Same as above, plus `haveSorted`: Whether the data is already sorted
`insertStringRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<String>> valuesList)`	Insert string-formatted records for a single device	`deviceId`: Device ID，`times`: List of timestamps，`measurementsList`: List of lists of measurement points，`valuesList`: List of lists of values
`insertStringRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<String>> valuesList, boolean haveSorted)`	Insert sorted string-formatted records for a single device	Same as above, plus `haveSorted`: Whether the data is already sorted序
`insertAlignedRecord(String deviceId, long time, List<String> measurements, List<TSDataType> types, List<Object> values)`	Insert a single aligned record	`deviceId`: Device ID，`time`: Timestamp，`measurements`: List of measurement points，`types`: List of types，`values`: List of values
`insertAlignedRecord(String deviceId, long time, List<String> measurements, List<String> values)`	Insert a single string-formatted aligned record	`deviceId`: Device ID`time`: Timestamp,`measurements`: List of measurement points，`values`: List of values
`insertAlignedRecords(List<String> deviceIds, List<Long> times, List<List<String>> measurementsList, List<List<Object>> valuesList)`	Insert multiple aligned records	`deviceIds`: List of device IDs，`times`: List of timestamps，`measurementsList`: List of lists of measurement points，`valuesList`: List of lists of values
`insertAlignedRecords(List<String> deviceIds, List<Long> times, List<List<String>> measurementsList, List<List<TSDataType>> typesList, List<List<Object>> valuesList)`	Insert multiple aligned records	Same as above, plus `typesList`: List of lists of data types
`insertAlignedRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<TSDataType>> typesList, List<List<Object>> valuesList)`	Insert multiple aligned records for a single device	Same as above
`insertAlignedRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<TSDataType>> typesList, List<List<Object>> valuesList, boolean haveSorted)`	Insert sorted multiple aligned records for a single device	Same as above, plus `haveSorted`: Whether the data is already sorted
`insertAlignedStringRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<String>> valuesList)`	Insert string-formatted aligned records for a single device	`deviceId`: Device ID，`times`: List of timestamps，`measurementsList`: List of lists of measurement points，`valuesList`: List of lists of values
`insertAlignedStringRecordsOfOneDevice(String deviceId, List<Long> times, List<List<String>> measurementsList, List<List<String>> valuesList, boolean haveSorted)`	Insert sorted string-formatted aligned records for a single device	Same as above, plus w `haveSorted`: whether the data is already sorted
`insertTablet(Tablet tablet)`	Insert a single Tablet data	`tablet`: The Tablet data to be inserted
`insertTablet(Tablet tablet, boolean sorted)`	Insert a sorted Tablet data	Same as above, plus `sorted`: whether the data is already sorted
`insertAlignedTablet(Tablet tablet)`	Insert an aligned Tablet data	`tablet`: The Tablet data to be inserted
`insertAlignedTablet(Tablet tablet, boolean sorted)`	Insert a sorted aligned Tablet data	Same as above, plus `sorted`: whether the data is already sorted
`insertTablets(Map<String, Tablet> tablets)`	Insert multiple Tablet data in batch	`tablets`: Mapping from device IDs to Tablet data
`insertTablets(Map<String, Tablet> tablets, boolean sorted)`	Insert sorted multiple Tablet data in batch	Same as above, plus `sorted`: whether the data is already sorted
`insertAlignedTablets(Map<String, Tablet> tablets)`	Insert multiple aligned Tablet data in batch	`tablets`: Mapping from device IDs to Tablet data
`insertAlignedTablets(Map<String, Tablet> tablets, boolean sorted)`	Insert sorted multiple aligned Tablet data in batch	Same as above, plus `sorted`: whether the data is already sorted

3.2.3 Data Deletion

Method Name	Function Description	Parameter Explanation
`deleteTimeseries(String path)`	Delete a single time series	`path`: The path of the time series
`deleteTimeseries(List<String> paths)`	Batch delete time series	`paths`: A list of time series paths
`deleteData(String path, long endTime)`	Delete historical data for a specified path	`path`: The path，`endTime`: The end timestamp
`deleteData(List<String> paths, long endTime)`	Batch delete historical data for specified paths	`paths`: A list of paths，`endTime`: The end timestamp
`deleteData(List<String> paths, long startTime, long endTime)`	Delete historical data within a time range for specified paths	Same as above, plus `startTime`: The start timestamp

3.2.4 Data Query

Method Name	Function Description	Parameter Explanation
`executeQueryStatement(String sql)`	Execute a query statement	`sql`: The query SQL statement
`executeQueryStatement(String sql, long timeoutInMs)`	Execute a query statement with timeout	`sql`: The query SQL statement, `timeoutInMs`: The query timeout (in milliseconds)
`executeRawDataQuery(List<String> paths, long startTime, long endTime)`	Query raw data for specified paths	paths: A list of query paths, `startTime`: The start timestamp, `endTime`: The end timestamp
`executeRawDataQuery(List<String> paths, long startTime, long endTime, long timeOut)`	Query raw data for specified paths (with timeout)	Same as above, plus `timeOut`: The timeout time
`executeLastDataQuery(List<String> paths)`	Query the latest data	`paths`: A list of query paths
`executeLastDataQuery(List<String> paths, long lastTime)`	Query the latest data at a specified time	`paths`: A list of query paths, `lastTime`: The specified timestamp
`executeLastDataQuery(List<String> paths, long lastTime, long timeOut)`	Query the latest data at a specified time (with timeout)	Same as above, plus `timeOut`: The timeout time
`executeLastDataQueryForOneDevice(String db, String device, List<String> sensors, boolean isLegalPathNodes)`	Query the latest data for a single device	`db`: The database name, `device`: The device name, `sensors`: A list of sensors, `isLegalPathNodes`: Whether the path nodes are legal
`executeAggregationQuery(List<String> paths, List<TAggregationType> aggregations)`	Execute an aggregation query	`paths`: A list of query paths, `aggregations`: A list of aggregation types
`executeAggregationQuery(List<String> paths, List<TAggregationType> aggregations, long startTime, long endTime)`	Execute an aggregation query with a time range	Same as above, plus `startTime`: The start timestamp, `endTime`:` The end timestamp
`executeAggregationQuery(List<String> paths, List<TAggregationType> aggregations, long startTime, long endTime, long interval)`	Execute an aggregation query with a time interval	Same as above, plus `interval`: The time interval
`executeAggregationQuery(List<String> paths, List<TAggregationType> aggregations, long startTime, long endTime, long interval, long slidingStep)`	Execute a sliding window aggregation query	Same as above, plus `slidingStep`: The sliding step
`fetchAllConnections()`	Get information of all active connections	No parameters

3.2.5 System Status and Backup

Method Name	Function Description	Parameter Explanation
`getBackupConfiguration()`	Get backup configuration information	No parameters
`fetchAllConnections()`	Get information of all active connections	No parameters
`getSystemStatus()`	Get the system status	Deprecated, returns `SystemStatus.NORMAL`