Stream Execution Environment

/**
 * Get the default execution environment, which is determined based on the context.
 * In an IDE or as a regular program: creates a local environment
 * In a cluster: creates the cluster environment
 */
static StreamExecutionEnvironment getExecutionEnvironment();

/**
 * Create a local execution environment for testing and development
 * @param parallelism - the parallelism for the local environment
 */
static StreamExecutionEnvironment createLocalEnvironment(int parallelism);

/**
 * Create a local execution environment with default parallelism
 */
static StreamExecutionEnvironment createLocalEnvironment();

/**
 * Create a remote execution environment for cluster deployment
 * @param host - the host of the JobManager
 * @param port - the port of the JobManager
 * @param jarFiles - JAR files to be shipped to the cluster
 */
static StreamExecutionEnvironment createRemoteEnvironment(
    String host, 
    int port, 
    String... jarFiles
);

// Get default environment (most common)
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

// Create local environment for testing
StreamExecutionEnvironment localEnv = StreamExecutionEnvironment.createLocalEnvironment(4);

// Create remote environment for cluster
StreamExecutionEnvironment remoteEnv = StreamExecutionEnvironment.createRemoteEnvironment(
    "jobmanager-host", 6123, "my-job.jar"
);

/**
 * Create a DataStream from the given elements
 * @param data - the elements to create the stream from
 */
<T> DataStreamSource<T> fromElements(T... data);

/**
 * Create a DataStream from a collection
 * @param data - the collection to create the stream from
 */
<T> DataStreamSource<T> fromCollection(Collection<T> data);

/**
 * Create a DataStream from a collection with type information
 * @param data - the collection to create the stream from
 * @param typeInfo - explicit type information
 */
<T> DataStreamSource<T> fromCollection(Collection<T> data, TypeInformation<T> typeInfo);

/**
 * Add a custom source function to create a data stream
 * @param function - the source function
 */
<T> DataStreamSource<T> addSource(SourceFunction<T> function);

/**
 * Add a custom source function with type information
 * @param function - the source function
 * @param typeInfo - explicit type information
 */
<T> DataStreamSource<T> addSource(SourceFunction<T> function, TypeInformation<T> typeInfo);

/**
 * Read text from a socket connection
 * @param hostname - the hostname to connect to
 * @param port - the port to connect to
 */
DataStreamSource<String> socketTextStream(String hostname, int port);

/**
 * Read text from a socket with custom delimiter
 * @param hostname - the hostname to connect to
 * @param port - the port to connect to
 * @param delimiter - the delimiter to split records
 */
DataStreamSource<String> socketTextStream(String hostname, int port, String delimiter);

/**
 * Read the entire text file from the file system
 * @param filePath - the path to the file
 */
DataStreamSource<String> readTextFile(String filePath);

/**
 * Read text file with character set
 * @param filePath - the path to the file
 * @param charsetName - the character set name
 */
DataStreamSource<String> readTextFile(String filePath, String charsetName);

/**
 * Generate a sequence of numbers (deprecated)
 * @deprecated Use fromSequence() instead
 * @param from - start of sequence (inclusive)
 * @param to - end of sequence (inclusive)
 */
@Deprecated
DataStreamSource<Long> generateSequence(long from, long to);

/**
 * Create a sequence of numbers from 'from' to 'to'
 * @param from - start of sequence (inclusive)
 * @param to - end of sequence (inclusive)
 * @return DataStream of Long values
 */
DataStreamSource<Long> fromSequence(long from, long to);

/**
 * Create a DataStream from a modern unified Source
 * @param source - the Source to read from
 * @param timestampsAndWatermarks - watermark strategy for event time
 * @param sourceName - name of the source
 * @return DataStream from the source
 */
<T> DataStreamSource<T> fromSource(
    Source<T, ?, ?> source, 
    WatermarkStrategy<T> timestampsAndWatermarks, 
    String sourceName
);

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

// From elements
DataStream<String> elements = env.fromElements("hello", "world", "flink");

// From collection
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
DataStream<Integer> fromList = env.fromCollection(numbers);

// Socket stream
DataStream<String> socketStream = env.socketTextStream("localhost", 9999);

// File stream
DataStream<String> fileStream = env.readTextFile("/path/to/input.txt");

// Sequence
DataStream<Long> sequence = env.generateSequence(1, 1000);

// Custom source
DataStream<MyEvent> customStream = env.addSource(new MyCustomSource());

/**
 * Execute the streaming job
 * @return JobExecutionResult containing execution information
 */
JobExecutionResult execute() throws Exception;

/**
 * Execute the streaming job with a custom name
 * @param jobName - the name of the job
 * @return JobExecutionResult containing execution information
 */
JobExecutionResult execute(String jobName) throws Exception;

/**
 * Execute the streaming job asynchronously
 * @return JobClient for managing the running job
 */
JobClient executeAsync() throws Exception;

/**
 * Execute the streaming job asynchronously with a custom name
 * @param jobName - the name of the job
 * @return JobClient for managing the running job
 */
JobClient executeAsync(String jobName) throws Exception;

// Execute with default name
JobExecutionResult result = env.execute();

// Execute with custom name
JobExecutionResult result = env.execute("My Streaming Job");

// Access execution results
System.out.println("Job ID: " + result.getJobID());
System.out.println("Execution Time: " + result.getNetRuntime());

/**
 * Set the parallelism for operations executed through this environment
 * @param parallelism - the parallelism
 */
StreamExecutionEnvironment setParallelism(int parallelism);

/**
 * Get the default parallelism
 */
int getParallelism();

/**
 * Set the maximum parallelism
 * @param maxParallelism - the maximum parallelism
 */
StreamExecutionEnvironment setMaxParallelism(int maxParallelism);

/**
 * Get the maximum parallelism
 */
int getMaxParallelism();

/**
 * Enable checkpointing for fault tolerance
 * @param interval - checkpoint interval in milliseconds
 */
StreamExecutionEnvironment enableCheckpointing(long interval);

/**
 * Enable checkpointing with mode
 * @param interval - checkpoint interval in milliseconds
 * @param mode - checkpointing mode (EXACTLY_ONCE or AT_LEAST_ONCE)
 */
StreamExecutionEnvironment enableCheckpointing(long interval, CheckpointingMode mode);

/**
 * Get the checkpoint configuration
 */
CheckpointConfig getCheckpointConfig();

/**
 * Set the time characteristic for the application (deprecated)
 * @deprecated Time characteristics are deprecated. Use source-based watermark assignment instead.
 * @param characteristic - the time characteristic (EventTime, ProcessingTime, IngestionTime)
 */
@Deprecated
StreamExecutionEnvironment setStreamTimeCharacteristic(TimeCharacteristic characteristic);

/**
 * Set the runtime execution mode (batch or streaming)
 * @param executionMode - BATCH for bounded data, STREAMING for unbounded data
 * @return StreamExecutionEnvironment for method chaining
 */
StreamExecutionEnvironment setRuntimeMode(RuntimeExecutionMode executionMode);

/**
 * Get the time characteristic
 */
TimeCharacteristic getStreamTimeCharacteristic();

/**
 * Set the buffer timeout for network buffers
 * @param timeoutMillis - timeout in milliseconds
 */
StreamExecutionEnvironment setBufferTimeout(long timeoutMillis);

/**
 * Get the buffer timeout
 */
long getBufferTimeout();

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

// Set parallelism
env.setParallelism(4);
env.setMaxParallelism(128);

// Enable checkpointing
env.enableCheckpointing(5000); // every 5 seconds
env.enableCheckpointing(5000, CheckpointingMode.EXACTLY_ONCE);

// Configure checkpointing
CheckpointConfig config = env.getCheckpointConfig();
config.setMinPauseBetweenCheckpoints(500);
config.setCheckpointTimeout(60000);

// Set time characteristic
env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);

// Set buffer timeout
env.setBufferTimeout(100);

/**
 * Get the execution configuration
 */
ExecutionConfig getConfig();

StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
ExecutionConfig config = env.getConfig();

// Configure execution settings
config.setAutoWatermarkInterval(1000);
config.setLatencyTrackingInterval(2000);
config.enableObjectReuse();
config.setGlobalJobParameters(ParameterTool.fromArgs(args));

abstract class StreamExecutionEnvironment {
    // Factory methods, source creation, execution, and configuration methods as above
}

class LocalStreamEnvironment extends StreamExecutionEnvironment {
    // Local execution environment implementation
}

class RemoteStreamEnvironment extends StreamExecutionEnvironment {
    // Remote cluster execution environment implementation
}

// Data source type
class DataStreamSource<T> extends SingleOutputStreamOperator<T> {
    // Represents a data source in the streaming topology
}

enum TimeCharacteristic {
    ProcessingTime,  // Processing time semantics
    IngestionTime,   // Ingestion time semantics  
    EventTime        // Event time semantics
}

enum CheckpointingMode {
    EXACTLY_ONCE,    // Exactly-once processing guarantees
    AT_LEAST_ONCE    // At-least-once processing guarantees
}

class ExecutionConfig {
    // Configuration for job execution
    void setAutoWatermarkInterval(long interval);
    void setLatencyTrackingInterval(long interval);
    void enableObjectReuse();
    void setGlobalJobParameters(GlobalJobParameters parameters);
}

class CheckpointConfig {
    // Configuration for checkpointing
    void setCheckpointingMode(CheckpointingMode mode);
    void setMinPauseBetweenCheckpoints(long minPause);
    void setCheckpointTimeout(long timeout);
    void setMaxConcurrentCheckpoints(int maxConcurrent);
}

class JobExecutionResult {
    // Result of job execution
    JobID getJobID();
    long getNetRuntime();
    long getNetRuntime(TimeUnit desiredUnit);
    Map<String, Object> getAllAccumulatorResults();
    <T> T getAccumulatorResult(String accumulatorName);
}