Struct SyncUmaDbClient 

pub struct SyncUmaDbClient { /* private fields */ }

Implementations

impl SyncUmaDbClient

pub fn connect( url: String, ca_path: Option<String>, batch_size: Option<u32>, api_key: Option<String>, ) -> DcbResult<Self>

pub fn subscribe( &self, query: Option<DcbQuery>, after: Option<u64>, ) -> DcbResult<Box<dyn DcbSubscriptionSync + Send + 'static>>

Subscribe to events starting from an optional position. This is a convenience wrapper around the async client’s Subscribe RPC. The returned iterator yields events indefinitely until cancelled or the stream ends.

Examples found in repository

examples/client_sync_insecure.rs (line 93)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Connect to the gRPC server
    let url = "http://localhost:50051".to_string();
    let client = UmaDbClient::new(url).connect()?;

    // Define a consistency boundary
    let boundary = DcbQuery::new().item(
        DcbQueryItem::new()
            .types(["example"])
            .tags(["tag1", "tag2"]),
    );

    // Read events for a decision model
    let mut read_response = client.read(Some(boundary.clone()), None, false, None)?;

    // Build decision model
    while let Some(result) = read_response.next() {
        match result {
            Ok(event) => {
                println!(
                    "Got event at position {}: {:?}",
                    event.position, event.event
                );
            }
            Err(status) => panic!("gRPC stream error: {}", status),
        }
    }

    // Remember the last-known position
    let last_known_position = read_response.head().unwrap();
    println!("Last known position is: {:?}", last_known_position);

    // Produce new event, attaching some metadata (e.g. provenance) that is
    // stored alongside the event and returned when it is read back.
    let event = DcbEvent::default()
        .event_type("example")
        .tags(["tag1", "tag2"])
        .data(b"Hello, world!")
        .uuid(Uuid::new_v4())
        .metadata_entry("source", "client_sync_insecure")
        .metadata_entry("correlation_id", Uuid::new_v4().to_string());

    // Append event in consistency boundary
    let append_condition = DcbAppendCondition {
        fail_if_events_match: boundary.clone(),
        after: last_known_position,
    };
    let position1 = client.append(vec![event.clone()], Some(append_condition.clone()), None)?;

    println!("Appended event at position: {}", position1);

    // Append conflicting event - expect an error
    let conflicting_event = DcbEvent::default()
        .event_type("example")
        .tags(["tag1", "tag2"])
        .data(b"Hello, world!")
        .uuid(Uuid::new_v4()); // different UUID

    let conflicting_result = client.append(
        vec![conflicting_event],
        Some(append_condition.clone()),
        None,
    );

    // Expect an integrity error
    match conflicting_result {
        Err(DcbError::IntegrityError(integrity_error)) => {
            println!("Conflicting event was rejected: {:?}", integrity_error);
        }
        other => panic!("Expected IntegrityError, got {:?}", other),
    }

    // Appending with identical event IDs and append condition is idempotent.
    println!(
        "Retrying to append event at position: {:?}",
        last_known_position
    );
    let position2 = client.append(vec![event.clone()], Some(append_condition.clone()), None)?;

    if position1 == position2 {
        println!("Append method returned same commit position: {}", position2);
    } else {
        panic!("Expected idempotent retry!")
    }

    // Subscribe to all events for a projection
    let mut subscription = client.subscribe(None, None)?;

    // Build an up-to-date view
    while let Some(result) = subscription.next() {
        match result {
            Ok(ev) => {
                println!("Processing event at {}: {:?}", ev.position, ev.event);
                if ev.position == position2 {
                    println!("Projection has processed new event!");
                    break;
                }
            }
            Err(status) => panic!("gRPC stream error: {}", status),
        }
    }

    // Track an upstream position
    let upstream_position = client.get_tracking_info("upstream")?;
    let next_upstream_position = upstream_position.unwrap_or(0) + 1;
    println!("Next upstream position: {next_upstream_position}");
    client.append(
        vec![],
        None,
        Some(TrackingInfo {
            source: "upstream".to_string(),
            position: next_upstream_position,
        }),
    )?;
    assert_eq!(
        next_upstream_position,
        client.get_tracking_info("upstream")?.unwrap()
    );
    println!("Upstream position tracked okay!");

    // Try recording the same upstream position
    let conflicting_result = client.append(
        vec![],
        None,
        Some(TrackingInfo {
            source: "upstream".to_string(),
            position: next_upstream_position,
        }),
    );

    // Expect an integrity error
    match conflicting_result {
        Err(DcbError::IntegrityError(integrity_error)) => {
            println!(
                "Conflicting upstream position was rejected: {:?}",
                integrity_error
            );
        }
        other => panic!("Expected IntegrityError, got {:?}", other),
    }

    Ok(())
}

examples/client_sync_secure.rs (line 116)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Connect to the gRPC server
    let url = "https://localhost:50051".to_string();
    let client = UmaDbClient::new(url)
        .ca_path("server.pem".to_string()) // For self-signed server certificates.
        .api_key("umadb:example-api-key-4f7c2b1d9e5f4a038c1a".to_string())
        .connect()?;

    // Define a consistency boundary
    let cb = DcbQuery {
        items: vec![DcbQueryItem {
            types: vec!["example".to_string()],
            tags: vec!["tag1".to_string(), "tag2".to_string()],
        }],
    };

    // Read events for a decision model
    let mut read_response = client.read(Some(cb.clone()), None, false, None)?;

    // Build decision model
    while let Some(result) = read_response.next() {
        match result {
            Ok(event) => {
                println!(
                    "Got event at position {}: {:?}",
                    event.position, event.event
                );
            }
            Err(status) => panic!("gRPC stream error: {}", status),
        }
    }

    // Remember the last-known position
    let last_known_position = read_response.head().unwrap();
    println!("Last known position is: {:?}", last_known_position);

    // Produce new event, attaching some metadata (e.g. provenance) that is
    // stored alongside the event and returned when it is read back.
    let mut metadata = Vec::new();
    metadata.push(("source".to_string(), "client_sync_secure".to_string()));
    metadata.push(("correlation_id".to_string(), Uuid::new_v4().to_string()));
    let event = DcbEvent {
        event_type: "example".to_string(),
        tags: vec!["tag1".to_string(), "tag2".to_string()],
        data: b"Hello, world!".to_vec(),
        uuid: Some(Uuid::new_v4()),
        metadata,
    };

    // Append event in consistency boundary
    let commit_position1 = client.append(
        vec![event.clone()],
        Some(DcbAppendCondition {
            fail_if_events_match: cb.clone(),
            after: last_known_position,
        }),
        None,
    )?;
    println!("Appended event at position: {}", commit_position1);

    // Append conflicting event - expect an error
    let conflicting_event = DcbEvent {
        event_type: "example".to_string(),
        tags: vec!["tag1".to_string(), "tag2".to_string()],
        data: b"Hello, world!".to_vec(),
        uuid: Some(Uuid::new_v4()), // different UUID
        metadata: Vec::new(),
    };
    let conflicting_result = client.append(
        vec![conflicting_event],
        Some(DcbAppendCondition {
            fail_if_events_match: cb.clone(),
            after: last_known_position,
        }),
        None,
    );

    // Expect an integrity error
    match conflicting_result {
        Err(DcbError::IntegrityError(integrity_error)) => {
            println!("Conflicting event was rejected: {:?}", integrity_error);
        }
        other => panic!("Expected IntegrityError, got {:?}", other),
    }

    // Conditional appends with event UUIDs are idempotent.
    println!(
        "Retrying to append event at position: {:?}",
        last_known_position
    );
    let commit_position2 = client.append(
        vec![event.clone()],
        Some(DcbAppendCondition {
            fail_if_events_match: cb.clone(),
            after: last_known_position,
        }),
        None,
    )?;

    if commit_position1 == commit_position2 {
        println!(
            "Append method returned same commit position: {}",
            commit_position2
        );
    } else {
        panic!("Expected idempotent retry!")
    }

    // Subscribe to all events for a projection
    let mut subscription = client.subscribe(None, None)?;

    // Build an up-to-date view
    while let Some(result) = subscription.next() {
        match result {
            Ok(ev) => {
                println!("Processing event at {}: {:?}", ev.position, ev.event);
                if ev.position == commit_position2 {
                    println!("Projection has processed new event!");
                    break;
                }
            }
            Err(status) => panic!("gRPC stream error: {}", status),
        }
    }

    // Track an upstream position
    let upstream_position = client.get_tracking_info("upstream")?;
    let next_upstream_position = upstream_position.unwrap_or(0) + 1;
    println!("Next upstream position: {next_upstream_position}");
    client.append(
        vec![],
        None,
        Some(TrackingInfo {
            source: "upstream".to_string(),
            position: next_upstream_position,
        }),
    )?;
    assert_eq!(
        next_upstream_position,
        client.get_tracking_info("upstream")?.unwrap()
    );
    println!("Upstream position tracked okay!");

    // Try recording the same upstream position
    let conflicting_result = client.append(
        vec![],
        None,
        Some(TrackingInfo {
            source: "upstream".to_string(),
            position: next_upstream_position,
        }),
    );

    // Expect an integrity error
    match conflicting_result {
        Err(DcbError::IntegrityError(integrity_error)) => {
            println!(
                "Conflicting upstream position was rejected: {:?}",
                integrity_error
            );
        }
        other => panic!("Expected IntegrityError, got {:?}", other),
    }

    Ok(())
}

pub fn close(&self)

Stops all streaming responses opened by this client.

Delegates to the underlying AsyncUmaDbClient; see its close() for details. Affects only streams opened by this client instance.

Trait Implementations

impl DcbEventStoreSync for SyncUmaDbClient

fn read( &self, query: Option<DcbQuery>, start: Option<u64>, backwards: bool, limit: Option<u32>, ) -> DcbResult<Box<dyn DcbReadResponseSync + Send + 'static>>

Reads events from the store based on the provided query and constraints

fn head(&self) -> DcbResult<Option<u64>>

Returns the current head position of the event store, or None if empty

fn get_tracking_info(&self, source: &str) -> DcbResult<Option<u64>>

Returns the greatest recorded upstream position for a tracking source, if any

fn append( &self, events: Vec<DcbEvent>, condition: Option<DcbAppendCondition>, tracking_info: Option<TrackingInfo>, ) -> DcbResult<u64>

Appends given events to the event store, unless the condition fails

fn read_with_head( &self, query: Option<DcbQuery>, start: Option<u64>, backwards: bool, limit: Option<u32>, ) -> Result<(Vec<DcbSequencedEvent>, Option<u64>), DcbError>

Reads events from the store and returns them as a tuple of (Vec<DcbSequencedEvent>, Option<u64>)