What is UmaDB?

UmaDB is a specialist open-source event store built for Dynamic Consistency Boundaries.

UmaDB supports event-driven architectures where consistency rules can adapt dynamically to business needs, rather than being hardwired into the database.

UmaDB directly implements the independent specification for Dynamic Consistency Boundaries created by Bastian Waidelich, Sara Pellegrini, and Paul Grimshaw.

UmaDB stores events in an append-only sequence, indexed by monotonically increasing gapless positions, and can be tagged for fast, precise filtering.

UmaDB offers:

• High-performance concurrency with non-blocking reads and writes
• Optimistic concurrency control to prevent simultaneous write conflicts
• Dynamic business-rule enforcement via query-driven append conditions
• Real-time subscriptions with seamless catch-up and continuous delivery
• OSI-approved permissive open-source licenses (MIT and Apache License 2.0)

UmaDB makes new events fully durable before acknowledgements are returned to clients.

Quick Start

Run Docker image (publish port 50051).

docker run --publish 50051:50051 umadb/umadb:latest

Install Python client (in a virtual environment).

pip install umadb

Read and write events (using the Python client).

from umadb import Client, Event

# Connect to UmaDB server
client = Client("http://localhost:50051")

# Create and append events
event = Event(
    event_type="UserCreated",
    data=b"user data",
    tags=["user", "creation"],
)
position = client.append([event])
print(f"Event appended at position: {position}")

# Read events
events = client.read()
for seq_event in events:
    print(f"Position {seq_event.position}: {seq_event.event.event_type}")