feat(py-client): Specify public API and add example to README.md (#163)

Author: lcian

clients/python/README.md

@@ -1,8 +1,37 @@
 # Objectstore Client
 
+The client is used to interface with the objectstore backend. It handles
+responsibilities like transparent compression, and making sure that uploads and
+downloads are done as efficiently as possible.
+
 ## Usage
 
-TODO
+```python
+import datetime
+
+from objectstore_client import ClientBuilder, NoOpMetricsBackend, TimeToLive
+
+client_builder = ClientBuilder(
+    "http://localhost:8888",
+    "my_usecase",
+    metrics_backend=NoOpMetricsBackend(),  # optionally, provide your own MetricsBackend implementation
+)
+client = client_builder.for_project(42, 424242)
+
+object_id = client.put(
+    b"Hello, world!",
+    metadata={"key": "value"},
+    expiration_policy=TimeToLive(datetime.timedelta(days=1)),
+)
+
+result = client.get(object_id)
+
+content = result.payload.read()
+assert content == b"Hello, world!"
+assert result.metadata.custom["key"] == "value"
+
+client.delete(object_id)
+```
 
 ## Development
 

clients/python/src/objectstore_client/__init__.py

@@ -0,0 +1,23 @@
+from objectstore_client.client import Client, ClientBuilder, ClientError, GetResult
+from objectstore_client.metadata import (
+    Compression,
+    ExpirationPolicy,
+    Metadata,
+    TimeToIdle,
+    TimeToLive,
+)
+from objectstore_client.metrics import MetricsBackend, NoOpMetricsBackend
+
+__all__ = [
+    "Client",
+    "ClientBuilder",
+    "ClientError",
+    "GetResult",
+    "Compression",
+    "ExpirationPolicy",
+    "Metadata",
+    "TimeToIdle",
+    "TimeToLive",
+    "MetricsBackend",
+    "NoOpMetricsBackend",
+]