Refactor Python user API (LangStream#495)

examples/applications/llamaindex-cassandra-sink/python/llamaindex_cassandra.py

@@ -16,19 +16,18 @@
 
 import base64
 import io
-from typing import List, Optional, Dict, Any
+from typing import Dict, Any
 
 import openai
 from cassandra.auth import PlainTextAuthProvider
 from cassandra.cluster import Cluster
-from langstream import Sink, CommitCallback, Record
+from langstream import Sink, Record
 from llama_index import VectorStoreIndex, Document
 from llama_index.vector_stores import CassandraVectorStore
 
 
 class LlamaIndexCassandraSink(Sink):
     def __init__(self):
-        self.commit_cb: Optional[CommitCallback] = None
         self.config = None
         self.session = None
         self.index = None
@@ -63,13 +62,8 @@ def start(self):
 
         self.index = VectorStoreIndex.from_vector_store(vector_store)
 
-    def write(self, records: List[Record]):
-        for record in records:
-            self.index.insert(Document(text=record.value()))
-            self.commit_cb.commit([record])
-
-    def set_commit_callback(self, commit_callback: CommitCallback):
-        self.commit_cb = commit_callback
+    def write(self, record: Record):
+        self.index.insert(Document(text=record.value()))
 
     def close(self):
         if self.session:

examples/applications/python-processor-embeddings/python/embeddings.py

@@ -25,11 +25,8 @@ def init(self, config):
         print("init", config)
         openai.api_key = config["openaiKey"]
 
-    def process(self, records):
-        processed_records = []
-        for record in records:
-            embedding = get_embedding(record.value(), engine="text-embedding-ada-002")
-            result = {"input": str(record.value()), "embedding": embedding}
-            new_value = json.dumps(result)
-            processed_records.append((record, [(new_value,)]))
-        return processed_records
+    def process(self, record):
+        embedding = get_embedding(record.value(), engine="text-embedding-ada-002")
+        result = {"input": str(record.value()), "embedding": embedding}
+        new_value = json.dumps(result)
+        return [(new_value,)]

examples/applications/python-processor-exclamation/python/example.py

@@ -15,10 +15,10 @@
 # limitations under the License.
 #
 
-from langstream import SimpleRecord, SingleRecordProcessor
+from langstream import SimpleRecord, Processor
 
 
 # Example Python processor that adds an exclamation mark to the end of the record value
-class Exclamation(SingleRecordProcessor):
-    def process_record(self, record):
+class Exclamation(Processor):
+    def process(self, record):
         return [SimpleRecord(record.value() + "!!", headers=record.headers())]

langstream-e2e-tests/src/test/resources/apps/python-processor/python/example.py

@@ -14,15 +14,15 @@
 # limitations under the License.
 #
 
-from langstream import SimpleRecord, SingleRecordProcessor
+from langstream import SimpleRecord, Processor
 
 
-class Exclamation(SingleRecordProcessor):
+class Exclamation(Processor):
     def init(self, config):
         print("init", config)
         self.secret_value = config["secret_value"]
 
-    def process_record(self, record):
+    def process(self, record):
         return [
             SimpleRecord(
                 record.value() + "!!" + self.secret_value, headers=record.headers()

langstream-e2e-tests/src/test/resources/apps/python-sink/python/example.py

@@ -20,25 +20,19 @@
 
 class TestSink(object):
     def __init__(self):
-        self.commit_callback = None
         self.producer = None
 
     def init(self, config):
         logging.info("Init config: " + str(config))
         self.producer = Producer({"bootstrap.servers": config["bootstrapServers"]})
 
-    def write(self, records):
-        logging.info("Write records: " + str(records))
+    def write(self, record):
+        logging.info("Write record: " + str(record))
         try:
-            for record in records:
-                self.producer.produce(
-                    "ls-test-output", value=("write: " + record.value()).encode("utf-8")
-                )
+            self.producer.produce(
+                "ls-test-output", value=("write: " + record.value()).encode("utf-8")
+            )
             self.producer.flush()
-            self.commit_callback.commit(records)
         except Exception as e:
             logging.error("Error writing records: " + str(e))
             raise e
-
-    def set_commit_callback(self, commit_callback):
-        self.commit_callback = commit_callback

langstream-runtime/langstream-runtime-impl/src/main/python/examples/example.py

@@ -27,12 +27,9 @@ def read(self):
         print(f"read {records}")
         return records
 
-    def set_commit_callback(self, cb):
-        pass
+    def process(self, record):
+        print(f"process {record}")
+        return [record]
 
-    def process(self, records):
-        print(f"process {records}")
-        return [(record, [record]) for record in records]
-
-    def write(self, records):
-        print(f"write {records}")
+    def write(self, record):
+        print(f"write {record}")

langstream-runtime/langstream-runtime-impl/src/main/python/langstream/__init__.py

@@ -22,9 +22,8 @@
     Sink,
     Source,
     Processor,
-    CommitCallback,
 )
-from .util import SimpleRecord, SingleRecordProcessor, AvroValue
+from .util import SimpleRecord, AvroValue
 
 __all__ = [
     "Record",
@@ -33,8 +32,6 @@
     "Source",
     "Sink",
     "Processor",
-    "CommitCallback",
     "SimpleRecord",
-    "SingleRecordProcessor",
     "AvroValue",
 ]

langstream-runtime/langstream-runtime-impl/src/main/python/langstream/api.py

@@ -16,7 +16,8 @@
 #
 
 from abc import ABC, abstractmethod
-from typing import Any, List, Tuple, Dict, Union
+from concurrent.futures import Future
+from typing import Any, List, Tuple, Dict, Union, Optional
 
 __all__ = [
     "Record",
@@ -25,7 +26,6 @@
     "Source",
     "Sink",
     "Processor",
-    "CommitCallback",
 ]
 
 
@@ -91,9 +91,9 @@ class Source(Agent):
     def read(self) -> List[RecordType]:
         """The Source agent generates records and returns them as list of records.
 
-        :returns: the list of records. The records must either respect the Record
-        API contract (have methods value(), key() and so on) or be a dict or
-        tuples/list.
+        :returns: the list of records.
+        The records must either respect the Record API contract (have methods value(),
+        key() and so on) or be a dict or tuples/list.
         If the records are dict, the keys if present shall be "value", "key",
         "headers", "origin" and "timestamp".
         Eg:
@@ -108,15 +108,15 @@ def read(self) -> List[RecordType]:
         """
         pass
 
-    def commit(self, records: List[Record]):
-        """Called by the framework to indicate the records that have been successfully
+    def commit(self, record: Record):
+        """Called by the framework to indicate that a record has been successfully
         processed."""
         pass
 
     def permanent_failure(self, record: Record, error: Exception):
         """Called by the framework to indicate that the agent has permanently failed to
-        process the record.
-        The Source agent may send the records to a dead letter queue or raise an error.
+        process a record.
+        The Source agent may send the record to a dead letter queue or raise an error.
         """
         raise error
 
@@ -129,61 +129,44 @@ class Processor(Agent):
 
     @abstractmethod
     def process(
-        self, records: List[Record]
-    ) -> List[Tuple[Record, Union[List[RecordType], Exception]]]:
-        """The agent processes records and returns a list containing the associations of
-        these records with the result of these record processing.
-        The result of each record processing is a list of new records or an exception.
-        The transactionality of the function is guaranteed by the runtime.
-
-        :returns: the list of associations between an input record and the output
-        records processed from it.
-        Eg: [(input_record, [output_record1, output_record2])]
-        If an input record cannot be processed, the associated element shall be an
-        exception.
-        Eg: [(input_record, RuntimeError("Could not process"))]
+        self, record: Record
+    ) -> Union[List[RecordType], Future[List[RecordType]]]:
+        """The agent processes a record and returns a list of new records.
+
+        :returns: the list of records or a concurrent.futures.Future that will complete
+        with the list of records.
         When the processing is successful, the output records must either respect the
         Record API contract (have methods value(), key() and so on) or be a dict or
         tuples/list.
         If the records are dict, the keys if present shall be "value", "key",
         "headers", "origin" and "timestamp".
         Eg:
-        * if you return [(input_record, [{"value": "foo"}])] a record
-        Record(value="foo") will be built.
+        * if you return {"value": "foo"} a record Record(value="foo") will be built.
         If the output records are tuples/list, the framework will automatically
         construct Record objects from them with the values in the following order :
         value, key, headers, origin, timestamp.
         Eg:
-        * if you return [(input_record, [("foo",)])] a record Record(value="foo") will
-        be built.
-        * if you return [(input_record, [("foo", "bar")])] a record
-        Record(value="foo", key="bar") will be built.
+        * if you return ("foo",) a record Record(value="foo") will be built.
+        * if you return ("foo", "bar") a record Record(value="foo", key="bar") will be
+        built.
         """
         pass
 
 
-class CommitCallback(ABC):
-    @abstractmethod
-    def commit(self, records: List[Record]):
-        """Called by a Sink to indicate the records that have been successfully
-        written."""
-        pass
-
-
 class Sink(Agent):
     """The Sink agent interface
 
     A Sink agent is used by the runtime to write Records.
     """
 
     @abstractmethod
-    def write(self, records: List[Record]):
+    def write(self, record: Record) -> Optional[Future[None]]:
         """The Sink agent receives records from the framework and typically writes them
-        to an external service."""
-        pass
+        to an external service.
+        For a synchronous result, return None/nothing if successful or otherwise raise
+        an Exception.
+        For an asynchronous result, return a concurrent.futures.Future.
 
-    @abstractmethod
-    def set_commit_callback(self, commit_callback: CommitCallback):
-        """Called by the framework to specify a CommitCallback that shall be used by the
-        Sink to indicate the records that have been written."""
+        :returns: nothing if the write is successful or a concurrent.futures.Future
+        """
         pass

langstream-runtime/langstream-runtime-impl/src/main/python/langstream/util.py

@@ -14,13 +14,12 @@
 # limitations under the License.
 #
 
-from abc import abstractmethod
 from dataclasses import dataclass
-from typing import Any, List, Tuple, Union
+from typing import Any, List, Tuple
 
-from .api import Record, Processor, RecordType
+from .api import Record
 
-__all__ = ["SimpleRecord", "SingleRecordProcessor", "AvroValue"]
+__all__ = ["SimpleRecord", "AvroValue"]
 
 
 class SimpleRecord(Record):
@@ -57,46 +56,15 @@ def timestamp(self) -> int:
 
     def __str__(self):
         return (
-            f"Record(value={self._value}, key={self._key}, origin={self._origin}, "
-            f"timestamp={self._timestamp}, headers={self._headers})"
+            f"SimpleRecord(value={self._value}, key={self._key}, "
+            f"origin={self._origin},timestamp={self._timestamp}, "
+            f"headers={self._headers})"
         )
 
     def __repr__(self):
         return self.__str__()
 
 
-class SingleRecordProcessor(Processor):
-    """A Processor that processes records one-by-one"""
-
-    @abstractmethod
-    def process_record(self, record: Record) -> List[RecordType]:
-        """Process one record and return a list of records or raise an exception.
-
-        :returns: the list of processed records. The records must either respect the
-        Record API contract (have methods value(), key() and so on) or be tuples/list.
-        If the records are tuples/list, the framework will automatically construct
-        Record objects from them with the values in the following order : value, key,
-        headers, origin, timestamp.
-        Eg:
-        * if you return [("foo",)] a record Record(value="foo") will be built.
-        * if you return [("foo", "bar")] a record Record(value="foo", key="bar") will
-        be built.
-        """
-        pass
-
-    def process(
-        self, records: List[Record]
-    ) -> List[Tuple[Record, Union[List[RecordType], Exception]]]:
-        results = []
-        for record in records:
-            try:
-                processed = self.process_record(record)
-                results.append((record, processed))
-            except Exception as e:
-                results.append((record, e))
-        return results
-
-
 @dataclass
 class AvroValue(object):
     schema: dict