add event-stream support

Author: giancarloromeo

packages/service-library/src/servicelib/aiohttp/rest_responses.py

@@ -7,7 +7,13 @@
 from models_library.rest_error import ErrorGet, ErrorItemType
 
 from ..aiohttp.status import HTTP_200_OK
-from ..mimetype_constants import MIMETYPE_APPLICATION_JSON
+from ..common_headers import (
+    CACHE_CONTROL,
+    CACHE_CONTROL_NO_CACHE,
+    CONNECTION,
+    CONNECTION_KEEP_ALIVE,
+)
+from ..mimetype_constants import MIMETYPE_APPLICATION_JSON, MIMETYPE_TEXT_EVENT_STREAM
 from ..rest_constants import RESPONSE_MODEL_POLICY
 from ..rest_responses import is_enveloped
 from ..status_codes_utils import get_code_description, get_code_display_name, is_error
@@ -36,6 +42,17 @@ def create_data_response(data: Any, *, status: int = HTTP_200_OK) -> web.Respons
     return web.json_response(enveloped_payload, dumps=json_dumps, status=status)
 
 
+def create_event_stream_response(event_generator: Any) -> web.Response:
+    return web.Response(
+        body=event_generator(),
+        headers={
+            CACHE_CONTROL: CACHE_CONTROL_NO_CACHE,
+            CONNECTION: CONNECTION_KEEP_ALIVE,
+        },
+        content_type=MIMETYPE_TEXT_EVENT_STREAM,
+    )
+
+
 MAX_STATUS_MESSAGE_LENGTH: Final[int] = 100
 
 

packages/service-library/src/servicelib/common_headers.py

@@ -1,5 +1,14 @@
 from typing import Final
 
+# HTTP Headers
+CACHE_CONTROL: Final[str] = "Cache-Control"
+CONNECTION: Final[str] = "Connection"
+
+# HTTP Header Values
+CACHE_CONTROL_NO_CACHE: Final[str] = "no-cache"
+CONNECTION_KEEP_ALIVE: Final[str] = "keep-alive"
+
+# Custom Headers
 UNDEFINED_DEFAULT_SIMCORE_USER_AGENT_VALUE: Final[str] = "undefined"
 X_DYNAMIC_SIDECAR_REQUEST_DNS: Final[str] = "X-Dynamic-Sidecar-Request-DNS"
 X_DYNAMIC_SIDECAR_REQUEST_SCHEME: Final[str] = "X-Dynamic-Sidecar-Request-Scheme"

packages/service-library/src/servicelib/mimetype_constants.py

@@ -7,12 +7,14 @@
 
 SEE https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types
 """
+
 from typing import Final
 
 # NOTE: mimetypes (https://docs.python.org/3/library/mimetypes.html) is already a module in python
 
 MIMETYPE_APPLICATION_JSON: Final[str] = "application/json"
 MIMETYPE_APPLICATION_ND_JSON: Final[str] = "application/x-ndjson"
 MIMETYPE_APPLICATION_ZIP: Final[str] = "application/zip"
+MIMETYPE_TEXT_EVENT_STREAM: Final[str] = "text/event-stream"
 MIMETYPE_TEXT_HTML: Final[str] = "text/html"
 MIMETYPE_TEXT_PLAIN: Final[str] = "text/plain"