python: Introduce a new connection API that is a bit less stateful.

python/dazl/__init__.py

@@ -53,6 +53,7 @@
 from .pretty.table import write_acs
 from .prim import ContractData, ContractId, DazlError, FrozenDict as frozendict, Party
 from .protocols.commands import Command
+from .protocols.ledgerapi import Connection, connect
 from .util.logging import setup_default_logger
 
 try:

python/dazl/client/api.py

@@ -142,10 +142,19 @@ class async_network:
     """
 
     def __init__(
-        self, url: "Optional[str]" = None, dars: "Optional[Union[Dar, Collection[Dar]]]" = None
+        self,
+        url: "Optional[str]" = None,
+        dars: "Optional[Union[Dar, Collection[Dar]]]" = None,
+        future_api: bool = False,
     ):
         LOG.debug("async_network.__init__")
-        self.network = Network()
+        if future_api:
+            # inline import here to avoid import cycles
+            from ..compat.v8_network import Network as V8Network
+
+            self.network = V8Network()
+        else:
+            self.network = Network()
         if url:
             self.network.set_config(url=url)
         self.dars = as_list(dars)  # type: List[Dar]
@@ -294,7 +303,7 @@ def start_in_background(
         """
         if validate_install_signal_handlers(install_signal_handlers):
             self._impl.invoker.install_signal_handlers()
-        return self._impl.start(daemon)
+        return self._impl.start_in_background(daemon, install_signal_handlers=False)
 
     def shutdown(self) -> "Optional[Awaitable[None]]":
         """

python/dazl/client/state.py

@@ -1,7 +1,7 @@
 # Copyright (c) 2017-2021 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
-from asyncio import Future, sleep
+from asyncio import Future, get_event_loop, sleep
 from collections import defaultdict
 from dataclasses import dataclass
 import datetime
@@ -60,7 +60,7 @@ class ContractContextualData:
 
 
 class ActiveContractSet:
-    def __init__(self, invoker: "Invoker", lookup: "SymbolLookup"):
+    def __init__(self, invoker: "Optional[Invoker]", lookup: "SymbolLookup"):
         self.invoker = invoker
         self.lookup = lookup
         self._tcdata = defaultdict(
@@ -207,8 +207,13 @@ def register_query(self, query: "PendingQuery") -> None:
 
 
 class PendingQuery:
-    def __init__(self, invoker: "Invoker", match, min_count: int):
-        self.future = invoker.create_future()  # type: Awaitable[Collection[ContractContextualData]]
+    def __init__(self, invoker: "Optional[Invoker]", match, min_count: int):
+        if invoker is not None:
+            self.future = (
+                invoker.create_future()
+            )  # type: Awaitable[Collection[ContractContextualData]]
+        else:
+            self.future = get_event_loop().create_future()
         self.match = match
         self.min_count = min_count
 

python/dazl/compat/__init__.py

@@ -0,0 +1,9 @@
+# Copyright (c) 2017-2021 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+__all__ = ["AIOGlobalClient", "AIOPartyClient", "Network", "NotSupportedError"]
+
+
+from .v8 import NotSupportedError
+from .v8_client_aio import AIOGlobalClient, AIOPartyClient
+from .v8_network import Network

python/dazl/compat/_messages.py

@@ -0,0 +1,16 @@
+_NS_LEDGER_ID_DEPRECATED = (
+    "fetching ledger_id from an event is deprecated; instead get it from the connection (or "
+    "consider if knowing the ledger ID is important to your usecase)"
+)
+
+_NS_ACS_DEPRECATED = (
+    "acs functions are deprecated; you should keep your own store, or use contract keys to avoid "
+    "needing to work with local state"
+)
+
+
+COMMAND_ID = "command_id is no longer accessible in the new API"
+WORKFLOW_ID = "workflow_id is no longer accessible in the new API"
+EVENT_ID = "event_id is no longer accessible in the new API"
+WITNESS_PARTIES = "witness_parties is no longer accessible in the new API"
+PARTY = "reading `party` from a connection is ambiguous when multi-party submissions are being used; consider an alternate way of determining an appropriate Party in this context"

python/dazl/compat/v8.py

@@ -0,0 +1,40 @@
+# Copyright (c) 2017-2021 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+"""
+This module contains symbols to aid in a gradual migration of v5-v7 code to v8. These symbols will
+be marked as deprecated in v8, and be removed in v9.
+"""
+from typing import TypeVar
+
+from ..protocols.core import AEventHandler, ArchiveEvent, CreateEvent, InitEvent, ReadyEvent
+
+__all__ = ["ConnectionReuseWarning", "CallbackReturnValueWarning", "NotSupportedError"]
+
+InitFn = TypeVar("InitFn", bound=AEventHandler[InitEvent])
+ReadyFn = TypeVar("ReadyFn", bound=AEventHandler[ReadyEvent])
+CreateFn = TypeVar("CreateFn", bound=AEventHandler[CreateEvent])
+ArchiveFn = TypeVar("ArchiveFn", bound=AEventHandler[ArchiveEvent])
+DEFAULT_TIMEOUT_SECONDS = 30
+
+
+class NotSupportedError(Exception):
+    """
+    Error raised when calling an API that exists on :class:`Network` but is not supported on
+    :class:`ConnectionFactory`.
+    """
+
+
+class ConnectionReuseWarning(DeprecationWarning):
+    """
+    Warning raised when Network.aio_party or Network.simple_party are called more than once with
+    the same party literal. Connection sharing will no longer explicitly be provided by dazl in the
+    v8 API; any connection sharing must be instead managed by your application.
+    """
+
+
+class CallbackReturnValueWarning(DeprecationWarning):
+    """
+    Warning raised when a callback returns a value instead of directly submitting a command itself.
+    This style of callback is not supported by the dazl v8 API.
+    """