anywise 0.1.5

Anywise let you write your application anywise

Anywise

Anywise is a framework designed to decouple the business logic of your application from its infrastructure, enabling you to use the same code to handle messages from various sources such as web APIs, message queues, AWS Lambda, and more.

Despite being inspired by Hexagonal Architecture and Event-Driven Architecture, Anywise does not bind itself to any specific purpose.

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Source Code: https://github.com/raceychan/anywise

Documentation: On its way here...

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Rationale

Anywise is designed and built to:

1. promote best practices and enterprise architecture in python.
2. isolating bussiness logic from input ports, encapsulate application core, maxmize reusability of logic, allowing one app for web api, kafka, flink, etc.
3. avoid redundant scripts
4. let you write less code than other wise

Install

pip install anywise

Quck Start

Let start with defining messages:

You can define messages however you like, it just needs to be a class, our recommendations are:

• msgspec.Struct
• pydantic.BaseModel
• dataclasses.dataclass

from anywise import Anywise, MessageRegistry, use

class UserCommand: ...
class CreateUser(UserCommand): ...
class UserEvent: ...
class UserCreated(UserEvent): ...

Next step, Register command handler and event listeners.

Function-based handler/listener

registry = MessageRegistry(command_base=UserCommand, event_base=UserEvent)

@registry 
async def create_user(
     command: CreateUser, 
     anywise: Anywise, 
     service: UserService = use(user_service_factory)
):
    await users.signup(command.username, command.user_email)
    await anywise.publish(UserCreated(command.username, command.user_email))

@registry
async def notify_user(event: UserCreated, service: EmailSender):
     await service.send_greeting(command.user_email)

# you can also menually register many handler at once

registry.register_all(create_user, notify_user)

Example usage with fastapi

from anywise import Anywise
from anywise.integration.fastapi import FastWise

@app.post("/users")
async def signup(command: CreateUser, anywise: FastWise) -> User:
    return await anywise.send(command)

Tutorial

Use MessageRegistry to decorate / register a function or a class as handlers of a command

use MessageRegistry to decorate / register a function as a handler of a command.

from anywise import MessageRegistry

registry = MessageRegistry(command_base=UserCommand)

registry.register(hanlder_func)

<<<<<<< HEAD <<<<<<< HEAD

use registry.factory to declear how a dependency should be resolved

@registry.factory
async def conn(engine=use(engine_factory)) -> AsyncGenerator[AsyncConnection, None]:
    async with engine.begin() as conn:
        yield conn

• factory must declear return type
• factory declear with generator/async generator would be considered as a resource
• resource will be opened / closed automatically across message
• declear reuse=False to config if the factory should be reused across handler/listeners.

checkout ididi-github for more details

=======

version/0.1.5

Command handler

a handler h for command c can be either a method or a function

Command handler

a handler h for command c can be either a method or a function

• For fucntion handler, dependency will be injected into h the handler during anywise.send(c)
• For method handler, dependency will be injected into its owner type during anywise.send(c)

refs/remotes/origin/master

<<<<<<< HEAD

registry = MessageRegistry(command_base=UserEvent)

@registry
class UserService:
    def __init__(self, users: UserRepository=use(user_repo_factory), anywise: Anywise):
        self._users = users
        self._anywise = anywise

    async def create_user(self, command: CreateUser, context: Mapping[str, Any]):
        await self._users.add(User(command.user_name, command.user_email))
        await self._anywise.publish(UserCreated(**comand))

<<<<<<< HEAD

• class that contains a series of methods that declear a subclass of the command base in its signature, each method will be treated as a handler to the corresponding command. =======
• For fucntion handler, dependency will be injected into h the handler during anywise.send(c)
• For method handler, dependency will be injected into its owner type during anywise.send(c)

version/0.1.5

registry = MessageRegistry(command_base=UserEvent)

@registry
class UserService:
    def __init__(self, users: UserRepository=use(user_repo_factory), anywise: Anywise):
        self._users = users
        self._anywise = anywise

    async def create_user(self, command: CreateUser, context: Mapping[str, Any]):
        await self._users.add(User(command.user_name, command.user_email))
        await self._anywise.publish(UserCreated(**comand))

• Function/Method that declear a subclass of the command base in its signature will be treated as a handler to that command and its subcommand.

• Class that contains a series of methods that declear a subclass of the command base in its signature, each method will be treated as a handler to the corresponding command.

• If two or more handlers that handle the same command are registered, only the lastly registered one will be used. =======

• Function/Method that declear a subclass of the command base in its signature will be treated as a handler to that command and its subcommand.

• Class that contains a series of methods that declear a subclass of the command base in its signature, each method will be treated as a handler to the corresponding command.

refs/remotes/origin/master

• If two or more handlers that handle the same command are registered, only the lastly registered one will be used.

Event listeners

• same register rule, but each event can have multiple listeners <<<<<<< HEAD <<<<<<< HEAD
• event listener can declear context in its signature, if so, a immutable context object will be shared between listeners. =======
• event listener should return None

refs/remotes/origin/master

registry = MessageRegistry(event_base=UserEvent)
@registry
async def notify_user(event: UserCreated, context: Mapping[str, Any], email: EmailSender) -> None:
    await email.greet_user(event.user_name, event.user_email)

@registry
async def validate_payment(event: UserCreated, context: Mapping[str, Any], payment: PaymentService):
    await payment.validte_user_payment(event.user_name, event.user_email)

=======

• event listener should return None

version/0.1.5

<<<<<<< HEAD

registry = MessageRegistry(event_base=UserEvent)
@registry
async def notify_user(event: UserCreated, context: Mapping[str, Any], email: EmailSender) -> None:
    await email.greet_user(event.user_name, event.user_email)

@registry
async def validate_payment(event: UserCreated, context: Mapping[str, Any], payment: PaymentService):
    await payment.validte_user_payment(event.user_name, event.user_email)

=======

refs/remotes/origin/master

Strategy

• Provide an async callble SendStrategy or PublishStrategy to change the default behavior of how anywise send or publish message
• You might provide strategy like a class with dependencies and async def call for more advanced usage.

from anywise import Anywise, MessageRegistry, concurrent_publish, EventListeners

anywise = Anywise(user_message_registry, publisher=concurrent_publish)

# now all event listeners that listen to type(event) will be called concurrently
await anywise.publish(event) 

Command Guard

you might use Guard to intercept command handling

It is recommended to

• encapsulate non-business logic inside guards, such as logging, rate-limiting, etc.
• store non-business related context info in a mutable context, such as request-id, x-country, etc.
• use inheritance-hierarchy to assign targets for guads.

Function-based Guard

• use MessageRegistry.pre_handle to register a function that only gets called before the command is handled.

@registry.pre_handle
async def validate_command(command: UserCommand, context: dict[str, ty.Any]) -> None:
    if not context["user"]:
        raise InvalidAuthError

• use MessageRegistry.post_handle to register a function that only gets called after the command is handled

@registry.post_handle
async def log_result(command: UserCommand, context: dict[str, ty.Any], response: R) -> R:
    logger.info(f"{command} is handled with {response=}")
    return response

• Guard that guards for a base command will handle all subcommand of the base command

from anywise import AnyWise, MessageRegistry

user_registry = MessageRegistry(command_base=UserCommand)

# in this case, `mark` will be called before `handler_update` or `handler_create` gets called.

@user_registry.pre_handle
async def mark(command: UserCommand, context: dict[str, ty.Any]) -> None:
    if not context.get("processed_by"):
        context["processed_by"] = ["1"]
    else:
        context["processed_by"].append("1")

@user_registry
async def handler_create(command: CreateUser, context: dict[str, ty.Any]):
    assert context["processed_by"]
    return "done"

@user_registry
async def handler_update(command: UpdateUser, context: dict[str, ty.Any]):
    return "done"

<<<<<<< HEAD <<<<<<< HEAD Guard that guards for a base command will handle all subcommand of the base command

Advanced class-based Guard

Example:

class-based Guard

version/0.1.5 =======

class-based Guard

refs/remotes/origin/master

Inherit from BaseGuard to make a class-based command guard

from anywise import BaseGuard

class LogginGuard(BaseGuard):
    _next_guard: GuardFunc

    def __init__(self, logger: ty.Any):
        super().__init__()
        self._logger = logger

    async def __call__(self, command: Any, context: dict[str, object]):
        if (request_id := context.get("request_id")) is None:
            context["request_id"] = request_id = str(uuid4())

        with logger.contextualize(request_id=request_id):
            try:
                response = await self._next_guard(command, context)
            except Exception as exc:
                logger.error(exc)
                response =  ErrorResponse(command, context, self._next_guard)
            else:
                logger.success(
                    f"Logging request: {request_id}, got response `{response}`"
                )
            finally:
                return response

# you can add either an instance of LoggingGuard:
user_registry.add_guard(LogginGuard(logger=logger), targets=[UserCommand])

# or the LoggingGuard class, which will be dynamically injected during anywise.send
user_registry.add_guard(LogginGuard, targets=[UserCommand])

Features

• builtin dependency injection(powerd by ididi)

  • Define your dependency after the message parameter, they will be resolved when you send a command or publish an event.
  • For each handler that handles the initial message, a scope will be created to manage resources.
  • Subsequent handlers will share the same scope.

• handler guards

• framework integration

• remote handler

Terms and concepts

what do we mean when we use these words

• A Message is a pure data object that is used to carry data that is needed for our application to respond. Also known as data transfer object.

• A Message class often contains no behavior(method), and is immutable.

Command, Query and Event

• Command carries pre-define intend, each command should have a corresponding handler that will mutate state, in the context of DDD, each command will always trigger a behavior of an aggregate root.

• Query is a subclass of Command, where it also carry pre-define intend, but instead of mutate state, it will be responded by a present state of the application.

In other words, command and query corresponds to write and read.

• Event carries a record of an interested domain-related activity, often captures the side effect caused by a Command. an Event can have zero to many listeners

Current limitations and planning fix

• currently Anywise.send does not provide accurate typing information, but annotated as return typing.Any This have no runtime effect, but is a good to have feature. It will be solved before anywise v1.0.0

• currently if a handler needs to receive context, it must declear the context parameter with name context, in future it will be decleared as type.

FAQ

On its way here...