service-framework 0.0.13

A package for re-defining microservice architecture

Service Framework

Installing

As a Library

pip install service_framework

For Debugging

To install locally for testing run the following command from the base directory.

pip install -e .

Running

From Command Line

Run the following from the directory the Service Framework was locally built. As this directory houses the packaged Service Framework as a python "Egg" file.

python -m service_framework

# OR

service_framework

Useful Comamnd Line Arguments

Below are a few useful arguments...

# Used for Service Setup
-a  Addresses Path (Relative)
-c  Config Path
-m  Main Mode Flag
-s  Service Path (Relative)

# Used for Logging
-cl Console Log Level
-f  File Log Level
-bc Backup Count (Number of hourly log files to keep)
-l  Log Path (Relative)

As An Object

To allow multiple services to be run in sync and programmatically created or destroyed it has been neatly packaged into a class for use. The Service Class should mirror the same requirements as running the framework from the command line. Quite frankly, because running it from the command line just uses this class underneath. Below are the commands on how to use this class:

# Useage Example

from importlib import import_module
from service_framework import Service

service_relative_path = './path_to_service_file/service_specification.py'
service_module = import_module('package.path.to.module')
config = {'some_config_key': 'some_config_value'}
addresses = {'look below this can get complicated'}

my_service = Service(service_path=service_relative_path, config=config, addresses=addresses)
also_my_service = Service(service_module=service_module, config=config, addresses=addresses)


# To run the service as a "main service" or in "main mode" in the background.
my_service.run_service_as_main()

# To run the service regularly and in the background/non-blocking.
my_service.run_service()

# To stop the service's execution.
my_service.stop_service()

# To run the service in it's respective mode and block (stop execution past this line):
my_service.run_service_as_main_blocking()
my_service.run_service_blocking()

Useful Optional Arguments

Here are some other, optional parameters, that can be passed into the Service object:

console_loglevel='INFO'
log_path=None
file_loglevel='INFO'
backup_count=24

These Parameters are the same as their command line compatriates.

Logging

To log inside of your service file import the logger that's precreated.

from service_framework import get_logger

LOG = get_logger()

Addresses Path

If the addresses path is provided, the addresses json file will be loaded into the service framework. This allows the framework to setup each connection of the services connections. Example:

# Command
-a "./addresses.json"

# Addresses.json
{
  "connections": {
    "in": {
      "connection_name": {
        "socket_name": "127.0.0.1:8001",
        "socket_name_2: "127.0.0.1:8002"
      },
      "connection_name_2": {
        "socket_name": "256.128.65.1:9000"
      },
    },
    "out": {}
  },
  "states": {
    "in": {
      "state_name": {
        "socket_name": "127.0.0.1:9001",
        "socket_name_2": "127.0.0.1:9002"
      },
      "state_name_2": {
        "socket_name": "111.111.11.1:2222"
      },
    },
    "out": {},
  }
}

Config Path

This is the relative path to the config json file that will be passed into the service. This file is not required but is useful if one wants to pass configuration information into a service. Example:

# Command:
-c "./config.json"

# Example Config.json:
{
  "required": {
    "config_property_1": 12345,
    "config_property_2": ["list_item_1", "list_item_2", "list_item_3"],
    "config_property_3": {
      "key_1": "value_1",
      "key_2": "value_2"
    }
  },
  "optional": {
    "config_property_4": "TestTestTest"
  }
}

Main Mode Flag

This flag is used to start the service in "main_mode". This mode DOES NOT allow the use of inbound connections or states at all. It simply runs the provided main function in the service and all the connections/statess corresponding with the provided models. The main function must have a predefined signature seen below.

# Example main function
def main(to_send, config):

Service Path

This is the relative path to the service python file that will be used for starting and running the service.

# Command
-s "./service.json"

Custom Environmental Arguments

Any additional arguments that are passed will automatically be added to the config. See below for an example...

# Calling the below
python -m service_framework -s ./service.py --random_variable HELLO

# Will cause a config similar to below
config = {
    'random_variable': 'HELLO',
}

Help Command

Use the below command to get a helpful output for the service framework.

python -m service_framework -h

Building Blocks

An abstract overview of the building blocks.

Connections

Connections are the glue that holds services together. Any communication between services should be done via connections.

Leading Edge Services

These are services that use the "main mode". If all services are plotted as a graph where they are connected by connections these services have no inbound connections from other services.

Services

A service is a block of code that does one thing and one thing well. The goal of this framework is to make spinning up and dealing with a large number of services easily.

States

States are where information is stored in the system. Any service is able to write to and get the most updated state.

Implementation

Leading Edge Services

Required Methods

• Main Method
  • Only Method called in this service
  • ex. main(to_send, states, config)

Optional Methods

• Setup Config
  • ex. setup_config(config)
  • This method is called before the main method.
  • This method is used to update the config before it's used.
  • This method merges the responses with the provided config. (Overwrites keys)
  • ex.

return {
    'required': {
        'argument_1': 'first_argument',
    },
    'optional': {
        'argument_2': 'the_second_argument',
    },
}

• Setup Connections
  • ex. setup_connections(config)
  • This method is called at the start of the service
  • This method must return all arguments for the given connection name.
  • ex.

return {
  'connection_name_1': {
    'argument_1': 'value',
    'argument_2': 123, 
  },
  'connection_name_2': {
    'argument_1': 'test_test',
  },
}

• Setup States
  • ex. setup_states(config)
  • This method is only required if a state has required arguments
  • This method is called at the start of the service
  • This method must return all arguments for the given state name.
  • ex.

return {
  'state_name_1': {
    'argument_1': 'value',
    'argument_2': 123, 
  },
  'state_name_2': {
    'argument_1': 'test_test',
  },
}

• Sigint Handler
  • ex. sigint_handler(sigint, frame, to_send, states, config)
  • This method is called whenever a sigint is provided.
• Sigterm Handler
  • ex. sigterm_handler(signum, frame, to_send, states, config)
  • This method is called whenever a sigterm is provided.

Optional Models

Each Model is only required if it's used in the leading edge service.

• config_model
• connection_models
• state_models

Services

Required Methods

• Method for each "in" Connection Model
  • This method is called whenever a message from this connection is recieved
  • The mapping between function and model is located in the model
  • ex. function_name_in_conn_model(args, to_send, states, config)

Optional Methods

• Setup Connections Method
  • ex. setup_connections(config)
  • This method is only required if a connection has required arguments
  • This method is called at the start of the service
  • This method must return all arguments for the given connection name.
  • ex.

return {
  'connection_name_1': {
    'argument_1': 'value',
    'argument_2': 123, 
  },
  'connection_name_2': {
    'argument_1': 'test_test',
  },
}

• Setup States Model
  • ex. setup_states(config)
  • This method is only required if a state has required arguments
  • This method is called at the start of the service
  • This method must return all arguments for the given state name.
  • ex.

return {
  'state_name_1': {
    'argument_1': 'value',
    'argument_2': 123, 
  },
  'state_name_2': {
    'argument_1': 'test_test',
  },
}

• Sigint Handler

  • ex. sigint_handler(sigint, frame, to_send, states, config)
  • This method is called whenever a sigint is provided.

• Sigterm Handler

  • ex. sigterm_handler(sigint, frame, to_send, states, config)
  • This method is called whenever a sigterm is provided.

• Init Function

  • ex. init_function(to_send, states, config)
  • This method is called before the main method or service framework.

Optional Models

Models are only needed if used in the service.

• config_model
• connection_models
• state_models

States

States are an abstract concept. They're used to hold information and are implemented entirely by the framework. All you, the developer, has to implement is the state models.

Parameters Passed

"args"::dict

When this function is called these are the "arguments" passed. These arguments are pulled from the in connector that is associated with this function.

"to_send"::function

def to_send(output_type, output_name, args):
    """
    output_type::str Either 'state' or 'connection' depending on which to update.
    output_name::str The name of the above output defined in the corresponding model.
    args::{'str': value} This is a dict of the args to be passed to the connection.
    """

This function takes the provided args and sends them to the desired output. If a connection is chosen, this method sends the arguments to the desired connection. If a state is chosen, this method sends the arguments to update that state.

states::dict

This is a dictionary that holds all of the current up-to-date state information that's defined in the model. All input states will be in this state dictionary as the following example:

states = {
    "state_name_1": 'value!',
    "state_name_2": {
        'key_1': Decimal(123.321),
    },
    "state_name_3": ['value1', 1234, 'value3'],
}

"config"::dict

This is a dictionary that is a culmination of config file data and environment variables.

Model Layout

Config Model

Overview

It's a key value store of config information that is passed into the model.

Example

config_model = {
    'required': {       # Optional
        'symbol': str,
    },
    'optional': {},     # Optional
}

Connection Models

Overview

Triggers work/functions between different services.

Example

connection_models = {
    'in': {
        'cancel_order': {
            'connection_type': 'replyer',                  # Required
            'required_creation_arguments': {               # Optional
                'on_new_cancel_order: on_new_cancel_order, # Optional
            },
            'optional_creation_arguments': {},             # Optional
            'required_connection_arguments': {},           # Depends on the Connection
            'optional_connection_arguments': {},           # Depends on the Connection
            'required_arguments': {                        # Optional
                'order_id': str,
            },
            'optional_arguments': {},                      # Optional
            'required_return_arguments': {                 # Optional
                'order_id': str,
            },
            'optional_return_arguments': {},               # Optional
        }
    },
    'out': {
        'cancel_order_on_coinbase': {
            'connection_type': 'external_target',     # Required
            'required_creation_arguments': {          # Optional
                'target': 'CbproClient.cancel_order', 
            },
            'optional_creation_arguments': {}         # Optional
            'required_connection_arguments': {},      # Depends on the Connection
            'optional_connection_arguments': {},      # Depends on the Connection
            'required_arguments': {                   # Optional
                'order_id': str,
            },
            'optional_arguments': {},                 # Optional
            'required_return_arguments': None,        # Optional
            'optional_return_arguments': None,        # Optional
        },
    },
}

State Model

Overview

The state holds information and can either be a database, local variable, global variable, etc.

Example

state_models = {
    'in': {
        'market_price': {
            'state_type': 'local_variable_delta_update', # Required
            'required_creation_arguments': {},           # Optional
            'optional_creation_arguments': {},           # Optional
            'required_state_arguments': {},              # Depends on the State
            'optional_state_arguments': {},              # Depends on the State
            'required_arguments': {                      # Optional
                'min_ask': Decimal,
                'max_bid': Decimal,
                'time_ask': datetime,
                'time_bid': datetime,
            },
            'optional_arguments': {},                    # Optional
            'required_return_arguments': {},             # Optional
            'optional_return_arguments': {},             # Optional
        },
        'order_book': {
            'state_type': 'local_variable_delta_update', # Required
            'required_creation_arguments': {},           # Optional
            'optional_creation_arguments': {},           # Optional
            'required_state_arguments': {},              # Depends on the State
            'optional_state_arguments': {},              # Depends on the State
            'required_arguments': {                      # Optional
                'asks': {Decimal: Decimal},
                'bids': {Decimal: Decimal},
                'updated_time': datetime,
            },
            'optional_arguments': {},                    # Optional
            'required_return_arguments': {},             # Optional
            'optional_return_arguments': {},             # Optional
        },
    },
}

Connection Types

In

Replyer

Used to wrap a ZMQ "Replyer" socket. Triggers a provided method on new requester message. Link to Replyer File

Subscriber

Used to wrap a ZMQ "Subscriber" socket. Triggers a provided method on a new published message. Also has XSUB support. Link to Subscriber File

Out

External Target

Used to wrap an external call and make sure all of the arguments are properly formatted and returned. Can use to_send('connection', 'external_target_name', {'args': 'here'} to send a payload to the external service.

Publisher

Used to wrap a ZMQ "Publisher" socket. Can use to_send('connection', 'publisher_conn_name', {'args': 'here'} to send a payload to the connected subscribers. Also has XPUB support. Link to Publisher File

Requester

Used to wrap a ZMQ "Requester" socket. Can use to_send('connection', 'requester_conn_name', {'args': 'here'} to send a payload to the connected replyer. Link to Requester File

State Types

In

Delta Update In

This state is used to perform delta updates. If a new message is marked as a snapshot it will overwrite the local state. Otherwise it will make sure the local state is exact with the tied to Delta Update Out State via the current number and perform only a delta update to the local state. Link to Delta Update In File

Full Update In

This state is used to perform full updates. If a new message is sent by the corresponding Full Update Out state it will fully overwrite the local state. Link to Full Update In File

Out

Delta Update Out

This state is used to output delta updates. If a payload is sent with the is_snapshat field set to True, then the dependant states will fully update their local state. Otherwise, the dependant states will only perform a delta update based on the provided information. Link to Delta Update Out File

Full Update Out

This state is used to perform a full update. Whenever a new message is recived it fully updates the local state. Link to Full Update Out File

Field and Argument Examples

Dictionary

# Abstract Model Representation
'dictionary_argument': {Type: Type},

# Actually Passed
'dictionary_argument': {Decimal: Decimal},

Service Framework Running Workflow

• Load Service File to get models
• Config:
  • Get config file location
  • Get additional environmental variables
  • Run setup_config function
  • Check config parameters
• Addresses:
  • Load addresses config
  • Run setup_addresses if available
• Connections:
  • Load Connections Config
  • Run setup_connections function
  • Get connections (in and out)
• States:
  • Load States Config
  • Run setup_states function
  • Get states (in and out)
• Sig Handlers:
  • Sets up Sigint and sigterm handling if needed
  • Runs sigint_handler and sigterm_handler
• Init Function:
  • Run init_function before running main or service loop
• Runs either main or service loop
• Honestly, check the entrance_point method