talepy 0.2.0

Distributed Transactions Helper

Tale Distributed Transactions
------------------------------

[](https://travis-ci.org/meadsteve/talepy)

## What?
Tale is a small library to help write a "distributed transaction like"
object across a number of services. It's loosely based on the saga pattern.
A good intro is available on the couchbase blog:
https://blog.couchbase.com/saga-pattern-implement-business-transactions-using-microservices-part/

## Installation
```bash
pipenv install talepy
```

## Example Usage
An example use case of this would be some holiday booking software broken
down into a few services.

Assuming we have the following services: Flight booking API, Hotel booking API,
and a Customer API.

We'd write the following steps:

```python
from talepy.steps import Step

class DebitCustomerBalance(Step):

def __init__(self):
self.payment_client= {}

def compensate(self, state):
state['payment_id'] = self.payment_client.bill(state.customer_id, state.payment_amount)
return state

def execute(self, state):
self.payment_client.refund(state['payment_id'])

```

and so on for any of the steps needed. Then in whatever is handling the user's
request a distributed transaction can be built:

```python
from talepy import run_transaction

run_transaction(
steps=[
DebitCustomerBalance(),
BookFlight(),
BookHotel(),
EmailCustomerDetailsOfBooking()
],
starting_state={}
)
```

If any step along the way fails then the compensate method on each step
is called in reverse order until everything is undone.

## Testing / Development
TODO