readme

README.md

@@ -1 +1,45 @@
-# Sagas
+# Sagas
+
+Sagas are a protocol for implementing long-running processes. The Saga protocol ensures that a process is atomic, that is, a process executes observably equivalent to completely or not at all.
+
+## Overview
+
+The booking saga workflow is responsible for coordinating the booking of a vacation package, consisting of a car, hotel, and flight reservation. In the event of a failure at any point during the booking process, the workflow will trigger compensating actions to undo any previous bookings.
+
+![](static/booking-saga.png)
+
+## Running
+
+Prerequisites:
+
+- Python >= 3.7
+- [Poetry](https://python-poetry.org)
+- [Local Temporal server running](https://docs.temporal.io/application-development/foundations#run-a-development-cluster)
+
+With this repository cloned, run the following at the root of the directory:
+
+```bash
+poetry install
+```
+That loads all required dependencies. 
+
+Then run the worker and workflow.
+
+```bash
+poetry run python run_worker.py
+poetry run python run_workflow.py
+```
+
+![](static/webui_success.png)
+![](static/success.gif)
+
+![](stat/../static/webui_failure.png)
+![](static/failure.gif)
+
+## Design
+
+The booking saga is implemented using the Temporal Workflow framework, which provides a robust and fault-tolerant platform for coordinating distributed transactions.
+
+The saga workflow consists of three activities: `book_car()`, `book_hotel)()`, and `book_flight)()`, each of which is responsible for making a reservation with the corresponding service provider. If any of these activities fail, the workflow will trigger the corresponding compensating action (`undo_book_car()`, `undo_book_hotel()`, or `undo_book_flight()`) to undo any previous bookings.
+
+The `non_retryable_error_types` parameter is used to specify a list of error types that should not be retried when a Workflow or Activity fails.

activities.py

@@ -23,7 +23,7 @@ async def book_flight(input: BookVacationInput) -> str:
         if seats_available < 1:
             raise Exception("No seats remaining")
         else:
-            print(f"Booking hotel: {input.book_flight_id}")
+            print(f"Booking flight: {input.book_flight_id}")
     except Exception:
         raise Exception("No seats remaining")
 

book_workflow.py

@@ -12,7 +12,7 @@ class BookWorkflow:
     @workflow.run
     async def run(self, input: BookVacationInput):
         compensations = []
-
+    
         try:
             compensations.append("undo_book_car")
             await workflow.execute_activity(

static/run.tape

@@ -0,0 +1,69 @@
+# VHS documentation
+#
+# Output:
+#   Output <path>.gif               Create a GIF output at the given <path>
+#   Output <path>.mp4               Create an MP4 output at the given <path>
+#   Output <path>.webm              Create a WebM output at the given <path>
+#
+# Require:
+#   Require <string>                Ensure a program is on the $PATH to proceed
+#
+# Settings:
+#   Set FontSize <number>           Set the font size of the terminal
+#   Set FontFamily <string>         Set the font family of the terminal
+#   Set Height <number>             Set the height of the terminal
+#   Set Width <number>              Set the width of the terminal
+#   Set LetterSpacing <float>       Set the font letter spacing (tracking)
+#   Set LineHeight <float>          Set the font line height
+#   Set LoopOffset <float>%         Set the starting frame offset for the GIF loop
+#   Set Theme <json|string>         Set the theme of the terminal
+#   Set Padding <number>            Set the padding of the terminal
+#   Set Framerate <number>          Set the framerate of the recording
+#   Set PlaybackSpeed <float>       Set the playback speed of the recording
+#
+# Sleep:
+#   Sleep <time>                    Sleep for a set amount of <time> in seconds
+#
+# Type:
+#   Type[@<time>] "<characters>"    Type <characters> into the terminal with a
+#                                   <time> delay between each character
+#
+# Keys:
+#   Backspace[@<time>] [number]     Press the Backspace key
+#   Down[@<time>] [number]          Press the Down key
+#   Enter[@<time>] [number]         Press the Enter key
+#   Space[@<time>] [number]         Press the Space key
+#   Tab[@<time>] [number]           Press the Tab key
+#   Left[@<time>] [number]          Press the Left Arrow key
+#   Right[@<time>] [number]         Press the Right Arrow key
+#   Up[@<time>] [number]            Press the Up Arrow key
+#   Down[@<time>] [number]          Press the Down Arrow key
+#   PageUp[@<time>] [number]        Press the Page Up key
+#   PageDown[@<time>] [number]      Press the Page Down key
+#   Ctrl+<key>                      Press the Control key + <key> (e.g. Ctrl+C)
+#
+# Display:
+#   Hide                            Hide the subsequent commands from the output
+#   Show                            Show the subsequent commands in the output
+
+Output ../static/success.gif
+# Output ../static/failure.gif
+
+Require echo
+
+Set Shell "bash"
+Set FontSize 32
+Set Width 1200
+Set Height 600
+
+Hide
+Type "cd ../" Enter
+Type "clear" Enter
+Show
+
+
+Type "poetry run python run_worker.py" Sleep 500ms  Enter
+
+Sleep 5
+
+