CS361: Microservice — Currency Exchange Rate

Note: this repository is not maintained. It is only here for archival purposes. If you would like to use this microservice, please fork this repository.

About

Microservice created for @jay2002shah's course project in Software Engineering 1 (CS 361) at Oregon State University. This microservice uses the Open Access EchangeRate-API endpoint to generate currency exchange rate information.

Getting Started

These instructions will get you a copy of the microservice up and running on your local machine.

Prerequisites

You need to have a machine with Python 3.10+ installed.

$ python --version
Python 3.10

This microservice requires requests 2.28+. This can be installed globally on your machine or alternatively using pipenv.

References

• Pipenv: A Guide to the New Python Packaging Tool

Installation

All installation is handled using pip or pipenv. The following steps will install the microservice dependencies.

Build and prepare the Microservice

# Terminal 1
$ git clone https://github.com/4N0NYM0U5MY7H/CS361_Microservice
$ cd CS361_Microservice

# Option 1: Install depencies globally
$ python -m pip install requests

# Option 2: Install dependencies using pipenv
$ pipenv install

# Run the microservice
$ cd exchange_rate
$ python main.py

Test the Microservice is working correctly

# Terminal 2
$ cd CS361_Microservice
$ python example.py

# Expected output
The exchange rate from USD to EUR is 0.932527.

Using the Microservice

Sending a Request

Send a request to this microservice by updating data/requests.txt with a request string containing two ISO 4217 Three Letter Currency Codes — e.g. USD for US Dollars, EUR for Euro etc. — separated by a comma.

# Example client-side request using Python
with open("data/reqeusts.txt", w) as request:
    request.write("usd,eur")

Note: Here's the list of supported currency codes.

Receiving a Response

This microservice sends responses to data/response.txt with an exchange rate string — e.g. request: USD,EUR. response: 0.932527.

Visual Request/Response Demo

Sample Client in Python

# Simple example client to run with the Currency Exchange Microservice
import time
import re

# <path_to_requests_file> points to the request file in the data directory
# NOTE: This example assumes the client is at the project root
path_to_requests_file = "data/requests.txt"

# <path_to_response_file> points to the request file in the data directory
# NOTE: This example assumes the client is at the project root
path_to_response_file = "data/response.txt"

# example currencies to exchange
base_currency = "usd"
target_currency = "eur"

# Send the request to the <path_to_request_file>
with open(path_to_requests_file, "w") as out_file:
    out_file.write(f"{base_currency},{target_currency}")

# Poll the <path_to_response_file> until you receive a response
while True:
    time.sleep(1)
    # Receive the response from the <path_to_response_file>
    with open(path_to_response_file, "r") as in_file:
        exchange_rate = in_file.readline()

    # No response received
    if exchange_rate == "":
        continue

    # Valid reponse received
    if re.search("^(0|[1-9]\d*)?(\.\d+)?(?<=\d)$", exchange_rate):
        # acknowledge valid response in <path_to_response_file>
        with open(path_to_response_file, "a") as out_file:
            out_file.write("\nResponse Received")
        break

# View the results
print(f"The exchange rate from USD to EUR is {exchange_rate}.")

# Expected Output
The exchange rate from USD to EUR is 0.932527.

Sequence Diagram

Project Integration

Option 1: Move or copy the data and exchange_rate directories to the root of your project.

# Unix systems
$ cd CS361_Microservice
$ mv exchange_rate data <path-to-project-root>

# windows
> cd CS361_Microservice
> move exchange_rate <path-to-project-root>
> move data <path-to-project-root>

# Run the microservice
$ cd <path-to-project-root>/exchange_rate
$ python main.py

• You can now send requests to the microservice by sending a valid request string to data/requests.txt.
• You can now recieve responses from the microservice by reading the information in data/response.txt.

Option 2: Clone this microservice to your project root.

Note: see Getting Started.

Optional: Configure the exchange_rate.py file.

* Open `exchange_rate.py` in a text editor.
* Change the values of any of the `internal variables` section to suit your needs.

Note: Any changes made here will need to be reflected in your client program when communicating with the microservice.

# Run the microservice
$ cd <path-to-project-root>/CS361_Microservice/exchange_rate
$ python main.py

• You can now send requests to the microservice by sending a valid request string to:
  • No changes made to exchange_rate.py:
    • CS361_Microservice/data/requests.txt.
  • Changes made to exchange_rate.py:
    • <your-changed-directory>/<your-changed-request-file>.
• You can now recieve responses from the microservice by reading the information from:
  • No changes made to exchange_rate.py:
    • CS361_Microservice/data/response.txt.
  • Changes made to exchange_rate.py:
    • <your-changed-directory>/<your-changed-response-file>.

Note: The microservice must be running BEFORE the client sends a request.

Troubleshooting

• Check that you have python 3.10+ installed on your local machine

  $ python --version
  Python 3.10.0

• Check that you have requests 2.28+ installed on your local machine

  $ python -m pip install requests

• Check that the exchange_rate and data folders are in the root of your project

  project
  |   README.md
  |   project files
  |   ...
  |___data
  |   |   requests.txt
  |   |   response.txt
  |
  |___exchage_rate
  |   |   exchage_rate.py
  |   |   main.py
  |
  |___folder
      |   folder files
      |   ...
      |
      |___subfolder
          |   subfolder files
          |   ...   
  

  • Run the microservice from the exchange_rate directory.

    $ cd my/project/root
    $ python main.py

    • If you do NOT, then you will encounter issues related to the communication files.

      # DO NOT do this!
      $ cd <project-root>
      $ python exchange_rate/main.py # Will cause issues with "requests.txt" and "response.txt"

• Check that your program is sending requests to data/requests.txt

• Check that your program is receiving responses from data/response.txt

  project
  |   ...
  |___data
  |   |   ...
  |   |   requests.txt 
  |   |   response.txt
  
  # from project root
  path_to_requests_file = "data/requests.txt"
  path_to_response_file = "data/response.txt"

  project
  |   ...
  |___data
  |   |   ...
  |   |   requests.txt
  |   |   response.txt
  |
  |___folder
      |   ...  
  
  # from project folder
  path_to_requests_file = "../data/requests.txt"
  path_to_response_file = "../data/response.txt"

  project
  |   ...
  |___data
  |   |   ...
  |   |   requests.txt
  |   |   response.txt
  |
  |___folder
      |   ...
      |
      |___subfolder
          |   ...   
  
  # from project subfolder
  path_to_requests_file = "../../data/requests.txt"
  path_to_response_file = "../../data/response.txt"

  Learn more about paths.

Built With

License

This project is licensed under the MIT License - see the LICENSE file for details.