Add examples for FastAPI

Author: gjbex

source-code/README.md

@@ -44,3 +44,4 @@ to create it.  There is some material not covered in the presentation as well.
 1. `subprocess`: illustrates executing a shell command from a Python script
     using the `subprocess` module.
 1. `xml-generator`: code to generate a random XML documents.
+1. `fastapi`: simple illustrations of using FastAPI for webservices.

source-code/fastapi/README.md

@@ -0,0 +1,26 @@
+# FastAPI
+
+FastAPI is a nice framework to build web applications and handle http requests.
+
+## What is it?
+
+* `main.py`: very simple hello world application.
+* `calculator.py`: implementation of an API that allows to
+  * push numbers on a stack (push/<number>)
+  * perform a computation (compute/add or compute/mult)
+* `calculations.sh`: shell script to illustrate use of the calculator API.
+
+## How to use it?
+
+### Hello world application
+```bash
+$ uvicorn  main:app  --reload
+```
+
+### Calculator
+```bash
+$ uvicorn  calculatorapp  --reload
+$ curl  --silent  http://127.0.0.1:8000/push/5
+$ curl  --silent  http://127.0.0.1:8000/push/7
+$ curl  --silent  http://127.0.0.1:8000/compute/add
+```

source-code/fastapi/calculations.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+# start the server with
+# uvivorn  calculator::app  --reload
+#
+
+source ~/.mamba_init.sh
+mamba activate python_for_systems_programming
+
+HOST=127.0.0.1:8000
+
+echo "push 5"
+curl --silent "http://$HOST/push/5"
+echo ""
+
+echo "push 7"
+curl --silent "http://$HOST/push/7"
+echo ""
+
+echo "perform addition"
+curl --silent "http://$HOST/compute/add" | json_pp
+echo ""

source-code/fastapi/calculator.py

@@ -0,0 +1,19 @@
+from fastapi import FastAPI
+from typing import Union
+
+app = FastAPI()
+stack = []
+
+@app.get('/push/{value}')
+def push(value: float, q: Union[str, None] = None):
+    stack.append(value)
+
+@app.get('/compute/{operator}')
+def compute(operator: str, q: Union[str, None] = None):
+    right_operand = stack.pop()
+    left_operand = stack.pop()
+    if operator == 'add':
+        result = left_operand + right_operand
+    elif operator == 'mult':
+        result = left_operand*right_operand
+    return {'result': result}

source-code/fastapi/main.py

@@ -0,0 +1,20 @@
+from typing import Union
+from fastapi import FastAPI
+
+app = FastAPI()
+
+
+@app.get("/")
+def read_root():
+    return {"Hello": "World"}
+
+
+@app.get("/items/{item_id}")
+def read_item(item_id: int, q: Union[str, None] = None):
+    return {"item_id": item_id, "q": q}
+
+
+@app.get("/users/{user_id}&{category}")
+def read_item(user_id: int, category: str,
+              q: Union[str, None] = None):
+    return {"user_id": user_id, "category": category, "q": q}