git'n a system-desgin-primer

B4/Solutions/system_design/Video_conferencing/features.text

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+Video Conferencing System:
+
+1. User: Represents a user in the system.
+
+2. Meeting: Handles participant management and audio/video streaming.

B4/Solutions/system_design/Video_conferencing/video.py

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+import random
+import threading
+import time
+
+class User:
+    def __init__(self, user_id, name):
+        self.user_id = user_id
+        self.name = name
+
+class Meeting:
+    def __init__(self, meeting_id):
+        self.meeting_id = meeting_id
+        self.participants = []
+        self.is_active = True
+
+    def add_participant(self, user):
+        self.participants.append(user)
+        print(f"{user.name} joined the meeting {self.meeting_id}.")
+
+    def remove_participant(self, user):
+        self.participants.remove(user)
+        print(f"{user.name} left the meeting {self.meeting_id}.")
+
+    def stream_audio_video(self):
+        # Simulated audio/video streaming
+        while self.is_active:
+            print(f"Streaming audio/video in meeting {self.meeting_id}...")
+            time.sleep(2)
+
+    def end_meeting(self):
+        self.is_active = False
+        print(f"Meeting {self.meeting_id} has ended.")
+
+class VideoConferencingSystem:
+    def __init__(self):
+        self.meetings = {}
+
+    def create_meeting(self):
+        meeting_id = random.randint(1000, 9999)
+        meeting = Meeting(meeting_id)
+        self.meetings[meeting_id] = meeting
+        print(f"Meeting {meeting_id} created.")
+        return meeting
+
+# Example Usage
+vcs = VideoConferencingSystem()
+meeting = vcs.create_meeting()
+
+user1 = User(1, "Alice")
+user2 = User(2, "Bob")
+
+meeting.add_participant(user1)
+meeting.add_participant(user2)
+
+stream_thread = threading.Thread(target=meeting.stream_audio_video)
+stream_thread.start()
+
+time.sleep(5)
+meeting.end_meeting()
+stream_thread.join()

B4/Solutions/system_design/payment_processing/features.text

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+Payment Processing System:
+
+1. User: Represents a user with a balance.
+
+2. Transaction: Represents a payment transaction between users.
+
+3. PaymentProcessingSystem: Processes transactions and handles fund transfers.

B4/Solutions/system_design/payment_processing/payment.py

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+import random
+
+class User:
+    def __init__(self, user_id, name, balance):
+        self.user_id = user_id
+        self.name = name
+        self.balance = balance
+
+class Transaction:
+    def __init__(self, sender, receiver, amount):
+        self.transaction_id = random.randint(1000, 9999)
+        self.sender = sender
+        self.receiver = receiver
+        self.amount = amount
+
+class PaymentProcessingSystem:
+    def process_payment(self, transaction):
+        if transaction.sender.balance >= transaction.amount:
+            transaction.sender.balance -= transaction.amount
+            transaction.receiver.balance += transaction.amount
+            print(f"Transaction {transaction.transaction_id} successful: {transaction.sender.name} paid {transaction.receiver.name} ${transaction.amount}.")
+        else:
+            print(f"Transaction {transaction.transaction_id} failed: Insufficient funds.")
+
+# Example Usage
+user1 = User(1, "Alice", 100)
+user2 = User(2, "Bob", 50)
+
+payment_system = PaymentProcessingSystem()
+transaction = Transaction(user1, user2, 30)
+payment_system.process_payment(transaction)
+
+print(f"{user1.name}'s balance: ${user1.balance}")
+print(f"{user2.name}'s balance: ${user2.balance}")

B4/Solutions/system_design/realtime_collaborative_editing/collab.py

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+import threading
+
+class Document:
+    def __init__(self, title):
+        self.title = title
+        self.content = ""
+        self.lock = threading.Lock()
+
+    def edit(self, new_content):
+        with self.lock:
+            self.content = new_content
+            print(f"Document '{self.title}' updated: {self.content}")
+
+class User:
+    def __init__(self, user_id, name):
+        self.user_id = user_id
+        self.name = name
+
+    def edit_document(self, document, new_content):
+        print(f"{self.name} is editing the document '{document.title}'...")
+        document.edit(new_content)
+
+# Example Usage
+document = Document("Project Plan")
+user1 = User(1, "Alice")
+user2 = User(2, "Bob")
+
+# Simulating concurrent edits
+thread1 = threading.Thread(target=user1.edit_document, args=(document, "Draft by Alice."))
+thread2 = threading.Thread(target=user2.edit_document, args=(document, "Draft by Bob."))
+
+thread1.start()
+thread2.start()
+
+thread1.join()
+thread2.join()

B4/Solutions/system_design/realtime_collaborative_editing/features.rext

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+1. Document: Represents a document being edited, with content locked for 
+    safe concurrent editing.
+
+2. User: Represents a user editing the document.
+
+3. Each user can edit the document concurrently, with proper locking to prevent 
+    data corruption.

B4/Solutions/system_design/smart_home/features.p[y

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+Smart Home System:
+
+1. SmartDevice: Represents a smart device with on/off control.
+
+2. SmartHomeSystem: Manages devices and controls their states.

B4/Solutions/system_design/smart_home/smart_home.py

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+class SmartDevice:
+    def __init__(self, device_id, device_type):
+        self.device_id = device_id
+        self.device_type = device_type
+        self.is_on = False
+
+    def turn_on(self):
+        self.is_on = True
+        print(f"{self.device_type} {self.device_id} turned on.")
+
+    def turn_off(self):
+        self.is_on = False
+        print(f"{self.device_type} {self.device_id} turned off.")
+
+class SmartHomeSystem:
+    def __init__(self):
+        self.devices = {}
+
+    def add_device(self, device):
+        self.devices[device.device_id] = device
+        print(f"Added {device.device_type} {device.device_id}.")
+
+    def control_device(self, device_id, action):
+        device = self.devices.get(device_id)
+        if device:
+            if action == "on":
+                device.turn_on()
+            elif action == "off":
+                device.turn_off()
+            else:
+                print("Invalid action.")
+        else:
+            print("Device not found.")
+
+# Example Usage
+smart_home = SmartHomeSystem()
+light = SmartDevice(1, "Light")
+thermostat = SmartDevice(2, "Thermostat")
+
+smart_home.add_device(light)
+smart_home.add_device(thermostat)
+
+smart_home.control_device(1, "on")  # Turn on the light
+smart_home.control_device(2, "off")  # Turn off the thermostat