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Lab 16: Building a Hybrid News Aggregator

Goal​

In this lab, you will build a sophisticated News Aggregator using a hybrid graph architecture. You will learn how to:

  1. Run two specialized research nodes in parallel (Fan-out).
  2. Synchronize the results using a JoinNode (Fan-in).
  3. Process the combined data in a sequential step.

The Architecture​

        ┌──── Node A (Tech News) ────┐
START ──┼                           ├──→ JoinNode → Summarizer → END
        └──── Node B (Market News) ──┘

Step 1: Create the Project​

uv run adk create news_aggregator
cd news_aggregator

Step 2: Implement the Specialist Nodes​

Open agent.py. Your task is to define three agents: two for research and one for synthesis.

# In agent.py (Starter Code)
from google.adk import Agent, Workflow
from google.adk.workflow import JoinNode

# TODO: Define 'tech_researcher'
# Instruction: Find 3 headlines about AI and Robotics.
# Output key: "tech_news"
tech_researcher = ...

# TODO: Define 'market_researcher'
# Instruction: Find 3 headlines about Stock Market trends.
# Output key: "market_news"
market_researcher = ...

# TODO: Define 'summarizer'
# Instruction: Combine {tech_news} and {market_news} into a newsletter.
summarizer = ...

Step 3: Assemble the Hybrid Graph​

Exercise: Complete the root_agent definition using the edges parameter to implement the Fan-out/Join pattern.

# 1. Create the synchronization point
syncer = JoinNode(name="news_sync")

# 2. Build the Workflow
# TODO: Define the edges to:
# - Start both researchers in parallel from "START".
# - Converge both researchers at the 'syncer'.
# - Connect the 'syncer' to the 'summarizer'.
root_agent = Workflow(
    name="NewsSystem",
    edges=[
        # Parallel Branch 1
        ("START", ..., ...),
        
        # Parallel Branch 2
        (..., ..., ...),
        
        # Sequential Final Step
        (..., ...)
    ]
)

Step 4: Run and Verify​

  1. Start the Dev UI: uv run adk web .
  2. Test: Send the prompt "Give me today's update."
  3. Inspect: Open the Graph View. Verify that the researchers start at the same time and the summarizer only runs after both finish.

Lab Summary​

You have built a hybrid multi-agent graph!

  • You mastered Fan-out by defining multiple edges from START.
  • You mastered Fan-in using the JoinNode.
  • You learned that sequential and parallel execution are just different edge configurations.

🕵️ Hidden Solution 🕵️​

Looking for the solution? Here's a hint (Base64 decode me): L2RvYy1hZGstdHJhaW5pbmcvbW9kdWxlMTYtc3RhdGljLW9yY2hlc3RyYXRpb24vbGFiLXNvbHV0aW9u

The direct link is: Lab Solution