Request aggregation in Microservices - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the aggregator service endpoint.

Microservices

app.get('/aggregate', async (req, res) => {
  const data = await [1]();
  res.send(data);
});

Drag options to blanks, or click blank then click option'

AfetchDataFromServices

BlistenToRequests

CstartServer

DhandleError

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function that starts the server instead of fetching data.

Using a function that listens to requests instead of aggregating data.

The aggregator service calls fetchDataFromServices to gather data from multiple microservices.

2fill in blank

medium

Complete the code to aggregate responses from two microservices.

Microservices

async function fetchDataFromServices() {
  const [data1, data2] = await Promise.all([
    fetchServiceA(),
    [1]()
  ]);
  return { data1, data2 };
}

Drag options to blanks, or click blank then click option'

AfetchServiceE

BfetchServiceC

CfetchServiceD

DfetchServiceB

Attempts:

3 left

💡 Hint

Common Mistakes

Using a service function that does not exist.

Calling the same service twice.

The aggregator calls fetchServiceA and fetchServiceB concurrently to get data from both services.

3fill in blank

hard

Fix the error in the aggregation function to handle failed service calls.

Microservices

async function fetchDataFromServices() {
  try {
    const data = await Promise.all([
      fetchServiceA(),
      fetchServiceB()
    ]);
    return data;
  } catch ([1]) {
    return { error: 'Service call failed' };
  }
}

Drag options to blanks, or click blank then click option'

Ae

Berr

Cexception

Derror

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving the catch block without a variable name.

Using a variable name not declared or inconsistent.

The catch block needs a variable to capture the error; e is a common and clear choice.

4fill in blank

hard

Fill both blanks to correctly merge and return aggregated data from services.

Microservices

async function fetchDataFromServices() {
  const [dataA, dataB] = await Promise.all([
    fetchServiceA(),
    fetchServiceB()
  ]);
  return { ...dataA[1]...dataB[2] };
}

Drag options to blanks, or click blank then click option'

A,

B;

C+

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using semicolons or plus signs inside object literals.

Omitting commas between spread objects.

Use commas to separate spread objects inside the returned object literal for correct merging.

5fill in blank

hard

Fill all three blanks to implement caching in the aggregator service.

Microservices

const cache = new Map();

async function fetchDataFromServices() {
  if (cache.has([1])) {
    return cache.get([2]);
  }
  const data = await Promise.all([
    fetchServiceA(),
    fetchServiceB()
  ]);
  cache.set([3], data);
  return data;
}

Drag options to blanks, or click blank then click option'

A'aggregateKey'

B'cacheKey'

C'dataKey'

D'serviceData'

Attempts:

3 left

💡 Hint

Common Mistakes

Using different keys for cache.has, cache.get, and cache.set.

Using undefined or variable keys inconsistently.

Using the same cache key 'cacheKey' consistently ensures correct caching and retrieval.