Understanding the differences between synchronous and asynchronous patterns is of paramount importance. These two integral communication patterns play an indispensable role in the AWS architectural landscape; hence, grasping these concepts will provide a firm foundation in the development and management of AWS solutions.
Synchronous Pattern
Synchronous communications typically involve processes that pause, await a response, and then proceed. It means that at any given time, only two parties are involved: a requester and a responder. After a request has been sent, the sender will pause and wait for the response before it can continue with other tasks.
Here’s an example of synchronous interaction using AWS Lambda function:
import boto3
lambda_client = boto3.client(‘lambda’)
response = lambda_client.invoke(
FunctionName=’MyLambdaFunction’,
InvocationType=’RequestResponse’)
print(response[‘Payload’].read())
In the above code snippet, the `RequestResponse` invocation type is suitable for synchronous operations where the immediate response of the function is needed.
Asynchronous Pattern
On the other hand, asynchronous communication allows a process to continue operating without waiting for a reply from the receiver. This way, a single sender can communicate with multiple receivers without having to wait for each to respond. AWS provides a service called Simple Notification Service (SNS) as an example of an asynchronous service.
Here’s an example of using AWS SNS for asynchronous communication:
import boto3
sns = boto3.client(‘sns’)
response = sns.publish(
TopicArn=’MySNSTopic’,
Message=’MyMessage’)
print(“MessageId: ” + response[‘MessageId’])
In this case, the message is immediately sent to the SNS topic and the script continues its execution without waiting for the message to be delivered.
Differences Between Synchronous and Asynchronous Patterns
| Synchronous | Asynchronous |
|---|---|
| The sender and receiver must both be available at the same time to communicate. | The sender and receiver do not need to be concurrently available. |
| The sender will wait for the receiver’s response after sending a request. | The sender doesn’t wait for a reply after sending a request. |
| AWS Lambda’s `RequestResponse` invocation type is an example of a synchronous service. | AWS Simple Notification Service (SNS) is an example of an asynchronous service. |
| Potential for reduced performance due to waiting times for the response. | Asynchronous patterns can boost performance by allowing tasks to continue without waiting for responses. |
Conclusion
In conclusion, understanding these concepts is vital when designing your AWS architecture as the choice between synchronous or asynchronous could significantly impact the performance and efficiency of your applications. For the AWS Certified Developer – Associate (DVA-C02) exam, be prepared to recognize scenarios when one approach would be more beneficial than the other to efficiently handle communication processes.
Practice Test
True or False: Asynchronous patterns perform tasks faster than synchronous ones.
- True
- False
Answer: True
Explanation: Because asynchronous tasks don’t have to wait on the tasks before them to complete, they typically complete tasks faster than synchronous ones.
Does synchronous pattern block the thread until the task is finished?
- Yes
- No
Answer: Yes
Explanation: In synchronous programming, tasks are executed one at a time and the thread is blocked until a task is completed.
True or False: Two concurrent tasks in an asynchronous pattern are always aware of each other’s state at all times.
- True
- False
Answer: False
Explanation: In an asynchronous pattern, two concurrent tasks do not generally have awareness of each other.
Which pattern is more likely to lead to unhandled errors: synchronous or asynchronous?
- Synchronous
- Asynchronous
Answer: Asynchronous
Explanation: It can be easy to overlook error handling in asynchronous code because of its complex nature. Errors may also occur “in the background” without stopping the program.
In which pattern, tasks are not necessarily completed in the order they started: synchronous or asynchronous?
- Synchronous
- Asynchronous
Answer: Asynchronous
Explanation: In asynchronous programming, tasks are not always completed in the order they started because while one task waits for a response, the program can continue with other tasks.
True or False: Asynchronous pattern works better when tasks are independent of each other.
- True
- False
Answer: True
Explanation: Asynchronous patterns work well when tasks are independent and don’t need to wait for each other’s completion.
Which of the following is a key difference between synchronous and asynchronous patterns?
- A) In asynchronous code, tasks block threads until completed.
- B) In synchronous code, tasks do not block threads and run concurrently.
- C) In asynchronous code, tasks don’t necessarily finish in the order they started.
- D) In synchronous code, tasks depend on each other to finish.
Answer: C) In asynchronous code, tasks don’t necessarily finish in the order they started.
Explanation: An asynchronous task can be started and allowed to run in the background while the next task starts, and hence tasks don’t necessarily finish in the order they started.
Will AWS Lambda support both synchronous and asynchronous invocation of a Lambda function?
- Yes
- No
Answer: Yes
Explanation: AWS Lambda supports both synchronous and asynchronous invocation of a Lambda function. The invocation type determines how flow continues after Lambda runs your function.
True or False: Asynchronous programming can be more complex and difficult to understand than synchronous programming.
- True
- False
Answer: True
Explanation: Because tasks in asynchronous programming can run concurrently and don’t necessarily finish in order, it can be more difficult to follow the flow of an asynchronous program compared to a synchronous one.
In which type of programming, tasks can start, run, and complete in overlapping time periods: Synchronous or Asynchronous?
- Synchronous
- Asynchronous
Answer: Asynchronous
Explanation: In asynchronous programming the tasks can start, run, and complete in overlapping time periods making it more efficient when tasks are large or depend on external resources.
In the context of AWS, what ensures an asynchronous messaging model?
- A) AWS Glue
- B) AWS DynamoDB
- C) AWS Simple Queue Service (SQS)
- D) AWS Lambda
Answer: C) AWS Simple Queue Service (SQS)
Explanation: AWS Simple Queue Service (SQS) is a fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications.
True or False: In synchronous programming model, a simple error in the code could cause the entire system to stop, until the task is fixed.
- True
- False
Answer: True
Explanation: In synchronous programming, a simple error could stop the entire system because each task directly depends on the completion of the previous task.
True or False: Debugging is easier in asynchronous programming model compared to a synchronous programming.
- True
- False
Answer: False
Explanation: Debugging can indeed be more challenging in asynchronous programming due to the non-linear execution of tasks.
In which type of pattern, the tasks are executed in the order they appear in the code: Synchronous or Asynchronous?
- Synchronous
- Asynchronous
Answer: Synchronous
Explanation: In synchronous programming, multiple tasks are executed one by one in the order they appear in the code. It waits for each task to complete before moving on to the next.
True or False: Synchronous code execution can be more predictable than asynchronous code execution.
- True
- False
Answer: True
Explanation: Since synchronous tasks run in order and the state is easier to manage, the execution can be more predictable than asynchronous code execution.
Interview Questions
What is the main difference between synchronous and asynchronous patterns in communication?
In synchronous communication, the sender waits for the receiver to acknowledge receipt of the message before continuing, while in asynchronous communication, the sender continues processing after sending the message without waiting for an acknowledgement.
In which communication pattern, the receiver’s response time doesn’t impact the sender’s capabilities?
In asynchronous communication, the receiver’s response time doesn’t impact the sender’s capabilities.
How does AWS Lambda function cater to synchronous and asynchronous invocation of a function?
For synchronous invocation, AWS Lambda runs the function and waits for a response. For asynchronous invocation, it returns a response immediately and runs the function in the background.
What services can invoke Lambda functions synchronously?
Services like Amazon Alexa, Amazon API Gateway, and Amazon Cognito can invoke Lambda functions synchronously.
List a few AWS services that invoke Lambda functions asynchronously?
AWS services like Amazon Simple Storage Service (S3), Amazon Simple Notification Service (SNS), and Amazon CloudWatch Logs can invoke Lambda functions asynchronously.
How does asynchronous pattern benefit in AWS architecture design?
Asynchronous pattern enables scalability, as it allows multiple tasks to run concurrently without waiting for a response, making the system more efficient and responsive.
Which AWS service is suitable for asynchronous message communication?
Amazon Simple Queue Service (SQS) is suitable for asynchronous message communication.
How does AWS manage errors in asynchronous measures?
In asynchronous measures, AWS can be set to automatically retry the execution of failed Lambda functions.
What is the primary advantage of synchronous communication over asynchronous communication?
The primary advantage of synchronous communication is that it ensures that a task has completed successfully before moving on to the next task.
What is the drawback of using synchronous invocation in AWS Lambda?
The drawback of synchronous invocation is that it could block the calling service until the function execution completes.
Is it possible to have a mix of synchronous and asynchronous patterns in AWS?
Yes, depending on the application requirements, a mix of these patterns can be used in AWS.
When using any asynchronous process such as AWS SQS, what can be done to handle any failed or delayed communication?
AWS provides Dead Letter Queues (DLQ) to capture failed or delayed communication for resolution.
What is the default invocation type when a service invokes an AWS Lambda function?
The default invocation type is synchronous.
When would you use asynchronous invocation in AWS Lambda?
Asynchronous invocation is used when there is no need to immediately return the result to the user, or when a task needs to be run in the background.
If a Lambda function is invoked asynchronously and it fails, what happens to the event that triggered the function?
If a Lambda function invoked asynchronously fails, AWS Lambda can automatically retry the invocation twice, after which the event may be sent to a Dead Letter Queue if one is configured.
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