Software Engineering Online Test

During sprint planning, one teammate proposed the following list of possible rate-limiting algorithms to manage incoming traffic, using the user ID as an identifier:

• Sliding Window
• Token Bucket (n tokens; 1 request for 1 token)

For the following requirements, specify and briefly explain the algorithm chosen, along with the reason for not selecting the alternative:

• Payment gateway attempts:
  • Allow 10 attempts per 10 min per user.
  • Prevents brute force attacks in short time periods.
• Social media feed API:
  • On app open and focus, permit burst of ~100 requests.
  • For steady updates, allow ~2 requests per second (sustained).

(An answer of 10 to 15 words is sufficient for each explanation)

You're designing an undo system for a text editor and need to choose a data structure to record user actions. Each action should be recorded so that the system can quickly reverse recent actions. The system has the following requirements:

• Every new user action must be recorded (for example, typing a character or deleting a line).
• The “undo” must retrieve and remove the most recent action in constant time O(1).

Your colleagues proposed using Stack or Queue based on the requirements. Write a short explanation on how the functionality of either data structure can or cannot fulfill the requirements.

(An answer up to 50 words is sufficient)

In a language that supports the OOP paradigm, we have the following code that serializes the content of a shopping cart to JSON format:

class ShoppingCart
  private content : Dictionary<Int, String> 

  public function serialize() : String
    return new JsonSerializer().serialize(content.clone())
  end function
end class

class JsonSerializer  
  public function serialize(value : Dictionary<Int, String>) : String
    // Code that serializes dictionary to JSON format and returns it as string
  end function
end class

A client wants to allow loosely coupled plugins to be able to serialize the shopping cart content to their own formats (e.g., XML). Select lines of code that, together, would extend the code above to allow this.

A large library uses a REST API that integrates with the library's web page and mobile app.

The following graph contains the frequency of various HTTP status codes for the REST API:

What can be concluded from this?

You are working on multilayer architecture for a new website for the largest news portal in your area. Your colleague has already prepared layers.

Your task is to choose the best option for each layer from the available technologies and programming languages your team knows.

A user types www.testdome.com into their browser's address bar for the first time, presses enter, the webpage loads, and renders successfully.

Select the statements that are correct.

The function below is used to search for an element in a binary tree that contains linked nodes.

function treeContains(treeNode : Node, element : int) : bool
  if (treeNode == NULL)
    return false
  else if (treeNode.getValue() == element)
    return true
  else 
    left : bool = treeContains(treeNode.getLeft(), element)
    right : bool = treeContains(treeNode.getRight(), element) 
    return left || right 
  end if
end function

What can be said about the treeContains function?

For the following pseudocode functions, choose the big O notation that accurately describes its worst-case complexity.

The following pseudocode functions will be used for managing student data using a Hashtable:

function addStudent(table : Hashtable, id : int, name : string) : void
  table.add(id, name)
end function

function findStudentIdByName(table : Hashtable, name : string) : int?
  loop (for each entry in table)
    if entry.value == name
      return entry.key
    end if
  end loop

  return null
end function

What can be correctly said about the pseudocode?

You are working on a solution for building a web server. According to an agreement, the web server should offer 99.99% availability.

Which components will help satisfy the agreement?

Answer the questions below regarding correct usage of data structures.

Your team has started to write software for managing a vehicle storehouse using a programming language that supports OOP. This is the class hierarchy you plan to use:

class Vehicle
class Car inherits Vehicle
class Bicycle inherits Vehicle
class MountainBike inherits Bicycle
class Downhill inherits MountainBike

Objects of which type can be assigned to a variable of type Bicycle?

You are searching for a web service that could be used to get the expected search volume of keywords for an online advertising platform. Before choosing the web service, your team wants to split web services into different categories.

Some web services lack proper documentation. Which documentation looks like it's describing RESTful APIs and which looks like it's describing SOAP-based web services?

{ 
  "keyword": "rio de janeiro hotels", 
  "volume": 10000 
}

<m:GetSearchVolume xmlns:m = "http://www.words.com/searchkeywordsvolume">
  <m:Keyword>brazilian carnival</m:Keyword>
</m:GetSearchVolume>

During a discussion about architecture for a new web app the following sketchup was made:

The authors of the sketchup forgot to write the descriptions for three components marked with red numbers.

Select the best choice, regarding the context, for the description that should define each component.

Select the statements about RESTful web services that are correct.

A word processor uses the following code for defining font format:

class FontFormat inherits Object
  private fontName : String
  private fontSize : Int

  public constructor(name : String, size : Int)
    fontName = name
    fontSize = size
  end constructor

  public function getFontName() : String
    return fontName
  end function

  public function getFontSize() : Int
    return fontSize
  end function

  override public function equals(obj : Object) : Bool
    if (!(obj instanceof FontFormat))
      return false
    end if
    
    FontFormat f = (FontFormat)obj
    return f.getFontName() == fontName && f.getFontSize() == fontSize
  end function

  override public function getHashCode() : Int
    return fontName.getHashCode() ^ fontSize.getHashCode()
  end function
end class

Analysis shows that even the largest documents use fewer than a hundred different combinations of font name and size. The same analysis shows that the application sometimes uses thousands of FontFormat objects, most of which share the same font name and size.

(Fill in the blank with the software design pattern that solves the issue.)

The ____________ software design pattern can be used to minimize the memory footprint by sharing FontFormat objects.