Blazor multi-user questionaire - asp.net

Question

I need to create an app thats basically functions like a multi-user realtime questionnaire or trivia.
I've gotten to the point where i've created a questionnaire and associated users to it, but i'm hitting a road block on how to go forward.
Basically what i need to do next is
For each question in the questionnaire:
1) have the server send the users a question
2) wait for all of the users to respond or a set timeout period
3) display to the users a question result page
I was wondering how i should attempt to do something like this. Any help or resources would be wonderful

Answer 1

I am building a chat application that has something very similar using Server Side Blazor.
The way I did was I inject a class I created called SubscriberService:
#inject Services.SubscriberService SubscriberService
Then in my ConfigureServices method in Startup.cs I add this:
services.AddSingleton<SubscriberService>();
The Add Singleton means only 1 instance will be created for all your browser instances (users).
This makes my Subscriber Services available to all my subcribers, which is just a name, Guid Id and a callback delegate
#region using statements
using DataJuggler.UltimateHelper.Core;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Transactions;
#endregion
namespace BlazorChat.Services
{
#region class SubscriberService
/// <summary>
/// This class is used to subscribe to services, so other windows get a notification a new message
/// came in.
/// </summary>
public class SubscriberService
{
#region Private Variables
private int count;
private Guid serverId;
private List<SubscriberCallback> subscribers;
#endregion
#region Constructor
/// <summary>
/// Create a new instance of a 'SubscriberService' object.
/// </summary>
public SubscriberService()
{
// Create a new Guid
this.ServerId = Guid.NewGuid();
Subscribers = new List<SubscriberCallback>();
}
#endregion
#region Methods
#region BroadcastMessage(SubscriberMessage message)
/// <summary>
/// This method Broadcasts a Message to everyone that ins't blocked.
/// Note To Self: Add Blocked Feature
/// </summary>
public void BroadcastMessage(SubscriberMessage message)
{
// if the value for HasSubscribers is true
if ((HasSubscribers) && (NullHelper.Exists(message)))
{
// Iterate the collection of SubscriberCallback objects
foreach (SubscriberCallback subscriber in Subscribers)
{
// if the Callback exists
if ((subscriber.HasCallback) && (subscriber.Id != message.FromId))
{
// to do: Add if not blocked
// send the message
subscriber.Callback(message);
}
}
}
}
#endregion
#region GetSubscriberNames()
/// <summary>
/// This method returns a list of Subscriber Names ()
/// </summary>
public List<string> GetSubscriberNames()
{
// initial value
List<string> subscriberNames = null;
// if the value for HasSubscribers is true
if (HasSubscribers)
{
// create the return value
subscriberNames = new List<string>();
// Get the SubscriberNamesl in alphabetical order
List<SubscriberCallback> sortedNames = Subscribers.OrderBy(x => x.Name).ToList();
// Iterate the collection of SubscriberService objects
foreach (SubscriberCallback subscriber in sortedNames)
{
// Add this name
subscriberNames.Add(subscriber.Name);
}
}
// return value
return subscriberNames;
}
#endregion
#region Subscribe(string subscriberName)
/// <summary>
/// method returns a message with their id
/// </summary>
public SubscriberMessage Subscribe(SubscriberCallback subscriber)
{
// initial value
SubscriberMessage message = null;
// If the subscriber object exists
if ((NullHelper.Exists(subscriber)) && (HasSubscribers))
{
// Add this item
Subscribers.Add(subscriber);
// return a test message for now
message = new SubscriberMessage();
// set the message return properties
message.FromName = "Subscriber Service";
message.FromId = ServerId;
message.ToName = subscriber.Name;
message.ToId = subscriber.Id;
message.Data = Subscribers.Count.ToString();
message.Text = "Subscribed";
}
// return value
return message;
}
#endregion
#region Unsubscribe(Guid id)
/// <summary>
/// This method Unsubscribe
/// </summary>
public void Unsubscribe(Guid id)
{
// if the value for HasSubscribers is true
if ((HasSubscribers) && (Subscribers.Count > 0))
{
// attempt to find this callback
SubscriberCallback callback = Subscribers.FirstOrDefault(x => x.Id == id);
// If the callback object exists
if (NullHelper.Exists(callback))
{
// Remove this item
Subscribers.Remove(callback);
// create a new message
SubscriberMessage message = new SubscriberMessage();
// set the message return properties
message.FromId = ServerId;
message.FromName = "Subscriber Service";
message.Text = callback.Name + " has left the conversation.";
message.ToId = Guid.Empty;
message.ToName = "Room";
// Broadcast the message to everyone
BroadcastMessage(message);
}
}
}
#endregion
#endregion
#region Properties
#region Count
/// <summary>
/// This property gets or sets the value for 'Count'.
/// </summary>
public int Count
{
get { return count; }
set { count = value; }
}
#endregion
#region HasSubscribers
/// <summary>
/// This property returns true if this object has a 'Subscribers'.
/// </summary>
public bool HasSubscribers
{
get
{
// initial value
bool hasSubscribers = (this.Subscribers != null);
// return value
return hasSubscribers;
}
}
#endregion
#region ServerId
/// <summary>
/// This property gets or sets the value for 'ServerId'.
/// </summary>
public Guid ServerId
{
get { return serverId; }
set { serverId = value; }
}
#endregion
#region Subscribers
/// <summary>
/// This property gets or sets the value for 'Subscribers'.
/// </summary>
public List<SubscriberCallback> Subscribers
{
get { return subscribers; }
set { subscribers = value; }
}
#endregion
#endregion
}
#endregion
}
Here is my SubscriberCallback.cs:
#region using statements
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
#endregion
namespace BlazorChat
{
#region class SubscriberCallback
/// <summary>
/// This class is used to register a subscriber with the ChatService
/// </summary>
public class SubscriberCallback
{
#region Private Variables
private string name;
private Guid id;
private Callback callback;
private List<Guid> blockedList;
#endregion
#region Constructor
/// <summary>
/// Create a new instance of a SubscriberCallback instance
/// </summary>
public SubscriberCallback(string name)
{
// store the Name
Name = name;
// Create the Id
Id = Guid.NewGuid();
// create a BlockedList
BlockedList = new List<Guid>();
}
#endregion
#region Methods
#region ToString()
/// <summary>
/// This method is used to return the Name of the Subscriber when ToString is called.
/// </summary>
/// <returns></returns>
public override string ToString()
{
// return the Name when ToString is called
return this.Name;
}
#endregion
#endregion
#region Properties
#region BlockedList
/// <summary>
/// This property gets or sets the value for 'BlockedList'.
/// </summary>
public List<Guid> BlockedList
{
get { return blockedList; }
set { blockedList = value; }
}
#endregion
#region Callback
/// <summary>
/// This property gets or sets the value for 'Callback'.
/// </summary>
public Callback Callback
{
get { return callback; }
set { callback = value; }
}
#endregion
#region HasBlockedList
/// <summary>
/// This property returns true if this object has a 'BlockedList'.
/// </summary>
public bool HasBlockedList
{
get
{
// initial value
bool hasBlockedList = (this.BlockedList != null);
// return value
return hasBlockedList;
}
}
#endregion
#region HasCallback
/// <summary>
/// This property returns true if this object has a 'Callback'.
/// </summary>
public bool HasCallback
{
get
{
// initial value
bool hasCallback = (this.Callback != null);
// return value
return hasCallback;
}
}
#endregion
#region HasName
/// <summary>
/// This property returns true if the 'Name' exists.
/// </summary>
public bool HasName
{
get
{
// initial value
bool hasName = (!String.IsNullOrEmpty(this.Name));
// return value
return hasName;
}
}
#endregion
#region Id
/// <summary>
/// This property gets or sets the value for 'Id'.
/// </summary>
public Guid Id
{
get { return id; }
set { id = value; }
}
#endregion
#region Name
/// <summary>
/// This property gets or sets the value for 'Name'.
/// </summary>
public string Name
{
get { return name; }
set { name = value; }
}
#endregion
#endregion
}
#endregion
}
And here is my delegate class:
/// <summary>
/// This delegate is used by the SubscriberService to send messages to any subscribers
/// </summary>
/// <returns></returns>
public delegate void Callback(SubscriberMessage message);
Then in my component I call methods like this:
// Send this message to all clients
SubscriberService.BroadcastMessage(message);
And each client has a listen method:
SubscriberCallback callback = new SubscriberCallback(SubscriberName);
callback.Callback = Listen;
callback.Name = SubscriberName;
// Get a message back
SubscriberMessage message = SubscriberService.Subscribe(callback);
Here is my Listen method, it just waits for messages;
using DataJuggler.UltimateHelper.Core; // Nuget package
public void Listen(SubscriberMessage message)
{
// if the message exists (part of DataJuggler.UltimateHelper.Core Nuget Package)
// Same as (message != null)
if (NullHelper.Exists(message))
{
// if the message contains Joined the conversation
if ((message.Text.Contains("joined the conversation")) ||
(message.Text.Contains("left the conversation")))
{
// this updates my list of 'Whose On' whenever a user joins or leaves
// Get the Names again
this.Names = SubscriberService.GetSubscriberNames();
// Update the UI
Refresh();
}
else
{
// my display message code is here
}
}
And finally here is my Subscriber message:
#region using statements
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
#endregion
namespace BlazorChat
{
#region class SubscriberMessage
/// <summary>
/// This class is used to send information between components / pages.
/// </summary>
public class SubscriberMessage
{
#region Private Variables
private string text;
private Guid fromId;
private Guid toId;
private string fromName;
private string toName;
private object data;
private string valid;
private DateTime sent;
private string invalidReason;
#endregion
#region Properties
#region Data
/// <summary>
/// This property gets or sets the value for 'Data'.
/// </summary>
public object Data
{
get { return data; }
set { data = value; }
}
#endregion
#region FromId
/// <summary>
/// This property gets or sets the value for 'FromId'.
/// </summary>
public Guid FromId
{
get { return fromId; }
set { fromId = value; }
}
#endregion
#region FromName
/// <summary>
/// This property gets or sets the value for 'FromName'.
/// </summary>
public string FromName
{
get { return fromName; }
set { fromName = value; }
}
#endregion
#region HasText
/// <summary>
/// This property returns true if the 'Text' exists.
/// </summary>
public bool HasText
{
get
{
// initial value
bool hasText = (!String.IsNullOrEmpty(this.Text));
// return value
return hasText;
}
}
#endregion
#region InvalidReason
/// <summary>
/// This property gets or sets the value for 'InvalidReason'.
/// </summary>
public string InvalidReason
{
get { return invalidReason; }
set { invalidReason = value; }
}
#endregion
#region Sent
/// <summary>
/// This property gets or sets the value for 'Sent'.
/// </summary>
public DateTime Sent
{
get { return sent; }
set { sent = value; }
}
#endregion
#region Text
/// <summary>
/// This property gets or sets the value for 'Text'.
/// </summary>
public string Text
{
get { return text; }
set { text = value; }
}
#endregion
#region ToId
/// <summary>
/// This property gets or sets the value for 'ToId'.
/// </summary>
public Guid ToId
{
get { return toId; }
set { toId = value; }
}
#endregion
#region ToName
/// <summary>
/// This property gets or sets the value for 'ToName'.
/// </summary>
public string ToName
{
get { return toName; }
set { toName = value; }
}
#endregion
#region Valid
/// <summary>
/// This property gets or sets the value for 'Valid'.
/// </summary>
public string Valid
{
get { return valid; }
set { valid = value; }
}
#endregion
#endregion
}
#endregion
}
BlazorChat is a sample project I am still working on as part of my Nuget package:
DataJuggler.Blazor.Components, which contains a Sprite component, ProgressBar and Validation component.
The full code is here in the Samples folder of this project if I left anything out.
https://github.com/DataJuggler/DataJuggler.Blazor.Components
Documentation and SQL scripts are missing, so sorry, its a work in progress.