Passing object messages in Azure Queue Storage

问题

I'm trying to find a way to pass objects to the Azure Queue. I couldn't find a way to do this.

As I've seen I can pass string or byte array, which is not very comfortable for passing objects.

Is there anyway to pass custom objects to the Queue?

Thanks!

回答1:

You can use the following classes as example:

 [Serializable]
    public abstract class BaseMessage
    {
        public byte[] ToBinary()
        {
            BinaryFormatter bf = new BinaryFormatter();
            byte[] output = null;
            using (MemoryStream ms = new MemoryStream())
            {
                ms.Position = 0;
                bf.Serialize(ms, this);
                output = ms.GetBuffer();
            }
            return output;
        }

        public static T FromMessage<T>(CloudQueueMessage m)
        {
            byte[] buffer = m.AsBytes;
            T returnValue = default(T);
            using (MemoryStream ms = new MemoryStream(buffer))
            {
                ms.Position = 0;
                BinaryFormatter bf = new BinaryFormatter();
                returnValue = (T)bf.Deserialize(ms);
            }
            return returnValue;
        }
    }

Then a StdQueue (a Queue that is strongly typed):

   public class StdQueue<T> where T : BaseMessage, new()
    {
        protected CloudQueue queue;

        public StdQueue(CloudQueue queue)
        {
            this.queue = queue;
        }

        public void AddMessage(T message)
        {
            CloudQueueMessage msg =
            new CloudQueueMessage(message.ToBinary());
            queue.AddMessage(msg);
        }

        public void DeleteMessage(CloudQueueMessage msg)
        {
            queue.DeleteMessage(msg);
        }

        public CloudQueueMessage GetMessage()
        {
            return queue.GetMessage(TimeSpan.FromSeconds(120));
        }
    }

Then, all you have to do is to inherit the BaseMessage:

[Serializable]
public class ParseTaskMessage : BaseMessage
{
    public Guid TaskId { get; set; }

    public string BlobReferenceString { get; set; }

    public DateTime TimeRequested { get; set; }
}

And make a queue that works with that message:

CloudStorageAccount acc;
            if (!CloudStorageAccount.TryParse(connectionString, out acc))
            {
                throw new ArgumentOutOfRangeException("connectionString", "Invalid connection string was introduced!");
            }
            CloudQueueClient clnt = acc.CreateCloudQueueClient();
            CloudQueue queue = clnt.GetQueueReference(processQueue);
            queue.CreateIfNotExist();
            this._queue = new StdQueue<ParseTaskMessage>(queue);

Hope this helps!

回答2:

Extension method that uses Newtonsoft.Json and async

    public static async Task AddMessageAsJsonAsync<T>(this CloudQueue cloudQueue, T objectToAdd)
    {
        var messageAsJson = JsonConvert.SerializeObject(objectToAdd);
        var cloudQueueMessage = new CloudQueueMessage(messageAsJson);
        await cloudQueue.AddMessageAsync(cloudQueueMessage);
    }

回答3:

I like this generalization approach but I don't like having to put Serialize attribute on all the classes I might want to put in a message and derived them from a base (I might already have a base class too) so I used...

using System;
using System.Text;
using Microsoft.WindowsAzure.Storage.Queue;
using Newtonsoft.Json;

namespace Example.Queue
{
    public static class CloudQueueMessageExtensions
    {
        public static CloudQueueMessage Serialize(Object o)
        {
            var stringBuilder = new StringBuilder();
            stringBuilder.Append(o.GetType().FullName);
            stringBuilder.Append(':');
            stringBuilder.Append(JsonConvert.SerializeObject(o));
            return new CloudQueueMessage(stringBuilder.ToString());
        }

        public static T Deserialize<T>(this CloudQueueMessage m)
        {
            int indexOf = m.AsString.IndexOf(':');

            if (indexOf <= 0)
                throw new Exception(string.Format("Cannot deserialize into object of type {0}", 
                    typeof (T).FullName));

            string typeName = m.AsString.Substring(0, indexOf);
            string json = m.AsString.Substring(indexOf + 1);

            if (typeName != typeof (T).FullName)
            {
                throw new Exception(string.Format("Cannot deserialize object of type {0} into one of type {1}", 
                    typeName,
                    typeof (T).FullName));
            }

            return JsonConvert.DeserializeObject<T>(json);
        }
    }
}

e.g.

var myobject = new MyObject();
_queue.AddMessage( CloudQueueMessageExtensions.Serialize(myobject));

var myobject = _queue.GetMessage().Deserialize<MyObject>();

回答4:

In case the storage queue is used with WebJob or Azure function (quite common scenario) then the current Azure SDK allows to use POCO object directly. See examples here:

• https://docs.microsoft.com/en-us/sandbox/functions-recipes/queue-storage
• https://github.com/Azure/azure-webjobs-sdk/wiki/Queues#trigger

Note: The SDK will automatically use Newtonsoft.Json for serialization/deserialization under the hood.

回答5:

That is not right way to do it. queues are not ment for storing object. you need to put object in blob or table (serialized). I believe queue messgae body has 64kb size limit with sdk1.5 and 8kb wih lower versions. Messgae body is ment to transfer crutial data for workera that pick it up only.

来源：https://stackoverflow.com/questions/8550702/passing-object-messages-in-azure-queue-storage