SeanFeldman/ServiceBus.AttachmentPlugin

Microsoft Azure Service Bus attachment plugin

2023-12-14: The latest ASB SDK doesn't support plugins and requires inheritance. See details in #201.

2021-07-14: Consider using native Azure Service Bus service large messages feature for attachments up-to 100 MB.

This is a plugin for Microsoft.Azure.ServiceBus client

Allows sending messages that exceed maximum size by implementing Claim Check pattern with Azure Storage.

Nuget package

Available here http://nuget.org/packages/ServiceBus.AttachmentPlugin

To Install from the Nuget Package Manager Console

PM> Install-Package ServiceBus.AttachmentPlugin

Contents

• Examples
  • Convert body into attachment, no matter how big it is
  • Sending a message without exposing the storage account to receivers
  • Configure blob container name
  • Configure message property to identify attachment blob
  • Configure custom blob name override
  • Configure message property for SAS uri to attachment blob
  • Configure criteria for message max size identification
  • Configuring connection string provider
  • Configuring plugin using StorageCredentials (Service or Container SAS)
  • Using attachments with Azure Functions
• Cleanup
• Who's trusting this plugin in production
• Icon

Examples

Convert body into attachment, no matter how big it is

Configuration and registration

var sender = new MessageSender(connectionString, queueName);
var config = new AzureStorageAttachmentConfiguration(storageConnectionString);
sender.RegisterAzureStorageAttachmentPlugin(config);

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Sending

var payload = new MyMessage
{
    MyProperty = "The Value"
};
var serialized = JsonConvert.SerializeObject(payload);
var payloadAsBytes = Encoding.UTF8.GetBytes(serialized);
var message = new Message(payloadAsBytes);

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Receiving

var receiver = new MessageReceiver(connectionString, entityPath, ReceiveMode.ReceiveAndDelete);
receiver.RegisterAzureStorageAttachmentPlugin(config);
var message = await receiver.ReceiveAsync().ConfigureAwait(false);
// message will contain the original payload

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Sending a message without exposing the storage account to receivers

Configuration and registration with blob SAS URI

var sender = new MessageSender(connectionString, queueName);
var config = new AzureStorageAttachmentConfiguration(storageConnectionString)
    .WithBlobSasUri(
        sasTokenValidationTime: TimeSpan.FromHours(4),
        messagePropertyToIdentifySasUri: "mySasUriProperty");
sender.RegisterAzureStorageAttachmentPlugin(config);

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Sending

var payload = new MyMessage
{
    MyProperty = "The Value"
};
var serialized = JsonConvert.SerializeObject(payload);
var payloadAsBytes = Encoding.UTF8.GetBytes(serialized);
var message = new Message(payloadAsBytes);

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Receiving only mode (w/o Storage account credentials)

// Override message property used to identify SAS URI
// .RegisterAzureStorageAttachmentPluginForReceivingOnly() is using "$attachment.sas.uri" by default
messageReceiver.RegisterAzureStorageAttachmentPluginForReceivingOnly("mySasUriProperty");
var message = await messageReceiver.ReceiveAsync().ConfigureAwait(false);

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Configure blob container name

Default container name is "attachments". The value is available via AzureStorageAttachmentConfigurationConstants.DefaultContainerName constant.

new AzureStorageAttachmentConfiguration(storageConnectionString, containerName:"blobs");

Configure message property to identify attachment blob

Default blob identifier property name is "$attachment.blob". The value is available via AzureStorageAttachmentConfigurationConstants.DefaultMessagePropertyToIdentifyAttachmentBlob constant.

new AzureStorageAttachmentConfiguration(storageConnectionString, messagePropertyToIdentifyAttachmentBlob: "myblob");

Configure custom blob name override

Default blob name is a GUID.

var sender = new MessageSender(connectionString, queueName);
var config = new AzureStorageAttachmentConfiguration(storageConnectionString)
    .OverrideBlobName(message =>
    {
        var tenantId = message.UserProperties["tenantId"].ToString();
        var blobName = $"{tenantId}/{message.MessageId}";
        return blobName;
    });
sender.RegisterAzureStorageAttachmentPlugin(config);

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Configure message property for SAS uri to attachment blob

Default SAS uri property name is "$attachment.sas.uri". The value is available via AzureStorageAttachmentConfigurationConstants.DefaultMessagePropertyToIdentitySasUri constant.

Default SAS token validation time is 7 days.

new AzureStorageAttachmentConfiguration(storageConnectionString)
    .WithBlobSasUri(
        messagePropertyToIdentifySasUri: "mySasUriProperty",
        sasTokenValidationTime: TimeSpan.FromHours(12));

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Configure criteria for message max size identification

Default is to convert any body to attachment.

// messages with body > 200KB should be converted to use attachments
new AzureStorageAttachmentConfiguration(storageConnectionString,
    messageMaxSizeReachedCriteria: message => message.Body.Length > 200 * 1024);

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Configuring connection string provider

When Storage connection string needs to be retrieved rather than passed in as a plain text, AzureStorageAttachmentConfiguration accepts implementation of IProvideStorageConnectionString. The plugin comes with a PlainTextConnectionStringProvider and can be used in the following way.

var provider = new PlainTextConnectionStringProvider(connectionString);
var config = new AzureStorageAttachmentConfiguration(provider);

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Configuring plugin using StorageCredentials (Service or Container SAS)

var credentials = new StorageCredentials( /*Shared key OR Service SAS OR Container SAS*/);
var config = new AzureStorageAttachmentConfiguration(credentials, blobEndpoint);

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See StorageCredentials for more details.

Using attachments with Azure Functions

Azure Functions currently has no way to register plugins, these extension methods are a workaround until this feature is added.

To use the extensions, your Function must return (send) or take as parameter (receive) an instance of Message.

Upload attachment to Azure Storage blob

//To make it possible to use SAS URI when downloading, use WithBlobSasUri() when creating configuration object
await message.UploadAzureStorageAttachment(config);

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Download attachment from Azure Storage blob

//Using SAS URI with default message property ($attachment.sas.uri)
await message.DownloadAzureStorageAttachment();

//Using SAS URI with custom message property
await message.DownloadAzureStorageAttachment("$custom-attachment.sas.uri");

//Using configuration object
await message.DownloadAzureStorageAttachment(config);

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Additional providers

• ServiceBus.AttachmentPlugin.KeyVaultProvider

Cleanup

The plugin does NOT implement cleanup for the reasons stated here. When cleanup is required, there are a few options available depending on the use case.

Who's trusting this plugin in production

Proudly list your company here if use this plugin in production

Icon

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