sorodriguezz/skills/accessing-cloud-storage

Accessing Cloud Storage

Introduction to Cloud Storage Adapters

InterSystems IRIS® makes it easy to retrieve, store, and delete data from a cloud storage provider like Amazon Web Services (AWS), Azure Blob Storage (Azure) or Google Cloud Platform (GCP). When using an InterSystems product to access cloud storage, you have two options: use an interoperability production or call low-level APIs.

Interoperability productions are designed to connect external systems, and you can use one to access cloud storage. If you want to bring data from cloud storage into your production, create a business service that uses the inbound adapter. Creating a business operation that uses the outbound adapter allows you to delete or upload data in the cloud.

Low-level APIs allow your code to access cloud storage without using the production framework. They give you programmatic access to cloud storage providers using simple calls within your code.

In AWS, data is stored as objects. However, other cloud storage providers use the term blob to refer to the same concept. Within InterSystems IRIS, data in cloud storage is referred to as a blob.

Note:

The cloud storage adapters were developed using the InterSystems PEX framework, so the source code for the adapter looks different from other adapters. For example, the outbound adapter methods are actually ObjectScript wrappers for methods written in a Java PEX component.

Using the Inbound Adapter for Cloud Storage

Within a production, you can include custom business services that use the inbound cloud adapter to retrieve data from cloud storage. To do so, create one or more business service classes as described here. Then add them to your production and configure them.

2.1 Overall Behavior of the Adapter

The cloud inbound adapter, EnsLib.CloudStorage.InboundAdapter, provides settings that you can use to specify the location of the cloud storage to examine, as well as settings to authenticate to the service provider. When included in a business service, the adapter periodically polls for available resources. Then at each polling interval:

If the adapter finds input from its configured data source, it constructs an input object to hold the data, and it calls the internal ProcessInput() method of the business service, passing the object to it. The input object depends upon the adapter.

2. The internal ProcessInput() method of the business service receives the input object. It then performs basic production tasks such as maintaining internal information as needed by all business services. You do not customize or override this method, which your business service class inherits.

3. The ProcessInput() method then calls your custom OnProcessInput() method, passing the input object. The

requirements for this method are described in Implementing the OnProcessInput() Method.

4. Your custom OnProcessInput() method examines the input object and sends it to other hosts in the production (or

creates and sends new messages based on the input object).

2.2 Creating a Business Service

To use the cloud inbound adapter, create a business service class as follows:

• Your business service class should extend Ens.BusinessService.

• In your class, the ADAPTER parameter should equal EnsLib.CloudStorage.InboundAdapter.

Using the Inbound Adapter for Cloud Storage

• Your class should implement the OnProcessInput() method, as described in Implementing the OnProcessInput() Method.

• For other options and general information, see Defining a Business Service Class .

2.3 Implementing the OnProcessInput() Method

Within your business service class, your OnProcessInput() method should have the following signature:

Method OnProcessInput(pInput As EnsLib.CloudStorage.InboundInput, Output pOutput As %RegisteredObject) As %Status { }

Where:

• pInput is the input object created by the adapter, using data retrieved from cloud storage.

• pOutput is the generic output argument required in the method signature. You can use a more specific message class in the method signature.

The OnProcessInput() method should do the following:

1. Examine the input object (pInput) and decide how to use it. The Content property of this object is a stream that contains

the data retrieved from the cloud storage.

2. Create an instance of the request message, which will be the message that your business service sends.

For information on creating message classes, see Defining Messages .

3. For the request message, set its properties as appropriate, using values in the input.

4. Call a suitable method of the business service to send the request to some destination within the production. Specifically , call SendRequestSync(), SendRequestAsync(), or (less common) SendDeferredResponse(). For details, see Sending Request Messages.

Each of these methods returns a status (specifically , an instance of %Status).

5. Make sure that you set the output argument (pOutput). Typically you set this equal to the response message that you

have received. This step is required.

6. Return an appropriate status. This step is required.

2.4 Properties of the Input Object

The input object is an instance of EnsLib.CloudStorage.InboundInput, which has the following properties:

• Name is the name of cloud storage blob.

• Meta contains the metadata associated with the cloud storage blob.

• Content is a stream that contains the data from cloud storage.

Your OnProcessInput() method should examine these properties and use them as needed for your business case.

Reprocessing a Blob

2.5 Reprocessing a Blob

Normally, if a blob has been processed, it will be ignored by future processing. If you need to force the production to reprocess a blob, you can remove the global node that tells the system the blob has been processed:

^Ens.AppData(..BusinessHost.%ConfigName, BucketName, BlobName)

For example, suppose that the business host MyProduction.MyService processes blobs and suppose that its configuration name is BucketProcessor. Also suppose that this business host has processed a blob named mysample/data1 in a bucket named Bucket1. To force this business host to reprocess this blob, use the ObjectScript shell, go to the namespace where the production is running, and execute the following command:

ObjectScript

kill ^Ens.AppData("BucketProcessor", "Bucket1", "mysample/data1")

2.6 See Also

• Using the Outbound Adapter for Cloud Storage

Within a production, you can use the cloud outbound adapter to access data in cloud storage. To do so, create a custom business operation as described here. After creating the business operation, add it to your production and configure it.

3.1 Creating a Business Operation to Use the Adapter

To use the cloud outbound adapter, create a business operation class as follows:

• Your business operation class should extend Ens.BusinessOperation.

• In your class, the ADAPTER parameter should equal EnsLib.CloudStorage.OutboundAdapter.

• In your class, the INVOCATION parameter should specify the invocation style you want to use, which must be one of the following.

–

–

Queue means the message is created within one background job and placed on a queue, at which time the original job is released. Later, when the message is processed, a different background job is allocated for the task. This is the most common setting.

InProc means the message will be formulated, sent, and delivered in the same job in which it was created. The job will not be released to the sender’s pool until the message is delivered to the target. This is only suitable for special cases.

• Your class should define a message map that includes at least one entry. A message map is an XData block entry that has the following structure:

XData MessageMap { <MapItems> <MapItem MessageType="messageclass"> <Method>methodname</Method> </MapItem> ... </MapItems> }

• Your class should define all the methods named in the message map. These methods are known as message handlers. Each message handler should have the following signature:

Using the Outbound Adapter for Cloud Storage

Class Member

Method Sample(pReq As RequestClass, Output pResp As ResponseClass) As %Status { }

Here Sample is the name of the method, RequestClass is the name of a request message class, and ResponseClass is the name of a response message class. See Defining Messages .

To use the adapter, the method code must call methods of the Adapter property of your business operation. See Deleting Blobs and Uploading Blobs.

• For other options and general information, see Defining a Business Operation Class .

The following example shows the general structure that you need:

Class Definition

Class ECLOUD.NewOperation1 Extends Ens.BusinessOperation { Parameter ADAPTER = "EnsLib.CloudStorage.OutboundAdapter";

Parameter INVOCATION = "Queue";

Method Sample(pReq As RequestClass, Output pResp As ResponseClass) As %Status { Quit $$$ERROR($$$NotImplemented) }

XData MessageMap { <MapItems> <MapItem MessageType="RequestClass"> <Method>Sample</Method> </MapItem> </MapItems> } }

3.2 Deleting Blobs

A business operation deletes an blob from cloud storage by calling the DeleteBlob() method of the outbound adapter. The signature of this method is as follows:

Class Member

method DeleteBlob(bucketName as %String, blobName as %String) as %Status { }

Where:

• bucketName is the name of the bucket where the blob is stored.

• blobName is the name of the blob.

For example, one of your custom methods could include this:

ObjectScript

Set tSC = ..Adapter.DeleteBlob(..BucketName, request.BlobName)

This code uses the BucketName property to refer to the cloud storage bucket. The name of the blob to delete is taken from the request message.

Uploading Blobs

3.3 Uploading Blobs

The outbound adapter provides three different methods for uploading blobs, depending on the source or data type of the data. The signatures of these methods are as follows:

Class Member

method UploadBlobFromFile(bucketName as %String, blobName as %String, filePath as %String) as %Status { }

Class Member

method UploadBlobFromStream(bucketName as %String, blobName as %String, content as %Stream.Object) as %Status { }

Class Member

method UploadBlobFromString(bucketName as %String, blobName as %String, content as %String) as %Status { }

Where:

• bucketName is the name of the bucket where the blob is stored.

• blobName is the name of the blob.

• fileP ath, used by UploadBlobFromFile(), is the full pathname of the file to be read and uploaded.

• content, used by the other methods, is the data to be uploaded. For UploadBlobFromStream(), this must be an instance of %Stream.Object. For UploadBlobFromString(), this is a string.

For example, one of your custom methods could include this:

ObjectScript

Set tSC = ..Adapter.UploadBlobFromStream(..BucketName, request.BlobName, request.Content)

3.4 Prebuilt Cloud Business Operation

For your convenience, InterSystems provides a simple business operation, EnsLib.CloudStorage.BusinessOperation, that demonstrates how to delete a blob and upload a blob from a stream. This sample business operation uses two simple message classes, EnsLib.CloudStorage.DeleteRequest and EnsLib.CloudStorage.UploadRequest to delete and upload blobs. EnsLib.CloudStorage.BusinessOperation includes the property BucketName as described above. The outbound adapter does not include this property, so custom business operations must include it.

3.5 See Also

• Settings for the Cloud Outbound Adapter This section provides reference information for the cloud adapters.

Also see Settings in All Productions.

Provides reference information for settings of EnsLib.CloudStorage.InboundAdapter. You can configure these settings after you have added a business service that uses this adapter to your production.

Summary The cloud inbound adapter has the following settings:

Group

Settings

Cloud Storage

BucketName, BlobNamePrefix, BlobNamePattern, DeleteAfterDownload, AppendTimeStamp, ArchiveBucket, ArchiveFolder, ErrorBucket, ErrorFolder, StorageProvider, EndPoint, ProviderCredentialFile, StorageRegion

The remaining settings are common to all business services. For information, see Settings for All Business Services.

Note:

The setting names use AWS terminology; however, they can be used with any cloud storage provider. For example, when using Microsoft Azure, to specify the BucketName setting, use the Microsoft Azure container name.

AppendTimeStamp Flag to indicate whether appending a timestamp when archiving a blob .

ArchiveBucket Name of the bucket to use when archiving a blob. This bucket must already exist and must be writable.

ArchiveFolder Name of the folder (in the ArchiveBucket) to use when archiving a blob.

BucketName Identifies the cloud storage b ucket that contains the blobs you want to work with. This bucket must already exist and must be writable.

BlobNamePrefix BlobNamePrefix and BlobNamePattern determine which blobs are retrieved from cloud storage. Looking at an example is the easiest way to understand how these properties work together. Consider an AWS S3 bucket that contains the following blobs:

foo/bar/baz foo/bar/bash foo/bar/bang foo/boo

AWS uses / in blob names to create virtual hierarchies, similar to how a file system or ganizes files into directories. Within this scheme, the BlobNamePrefix works like a directory name. For example, foo/ chooses all blobs, while foo/bar/ only selects the first three blobs. This selection happens on the AWS server side.

After the client gets a list of blobs from the server, BlobNamePattern is used to filter the list further . For example, if BlobNamePrefix="/foo/bar/" and BlobNamePattern="*ba?", the adapter retrieves just the first blob . This filtering happens on the client side. The BlobNamePattern property supports the wildcards * and ?.

If more than one blob meets the criteria set by BlobNamePrefix and BlobNamePattern, the adapter forwards each blob to the business service individually in separate InboundInput objects.

BlobNamePattern See BlobNamePrefix .

DeleteAfterDownload If this setting is enabled, the adapter deletes the blob after downloading it.

ErrorBucket Name of the bucket to use when an error occurs when archiving a blob. This bucket must already exist and must be writable.

ErrorFolder Name of the folder (in the ErrorBucket) to use when an error occurs when archiving a blob.

StorageProvider Identifies the cloud storage pro vider.

EndPoint PrivateLink endpoint.

ProviderCredentialFile Credentials needed to access the provider. These should be stored securely.

• AWS — With AWS, you can leave this blank to use the default credential provider chain to obtain the credentials needed to access and S3 bucket. If you prefer to use a credentials file, you can do wnload the credentials file from AWS and then specify its file path. See, Sign Up for AWS and Create an IAM User for more details.

• GCP — Create access credentials by following Create and manage service account keys.

• Azure — Azure doesn’t support credentials files. It uses a connection string instead, see Configure Azure Storage connection strings for details. The connection string contains key-value pairs delimited by semicolons. The string should be edited to remove the semicolons and each key-value pair placed on its own line.

A sample connection string looks like:

DefaultEndpointsProtocol=https;AccountName=sampleuser;AccountKey=5X774mvEs41WxQsOw19PB2Y;EndpointSuffix=core.windows.net

This needs to be broken down to create a file that looks lik e:

DefaultEndpointsProtocol=https AccountName=sampleuser AccountKey=5X774mvEs41WxQsOw19PB2Y EndpointSuffix=core.windows.net

StorageRegion Identifies the re gion of your cloud storage.

• AWS — For a list of AWS regions, see Amazon Regions, Availability Zones, and Local Zones.

• GCP — For a list of GCP regions, see Bucket Locations.

• Azure — The region is implied in the connection string. No explicit setting is required.

Settings for the Cloud Outbound Adapter

Provides reference information for settings of EnsLib.CloudStorage.OutboundAdapter. You can configure these settings after you have added a business operation that uses this adapter to your production.

Summary The cloud outbound adapter has the following settings:

Group

Settings

Cloud Storage

StorageProvider, EndPoint, ProviderCredentialFile, StorageRegion

The remaining settings are common to all business operations. For information, see Settings for All Business Operations.

StorageProvider Identifies the cloud storage pro vider.

EndPoint PrivateLink endpoint.

ProviderCredentialFile

• AWS — With AWS, you can leave this blank to use the default credential provider chain to obtain the credentials needed to access and S3 bucket. If you prefer to use a credentials file, you can do wnload the credentials file from AWS and then specify its file path. See, Sign Up for AWS and Create an IAM User for more details.

• GCP — Create access credentials by following Create and manage service account keys.

• Azure — Azure doesn’t support credentials files. It uses a connection string instead, see Configure Azure Storage connection strings for details. The connection string contains key-value pairs delimited by semicolons. The string should be edited to remove the semicolons and each key-value pair placed on its own line.

A sample connection string looks like:

DefaultEndpointsProtocol=https;AccountName=sampleuser;AccountKey=5X774mvEs41WxQsOw19PB2Y;EndpointSuffix=core.windows.net

This needs to be broken down to create a file that looks lik e:

DefaultEndpointsProtocol=https AccountName=sampleuser AccountKey=5X774mvEs41WxQsOw19PB2Y EndpointSuffix=core.windows.net

If you are working with AWS, leave blank to use the default credential provider chain to obtain the credentials needed to access an S3 bucket. If you prefer to use a credential file, enter its pathname.

StorageRegion Identifies the re gion of your cloud storage. For a list of AWS regions, see Amazon Regions, Availability Zones, and Local Zones.

• AWS — For a list of AWS regions, see Amazon Regions, Availability Zones, and Local Zones.

• GCP — For a list of GCP regions, see Bucket Locations.

• Azure — The region is implied in the connection string. No explicit setting is required.

Your ObjectScript code can upload, download, and delete data from a cloud storage provider by calling a set of low-level APIs, allowing you to access cloud storage without using an interoperability production. Your code interacts with the cloud storage provider by creating a client, then calling the client’s methods to perform actions like uploading a blob or deleting a blob. The class for this cloud storage client is %Net.Cloud.Storage.Client. It is the same class for each cloud storage provider.

The cloud storage APIs are simple to use. For example, the following code is all you need to upload a file to an Amazon Web Services S3 bucket:

ObjectScript

Set bucketName = "s3-bucket" Set blobName = "s3-object-blob" // Create Cloud Storage Client for S3 Set myClient = ##class(%Net.Cloud.Storage.Client).CreateClient(,0, "/home/AWSCredentials", "us-east-1", .tSC)

// Upload file to S3 If myClient.BucketExists(bucketName){ Do myClient.UploadBlobFromFile(bucketName, blobName, "/usr/file.jpg") } // Close client

4.1 Creating a Client

Before working with a cloud storage provider’s buckets and blobs, your code must create a cloud storage client using the following syntax:

ObjectScript

Set myClient = ##class(%Net.Cloud.Storage.Client).CreateClient(javaServer, provider,credentialsFile,region,.tSC,endPoint)

Where:

• javaServer is the name of an InterSystems external server for Java (also known as a Java gateway). To use the default Java external server rather than creating a custom one, simply leave this argument empty.

• provider is an integer that indicates which cloud storage provider is being accessed with the client. For S3 buckets, use 0.

• credentialsFile is a file that contains the credentials used to access the cloud storage pro vider. The file must be formatted according to the provider’s specifications. If you are accessing an S3 b ucket, you can leave this argument empty to use the default credential provider chain.

• region is the region containing the buckets you want to work with. For a list of AWS regions, see Amazon Regions, Availability Zones, and Local Zones.

• tSC, which is returned by reference, is the status code returned by the method call.

• endPoint is an optional endpoint for AWS PrivateLink.

4.1.1 Closing a Client

Once you are done working with a provider’s buckets and blobs, be sure to use the Close() method to close the client that you created. For example:

ObjectScript

4.2 Working with Buckets

The cloud storage client includes a set of methods designed to work with a provider’s buckets, which are the storage con- tainers for blobs. The signatures of these methods are:

Method BucketExists(bucketName As %String) As %Boolean Method GetBucketInfo(bucketName As %String) As BucketInfo Method ListBuckets() As %ListOfObjects Method CreateBucket(bucketName As %String) Method DeleteBucket(bucketName As %String)

For example, to create a cloud storage client in order to retrieve details about a bucket, enter:

ObjectScript

Set bucketName = "s3-bucket" Set myClient = ##class(%Net.Cloud.Storage.Client).CreateClient(,0, "/home/AWSCredentials", "us-east-1", .tSC) Set bucketDetails = myClient.GetBucketInfo(bucketName)

4.2.1 Bucket Details

The cloud storage client uses a %Net.Cloud.Storage.BucketInfo object to represent the details about a bucket. When you call GetBucketInfo(), the details about the specified b ucket are returned in an instance of %Net.Cloud.Storage.BucketInfo object. Likewise, a call to ListBuckets() returns all of the available buckets in a collection of these objects, allowing you to access details about each bucket. To learn more about what bucket details are available, see the properties of %Net.Cloud.Storage.BucketInfo.

For convenience, the %Net.Cloud.Storage.BucketInfo class includes a method that allows you to put the details of a bucket into JSON format; the method is toJSON().

Retrieving Blob Information

4.3 Retrieving Blob Information

The cloud storage client uses the following methods to retrieve information about blobs in a particular bucket:

Method BlobExists(bucketName As %String, blobName As %String) As %Boolean Method GetBlobInfo(bucketName As %String, blobName As %String) As BlobInfo Method ListBlobs(bucketName As %String) As %ListOfObjects

The client provides separate methods to download the content of a blob.

As an example, if you wanted to retrieve details about a particular blob, like its size, you could enter:

Set bucketName = "s3-bucket" Set blobName = "s3-object-blob" Set myClient = ##class(%Net.Cloud.Storage.Client).CreateClient(,0,"/home/AWSCredentials", "us-east-1", .tSC) Set blobDetails = myClient.GetBlobInfo(bucketName, blobName)

4.3.1 Blob Details

The cloud storage client uses a %Net.Cloud.Storage.BlobInfo object to represent the details about a blob. When you call GetBlobInfo(), the details about the specified blob are returned in an instance of %Net.Cloud.Storage.BlobInfo object. Likewise, a call to ListBlobs() returns all of the available blobs in a collection of these objects, allowing you to access details about each blob. To learn more about what blob details are available, see the properties of %Net.Cloud.Storage.BlobInfo.

For convenience, the %Net.Cloud.Storage.BlobInfo class includes a method that allows you to put the details of a blob into JSON format: toJSON().

4.4 Uploading Blobs

The cloud storage APIs allow you to upload data and files to cloud storage from InterSystems IRIS®. You can use any of the following methods to upload blobs to a cloud storage provider, depending on the source of the blob’s data:

Method UploadBlobFromString(bucketName As %String, blobName As %String, content As %String) Method UploadBlobFromFile(bucketName As %String, blobName As %String, filePath As %String) Method UploadBlobFromStream(bucketName As %String, blobName As %String, stream As %GlobalBinaryStream)

For example, to upload a file to an S3 b ucket, you could include:

ObjectScript

Set bucketName = "s3-bucket" Set blobName = "s3-object-blob" Set myClient = ##class(%Net.Cloud.Storage.Client).CreateClient(,0, "/home/AWSCredentials", "us-east-1", .tSC) Do myClient.UploadBlobFromFile(bucketName, blobName, "/usr/file.jpg")

4.5 Downloading Blobs

You can use the cloud storage APIs to download data from a cloud storage provider in order to work with it in InterSystems IRIS. Various methods are available, allowing you to choose the target format of the data:

Method DownloadBlobToString(bucketName As %String, blobName As %String) As %String Method DownloadBlobToFile(bucketName As %String, blobName As %String, filePath As %String) Method DownloadBlobToStream(bucketName As %String, blobName As %String) As %GlobalBinaryStream

For example, to download a blob from an S3 bucket and store it in a stream, enter:

ObjectScript

Set bucketName = "s3-bucket" Set blobName = "s3-object-blob" Set myClient = ##class(%Net.Cloud.Storage.Client).CreateClient(,0, "/home/AWSCredentials", "us-east-1", .tSC) Set IRISStream = myClient.DownloadBlobToStream(bucketName, blobName)

4.6 Single Method for Uploading Blobs

The cloud storage APIs allow you to upload data and files to cloud storage without using an interoperability production. These class methods allow you to make a single call which will create a client, upload the blob, then close the client:

• SingleUploadBlobFromFile

• SingleUploadBlobFromStream

• SingleUploadBlobFromString

For example, to upload a file to Amazon S3, you could include:

ObjectScript

Set bucketName = "s3-bucket" Set blobName = "s3-object-blob" Set credentials = "/home/AWSCredentials" Set region = "us-east-1" Set filePath = "/usr/file.jpg" Set status = ##class(%Net.Cloud.Storage.Client).SingleUploadBlobFromFile(, 0, credentials, region, bucketName, blobName, filePath)

4.7 Single Method for Downloading Blobs

You can use the cloud storage APIs to download data from a cloud storage provider in order to work with it in InterSystems IRIS. These class methods allow you to make a single call which will create a client, download the blob, then close the client:

• SingleDownloadBlobToFile

• SingleDownloadBlobToStream

• SingleDownloadBlobToString

ObjectScript

Set bucketName = "s3-bucket" Set blobName = "s3-object-blob" Set credentials = "/home/AWSCredentials" Set region = "us-east-1" Set status = ##class(%Net.Cloud.Storage.Client).SingleDownloadBlobToStream(, 0, credentials, region, bucketName, blobName)

4.8 Deleting Blobs

Like the other cloud storage APIs, the method to delete a blob from cloud storage is straightforward. All it requires is the name of the blob you want to delete, including the bucket where it is stored.

Deleting Blobs

Method DeleteBlob(bucketName As %String, blobName As %String)

For example, to delete a blob from an S3 bucket, enter:

ObjectScript

Set bucketName = "s3-bucket" Set blobName = "s3-object-blob" Set myClient = ##class(%Net.Cloud.Storage.Client).CreateClient(,0, "/home/AWSCredentials", "us-east-1", .tSC) Do myClient.DeleteBlob(bucketName, blobName)

4.9 Working with Presigned Blobs

%Net.Cloud.Storage.Client includes methods for generating and working with presigned blobs. These methods are as follows:

GeneratePresignedURL()

Method GeneratePresignedUrl(bucketName As %String, blobName As %String, duration As %BigInt, method As %String, metadata As %String = "") As %String

Generates a presigned URL. The arguments are as follows:

• bucketName specifies the b ucket.

• blobName specifies the blob .

• duration specifies the duration of the URL in milliseconds.

• method specifies the URL method to use. The options depend on the cloud storage provider:

– Amazon S3 supports DELETE, GET, HEAD, PATCH, POST, and PUT.

– Azure supports a subset of "acdrw"(ADD,CREATE,DELETE,READ,WRITE).

– GCS supports DELETE, GET, HEAD, OPTIONS, POST, and PUT.

• metadata specifies an y user metadata as a JSON string. Note the following points:

–

For Amazon S3, user metadata must be specified when generating the URL and cannot be later modified. The property names have the prefix x-amx-meta-

– Azure ignores user metadata when generating a presigned URL.

–

For GCS, user metadata must be specified when generating the URL and cannot be later modified. The property names have the prefix x-goog-meta-. In this case, the generated signature contains user metadata information.

GetBlobMetadata()

Method GetBlobMetadata(bucketName As %String, blobName As %String) As %String

Returns user metadata (as a JSON string) for the given blob. The arguments are as follows:

• bucketName specifies the b ucket.

• blobName specifies the blob .

Note that in this metadata, property names have no prefix es.

GetBlobMetadataWithPresignedUrl()

ClassMethod GetBlobMetadataWithPresignedUrl(presignedUrl As %String, Output metadata As %String, javaServer As %RawString

Retrieves metadata (as a JSON string) from the blob, accessible via a presigned URL. The arguments are as follows:

• presignedUrl is the presigned URL.

• metadata, which is returned as output, is the metadata as a JSON string.

• javaServer is the name of the Java External Language Server to use.

This method returns a status value, which you should check before proceeding.

UploadBlobWithPresignedUrl()

ClassMethod UploadBlobWithPresignedUrl(presignedUrl As %String, input As %Stream.Object, metadataJson As %String = "" javaServer As %RawString

Uploads data to the given blob, accessible via a presigned URL. The arguments are as follows:

• presignedUrl is the presigned URL.

• input is an instance of %Stream.Object, containing the data to be uploaded.

• metadataJson is the optional metadata as a JSON string. Note the following points:

–

–

–

For Amazon S3, user metadata should not be provided here; it can be provided only when generating the URL.

For Azure, the property names have the prefix x-ms-meta-. Also, the property x-ms-blob-type with value BlockBlob must be included.

For GCS, user metadata should exactly match what was provided when generating the presigned URL.

• javaServer is the name of the Java External Language Server to use.

This method returns a status value, which you should check before proceeding.

DownloadBlobWithPresignedUrl()

Working with Presigned Blobs

ClassMethod DownloadBlobWithPresignedUrl(presignedUrl As %String, start As %BigInt = "", end As %BigInt = "", Output outStream As %Stream.GlobalBinary, javaServer As %RawString

Downloads data from the given blob, accessible via a presigned URL. The arguments are as follows:

• presignedUrl is the presigned URL.

• start is the first position within the blob to be do wnloaded. The first position in the blob is 0. If this ar gument is a negative value, it is treated as 0. If this argument is an empty string, the entire blob is downloaded.

• end is the last position within the blob to be downloaded. If this argument is a negative value, the last position downloaded is the last position in the blob. If this argument is an empty string, the entire blob is downloaded.

• output, which is returned as output, is an instance of %Stream.Object containing the downloaded data.

• javaServer is the name of the Java External Language Server to use.

This method returns a status value, which you should check before proceeding.