Adobe Experience Manager Assets developer use cases, APIs, and reference material

The article contains recommendations, reference materials, and resources for developers of Assets as a Cloud Service. It includes new asset upload module, API reference, and information about the support provided in post-processing workflows.

Experience Manager Assets APIs and operations

Assets as a Cloud Service provides several APIs to programmatically interact with digital assets. Each API supports specific use cases, as mentioned in the table below. The Assets user interface, Experience Manager desktop app and Adobe Asset Link support all or some of the operations.

Asset upload

In Experience Manager as a Cloud Service, you can directly upload the assets to the cloud storage using HTTP API. The steps to upload a binary file are below. Execute these steps in an external application and not within the Experience Manager JVM.

1. Submit an HTTP request. It informs Experience Manager deployment of your intent to upload a new binary.
2. PUT the contents of the binary to one or more URIs provided by the initiation request.
3. Submit an HTTP request to inform the server that the contents of the binary were successfully uploaded.

The approach provides a scalable and more performant handling of asset uploads. The differences as compared to Experience Manager 6.5 are:

• Binaries do not go through Experience Manager, which is now simply coordinating the upload process with the binary cloud storage configured for the deployment.
• Binary cloud storage works with a Content Delivery Network (CDN) or Edge network. A CDN selects an upload endpoint that is nearer for a client. When data travels a shorter distance to a nearby endpoint, the upload performance and user experience improve, especially for geographically distributed teams.

Initiate upload

Submit an HTTP POST request to the desired folder. Assets are created or updated in this folder. Include the selector .initiateUpload.json to indicate that the request is to initiate upload of a binary file. For example, the path to the folder where the asset should be created is /assets/folder. The POST request is POST https://[aem_server]:[port]/content/dam/assets/folder.initiateUpload.json.

The content type of the request body should be application/x-www-form-urlencoded form data, containing the following fields:

• (string) fileName: Required. The name of the asset as it appears in Experience Manager.
• (number) fileSize: Required. The file size, in bytes, of the asset being uploaded.

A single request can be used to initiate uploads for multiple binaries, as long as each binary contains the required fields. If successful, the request responds with a 201 status code and a body containing JSON data in the following format:

{
    "completeURI": "(string)",
    "folderPath": "(string)",
    "files": [
        {
            "fileName": "(string)",
            "mimeType": "(string)",
            "uploadToken": "(string)",
            "uploadURIs": [
                "(string)"
            ],
            "minPartSize": (number),
            "maxPartSize": (number)
        }
    ]
}

• completeURI (string): Call this URI when the binary finishes uploading. The URI can be an absolute or relative URI, and clients should be able to handle either. That is, the value can be "https://[aem_server]:[port]/content/dam.completeUpload.json" or "/content/dam.completeUpload.json" See complete upload.
• folderPath (string): Full path to the folder in which the binary is uploaded.
• (files) (array): A list of elements whose length and order match the length and order of the list of binary information provided in the initiate request.
• fileName (string): The name of the corresponding binary, as supplied in the initiate request. This value should be included in the complete request.
• mimeType (string): The mime type of the corresponding binary, as supplied in the initiate request. This value should be included in the complete request.
• uploadToken (string): An upload token for the corresponding binary. This value should be included in the complete request.
• uploadURIs (array): A list of strings whose values are full URIs to which the binary’s content should be uploaded (see Upload binary).
• minPartSize (number): The minimum length, in bytes, of data that may be provided to any one of the uploadURIs, if there is more than one URI.
• maxPartSize (number): The maximum length, in bytes, of data that may be provided to any one of the uploadURIs, if there is more than one URI.

Upload binary

The output of initiating an upload includes one or more upload URI values. If more than one URI is provided, the client may split the binary into parts and make PUT requests of each part to the provided upload URIs, in order. If you choose to split the binary into parts, adhere to the following guidelines:

• Each part, with the exception of the last, must be of a size greater than or equal to minPartSize.
• Each part must be of a size less than or equal to maxPartSize.
• If the size of your binary exceeds maxPartSize, split the binary into parts to upload it.
• You are not required to use all URIs.

If the size of your binary is less than or equal to maxPartSize, you may instead upload the entire binary to a single upload URI. If more than one upload URI is provided, use the first one and ignore the rest. You are not required to use all URIs.

CDN edge nodes help accelerate the requested upload of binaries.

The easiest way to accomplish this is to use the value of maxPartSize as your part size. The API contract guarantees that there are sufficient upload URIs to upload your binary if you use this value as your part size. To do this, split the binary into parts of size maxPartSize, using one URI for each part, in order. The final part can be of any size less than or equal to maxPartSize. For example, assume the total size of the binary is 20,000 bytes, the minPartSize is 5,000 bytes, maxPartSize is 8,000 bytes, and the number of upload URIs is 5. Execute the following steps:

• Upload the first 8,000 bytes of the binary using the first upload URI.
• Upload the second 8,000 bytes of the binary using the second upload URI.
• Upload the last 4,000 bytes of the binary using the third upload URI. Since this is the final part, it does not need to be larger than minPartSize.
• You do not need to use the last two upload URIs. You can ignore them.

A common error is to calculate the part size based on the number of upload URIs provided by the API. The API contract does not guarantee that this approach works, and may actually result in part sizes that are outside the range between minPartSize and maxPartSize. This can result in binary upload failures.

Again, the easiest and safest way is to simply use parts of size equal to maxPartSize.

If the upload is successful, the server responds to each request with a 201 status code.

Complete upload

After all the parts of a binary file are uploaded, submit an HTTP POST request to the complete URI provided by the initiation data. The content type of the request body should be application/x-www-form-urlencoded form data, containing the following fields.

Like the initiate process, the complete request data may contain information for more than one file.

The process of uploading a binary is not done until the complete URL is invoked for the file. An asset is processed after the upload process is complete. Processing does not start even if the asset’s binary file is uploaded completely but upload process is not completed. If upload is successful, the server responds with a 200 status code.

Open-source upload library

To learn more about the upload algorithms or to build your own upload scripts and tools, Adobe provides open-source libraries and tools:

• Open-source aem-upload library.
• Open-source command-line tool.

Deprecated asset upload APIs

The new upload method is supported only for Adobe Experience Manager as a Cloud Service. The APIs from Adobe Experience Manager 6.5 are deprecated. The methods related to upload or update assets or renditions (any binary upload) are deprecated in the following APIs:

• Experience Manager Assets HTTP API
• AssetManager Java API, like AssetManager.createAsset(..)

Asset processing and post-processing workflows

In Experience Manager, the asset processing is based on Processing Profiles configuration that uses asset microservices. Processing does not require developer extensions.

For post-processing workflow configuration, use the standard workflows with extensions with custom steps.

Support of workflow steps in post-processing workflow

If you upgrade from a previous version of Experience Manager, you can use asset microservices to process assets. The cloud-native asset microservices are simpler to configure and use. A few workflow steps used in the DAM Update Asset workflow in the previous version are not supported. For more information about supported classes, see the Java API reference or Javadocs.

The following technical workflow models are either replaced by asset microservices or the support is not available:

• com.day.cq.dam.cameraraw.process.CameraRawHandlingProcess
• com.day.cq.dam.core.process.CommandLineProcess
• com.day.cq.dam.pdfrasterizer.process.PdfRasterizerHandlingProcess
• com.day.cq.dam.core.process.AddPropertyWorkflowProcess
• com.day.cq.dam.core.process.CreateSubAssetsProcess
• com.day.cq.dam.core.process.DownloadAssetProcess
• com.day.cq.dam.word.process.ExtractImagesProcess
• com.day.cq.dam.word.process.ExtractPlainProcess
• com.day.cq.dam.ids.impl.process.IDSJobProcess
• com.day.cq.dam.indd.process.INDDMediaExtractProcess
• com.day.cq.dam.indd.process.INDDPageExtractProcess
• com.day.cq.dam.core.impl.lightbox.LightboxUpdateAssetProcess
• com.day.cq.dam.pim.impl.sourcing.upload.process.ProductAssetsUploadProcess
• com.day.cq.dam.core.process.SendDownloadAssetEmailProcess
• com.day.cq.dam.similaritysearch.internal.workflow.smarttags.StartTrainingProcess
• com.day.cq.dam.similaritysearch.internal.workflow.smarttags.TransferTrainingDataProcess
• com.day.cq.dam.switchengine.process.SwitchEngineHandlingProcess
• com.day.cq.dam.core.process.GateKeeperProcess
• com.day.cq.dam.s7dam.common.process.DMEncodeVideoWorkflowCompletedProcess
• com.day.cq.dam.core.process.DeleteImagePreviewProcess
• com.day.cq.dam.video.FFMpegTranscodeProcess
• com.day.cq.dam.core.process.ThumbnailProcess
• com.day.cq.dam.video.FFMpegThumbnailProcess
• com.day.cq.dam.core.process.CreateWebEnabledImageProcess
• com.day.cq.dam.core.process.CreatePdfPreviewProcess
• com.day.cq.dam.s7dam.common.process.VideoUserUploadedThumbnailProcess
• com.day.cq.dam.s7dam.common.process.VideoThumbnailDownloadProcess
• com.day.cq.dam.s7dam.common.process.VideoProxyServiceProcess
• com.day.cq.dam.scene7.impl.process.Scene7UploadProcess
• com.day.cq.dam.s7dam.common.process.S7VideoThumbnailProcess
• com.day.cq.dam.core.process.MetadataProcessorProcess
• com.day.cq.dam.core.process.AssetOffloadingProcess
• com.adobe.cq.dam.dm.process.workflow.DMImageProcess

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