All files from Digizuite are served using the media pipelines.

It is configurable which one is used and this is controlled by a config parameter in DFS.Settings.config:

DFS.Settings.config

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <settings>
		<setting name="DFS.MediaPipeline" value="dfsmedia"/>
	</settings>
  </sitecore>
</configuration>

Understanding the request

The dfsmedia pipeline is accessible on the following endpoint: http(s)://<sitecore>/dfsmedia

The syntax of the URL is: dfsmedia/[SiloId]/[AssetId]-[Quality]/resize/[Width]x[Height]/compress/[0-100]/options/[Options]

If a parameter is not optional, it may be discarded, but it has to follow the order above. For instance if you want to compress only, then the following scheme is used:

dfsmedia/[SiloId]/[AssetId]-[Quality]/compress/[0-100]

Each parameter is described as follows:

Field	Description
SiloId	This is the Id of the silo that has the asset requested.
AssetId	Is the Id of the asset that is requested.
Quality	Overrides the quality specified in the Sitecore field. Quality supports both 'by name' and 'by id'
Resize *	Only applies to image assets. One of the concepts and principles when using a DAM system is to use specific qualities for every use. If images are needed in different sizes, it should be configured in Digizuite™ DAM. However, there is a resize feature. Width How wide the image will be in pixels. Height How high the image will be in pixels. By default a resize does not keep aspect ratio, but you can set an option to keep aspect ratio.
Compress *	Only applies to image assets. Indicates whether the asset should be saved using a worse quality, thereby reducing the physical size. from 0-100 is allowed, where 0 is the worst quality, but least physical storage.
Options *	Options is a dash ("-") separate list and can contain these options: download - Will download the asset requested. keepaspectratio - Will enforce aspect ratio on from the original asset, if a resize is requested. upscaleallowed - Will allow upscaling an image. The default is to disallow that.

*Optional

Understanding the DigizuiteMediaCache

The DigizuiteMediaCache is where everything, except videos, is saved. The cache location is configurable and is located in DFS.Settings.config

DFS.Settings.config

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <settings>
	  <!-- Path to DAM For Sitecore MediaCache. The following is supported: 
             -UNC (\\server\example\cahcepath)
             -Full path (C:\example\cachepath)
             -Relative path (/App_Data/cachepath)      
      -->
      <setting name="DFS.CacheLocation" value="/App_Data/DigizuiteMediaCache"/>
	</settings>
  </sitecore>
</configuration>

The default location is in the website root under App_Data/DigizuiteMediaCache/.

Files are cached based on the request made to the asset. An example request could be: http(s)://<sitecore url>/dfsmedia/29a605d46a3340418c16542f7272c3ec/110-50035

According to the specification of the URL, this request has the following properties:

AssetSiloId: 29a605d46a3340418c16542f7272c3ec
AssetId: 110
FormatId: 50035

The cache is then build using a naming scheme. Each asset is placed in a sub-folder which has the name of the assetid. In the case of the example, the path in which the file is saved would be App_Data/DigizuiteMediaCache/110

The filename is then constructed based on the given properties using the following scheme:

{Assetid}_{formatid}_{width}_{height}_{options}.{extension}

where width, height and options are not used, if not requested (i.e. not used in the example), which means in the example, the requested asset would have the following name:

110_50035.{extension}

The extension is retrieved from the file saved in the cache. The naming scheme enable unique names and hence the extension can be extracted from the file in the cache. Originally, the file is saved with the correct extension based on what is served from the Digizuite.

UNC path

The dfsmedia pipeline also supports having a centralized cache, which means multiple servers can have the same cache. This decreases storage, but also performance, because files are then cached on a UNC which is slower than having it locally. This is something each client has to have an opinion on.

Implementation

The new dfsmedia pipeline is implemented as a httphandler, using a pipeline in Sitecore. This pipeline is located in the DFS.Pipelines.config file:

DFS.Settings.config

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
	<pipelines>     
	 <DFS.Services.DFSMedia>      
        <processor type="DFS.Client.Services.Pipelines.DFSMedia.SynchronizeAsset, DFS.Client.Services" role:require="Standalone or ContentManagement" />
        <processor type="DFS.Client.Services.Pipelines.DFSMedia.LoadAssetEntity, DFS.Client.Services" />        
        <processor type="DFS.Client.Services.Pipelines.DFSMedia.GetMediaFromCache, DFS.Client.Services" />
        <processor type="DFS.Client.Services.Pipelines.DFSMedia.GetMediaFromDigizuite, DFS.Client.Services" />
        <processor type="DFS.Client.Services.Pipelines.DFSMedia.ResizeImage, DFS.Client.Services" />
        <processor type="DFS.Client.Services.Pipelines.DFSMedia.SaveToCache, DFS.Client.Services" />
        <processor type="DFS.Client.Services.Pipelines.DFSMedia.ResolveFilename, DFS.Client.Services" />
      </DFS.Services.DFSMedia>
    </pipelines>
  </sitecore>
</configuration>

Each step is explained as follows:

Pipeline name	Description
DFS.Client.Services.Pipelines.DFSMedia.SynchronizeAsset	This is only running in role:require="Standalone or ContentManagement". Will sync the asset into the asset silo if it does not exist.
DFS.Client.Services.Pipelines.DFSMedia.LoadAssetEntity	This pipeline looks up the asset in the index using the context user.
DFS.Client.Services.Pipelines.DFSMedia.GetMediaFromCache	This pipelines constructs a unique name based on the request and checks if the requested asset exists in the cache.
DFS.Client.Services.Pipelines.DFSMedia.GetMediaPrerequisites	If the asset is not cached, it needs to be requested from Digizuite. This pipeline gets all the prerequisites for requiring the asset in Digizuite
DFS.Client.Services.Pipelines.DFSMedia.GetMediaFromDigizuite	This pipeline executes the request towards Digizuite
DFS.Client.Services.Pipelines.DFSMedia.ResizeImage	If a resize or #compres?? is requested, the bytes are processed here
DFS.Client.Services.Pipelines.DFSMedia.SaveToCache	This pipeline saves the asset to the cache
DFS.Client.Services.Pipelines.DFSMedia.ResolveFilename	Set the donwload filename header, if a download is requested.

This pipeline may be modified according to customer needs.

Extending the pipeline

If the pipeline is to be extended, for instance if some custom processing needs to be done to the image, then this may be done in between any of the steps above.

The pipeline step should have the following construction:

public class PipelineName : ProcessorBase<DFSMediaPipelineArgs>
{
	public override void Process(DFSMediaPipelineArgs args)
	{
		if (args.Result.StopPipeline)
        {
          return;
        }

        if (args.Request.Download)
        {
          return;
        }

        if (args.Result.Cached)
        {                       
          return;
        }
	    //code goes here
	}
}

Remember to include the custom step in the configuration file!

The object DFSMediaPipelineArgs contains a Request and a Result. These two objects has the following properties:

Request

Parameter	Type	Description
AssetSiloId	string	Id of the asset silo from which the asset should be fetched
AssetId	string	Id of the requested asset
FormatId	string	Id of the format requested
DestinationId	string	Digizuite id of the destination - where to get the asset from
BaseUrl	string	BaseUrl of the Digizuite
AccessKey	string	AccessKey to the Digizuite
MimeType	string	Mimetype of the requested asset
Width	string	If a resize of the asset is requested, then this property contains the new width
Height	string	If a resize of the asset is requested, then this property contains the new height
Download	bool	If a download is requested, then this property is true
KeepAspectRatio	bool	if the aspect ratio should be kept, then this property is true
UpscaleAllowed	bool	if upscale is allowed, then this property is true
Compress	string	If the image should be compressed, then this has a value between 0 and 100

Result

Parameter	type	Description
ResultPath	string	Path to the directory in which the asset is cached
FileName	string	Name of the cached asset
Cached	bool	Boolean to indicate whether the asset is cached
ResultStream	Task<Stream>	Handle for the result stream used to get the asset from Digizuite
ResizeBytes	byte[]	If the image is resized and/or compressed, this array contains the result bytes
DownloadUrl	string	Redirect URL for download requests
StopPipeline	bool	If the pipeline should be aborted, for instance due to security violation, then this is true
Asset	AssetIndexable	Asset model from the index
StatusCode	HttpStatusCode	Status code used to indicate the request status.

Manually deleting cache entries

The cache is invalidating if the image in Digizuite is re-transcoded. The cache invalidation results in all the entries for the given asset, being deleted. If one wishes to manually clear the cache this is also an option. There are two ways in which this can be accomplished:

Manually deleting the folder in the cache (i.e. delete the folder that has the asset ID of the asset that should be deleted).
Use the Administration DAM for Sitecore dashboard, it has a function called Image cache where you can delete the cache from through UI. DFS 11.0 - Administration dashboard

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