DFS 9.2.0 - 9 Serving media

All files from Digizuite are served using the media pipelines. From DFS 9.0.0 the media pipeline has been redesigned, however, the old is still there for compatibility reasons.

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

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

There are two options

• dfsmedia - the new implementation
• media - the old implementation

The default valie is dfsmedia.

This section describes the new dfsmedia pipeline and its capabilities.

Understanding the request

The new 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:

*Optional

Understanding the DigizuiteMediaCache

The DigizuiteMediaCache is where everything, execpt videos, is saved. The cache location is configurable and is located in 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.{extention}

The extention is retrieved from the file saved in the cache. The naming scheme enable unique names and hence the extention can be extracted from the file in the cache. Orginally the file is saved with the correct extention 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.Services.config file:

<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
	<pipelines>     
	 <DFS.Services.DFSMedia>
        <processor type="DFS.Services.Pipelines.DFSMedia.CheckSecurity, DFS.Services" />        
        <processor type="DFS.Services.Pipelines.DFSMedia.GetMediaFromCache, DFS.Services" />
        <processor type="DFS.Services.Pipelines.DFSMedia.GetMediaPrerequisites, DFS.Services" />
        <processor type="DFS.Services.Pipelines.DFSMedia.GetMediaFromDigizuite, DFS.Services" />
        <processor type="DFS.Services.Pipelines.DFSMedia.ResizeImage, DFS.Services" />
        <processor type="DFS.Services.Pipelines.DFSMedia.SaveToCache, DFS.Services" />        
     </DFS.Services.DFSMedia>
    </pipelines>
  </sitecore>
</configuration>

Each step is explained as follows:

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

Result

Changing the url

If the new "dfsmedia" pipeline is used, it is possible to use another prefix for the media url. An example could be that one wanted the company name instead of dfsmedia as the media url prefix. This can be done doing the following:

1. Change setting: DFS.MediaPipeline to new prefix (e.g. company name) in config file DFS.Settings.config
2. Change path in httphandler section in web.config (See link, section 3.1) to be the new prefix
3. Change trigger in customHandlers section in DFS.Services.config to be the new prefix
4. Resynchronize the silo

Doing this ensures the following URL scheme: http(s)://<sitecore url>/<new prefix>/29a605d46a3340418c16542f7272c3ec/110-50035

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 assetid of the asset that should be deleted).
• Call the following endpoint in Sitecore: http(s)://<sitecore url>/damforsitecore/mediacache/assetactions/<assetid>, which will also delete the cacheentry for the given assetid.