1)     The first decision is to what degree one wants to provide access to a digital object, and where it fits in the group types: .   The Default Group is required by all.  The other groups are: 


Structured Texts

Image Books/Texts

Currently, only the Default Action Group and the Basic Image Action Groups are finalized.



2)     The second problem is to create all the constituent materials to be retrieved by the URLs in the chosen Asset Action package, make sure they are valid and complete.  Challenges here include determining how to identify each bitstream and organize them for access and delivery.


The Default action group contains 6 actions.  Create the content if necessary, and determine the URL and location for delivery, for each one:

o        getAssetDefintion : returns the current version of the asset definition. This is always of type XML.

o        getPreview : returns the appropriate view of the resource that can share the viewing space with other previews. This is currently defined as being a thumbnail-sized image of type GIF, JPEG, PNG or a short string of plain text.  Either create (or use existing) thumbnails, or extract a sentence or two from each textual object for this purpose.

o        getLabel: returns the appropriate string of plain text that can be included in a list of labels. This is always defined as plain text. An example label would be a title:  extract these into database entries or text files.

o        getDCRecord : returns an XML OAI-DC Dublin core record. If necessary, extract this from the existing metadata.

o        getWebView : returns the appropriate view of the resource when it has the whole viewing space to itself. It is always of type HTML.  If an appropriate webview is not available, one must be constructed.

o        getDefaultContent: returns a byte stream of raw content for the resource. This can be of any type appropriate to the resource.  For an image, this is the unembedded image file, such as JPEG or TIF.  For a text, examples would be TEI, or PDF.

The Basic Image Action group adds four more actions. If this group is used, determine the location for delivery and obtain or create a URL for each:

o        getThumbnail returns a small image that can share the viewing space with other images. It is always of type GIF, JPEG or PNG.  This is usually the same as getPreview in the Default Action group, and this call will be combined with that one in the Atom serialization.

o        getScreenSize returns an image that assumes the entire viewing space. It is always of type GIF, JPEG or PNG. 

o        getMaxSize returns the largest image that will be made available. . It is always of type GIF, JPEG or PNG.  This may be the same as getScreenSize.

o        getDynamicView :   returns the image embedded in a web page; it is intended to provide the image in an interactive setting. It is always of type HTML.


  3)   After assembling and organizing all the constituent files, and collecting their access URLs, determine the reference identifier (the OAI identifier is recommended) for the object itself, and create the XML Asset Action Package.

A sample XML Asset Action package containing both Default and Basic Image Action groups ( ):

<assetActions type="image" objid="">

   <actionGroup name=" defaultActionGroup " label="default Action Group">

      <action format="text/xml" name=" getAssetDefinition " label="Asset Definition" uri=" "/>

      <action format="image/png" name=" getPreview " label="Preview" uri=" "/>

      <action format="text/plain" name=" getLabel " label="Label" uri=" "/>

      <action format="text/xml" name=" getDCRecord " label="Description" uri=" "/>

       <action format="text/html" name=" getWebView " label="Web View" uri=" "/>

       <action format="image/jpg" name=" getDefaultContent " label="Default Content" uri=" "/>



   <actionGroup name=" basicImageActionGroup " label="basic Image Action Group">

       <action format="image/png" name=" getThumbnail " label="Thumbnail" uri=" "/>

       <action format="image/png" name=" getScreenSize " label="Screen Size" uri=" "/>

       <action format="image/png" name=" getMaxSize " label="Max Size" uri=" "/>

        <action format="text/html" name=" getDynamicView " label="Dynamic View" uri=" "/>




4) Create the link to this XML document and add it to the related MODS record in OAI, by adding an <extension> element into the MODS:



      <url access="asset action

package"> </url>



Examples of full MODS records containing extension elements can be seen at: