The functions of the Access Functional Entity are illustrated in figure 4-7.
Figure 4-7: Functions of the Access Functional Entity
The Coordinate Access Activities function provides one or more interfaces to the information holdings of the Archive. This interface will normally be via computer network or dial-up link to an on-line service, but might also be implemented in the form of a walk-in facility, printed catalog ordering service, or fax-back type service. Three categories of Consumer requests are distinguished: query requests, which are executed in Data Management and return immediate query responses for presentation to the user; report requests, which may require a number of queries and produce formatted reports for delivery to the Consumer; and orders, which may access either or both Data Management and Archival Storage to prepare a formal Dissemination Information Package (DIP) for on- or off-line delivery. An order may be an Adhoc Order that is executed only once, or an Event Based Order that will be maintained by the Activate Requests function in Administration, and initiated by a dissemination request that may result in periodic deliveries of requested items. The Archival Information Update function in Administration also submits dissemination requests to obtain DIPs needed to perform its update functions. Other special request types are allowed, but are not detailed. This function will determine if resources are available to perform a request, assure that the user is authorized to access and receive the requested items, and notify the Consumer that a request has been accepted or rejected (possibly with an estimate of request cost and an option to cancel the request). It will then transfer the request to Data Management or to the Generate DIP function for execution. This function also provides assistance to OAIS Consumers including providing status of orders and other Consumer support activities in response to an assistance request.
The Generate DIP function accepts a dissemination request, retrieves the AIP from Archival Storage, and moves a copy of the data to a temporary storage area for further processing. This function also transmits a report request to Data Management to obtain Descriptive Information needed for the DIP. If special processing is required, the Generate DIP function accesses Data Objects in temporary storage and applies the requested processes. The types of operations which may be carried out include statistical functions, sub-sampling in temporal or spatial dimensions, conversions between different data types or output formats, and other specialized processing (e.g., image processing). Inserting DRM information and filtering the personal data to ensure consistency with the user rights also come under this type of operation. This function places the completed DIP response in the temporary storage area and notifies the Coordinate Access Activities function that the DIP is ready for delivery. It is worth noting that in some implementations the AIP content or the DIPs could be kept in temporary storage for ready availability.
The Deliver Response function handles both on-line and off-line deliveries of responses (DIPs, query responses, reports and assistance) to Consumers. For on-line delivery, it accepts a response from Coordinate Access Activities and prepares it for on-line distribution in real time via communication links. It identifies the intended recipient, determines the transmission procedure requested, places the response in the temporary storage area to be transmitted, and supports the on-line transmission of the response. For off-line delivery it retrieves the response from the Coordinate Access Activities function, prepares packing lists and other shipping records, and then ships the response. When the response has been shipped, a notice of shipped order is returned to the Coordinate Access Activities function and billing information is submitted to Administration.