This chapter provides an overview of services to manage files and content on the ACCESS Linux Platform.
What is Content Management?
This document describes the technologies and tools which the ACCESS Linux Platform provides for content management. In this case, content is defined as "digital information," stored in various types of files. To manage these files through their lifecycle, the platform needs to provide mechanisms to create, store, update, run, modify, and remove files. To simplify these operations for the content user, the platform must provide mechanisms to allow the user to select and interact with the files. A file manager provides an interface to the file system and its content.In addition it provides mechanisms to translate the content format into a usable form of information for the user. Sometimes this information is encrypted and must be converted for use. These components, file management and user interface, and the processes that use them define content management for the platform.
The ACCESS Linux Platform supports content management services including digital rights management, file management, and media selection mechanisms.
Content, Media, and Multimedia
This document deals with the following types of electronic media:
- Multimedia, communications that incorporate multiple forms of information content and processing
- Digital media, electronic media used to store, transmit and receive digitized information
In the context of the ACCESS Linux Platform, a media file refers to "digital media", rather than multimedia. A media file is defined as any file stored on an electronic medium, that is, on the device itself or on external storage cards. A multimedia file is used in the general sense as multiple forms of mixed format media, graphics, documents, audio, and video files, which are captured, managed, and displayed by a variety of browsers, viewers, and players.
In the ACCESS Linux Platform there are two frameworks in place for handling media files, each with a different purpose. Loosely defined, the Content Management framework is responsible for administering data, metadata, and files stored in various media, such as device memory and on external storage cards. This includes many file types— multimedia, audio, photo, document, and others. This framework uses a Media Selector Services to manage lists of media files. The Multimedia framework, on the other hand, is responsible for the playback and recording of specific file types managed by the Content Management framework.
The focus of this manual is on the Content Management framework. The Multimedia framework is described in Working with Multimedia.
Content, Data, and Metadata
Generally the content stored in a file, the digital information, is defined as data. Data must undergo some sort of transformation to become user-consumable information. Processes that operate on data need information about how to manipulate the content in the file. The data that describes attributes of that content is defined as metadata, that is, data about data.
When dealing with files, the actual content of the file is data; information about the file and its content is metadata. (Metadata can be stored in the file itself, as part of the data.) The content of the file determines what information should be stored as metadata. For example, general files have location, size, and type information associated with them, while an audio file might include additional information on play length and have digital rights managements attributes. Applications use this metadata in determining how to deal with the file.
Content Management Architecture
The basic components of the Content Management architecture are illustrated in Figure 1.1. The complete picture spans from physical hardware, the device itself and external storage cards, to system-supported applications and third-party packages. This document focuses on Digital Rights Management and Media Selector Services.
Figure 1.1 
- Applications Level
Applications created by applications developers, third-party vendors, licensees, or provided with the ACCESS Linux Platform.
- User Level
Frameworks, services, APIs, and libraries for applications development.
- Digital Rights Management (DRM)
Described in Chapter 2, "Digital Rights Management."
- ALP Media Selector Services
Described in Chapter 3, "Introducing Media Selector."
- ALP Multimedia Framework
Used to capture and display multimedia files. Described in detail in Working with Multimedia.
- Hiker Volume Services
Described in "Volume Services" in ACCESS Linux Platform Programming.
- Hiker Vault Services
- Hiker SQL Abstraction Layer Libraries
Described in "SQL Abstraction Layer" section, "Data Storage", in ACCESS Linux Platform Programming.
- Digital Rights Management (DRM)
- Kernel Level
- Hardware Level
Physical hardware, the device, external storage cards; multimedia devices.
