Ordered ole file structure

Details Ordered ole file structure Ordered ole file structure

1998-06-22

2001-03-20

Black, Thomas (Department: 2171)

Data processing: database and file management or data structures

Data integrity

Transactional processing

C707S793000, C707S793000, C707S793000, C707S793000, C707S793000

Reexamination Certificate

active

06205457

ABSTRACT:

BACKGROUND
The invention relates generally to formatting an object linking and embedding file so that the file can provide progressive viewing during file transfer operations.
Object embedding and linking (OLE, pronounced oh-lay) technology allows a user to “embed” or “link” different types of objects (e.g., text and graphic objects) into a common document. An embedded/linked object retains the data format of the application used to create it. In addition, the common document incorporates information about the format such as what application should be executed to view the embedded object.
The basic OLE concept has been extended through the definition of a structured storage model that treats a single file system entity as a structured collection of two types of objects; streams and storages. A stream object is the conceptual equivalent of a single disk file. Streams are the basic file system component in which data persists and are treated as a flat sequence of bytes (each stream has access rights and a single seek pointer). A storage object is the conceptual equivalent of a directory. Each structured storage file, referred to as a compound file, may contain any number of substorages and any number of streams.
One embodiment of the OLE structured storage model, targeted specifically for image data, is the FLASHPIX format. (See “The FlashPix Format Specification,” version 1.0.1, July 1997.) FLASHPIX is a multi-resolution image format in which an image is stored as a series (hierarchy) of independent arrays, each array representing the image at a different spatial resolution. The hierarchy is created by starting with the highest resolution image, generally determined by the resolution of the image's capture device. Each successive image's resolution is reduced (decimated) by a factor of two in both the height and width until the final resolution fits within a 64-by-64 pixel area. As with all compound files, FLASHPIX files contain storages and streams. Allocation of space within a file for each of these elements is done in units called “sectors.” The size of a sector may be specified at file creation time and is often 512 bytes. OLE compound files are organized into a series of logical components, each component being one or more sectors in length. After briefly describing some of these components, an example will be provided that shows how they are interrelated.
Referring to
FIG. 1
, logical components can include header
100
, directory
102
, file allocation table (FAT)
104
, data
106
, and metadata
108
. Header
100
contains information vital to the identification and use of the OLE compound file including, for example, data specifying the size of a sector, and references to the first sector of directory
102
and FAT
104
. There is one header in any compound file, and it is always begins at a file offset of zero. Directory
102
includes a reference to the first data sector for each stream in the OLE compound file. For example, if the OLE compound file is a FLASHPIX file having four images (one high resolution image and three lower resolution images), directory
102
will have a reference to the first data sector for each of the four images. FAT
104
is the primary space allocation table in an OLE compound file. Every sector in an OLE compound file is represented within FAT
104
in some fashion, including those sectors that are unallocated (free). Each entry in FAT
104
contains a reference to the next sector in an object's (e.g., an image's) chain of data sectors. Those FAT entries associated with the last data sector of an object contain a special end-of-chain value. (Directory
102
is represented as a standard chain of sectors within a FAT, but is separated here for logical clarity.) Data
106
includes one or more sectors associated with each user stream such as a FLASHPIX image. Within a stream, the information stored in data
106
is a sequence of arbitrary bytes; no restrictions are imposed on its content. Metadata
108
represents one or more sectors of user (e.g., application) defined information. Examples of metadata include the time and date a file was created and file author information.
Referring now to
FIG. 2
, consider a FLASHPIX file having two images—a high resolution image and a low resolution image. As required by the FLASHPIX specification, Header
100
includes information identifying the file as a FLASHPIX file
200
and a reference to the compound file's directory
202
. Directory
102
includes references to the first sector associated with the compound file's metadata
204
, low resolution (LOWRES) image data
206
, and high resolution (HIRES) image data
208
. High resolution image data reference
208
indicates the first data sector
210
in data component
106
associated with the high resolution image. The corresponding FAT entry
212
contains a reference to the image's next data sector
214
, and so on until the last data sector
222
of the high resolution image is linked. The FAT entry
224
corresponding to the last data sector
222
contains a special end-of-chain value (EOC). A similar chain of data sectors and FAT entries exist for the low resolution images (a two data sector—
226
and
228
—stream) and the metadata (a one data sector—
230
—stream). In accordance with the FLASHPIX specification, all file components (e.g., FAT
104
and data
106
) except header
100
may be located at any position in the file; header
100
must begin at file offset zero.
As long as a FLASHPIX file is resident on a local computer, the display of any one of the file's available resolutions can be fast. If the FLASHPIX file of
FIG. 2
were to be transferred from a first computer system (e.g., a website) to a second computer system (e.g., an individual user's computer) using a standard browser executing the hypertext transport protocol (HTTP), however, it would not be possible for the user to view any of the file's images until the entire file was transferred. If the high resolution image is large, say more than one megabyte, the time required to complete a transfer can make use of FLASHPIX files unacceptable for many users. (The time to transfer an image is exacerbated by the fact that FLASHPIX files are 33% larger than the original, high resolution, image due to the lower resolution images included therein.) This “download time” constraint has become more and more significant with the increased use of computer networks (e.g., the internet and intranets) to access information.
The internet imaging protocol (IIP) was developed to provide access to FLASHPIX file images over computer networks. For example, one benefit of the IIP is that it can provide a progressive view of a file during the download process. Thus, the user does not have to wait until the entire FLASHPIX file is downloaded before they begin to see an image. This capability is similar, from the user's point of view, to the familiar progressive joint photographic experts group (JPEG) download mechanism. To obtain this benefit, however, a user must have access to a server-side executable (i.e., an IIP server application) capable of parsing and selectively transmitting any one of the images within a FLASHPIX file. Because IIP servers are not available to the typical user, who generally connects to the internet via local telephone lines, there is a need for a mechanism to allow progressive viewing of OLE structured files that does not require server side processing.
SUMMARY
In one aspect the invention provides a method to order an object linking and embedding file by locating a stream in the file, the stream being associated with a plurality of sectors having a predetermined sequential order, the sectors not in the predetermined sequential order, and placing the sectors of the stream in the predetermined sequential order. The ordered file may retain the structure of a standard object linking and embedding (OLE) file. The method may further include ordering a plurality of streams in an OLE file, where each stream has an ordering relat

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