CA2479606C - Method for document page delivery to a mobile communication device - Google Patents

Abstract

A process for viewing a selected portion of a document on a mobile communication device without having to request multiple pages of the document contents containing document global properties applied to the selected part of the document, comprising marking pages of the document within a server, based on size required by the mobile device, associating properties and attributes of the selected portion with the pages, and transmitting the pages with the properties and attributes for display by the mobile device.

Description

2 Method far ~ocument Page Delivery to a Mobile rCommunication Device t=laid of the Inyention ~t~p49 ] The following is directed in general to displaying content nn mobile communication devices, and more particularly to a method for viewirx,~ a selected portion of a document on a mobile communication device without having to reguest multiple pages of the document contents containing document global properties applied to the selected part of the document I~ackaround of the invention [0002] Mobile communication devices are becoming increasingly popular for business and persarral use due to a relatively recetrt increase in number of services and features that the devices and mobile infrastructures support Handheld mobile corrrmunioatinn devices, sometimes referred to as mobile stations, are essentially portable computers having wireless capability, and come in various fon~r~s. These include Personal Digital Assistants (PPA).
eellular phones and smart phones. While their reduced size is an advantage to portability, bandwidth and pmcessir~ constraints of such devices present challenges to the downloading and viewing of documents, such as word processing documents, tables and images.
[0a03] Electronic dvcume~nts are produced using various computer programs, such as word processors, spreadsheet programs, fiinancial software, and presentation software. in addition to text, such documents captain structural and property information such as paragraph indentation, text color and table size, etc.
[8004] When a user of a mo>~ile communication device wishes to view only selected portions of a document stared on a remote sErver, other portions of the document that contain the structural information alai properties used by the selected portion must also typically be transmitted to the mobile communication device. The required downloading of these other portions occurs over a potentially bandwidth-Constrained wireless nefinroric. FQr example, if a user wishes to view only a single paragraph in a Section at the middle of a 400-page document, the entire section (and sometimes even entire doGUment~ that contains default properties for the paragraph must be transmitted to the mobile communication devlCS.
(0Q05] Once downloaded to the device, the electronic document is viewed using a e~ser interface on the mobile communication device, which typically differs from tha user interface

3 used to create and view a d~ument on a pt;rsanal computer: For example, whereas the user interface on a personas computer may include a large, color display and a pointing device such as a mouse, the mobile communication device typically has only a small, possibly nan~color, screen, and may not have a mouse. 1n addition, the mobile communication device typically has gniater processing power and memory limitations than a personal computer Summary of the Inyention [OO~B] According to an aspect of the Pnvention, a method is provided for viewing a selected portion (page) of a document on a mobile communicatson device without having to retrieve the full document onto the device. In one embodiment, a server pagination function is used for marking pages of a document based on size required by a mobile communication device. According to another aspect of the invention, document pages are generated and transmitted by the server to the mobile device in such a way as to associate all of the required properties and attributes for the selected portion (page).
EO~OTI BY using this approach for page delivery from the server, the client on the mobile device is able to retrieve any portion (page) of a document and display it independently, since alt of its properties and attributes are already associated. This eliminates the order dependence for displaying a document such as required by a desktbp application, More importantly overall network bandwidth usage is limited.
j0~08] Additional aspects and advantages will be apparent to a person of ordinary skill in the art, residing in the detar7s of constn,~ction and operation as more fully hereinaf6er described ar>d claimed, reference being had to the accompanying drawings.
Brief Description of the Drawings Eooag] A detailed description of the prefierred embodiment is set forth in detail below, with referer~e to the following drawings, in which:
Figure 1 is a block diagram of a network environment in which the preferned embodiment may be practiced;
Figure 2 is a tree diagram showing the 6aslc structure of a Document Object Model (DOM) used in the preferred embodiment of the invention;
Figure 8 shows the top-level of the DpM structure in Figure 2;
Figure 4 shows an exemplary DOM struckure for a word processing document;
Figure 5 shows an exemplary DC1AA structure for a table document;

Figure 6 shows an exemplary DDM structure for a word processing document containing an image subdocurnent;
Figure 7 is a flowchart showing document DOM stnacture construction and pagination according to the preferred embodimernt; and Figure 8 is a flowchart showing document 170M page generation and delivery according to the preferred embodiment.
Detailed De$criation of the Pr$ferred Embodiment [DalO] VUrth reference to Figure 1, network envirt~r~ment 10 is shown in which the preferred embodiment of the invention may be pracf'iced. Network environment 10 includes mobile devices 12 communica~ng via a wireless network 14 to a server 2$ for downloading document athactxnents to the mobile devices 12. While only one server 28 is shown for illustration purposes, a person of skill in the art will understand that network environment 90 could have many such servers for hosting web sites or graphic download sites, providing access to picture files such as ,1PE;G, TIFF,13MP, PNG, SGI, MP4,MOV, GIF, SV~
etc. As would be understood by one of ordinary ski61 in the art, wireless networks 14 include GSMIGPRS, CDPD, TDMA, ioEN Mobitex, DataTAC netvuarks, or future networks such as EDGE or UMTS, and broadband networks like Bluetooth and variants of $02.11.
[001 t] A connection to a faced service nrquires special considerations, and may require special permission as authorized through a Network Access Point (NAP) 16. For generic $ervioes, such as web access, a foxy-gateway or Network Address'franslator (NAT) 1$
may be pro~rided so that a network operator can control and bill for the access. NATs 18 enable management cat a limited supply 4f public lntemet addresses for largo populations of wireless mobile devices. Solutions ofifered by a prox~gateway yr NAT 1$ can require a complex infrastructure and thus may be managed by a value-added service providers (VASPsy, which provide, fior instance, WAP gatewaysi WAP proxy gateway solutions, multi-media messaging servers (MMS) and Internet Multi-Media Services (IMSy.
j0012] private Irttranet services 26 afro connected ~6nn Internet 20 may require their own Private Intranet Proxy Gateway 24. for accessing content on server 2$. Such private services include WML access to corporate mall systems, HTML access to GRM databases, or any other services that deliver tnformatlon as formatted data w~h links and UI~Ls embedded, As shown, it is possible that a private service 26 may be connected directly to wireless network 14, as opposed to connected via Internet 20.
(OU13, Referred to throughout this document for the purpose of describing the preferred r~
embodiment is the structure of a l7~acurnent Object Model {DOM) far a document attachment to be viewed on a mobile dev'~ 92.
[1701 A~j The attachment server 28 uses a designated file-parsing distiller for a specific document type to build an in-memory Document Object Model {DOM) structure representing an attachment of that document type. The document C~OM structure is stored in a memory cache of server 28, and can be iterated bi-directionally [0015] As shown in Figure 2, the graph-.based documentDOM structure consists of nodes arxt leaves. The nodes serve as the parents of leaves and nodes, while leaves are end points of a branch in the graph. Each node and leaf can have a set of attributes to specify its own characteristics. For example, a paragraph node can contain attributes to specify its 2~lignment, style, entry of document TOG, etc. In additson, each of the nodes and the leaves has a unique idenfifier; called a ~0M ID, to identify itself in the document DONI
structure.
[0016] The document DOM structure is divided into three parts: top-level, component and references. The tap level refers to the document root structure, while the main document is constructed in the component and the references represent document;
references to either internal or external sub-document parts. The following paragraphs examine each part in detail.
[0017] The rnot node of a document DOM structure, referred to as °Document', contains several children nodes, referred to as "Conien'~", which represent different aspects of the document cardents. Each "Contents° node contains one or multiple °Corrt~ainer° nodes used to store various document global attributes. The children of the "Gorrtainer"
nodes are components, which store the document structural and navig2~tional information.
When tt~
attachment server 28 builds the DOM structure for an attachment file for the first time, the top-level structure is a single parent child chain as shosnm in Figure 3:
[1018, Three types of components are defined by the attachment server 2$: text components, table components and image componerds, which represent text, tables arid images in a document, respectively, The text and fiable components are described in detail below, and the image component structure is identical.
[0019] A component consists trf a hierarchy of command nodes, Each command represerns a physical entity, a property, or a reference defined in a document. For the text component. the physical entity commands are page, section, paragraph, text segments, comments, footnote and er~dnote commands, which by name define the corresponding entity contained in a dvcurnent. The property commands for the text component are font, tact Color, text background color, hyperlink startlend and bookmark commands. The text component has only one reference command, referred to as the text reference command, which is used to reference a subdoeument defined in the main body of a document. Usually, the children of a text component are page or section command nodes that, in tum, comprise a set of paragraph command nodes_ The paragraph command can contain one or multiple nodes for the remaining command types.
[420] Using the following sample text document, the corresponding document DOM
strut:kure is shown in Figure 4:
First paragraph.
second paragraph with bold and red text.
[0021] As Figure 4 demonstrates, the section command, which is the child of the text component, consists of two paragraph commands. The first paragraph command contains one text segment command and the text content for that paragraph is added as an attribuke to the text segment command. The second paragraph ctsnmand h~ a relatively more complex structure, as the text properties in the paragraph are much richer.
Each time a text properky (font, text color, etc) changes, a corresponding text property command is created and the change value is added to that command as an attribute. The following text segment command recnrds the text with the same Text properky as an attribute. As document structure gets richer and more complex, more ta~mmands of corresponding types are created and the document properties are added as attributes to those commands.
[r?022] The table component has the same three types of commands as the text component, but different command names. The document LOOM structure for the sample table dacumerrt below is shown in Figure 5:
[p023I As shown in ttte Frgure 5, the table component has physics) entity type commands of table, tabterow and tabl~ell, where the tablecell command can contain all available commands for the text component, fn the example above, the first child TabIeRow command of the table command has an attribute "Index" defined by value of 0.
'fhls indicates that the indicated table row is the first one defined in the table. The attribute of the leftrnost table cell command ire Figure 5 has the same meaning.

[I102~] A document sometimes contains subdacurnents, for example images, tables, text boxes ets The QOM structure set forth herein uses a reference command to point to the graph of such subdocuments. Thus, far the following sample document, the attachment server 28 generates the DOM structure shown in Figure 6:
This document has subdocument of images lifts this an Second paragraph contains the same image.
[0025) The structure shown in Figure G is identical to that discussed above in connection with Figures 4 and 5, except for the attributes of the two reference commands.
The attachment server 28 constructs the image in "Sample Three° as a separate image component, which contains all of the image data In its own DOM hierarchy !n the DOM
structure for the main document, the values of the "Ref' attributes of those two reference commands paint to the image component, as indicated by the dashed lines, such that the DOM structure connects together all parts of the document.
[Oo26~ Having described the document DOM structure used to implement an embodiment of the invention, a detailed discussion will now be provided of a pagination function or method according to the preferred embodiment.
[0027] The pagination function is a client and server side operation. Fgure 7 shows the processing steps, from which it wilt be noted that the server 28 uses a map in memory for document DOM cache storage and the key ~ the map is the document ID.
initially, when the user of a mobile rommurdcation device 12 sends a request to the server 28 to view a document. the device '12 sends two attributes and fhe nut~nber of bytes it requires (RequireS~e) as a response from the server (e.g. 3K bytes). The two attributes are whether the device is a color or monochrome device, and the screen size (width x height x color depth) of the device in pixels. Other information about the device '12 can also be transmifted to the server 28 (e_g. memory size). After the server 2g receives a dncument-viewing request, it starts the pagination process (step 30), and initializes the rrariables Pagelndex and PageSize.
f~p2$I ~e ~Itowirs9 teams and variables are used in the process of Figure 7:
[0029] The Pagelndex variable is defined in the server 28 and used by the server to record the current page index being paginated by the serves The page index is initially set to D indicating "Page 1".
~o030] PageSize is a variable defined in the server ~8 and used fey the server to record the current size far the page being paginated and is reset to D when paginating a new page.
jOD31] Hyperlink map is a u2frfabla defined in the server 28, which is a container consisting of the elemerrk type of hyperlink node in the document DOM
structure. The key (ID) for each element in the container is the hypertink target string.
[0032 Bookmartc map is a variable defined in the Server ~8 which is a container consisting of the element type of current page index (Pagelndex value) far the bookmark in the dAcument DOM structure. The key (1D) for each element in the container is the bookmark ring.
[0033) The server process constricts a document 1l7 (step ~2) based an the document contents and uses tha ILa to check the document DOM cache (step 33) to determine whether the document DOM structure for that document has been constructed. If the document DOM
strcrature does not exist in the cache, the server. builds the DOM structure (step 34) for the document and adds it to the cache (step 35).
[0034' To constnrct the document ID, the original document hle is opened and read in binary mode_ The server 28 creates a MD5 Context structure, hashes the MD5 context structure with raw binary data, byte-by byte, from the file, finalizes the MD5 confiext structure and re#rieves the l6byte key fortrie fife. The MDa content s#ruchare has the following structure in syntax of C+* language iypedef strucf f unsigned long ad~rStatej4J; !* state (~4BCD) 'l unsigrtedlong adwCounfj2),~ l"numberofbits, mOduto 2"64 (lab first) *l unsigned Char abyBuflerj64J; P input buffer'/
} tMD5_C7X,~
[~~35J Caching the document DC7M structure requires considerable memory, and therefore increases the overall hardware deptoyrnent co$t. On the oth~r hand, building the DOM structure for a document is even more time and CPU Intensive 'err contrast to the document key construction operation, especially for big documents. Since processing Time is more critical than hardware deployment cost for wireless operation, caching the doeurnent DOM is the approach adopted for the preferred emtyodiment, rather than building the DOM
structure for the document each time the server receives a viewing request and then discarding the structure after sending the response back to the client device 12.
(0o3~) Once the document GOM structure has been built and stored in the cache, the server 2$ determines whether a page mark has already been set in the root (step 3f3)_ if not, the server traverses through the DbM structure (steps 38, 39, ~0 and ~1 ) and calculates the output size (PageSize) for each node in the DOM structure based on the number of bytes (RequireSize) provided by the device 12. The sErver increments the Pagelndex (step ~4Z), adds it as an attribute to each node in order to mark the start of each page, and adds each node as an attribute to the root node with the string representation of Pagelndex as the attribute name (step 43). Following this pagination function, the attachment server 2$ is able to transmit the document page-by-page tc~ the requesting mobile device 12 based on client generated requests, and process flow continues to Figure 8 for CtOM page generation and defrvery (step 44j.
[003?, The page mark attribute name is associated with the device inforrnatian and required response size (RequireSize) provided by the device 12, to enable the server to paginate through the document DOM structure and generate the response based ~
device capabilitx For example if the device is a monochrome type, the color infannation contained inside the Dt7M structure will be ignored during the server pagination and response generation operations and therefore optimize the wireless bandwidth utilization.
[0038] Since the key to the memory map is the document ID, the algorithm used to calculate the document ID (step 32j must guarantee the uniqueness of the key.
According to the best made, as set forth above, the algorithm used inside the center 2$ is the MD5 messaging encryption algorithm invented by Professor Ronald L. Rivest of MIT
L.abor~tory for Computer Science and RSA Data Security, Inc. There are several other hashing options that can be used. However MD5 is the most efficient and retiabls one based on the broad range of different document content required to be processed by the server 28.
[oa3s~3 In the proeESS of FigureB, PageSlertNode is DOM structure node type which, in the preferred embodiment is a COM (Common obiect modutey object base intertace. VecParent is typically a one-tiimerrsionat cont~aine~ fnr example vector, coryiaiMng elements of DOM
structure node type. It 1s used to scare the parents (recursively until the node of component type) for the page-starting node. as discussed in greater detail below bStart is a Boolean variable de~rned in the server 28 and used to signal that the required page has already been been trmversed.
jOQ40a In operation, the server 2$ uses Pagelndex to build the page mark attribute (step 48j and search for tile node representing the page start (step ~47j for the page of interest identified by the client device 92. It is used by the server 28 to cache the node which marks the start for the page required by the client device 72. ante the node is found, the server 2$

recursively retrieves the parent of the node (step A.8) until it reaches the component level (step 49) and puts all the parents into storage (llecParent}, namely the parent container (step 5s7). The server 28 then traverses the DOM structure again (steps 51 et seq) to persist the irrmemory structure to a form that can be transmitted across the network to the mobile device 12. if a node is one of those stored in the parent container (step 54), it generates the output for the node (step 57}. The output includes the contents and attributes far all of the nodeslleaves belonging to that page as veil as the attributes of the parents far the page start node.
[0041 Upon locating the corresponding page start node (step 55), the server 28 sets a Boolean (bStart) to true, indicating that the page has been traversed (step 56), and generates the output (step 57) for each following node to be iterated until the next page mark is found (step 58). Once the server 28 determines that it has completed traversing the DOM
structure (step 52), or has found the next page start mark (step 58), the process finishes (step 59).
[Q04x] Frorn Figure $, it wilt be noted that all of the parents for #~e page~.start node are output into the response, which means the default attributes and properties defined for the node but rontained in ii=s parents, will persist. However, the siblings of the node are ignored if they do not belong to the resporsse page. Fc~r exarrtple, if the client (mobile device 12) requires the second part for a spreadsheet, the server 28 not only generates the response containing the corresponding text cont~rrt;~ but also includes the global information for the table such as number of rows and columns and current table row and cell index, etc., into the response. Once the client receives the response, it can display the text at the Correct position without having to request the first partof the spreadsheet from the server:
jai943, A person skitied in the ark, having read this description of the preferred embodiment, may conceive of variations and altema#ve embodiments. For example.
generating multiple sets of page marks for successive pages requires considerable time arid CPU usage since the server 28 has to re-traverse the 1~QM struoiwe.
Acco~ir~ly, one alterrtatave is for the server 28 td create only one set of page marks in a document DOM
structure and generatE the response based an the device information. However, this approach is likely to create more page marks than necessary and will introduce extra transactions between the wireless device 12 and the server 28 if the user wants to view a Large porkion at a document. Based on the understanding that minimizing the wireless bandwidth usage is more critical than the processing time on the server, creating multiple sets of the page marks and caching them is the approach adopted in the preferred rmbadiment.

[~0~14.] Ail such variations and alternative embodiments ere believed to be within the ambit Ql=the ciairrts appended hereto.

Claims (11)

What is claimed is:

1. A process for viewing a selected portion of a server stored document on a mobile device, comprising:
marking pages of the document within said server based on size required by said mobile device;
associating properties and attributes of said selected portion with said pages; and transmitting said pages with said properties and attributes for display by said mobile device.

2. The process of claim 1, wherein said marking pages further comprises:
building a graph structure within said server representing a map of said document transmitting a page size limit from said mobile device to said server indicative of the size of a single page of said document to be displayed by said mobile device;
traversing and paginating said graph structure into successive pages within said server based on said page size limit: and caching said pages within said server.

8. The process of claim 2, wherein traversing and paginating said graph structure further comprises:
initializing a page size value;
retrieving and calculating output size of successive nodes of the graph structure;
adding the output size of said successive nodes to laid page size value; and in the event said page size value exceeds said page size limit for a given node then marking said graph structure to identify said node as starting a new page for transmission to said mobile device.

5. The process of claim 3, wherein marking said graph structure further comprises:
maintaining a page index value that is incremented with each new page;

adding said page index value as an attribute to each said given node for marking each said new page; and adding each said given node as an attribute to a root node of said graph structure with a string representation of said page index value as attribute name.

5. The process of claim 2, further comprising calculating a document ID based on contents of said document before building said graph structure, checking a memory cache of said server using said document ID for said graph having been previously built, and in the event said graph structure exists in the memory cache then omitting the building of said graph structure.

6. The process of claim 5, wherein calculating said document ID further comprises performing a hashing function on the contents of said document and in response generating said document ID as a unique key to said map.

7. The process of claim 8, wherein said hashing function comprises the MD5 messaging encryption algorithm.

8. The process of any one of claims 1 to 7, wherein said graph structure is a Document Object Model (DOM).

9. The process of claim 4, wherein said associating properties and attributes further comprises:
searching said graph structure for a node representing a page start for said selected portion of said document;
traversing said graph structure and recursively storing each parent of said node representing the page start in a parent container within said server: such that said parent container contains all nodes and leaves belonging to said page start and each parent of said node; and generating an output for each said page start containing contents and attributes of all said nodes and leaves belonging to said page start and attributes of each parent of said node representing the page start, for transmission to said mobile device.

10. The process of claim 9, wherein said traversing said graph structure and recursively storing each parent of said node representing the page start in said parent container persists until a node of component type is reached.

11. The process of claim 10, wherein said generating an output for each said page start persists until a further page start is located.