US20020049786A1 - Collaboration framework - Google Patents

Abstract

One or more embodiments of the invention provide a collaboration framework for collaborating access to a drawing document on a network. A drawing document is stored on a server. Thereafter, a collaboration session comprised of two or more collaborators on a network is established. During the collaboration session, the server permits the two or more collaborators to work simultaneously across the network on the drawing document stored on the server. A command to modify the drawing document from a first collaborator is received by the server. The server then distributes the command to modify the drawing document to other collaborators in the session.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is related to the following co-pending and commonly-assigned patent applications, which applications ate incorporated by reference herein:[0001]
• Patent Cooperation Treaty Patent Application Serial No. PCT/US01 /02310, entitled “METHOD AND APPARATUS FOR PROVIDING ACCESS TO AND WORKING WITH ARCHITECTURAL DRAWINGS ON THE INTERNET”, by Douglas G. Look, et. al., Attorney Docket No. 30566.101-WO-U1, filed on Jan. 24, 2001, which application claims priority to United States Provisional Patent Application Serial No. 60/177,988, entitled “METHOD AND APPARATUS FOR PROVIDING ACCESS TO AND WORKING WITH ARCHITECTURAL DRAWINGS ON THE INTERNET,” filed on Jan. 25, 2000, by Douglas G. Look, et. al., attorney's docket number 30566.101USP1.[0002]
BACKGROUND OF THE INVENTION
• 1. Field of the Invention[0003]
• The present invention relates generally to computer-implemented drawing programs, and in particular, to a method, apparatus, and article of manufacture for multiple collaborators to simultaneously work on a drawing.[0004]
• 2. Description of the Related Art[0005]
• The use of Computer Aided Design (CAD) application programs is well known in the art. CAD application programs are often expensive, complex, and difficult to learn how to use. Additionally, architects, contractors, engineers, owners, and other patties involved with a project (referred to as project participants or collaborators) are often mobile or at different locations. With new technology and the increased use of the Internet, project participants often have computers, Internet access, and personal digital assistants (PDAs). Further, the coordination and exchange of information between project participants can be increasingly complex.[0006]
• Existing prior art applications allow a user to download a drawing, edit the drawing, and upload the drawing after completing the edits. Alternatively, prior art applications/features may allow the creation of a two-dimensional in-memory document where graphic information is transmitted from one client to another client during a session. However, in such prior art applications, to refer to a document in the future (i.e., to store the document), the document must be saved locally by a client and then uploaded later. Further, since only an in-memory document is used, there is no capability to undo a modification or to restore the document in the event of a network or computer failure. Further, only a primitive set of two-dimensional graphic manipulation tools is often provided.[0007]
• Accordingly, existing prior art applications do not provide the ability for multiple users to collaborate on an actual stored document with a full set of modeling tools (in two and three dimensions).[0008]
SUMMARY OF THE INVENTION
• One or more embodiments of the invention provide a method, apparatus, and article of manufacture for a collaboration framework that permits multiple users to simultaneously modify a document/workspace that is stored on a server across a network. Collaboration applications on multiple clients/collaborators communicate with a server application on a server.[0009]
• The collaboration application provides a full set of three-dimensional drawing tools to manipulate a drawing and transmit such manipulations to the server application. The server application maintains a history of the manipulations and the collaborators in a session. Once a manipulation command is received by the server application from one collaborator, the server distributes the command to the remaining collaborators. Thereafter, the collaboration applications modify the local version of the drawing space in accordance with the command. The history maintained by the server may then be used by any one of the collaborators to rollback a modification (e.g., a modification made by another collaborator or themselves) or to rebuild a drawing space in the event of a network failure.[0010]
BRIEF DESCRIPTION OF THE DRAWINGS
• Referring now to the drawings in which like reference numbers represent corresponding parts throughout:[0011]
• FIG. 1 schematically illustrates a hardware and software environment in accordance with one or more embodiments of the invention;[0012]
• FIG. 2 illustrates a collaboration palette displayed in accordance with one or more embodiments of the invention;[0013]
• FIG. 3 illustrates a dialog window and collaboration palette in accordance with one or more embodiments of the invention; and[0014]
• FIG. 4 is a flow chart illustrating the use of the collaboration framework in accordance with one or more embodiments of the invention.[0015]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown, by way of illustration, several embodiments of the present invention. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.[0016]
• Overview[0017]
• A collaboration framework provides the ability for multiple users to simultaneously modify a document across a network using a full set of tools. Client based applications generate specific messages (e.g., XML messages) which are communicated across a network to a server (e.g., via TCP/IP [transmission control protocol/internet protocol]). Once received by the server, the server manages the collaboration session by storing document changes and distributing the command to other collaborators. The server maintains a history of document changes so these can be recommunicated in the event of a network failure or temporary Internet outage. Additionally, the server may manage a record of the collaboration session including the name, number and status of collaborators, and similar information for the workspace being collaborated on.[0018]
• Hardware Environment[0019]
• FIG. 1 schematically illustrates a hardware and software environment in accordance with one or mote embodiments of the invention, and more particularly, illustrates a typical[0020]distributed computer system100 using anetwork102 to connect client computers/collaborators104 toserver computers106. A typical combination of resources may include anetwork102 comprising the Internet, LANs (local area networks), WANs (wide area networks), or the like, clients/collaborators104 that are personal computers, personal digital assistants (PDAs), or workstations, andservers106 that are personal computers, workstations, minicomputers, or mainframes.
• In accordance with one or more embodiments of the invention, the[0021]network102 connectscollaborators104 executing acollaboration application108 toserver computers106 executingserver applications110. Thecollaboration application108 enablescollaborators104 to communicate withother collaborators104 and work on a document stored on/byserver106. Theserver application110 may be aserver106 collaboration application that provides for storage of a commonly used document and enables the ability formultiple collaborators104 to simultaneously work on the same document.Server application110 may also be configured to manipulate data (e.g., a document) indatabase114 through a database management system (OBMS)112.
• Generally, these[0022]components108,110,112, and114 all comprise logic and/or data that is embodied in or retrievable from device, medium, signal, or carrier, e.g., a data storage device, a data communications device, a remote computer or device coupled to the computer across a network or via another data communications device, etc. Moreover, this logic and/or data, when read, executed, and/or interpreted, results in the steps necessary to implement and/or use the present invention being performed.
• Thus, embodiments of the invention may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof. The term “article of manufacture” (or alternatively, “computer program product”) as used herein is intended to encompass logic and/or data accessible from any computer-readable device, carrier, or media.[0023]
• Those skilled in the art will recognize many modifications may be made to this exemplary environment without departing from the scope of the present invention. For example, those skilled in the art will recognize that any combination of the above components, or any number of different components, including different logic, data, different peripherals, and different devices, may be used to implement the present invention, so long as similar functions are performed thereby.[0024]
• Collaboration Framework[0025]
• [0026]Collaboration application108 andserver application110 executing onclient104 andserver106 respectively, provide a collaboration framework that enables modifications to drawings to be shared in real time among a set of collaborators104 (i.e., two or more users working simultaneously on the same document from different computers orother network102 devices).
• The collaboration framework provides the ability for all[0027]collaborators104 to modify a document at the same time, with no need for permission to modify to be passed around among thecollaborators104. Once acollaborator104 has joined a session, thecollaborator104 is likely on equal footing with allother collaborators104. Thus, by default, anyone may join a collaboration session and begin collaborating with others that may already be working in the session. Alternatively, whilemultiple collaborators104 may edit the document, anothercollaborator104 may not have write access and may only have read capability to watch the modifications ofother collaborators104.
• Collaboration Process[0028]
• The initial user in a collaboration session opens a workspace or document to work on. Once opened, a collaboration palette may be displayed on the[0029]computer104 bycollaboration application108. For example, the palette may be placed in the lower-right corner of the window representingcollaboration application108. Alternatively, when not in use, the palette may roll-up or be hidden from the user.
• The collaboration palette provides information on the current collaborators/[0030]users104 in the collaboration session. Thus, when a document is opened by a user, the user's name is added to the collaboration palette. Further, an access level may be assigned to the user. For example, a user's access level may default to “write-access”. Beyond this general information, the palette may not open or show any additional feedback when the initial user opens a workspace.
• FIG. 2 illustrates a collaboration palette displayed in accordance with one or more embodiments of the invention. As illustrated, elements of the[0031]collaboration palette200 may include a user image/icon202. Theicon202 used for the user may be a standard 32×32 GIF (graphic image format) for all users.
• In addition, the[0032]top line204 of a data area ofpalette200 may contain the user's name. Further, thesecond line206 of the data area may contain the user's status. Eachstatus type206 may have an associated color. For example, the status types206 and colors a user may have are joining (green), write-access (black), accidental disconnect (red), intentional disconnect (yellow), and working offline (blue). In order to show a status change, all of the status labels, except “joining,” may blink then disappear after a short duration. The joining status may remain until the user either connects or cannot connect to the workspace.
• A user's[0033]status206 may also reflect a controlled environment wherein a single user may be a moderator that has the ability to grant or deny access to new and existing users. FIG. 3 illustrates a dialog window in such a controlled environment. As illustrated, thestatus field206 may identify the first user as a moderator. Further, when a new user attempts to join a session, thestatus field206 may display a message such as “request write” to indicate that a user is requesting write access. Additionally, adialog window302 may be presented to the moderator that allows the moderator to grant or deny the new user permission to join the workspace as acollaborator104. Advanced options may also be available such as allowing a user to join the session but with read-only capability.
• A scroll bar may be activated on the palette if necessary to display additional information. Further, a[0034]palette titlebar208 includes the title of thepalette200 and may flash for a short duration when the status of anycollaborator104 changes. The color thetitlebar208 flashes may depend on the new status of the collaborator.
• When a second user opens a document or workspace, the workspace opens as usual on the user's[0035]computer104, along with opening thecollaboration palette200 to signal the beginning of a collaboration session. However, thecollaboration palette200 automatically indicates that another user has the workspace open already.
• The[0036]palette200 also provides a mechanism for displaying thestatus206 of the second user's connection to the workspace. When initially opened, the second user'sstatus206 likely reads “joining.” When the second user successfully joins the collaboration session, thestatus line206 changes to “write-access.” Thereafter, if current users of the workspace have closed thecollaboration palette200, thetitlebar208 may flash to signify the addition of a user to the workspace.
• As the workspace is being opened for a second user, a “glass plane” may be placed over the workspace,[0037]palettes200, and menu. Further, in some embodiments, a user may not be able to cancel the open, or start to open another workspace until the current one is fully opened. As illustrated in FIG. 2, thepalette200 indicates that a first user (i.e., “Joe User”) has write-access and a second user (i.e., “User #2”) is joining the session.
• Accordingly, as users join the session, each user's[0038]collaboration palette200 indicates the addition of a user, with astatus206 of “joining.” When a user leaves the workspace on purpose, the user's status206 (e.g., “left workspace”) may be shown in a specific color (e.g., yellow), and after some amount of time, the user'sname204 will be removed from thepalette200. Similarly, if a user leaves the workspace accidentally, the user's status206 (e.g., “disconnected”) may be shown in a different color (e.g., red), and after some amount of time, the user'sname204 will be removed from thepalette200.
• Once a session has begun, modifications to the drawing may be seen by any users in the session. For example, a pan or zoom operation performed on the workspace by a user will be reflected in other users' view of the workspace. Accordingly, the pan and zoom state of the workspace may be stored with the document. Thereafter, the next time the workspace is opened, the view will be the same as when it was last closed. Similarly, if the view of a 3D model is changed by a user, the other users' view of the model will be changed. Additionally, any action that causes data to be saved to the workspace will be seen by all of the users in the collaboration session. For example, creating new documents, moving documents, minimizing documents, and using tools on documents, are all actions that will be seen by everyone.[0039]
• Additionally, the collaboration framework may provide communication capabilities such as chat and instant messaging to[0040]collaborators104 in the session.
• However, to preserve individual user's preferences, certain actions performed by a user may not be seen by other users in the session. For example, a user's[0041]palette200 may not be part of the collaboration session. Thus, if a user moves his or herpalette200 or drawing tools from the upper left to the lower right, thecollaborators104 will not see a change in their view of the workspace. Further, any object selected by acollaborator104 may not be seen in the other collaborator's104 view of the workspace. However, any action done to the object that changes its data (e.g., color or size change) will be seen by the other users. Additionally, the activation of documents may not be seen by collaboration users. For example, if a user has “Drawing 1” active, and is actively placing strokes into it (which is seen by the other users), he or she will not see that another user may have a model document active. However, if the second user begins to rotate the model in the document, the result will be seen by all of thecollaborators104.
• The loss of a[0042]network102 connection by a user affects the way the user continues. When a single user of a workspace (i.e., noother collaborators104 are members of the session) loses his or hernetwork102 connection, the user may be automatically switched to an offline mode during which the user may keep write-access while offline, and theserver106 marks the workspace as offline so it may not be edited by online users. When a user in a collaborative environment loses a connection, the remaining users will be notified that the user has timed-out with the disconnected status in thedata field106 of the palette. The disconnected user may also receive a dialog notice that the connection to the workspace has been lost, and the user has therefore been switched to read-only mode.
• Colaboration Details[0043]
• As described above,[0044]collaborators104 participating in a session may all modify a drawing document that is stored in theserver106 wherein the drawing modifications are then reflected in the other collaborators'104 views. To enable such capabilities, the collaboration framework provides for the transmission of commands to theclient104 andserver106 sides of the framework. The description below provides information regarding some of the commands that may be used including background information, implementation information, and formatting information, It should be noted that while the formatting information is described in terms of extensible markup language (XML), any acceptable format or formatting language may be used and the invention is not intended to be limited to XML formatted messages.
• There are two types of command communication between[0045]clients104 andserver106 in the framework100: synchronous and asynchronous.
• Synchronous commands are sent from the[0046]client104 to theserver106, and processed immediately. The server's106 response is a command response containing the processing results.
• Asynchronous commands ate sent from the[0047]client104 to theserver106, but are not necessarily processed immediately. Theserver106 response to theclient104 may contain multiple command responses toearlier client104 requests, collaboration state changes, collaboration user information, and other data waiting in the client's104 outgoing message queue. As described below, a command referred to herein as “heartbeat” is an example of such an asynchronous command.
• While strictly speaking, there may only be a single command type, there are three distinct types of command messages: Commands, Responses, and Heartbeats.[0048]
• Commands initiate a request or an action. Commands may typically contain one or more <param\> sub-nodes. Usually, commands are a request from the[0049]client104 to theserver106 to initiate an action or request data.
• Responses are commands containing processing results and return data from previously issued commands. There is typically a one to one correspondence for a response to a specific command. For example, a “Version” command likely has a corresponding “Version” response command which is returned to the[0050]client104 and contains data pertaining to the current version of the framework. Responses typically contain a <success\> sub-node, a <rspMsg\> sub-node, and one or more <return\> sub-nodes.
• Heartbeats are asynchronous commands that can contain other commands, responses, or collaboration data.[0051]
• As described above, messages may be implemented in any format. In one or more embodiments of the invention, messages are simple XML structures. Using a login command message from the[0052]client104 as an example, the basic structure is shown below:

  <msg msgID=“1” sessID=“1” resID=“23058” retry=“0”>

  <cmd name=“Login”>

  	<param name=“username” val=“joe smith” />
  	<param name=“password” val=“JoesPswd” />

  </cmd>

  </msg>

• The outermost node, <msg\>, wraps the entire message. A message tag may be required to contain the following attributes in Table 1.[0053]

  TABLE 1
  Attribute Name	Values	Meaning
  MsgID	Any positive integer.	Client 104 generated numeric identifier of the
  		message. When the message is sent from theserver
  		106 to theclient 104, theserver 106 echoes the
  		msgID number it is responding to. This pairs the
  		client 104 request andserver 106 response message
  		with the same ID.
  SessID	A valid session ID.	the sessionID.
  ResID	A valid resource ID.	the resourceID.
  Retry	A positive integer, or zero.	number of times client has sent this message.

• The first and only sub-node, <cmd\>, contains a single command. This single command may be a heartbeat command, which itself may contain sub-commands. The command node may contain multiple attributes including a name that specifies a unique command name for the command being sent.[0054]
• Additionally, each <cmd\> node may contain one or more of the sub nodes described in Table 2, depending on it's type:[0055]

  TABLE 2
  Sub Node
  Name	Contains	Attributes
  Param	A parameter for the	Name - the parameter name.
  	command.	Val - the parameter's value.
  Filedata	An XML file of a non-	NONE.
  	specific type. Currently used
  	for user data, workspace files
  	and Workspace Trees.
  Success	Found only in response	Val - return value. The constant names and values:
  	commands, this contains a	RESPONSE_SUCCESS = 0 × 0
  	flag indicating whether the	RESPONSE_LOGIN_REQUIRED = 0 × 1
  	command was executed	RESPONSE_FAILURE = 0 × 2
  	successfully. If it was not,	RESPONSE_RESOURCE_NOT_FOUND = 0 × 3
  	the attribute contains a	RESPONSE_INSUFFICIENT_PERMISSION = 0 × 4
  	constant indicating the nature	RESPONSE_DUPLICATE_NAME = 0 × 5
  	of the failure.	RESPONSE_BAD_TOKEN = 0 × 6
  		RESPONSE_UNKNOWN_FILETYPE = 0 × 7
  		RESPONSE_SYSTEM_FAILURE = 0 × 80
  Return	Found only in response	Name - the return parameter's name.
  	commands, this contains	Val - the value of the return parameter.
  	return values for the previous
  	commands. There may be
  	more than one return node
  	per response message.
  RspMsg	Found only in response	Val - the text of the response message.
  	commands, this contains text
  	corresponding to the result.
  	It may be used for providing
  	error description text to be
  	displayed to the user, for
  	example.

• Accordingly, for each command, whether issued by a[0056]client104 or aserver106, the command name is specified along with optional parameters. The following XML illustrates an example of a version command in accordance with one or more embodiments of the invention:

  <!-- Client request command -->

  <cmd name=“Version”>

  	<param name=“major” val=“1” />
  	<param name=“minor” val=“1” />
  	<param name=“revision” val=“2” />

  </cmd>

  <!-- Server response command -->

  <cmd name=“VersionResp”>

  	<success val=“1” />
  	<rspMsg val=“a resp mesage” />
  	<return name=“VersionResp”>

  	<param name=“major” val=“1” />
  	<param name=“minor” val=“1” />
  	<param name=“revision” val=“1” />

  </return>

  	</cmd>

• As illustrated, the[0057]client104 request command name is “Version” and various parameters are specified. In response, theserver106 specifies the command name along with information described in Table 2 (i.e., a success with a value of 1, a response message with a value of “a resp message”, a return name with a value of “VersionResp”, and various parameters with values).
• Synchronous Commands: Client Sent, Server Processed[0058]
• Various synchronous commands may be processed in the[0059]framework100 of the invention. The synchronous commands described below are commands sent by aclient104 and processed by aserver106.
• Version Command[0060]
• The “version” command results in a return of the current version number of the framework. The syntax for the command is:[0061]

  version( localmajor, localminor, localrevision : major,
  minor, revision, upgradeFlag, ChangesXML : success,
  message )

• The “version” command is sent by the[0062]client104 at startup, before attempting a login or displaying the main application window. Even if theclient104 has a stored session id, it should issue this command first.
• The upgradeFlag indicates the result of the version check and can be VersionsIdentical ([0063]0), ServerUpgraded (1), ClientUpgradeAvailable (2), ClientUpgradeRequired (4). If the upgradeFlag has a VersionsIdentical value, no code in theframework100 has been updated since the last time theclient104collaboration application108 was run. If the upgradeFlag has a ServerUpgraded value, theserver106 has new code that may affect theclients104 perception of how theframework100 works (faster save times, fixes, etc.), but there are noclient104 binary changes.
• A value of ClientUpgradeAvailable means that there is a newer version of the[0064]client104 available, but theclient104 is not required to get the newer version in order to work with the current version of the server106 (i.e. no file formats or interfaces have changed). A value of ClientUpgradeRequited means that significant changes have occurred in theclient104 and file formats or interfaces with theserver106 have changed. Accordingly, theclient104 must upgrade before theclient104 can go online. Note that this does not necessarily mean theclient104 is forced to upgrade immediately. Instead, theclient104 may be able to work offline using the local cache until the user is ready to upgrade. However, if theclient104 desires to obtain data from the site/server106, theclient104 must upgrade.
• Also, any new features and/or noteworthy fixes that have been implemented since the version of the[0065]client104 passed in will be returned in the ChangesXML parameters, and these changes can be displayed in theclient104. It may be possible to have some updates and not require an upgrade. For example, there may have been server-only changes that would be nice to let the user know about (e.g., a bug fix or improved performance). The ChangesXML may be useful to users when the value of upgradeFlag is ClientUpgradeAvailable, since the ChangesXML content is what provides the basis upon which theclient104 decides if the upgrade should be made (new features and fixes vs. risk assessment). Further, the ChangesXML value does not need to be overly verbose. For example, the ChangesXML value may comprise a short bulleted list containing only changes that the average user would care about, or possibly a hyperlink pointing to a page on a web site that may be accessed for more detailed information.
• In response to the version command, an object is returned with the current version numbers that may be read from a local versions XML file. Alternatively, a data cache product may be used such that the version numbers are stored in a[0066]database114 and read from the cache. Thereafter, collaboration application stores the returned major/minor/revision numbers and ensures that the returned numbers are used in the next version command.
• The versions XML file may contain all changes over time (occasionally pruned manually) and will be read by the[0067]application server110 at start time and stored globally into an efficiently searched data structure that may be keyed by major.minor.revision. Each one of thedatabase114 entries may have an upgradeFlag that will be set to one of the levels defined above. The upgradeFlag's values may be binary to ease in the use of a bitwise OR operation. Each entry may also contain any number of new feature/fix nodes, and each node might specify an attribute classifying the type (new feature vs. enhancement vs. fix, etc). When processing a version command, if the major/minor/revision passed in is lower than the current maximum parsed from the file, then an update has occurred and an upgrade may be required.
• The upgradeFlag is determined by a simple bitwise OR operation of all upgradeFlags of the versions greater than the version passed in. The ChangesXML is built in a similar way, by combining all of the change nodes for the versions greater than the one passed in. If the provided version is not found, then the version has been pruned, and the earliest version in the data structure is used to determine the upgradeFlag and the ChangesXML.[0068]
• The version command likely executes quickly and efficiently and avoids a Denial of Service attack, since no login is required. Accordingly, the version command does not perform any[0069]database114 read operations,database114 write operations, and only performs a single remote method invocation (RMI) call.
• Login Command[0070]
• The login command is executed by the[0071]client104 at startup to logon to a session. In one or more embodiments, the login command is used when the user does not have a session id, or when the user determines that the sessionid that the user has is invalid. Such a login may be required in when theserver106 requires theclient104 to logon (e.g., during the processing of a loginrequired command from the server106 [see below]). The syntax for the login command is:

  login( username, password : success, message, sessionID,
  userID, imageURL )

• In response to a login command, the[0072]server106 returns a new sessionID and the userlD to theclient104. The same user can be logged on multiple times and have multiple active sessionID's.
• Open User Data Command[0073]
• Once logged in pursuant to the login command, the[0074]client104 will next transmit the Open User Data command. More particularly, if theclient104 has a cached sessionID from a previous instance, theclient104 will first try this sessionID. If the prior sessionID fails, theclient104 will receive a loginrequired command from theserver106 in response. The subsequent login (i.e., using the login command) provides a sessionid to be used with the Open User Data command. The Open User Data command opens specified user data for theclient104.
• New Workspace Command[0075]
• This command is used by a[0076]client104 whenever the user selects an option to create a new workspace/document. The newworkspace command is executed before the closeworkspace command of an open workspace (if there is one open) is executed. If the newworkspace command is successful, the resourcelD of the new workspace is returned, and the workspace should be considered to be in a SoloPending state for the specified user.
• Copy Workspace Command[0077]
• The copy workspace command is issued by the[0078]client104 whenever the user selects an option to copy a workspace.
• Delete Workspace Command[0079]
• The delete workspace command is issued by the[0080]client104 whenever the user tries to delete a workspace that the user has opened. The delete workspace command is executed before the closing an open workspace. If successful, the deleted workspace will be gone and the user will have to select a workspace to work on or create a new workspace. The use of the delete workspace command may be restricted. For example, the delete workspace command may not execute if the workspace is in CollabPending or Collab state. Accordingly, in order to delete a workspace, the user must be the only person in the workspace. The syntax for the delete workspace command is:
• deleteworkspace(userID, resourceID:success, message)
• To enable the delete workspace command, the[0081]server106 may ensure that the workspace is either open by nobody, or open by exactly the user trying to delete it. The user must also have the appropriate permissions. If all of these conditions have been complied with, then the delete workspace command will delete the workspace and remove the workspace from a ResourceSession. Once deleted, the workspace cannot be opened at a later time.
• Open Workspace Command[0082]
• The open workspace command is the backbone of collaboration, and occurs whenever the[0083]client104 opens a new workspace. The command is issued by theclient104 before the closeworkspace command when switching workspaces. If the workspace is already open by two or more users (i.e., the workspace is in Collab state), then this user joins the collaboration session. If the workspace is open by only one person (i.e., the workspace is in Solo state), then a collaboration session is started (CollabPending state) and bothclients104 are synchronized. Once synchronized, the state changes to Collab. If the workspace is not open, the user (that is in SoloPending state) marks the workspace as open.
• A workspace session and user's workspace session may be in one of the following states: 0-Solo Pending; 1-Solo; 2-Collab Pending; 3-Collab; or 4-Disconnected. When a workspace is not open, the workspace has no state. When the workspace is opened, the workspace transitions into Solo Pending, as does the workspace's user.[0084]
• Upon the new user's/client's[0085]104 heartbeat, the state is transitioned from Solo Pending to Solo. If another user opens the document, the state is transitioned to Collab Pending. Once theoriginal client104 confirms synchronization of the document, the state is transitioned to Collab. If another user joins, the workspace remains in Collab state, but the user is in Collab Pending until the first heartbeat is received, at which time theclient104 is transitioned into full Collab.
• If at any point enough users close the workspace such that there is only one[0086]client104 left, the state is transitioned into Solo Pending for that user and the workspace. Once thisclient104 confirms synchronization of the document and started creating deltas, the state is transitioned into Solo for the workspace and the user. If at anytime a user is determined to have gone link dead, the user's state is changed to Disconnected. If at any time all users left in a workspace session are Disconnected, then the state of the document is changed to Disconnected. Once users have been disconnected for a sufficient time without returning, the disconnected users are removed from the session. If all users are removed from a session, the session is closed.
• Close Workspace Command[0087]
• The close workspace command is executed when a user closes a workspace. If the user is closing the workspace due to opening an existing or creating a new workspace, then the open or create commands are executed first, and the close executing after their success. If the user closes the application, closeworkspace is sent after the final save.[0088]
• While processing this command, if the state is Collab then a collabuserinfo command may be placed in the CommandOut queues of the remaining workspace session users. If there is only one other workspace session user, then the state of the workspace session may be changed from Collab to Solo Pending.[0089]
• Get Object IDs Command[0090]
• The Get Object IDs command is issued by a[0091]client104 to obtain a range of unique Object IDs theclient104 can use when creating application objects. A GetObjectIDs command with no parameters is requesting a default number of IDs. The default should be sufficient for typical online work, yet large enough to allow for sufficient IDs in the case of subsequent connection failures so theclient104 can keep working. A “quantity” parameter may be specified to request a specific quantity of Object ID's.Clients104 can use numeric constants for typical quantities or simply specify a number for the quantity. The syntax for the Get Object IDs command is:

  getObjectIDs( userID : success, message, Object ID
  start, Object ID end )

• In response to the command, the[0092]server106 returns a range of object IDs that can be used by theclient104. In other words, a first/start object ID and a last/end object ID are returned by theserver106 for use by theclient104.
• The GetObjectIDs command may or may not be utilized depending on the implementation. For example, if the GetObjectIDs command is not utilized, the[0093]server106 may map object IDs as using a Mapped Objects command described in detail below.
• Synchronous Responses Server Sent, Client Processed[0094]
• The commands described below are synchronous commands/responses that are transmitted by a[0095]server106 and processed by aclient104.
• Login Required Response[0096]
• The[0097]server106 generates the login required command whenever processing a message or command and it is determined that the specified sessionID is missing or invalid (timed out). Upon receipt and execution, theclient104 sends a login command to the server106 (see above).
• System Failure Response[0098]
• The[0099]server106 generates the system failure response/command whenever an internal system failure occurs processing a message or command. Upon receipt of the system failure command, theclient104 takes appropriate measures to retry the command it received the system failure response message for.
• Heartbeat Commands[0100]
• Heartbeat messages are different from other commands, as they may contain sub commands and collaboration data. The heartbeat message uses two sub-nodes to contain the different types of data. These are the <transientcmd\> node, which contains zero or more commands and responses, and the <persistentcmd\> node, which contains actual collaboration data, i.e., the actions performed in the[0101]client104 by thecollaborators104.
• As an example, a heartbeat command demonstrating the full structure is shown below, although any individual heartbeat command may or may not have all the components shown below the <cmd\> node. The example shows a heartbeat command with a single SaveUserData sub-command, and a comment in the <persistentcmds\> section where a real message would have one or[0102]more client104 collaboration commands:

  <cmd name=“Heartbeat” deltalevel=“45” beat=“1”

  	strong=“0”>
  	<transientcmds>

  <cmd name=“SaveUserData”>

  <param name=“file”

  	val=“woof_tools.xml”>
  	<filedata>

  	<!-- user data file xml -->
  	<filedata>

  </param>

  </cmd>

  	</transientcmds>
  	<persistentcmds deltalevel=“45>

  <!-- client collaboration commands -->

  </persistentcmds>

  </cmd>

• The heartbeat </cmd> node may be required to contain the attributes identified in Table 3.[0103]

  TABLE 3
  Attribute Name	Values	Meaning
  DeltaLevel	The current delta level. In solo	See text.
  	mode, this value is determined
  	by theclient 104 and echoed by
  	theserver 106 in the response.
  	In collaboration mode, these
  	are temporary IDs when sent
  	from theclient 104, and actual
  	IDs when sent from theserver
  	106.
  Beat	BEAT_TYPE_COLLAB = 1	A collaboration or solo beat.
  	BEAT_TYPE_SOLO = 2
  Strong	BEAT_STRONG = 1	Theserver 106 updates theclient 104 last contacted
  	BEAT_WEAK = 0	time on Strong beats, whether or not any other data
  		is sent.

• The heartbeat command is executed by the[0104]client104 with a delay between heartbeats of N seconds, where N varies depending if theclient104 is collaborating or not. Tentatively heartbeats may beat execute every 10 seconds when solo and every 2 seconds when collaborating. Occasionally heartbeats will be strong. A strong heartbeat signifies that even if no data modification commands (referred to as delta commands) are sent in the heartbeat, the users' workspace session should be marked as active so that it does not timeout. For example, if aclient104 does not perform any modifications or is away from the keyboard for 20 minutes while in a collaborative session, theclient104 won't be generating any data but the strong heartbeats will keep the client's104 workspace session alive.
• The syntax for the heartbeat command is:[0105]

  heartbeat( userID, resourceID, deltaLevel, strongflag :
  transientcmds, persistentcmds [ deltalevel ] )

• The heartbeat may contain either transient commands, persistent commands (i.e., delta commands), or both. Transient commands are executed immediately and persistent commands are stored for asynchronous processing by a separate server-side process. Some transient heartbeat commands are described below.[0106]
• If the heartbeat comes from a solo user of the workspace, then the DeltaID's will already be present, and the specified DeltaLevel will represent the new DeltaLevel of the workspace. If the heartbeat comes from a[0107]collaborator104, then none of the delta commands will have a DeltaID, and theserver106 is responsible for numbering them. In either case, the DeltaLevel of the workspace session needs to be updated. If the heartbeat comes from acollaborator104, then the heartbeat response will contain any delta commands that theserver106 has received that are higher than theclients104 specified DeltaLevel, and this will include new delta commands that theclient104 just sent. Accordingly, the heartbeat command enables theclient104 to receive the work done by anotherclient104 during a session.
• If the[0108]client104 is collaborating, then any new ObjectID's specified in the delta commands will be temporary and will be marked as such. Temporary ObjectIDs are mapped to real server-generated ObjectID's, and a persistent map is maintained for each user mapping the user's temporary ObjectID to the real ObjectID. When collaborating, the response to a user's heartbeat command will contain the same persistent commands that came up in the command, but with DeltaID's and real ObjectID's set in them, so that theclient104 can update itself.
• Part of the persistent commands node is the delta level that the[0109]client104 is currently at. In the collaborative case, there may be delta commands that aclient104 has received from other users that have been given DeltaID's that thisclient104 may not yet have. Therefore, the response message may contain not only the updated DeltaID's that thisclient104 generated, but it may also contain those DeltaIDs specified byother clients104, all in the correct DeltaID order.
• Depending on the implementation, the heartbeat processing may utilize a beat flag for the status of a[0110]particular client104. The beat flag is utilized to maintain the appropriate state betweenclients104 and to facilitate the collaboration betweenclients104. Such heartbeat processing utilizing a beat flag is described in detail below.
• Alternatively, instead of using a flag to maintain the state of a[0111]client104, the heartbeat processing may result in the generation of several different collaboration transient commands that are sent to theclient104. If the client's104 state is Solo but the sessions state is Collab Pending, then theclient104 may receive a collabstart command. If the client's104 state is Collab but the sessions state is Solo Pending, then theclient104 may receive a collabstop command. If the client's104 state is Joining but the sessions state is Collab, then theclient104 may receive a collabjoined command.
• The user may also have other transient commands that have been queued up in a queue of outgoing commands for a particular user (referred to as a user's CommandOut queue) waiting for this heartbeat (for example, somebody may have joined the collaborative session, left the collaborative session, etc). These transient commands in the CommandOut queue ate sent from the[0112]server106 to theclient104 in the response message, and marked in a record of the session as having been sent in this particular message ID.
• A retry count for each message may also be maintained. During heartbeat processing, the retry count of the message may be checked. When the message is not a retry, message responses to all previous messages have been received and processed by the client. Therefore, if there are any transient commands in the CommandOut queue which are marked as sent in a previous message, such transient commands can be removed from the queue.[0113]
• The following transient heartbeat commands are transmitted by a[0114]client104 and processed by theserver106.
• Save User Data[0115]
• The save user data command is executed by the[0116]client104 when a session is closed and optionally during sessions as user preferences/options change. The save user data command may execute based on an interval and a dirty flag. If the time interval has passed and the flag/preferences are dirty, then the preferences are saved.
• The save user data command uses a user ID, filename, and file data as parameters. The filename should be a valid system file type, otherwise the operation to store/save the data may fail. If a failure occurs, a saveuserdatafailed command will likely be generated and returned in the response message.[0117]
• Save Workspace Command[0118]
• The save workspace command is generated by any[0119]client104 that has a non-read-only workspace open. When solo, theclient104 is responsible for sending up all delta commands in the persistent section of a heartbeat command that will update theserver106 from the previous delta level to the new delta level specified. If any of the delta commands are missing, the save will fail.
• In collaborative mode, the detaLevel is the latest server-approved delta level of the workspace that the[0120]client104 is aware of. Therefore, theclient104 does not need to transmit persistent commands to update the workspace, since the server already has the delta levels. Allclients104 in a collaboration session may issue the saveworkspace command. Further, saves may occur at a regular interval (e.g., every 1 minute). Accordingly, solo saveworkspace commands come up pursuant to regular heartbeat intervals (e.g., 6 heartbeats), and when collaborating saveworkspace commands are likely issued at greater heartbeat intervals (e.g., every 30 heartbeats).
• Collaboration Start Confirmation Command[0121]
• As described above, various transient collaboration commands may or may not be utilized depending on the implementation. The collaboration start confirmation command may be generated by a[0122]client104 upon receiving and executing a collabstart command. The command occurs only when going from the solo to collaborative mode (i.e., from 1 document viewer to 2). When theserver106 receives this command, theclient104 is signaling that theclient104 has stopped generating delta commands that have DeltaID's, and that it is now theservers106 responsibility to generate the delta commands. The collaboration start confirmation command typically arrives in the same message as theclients104 final solo saveworkspace. Subsequent to execution, heartbeats contain delta commands without DeltaID's, and all new ObjectID's are temporary.
• Once the[0123]server106 receives the start collaboration confirmation command, the user or users that are in the Joining state can be migrated to the Joined state (they are issued collabjoined commands), as well as placing collabuserinfo commands into the CommandOut queues of all users in the workspace session for all of the users that just Joined. The workspace session state may also be updated from CollabPending to Collab.
• Collaboration Stop Confirmation Command[0124]
• The collaboration stop confirmation command is generated by a[0125]client104 upon receiving and executing a collabstop command from theserver106. This command is only executed when going from the collaborative mode to the solo mode (i.e., from 2 or more document viewers to 1). When theserver106 receives this command, theclient104 is signaling that theclient104 has started generating delta commands that have DeltaID's, and that it is no longer the servers'106 responsibility to generate delta commands. Subsequently, heartbeats executed by theclient104 contain delta commands withclient104 generated DeltaID's, and all new ObjectID's are real and not temporary.
• Once the[0126]server106 receives the collaboration stop confirmation command, the user or user may be migrated from the Pending Solo state to the Solo state. Additionally, the workspace session state may be updated from SoloPending to Solo.
• Collaboration Joined Formation Command[0127]
• The collaboration joined formation command (referred to as collabjoinedconfirm) is generated by a[0128]client104 upon receiving and executing a collabjoined command. A collabjoined command is only received when the user's state transitions from the collaborative pending state to the collaborative mode state. When theserver106 receives the collaboration joined formation command, theclient104 is signaling that theclient104 has received the collabjoined command and is now generating delta commands (unnumbered).
• Once the[0129]server106 receives the collaboration joined formation command, the user is likely migrated from the Pending Collab state to the Collab state.
• Mopped Objects Command[0130]
• Depending on the implementation, a mapped objects command may or may not be provided. For example, if a Get Object IDs command (as described above) are implemented, the Mapped Objects Command may not be utilized. As described above, the GetObjectIDs provides the[0131]client104 with a pool of valid IDs which are guaranteed unique. Accordingly, there is no need for theserver106 to map the objects to IDs. However, without the GetObjectIDs command, such mapping may be necessary.
• The purpose of the mapped objects command is so that the[0132]server106 can truncate the real-to-temp ObjectID maps for each client's104 workspace session once theclient104 has acknowledged that the real ID's have been received. Accordingly, the mapped objects command may only be used when in a collaborative mode. Further, the command is originallyserver106 generated and simply forwarded back up to theserver106 by theclient104. By making a trip through the clients'104 queues, once received by theserver106, any temporary ObjectID's in the command are no longer in use by theclient104. Accordingly, temporary ObjectIDs may be removed from a state map of theserver106.
• The removal of a temporary ObjectIDs causes object mapping to run considerably faster when processing commands from[0133]active clients104 who are generating numerous delta commands. Without the mapped objects command, the mapping table may continue to grow unchecked.
• The execution of the mapped objects command may contain a series of elements, with a tempID and realID attribute/value pair. The elements are parsed and the tempID's are placed into a string. The string may then be transmitted to a[0134]single server106 processor (along with the userlD and resourceID) that can efficiently delete all of the temporary objects efficiently.
• In addition to transient commands sent by a[0135]client104 and processed by aserver106, the following transient commands are transmitted by theserver106 and processed by aclient104.
• Collaboration Start Command[0136]
• The[0137]server106 generates the collaboration start command while processing a heartbeat if the heartbeat originated from asolo client104 and the state of the workspace session has been changed to Pending Collab. The collaboration start command signals that a collaborative session is beginning so that theclient104 can begin the transition from the solo state to the pending collaboration state. Once theclient104 has finished this transition, dieclient104 will issue a collabstartconfirm command to theserver106 as described above.
• Collaboration User Information Command[0138]
• The[0139]server106 generates the collaboration user information command in response to every heartbeat for a user in a collaborative session. This command contains all of the data regarding users currently in the session including disconnected (link dead) users. It is the client's104 responsibility to compare the data structure to previously received data structures to figure out what users are new, what users are gone, what users had state changes, what users had icon changes, etc., and then render appropriately.
• Collaboration Joined Command[0140]
• The[0141]server106 generates the collaboration joined command while processing a heartbeat command. If the heartbeat comes from a joiningclient104 and the state of the workspace session is Collaborating, then this command is generated and returned on the heartbeat.
• Collaboration Stop Command[0142]
• The[0143]server106 generates the collaboration stop command while processing a heartbeat command if the specified userID is the only user left in the workspace session. The command signals that the collaborative mode should stop, and that theclient104 should enter the pending solo mode and signal to theserver106 that theclient104 has sent up all of the client's104 un-numbered delta commands.
• Beat Flag[0144]
• The various transient collaboration commands described above (e.g., Collaboration Start Confirmation Command, Collaboration Stop Confirmation Command, Collaboration joined Formation Command, Collaboration Start Command, Collaboration User Information Command, Collaboration joined Command, and Collaboration Stop Command) may not be utilized in one or more embodiments of the invention. Instead, a flag may be used in the Heartbeat command that maintains state information for[0145]clients104.
• At the[0146]server106 level, the state of the workspace itself as well as the state of theclient104 may be considered. However, eachclient104 only needs to keep track of their own state. The state may be described using the following values: 0=closed, 1=disconnected, 2=solo pending, 3=solo, 4=collab pending, and 5=collab.
• Upon executing an open workspace command, the[0147]client104 is placed in one of two states: solo pending or collab pending. The heartbeat command always echoes this state to theserver106. In turn, theserver106 will update the value of this flag after examining the state of the workspace and the state of the users in the session.
• An example of three clients collaborating using the various flags are illustrated in Table 4.[0148]

  TABLE 4
  				Server
  				Work-
  Command	Client1	Client2	Client3	space	C1	C2	C3
  1. Client1 exe-	2			2	2
  cutes open work-
  space
  2. Client1	3			3	3
  heartbeats
  3. Client2	3	4		4	3	4
  executes open
  workspace
  4. Client1	4	4		4	4	4
  heartbeats
  5. Client2	4	(no			4	4	4
  heartbeats		changes)
  		4
  6. Client1	5	4		5	5	4
  heartbeats
  7. Client2	5	5		5	5	5
  heartbeats
  8. Client3	5	5	4	5	5	5	4
  executes open
  workspace
  9. Client3	5	5	5	5	5	5	5
  heartbeats
  10. Client2	5	0	5	5	5	0	5
  executes
  close workspace
  11. Client3	5	0	0	2	5	0	0
  executes
  close workspace
  12. Client1	2	0	0	2	2	0	0
  heartbeats
  13. Client1	3	0	0	3	3	0	0
  heartbeats

• As illustrated in Table 4, the values in each row are the final values after successful execution of each command indicated. The first user in a workspace session must confirm (e.g., by issuing a heartbeat command with a collab pending flag) to synchronize all deltas and start a collaboration session. The[0149]client104 always checks the flag returned from the server to determine whether it should change its current state or not.
• The command executed in Table 4 and the actions taken may resemble the transient collaboration commands described above in the following manner:[0150]
• Step 3 (Client[0151]2 executes open workspace) is the equivalent of the collab joined command (sent by the server106).
• Step 4 (Client[0152]1 heartbeats) is the equivalent of the collab start command (set by the server106).
• Step 6 (Client[0153]1 heartbeats) is the equivalent of the collab start confirm command (sent by client104).
• Step 7 (Client[0154]2 heartbeats) is the equivalent of the collab joined confirm command (sent by client104).
• Step 12 (Client[0155]1 heartbeats) is the equivalent of the collab stop command (sent by server106).
• Step 13 (Client[0156]1 heartbeats) is the equivalent of the collab stop confirm command (sent by client104).
• By using the beat flag in this manner, transient collaboration commands are not needed between a[0157]client104 and aserver106. Further, the beat flag provides a mechanism to maintain state information for eachclient104 in a collaboration session without the use of extraneous communications between theclient104 andserver106.
• Save User Data Failed Command[0158]
• The[0159]server106 generates the save user data failed command when the processing of a saveuserdata command fails for reasons other than system failure (system failures are handled separately and consistently for all commands/messages). For example, some causes for the saveuserdata command failing may include invalid filename specified or invalid userlD specified.
• Save Workspace Failed Command[0160]
• The[0161]server106 generates the save workspace command when the processing of a saveworkspace command fails for reasons other than system failure. Failed commands due to system failures are handled separately and consistently for all commands/messages. For example, some of the causes for the failure of the saveworkspace command may include: invalid userlD specified, invalid resourcelD specified, no access, and possibly workspace not open.
• Collaboration Flow[0162]
• As described above, numerous commands may be used as part of the collaboration framework to enable multiple users to simultaneously access and modify an actual document that is stored on a[0163]server106. Further, thecollaboration application108 andserver application110 enable the use of a full set of three-dimensional tools to modify a drawing while in a collaboration session.
• The[0164]server106 also maintains a history of all modifications to the document. Using the history, aclient104 may undo any client's104 modification to a drawing document/workspace. Further, in the event of a network or system failure, the history can be used to rebuild/regenerate a document including all modifications on anyclient104 by recommunicating commands received from aclient104 tocollaborators104 in a session. To provide such functionality, in addition to the history, theserver106 may maintain a record of the collaboration session including the name, numbers, and statuses ofcollaborators104 in the session.
• FIG. 4 is a flow chart illustrating the use of the collaboration framework in accordance with one or more embodiments of the invention. At[0165]step402, a document/workspace is stored on aserver106. Atstep404, a collaboration session is established. During a session, theserver106 permits two ormore collaborators104 on anetwork102 to work simultaneously across the network on the drawing document stored on the server106 (e.g., all of thecollaborators104 have write-access for the drawing document during the session). A collaboration palette may be displayed tocollaborators104 in the session that provides information relating to thecollaborators104 in the session (e.g., the name of eachcollaborator104, status of eachcollaborator104, an icon for eachcollaborator104, etc.).
• At[0166]step406, theserver106 receives a command (e.g., an XML formatted command) to modify the drawing document from acollaborator104 in the session. Such a command may be invoked pursuant to the collaborator's104 use of a tool selected from a full set of drawing modification tools. The command may identify an object in the drawing document that thecollaborator104 has modified.
• At[0167]step408, theserver106 distributes the command to modify the drawing document to theother collaborators104 in the session. Such a distribution may be pursuant to regularly transmitted commands (e.g., heartbeat commands as described above) received fromcollaborators104 in the session. Further, as part of the command's distribution, an identifier may be assigned to the command and distributed with the command to thecollaborators104. Theclient104 then uses the identifier to determine whether the command has already been reflected in its display or not.
• Conclusion[0168]
• This concludes the description of the preferred embodiment of the invention. The following describes some alternative embodiments for accomplishing the present invention. For example, any type of computer, such as a mainframe, minicomputer, or personal computer, or computer configuration, such as a timesharing mainframe, local area network, or standalone personal computer, could be used with the present invention.[0169]
• The foregoing description of one or more embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.[0170]

Claims (57)

What is claimed is:

1. A method for collaborating access to a drawing document on a network, comprising:

storing a drawing document on a server;

receiving, in the server, a request to open the drawing document;

in response to the request, the server establishing a collaboration session, wherein during the collaboration session, the server permits two or more collaborators to work simultaneously across the network on the drawing document stored on the server;

receiving, in the server, a command to modify the drawing document from a first one of the collaborators in the collaboration session; and

the server distributing the command to modify the drawing document to other ones of the collaborators in the collaboration session.

2. The method ofclaim 1, further comprising the server maintaining a history of modifications to the drawing document.

3. The method ofclaim 2, wherein the history is used to support an undo command.

4. The method ofclaim 2, wherein the history is used to recommunicate modifications to the two or mote collaborators.

5. The method ofclaim 1, further comprising the server maintaining a record of the collaboration session including name, numbers, and statuses of the two or more collaborators.

6. The method ofclaim 1, wherein the command comprises an extensible markup language (XML) command.

7. The method ofclaim 1, wherein the two or more collaborators all have write-access for the drawing document during the collaboration session.

8. The method ofclaim 1, wherein the command is received in the server from a first collaborator pursuant to a regularly transmitted command.

9. The method ofclaim 1, further comprising:

generating an identifier for the command;

distributing the identifier with the command to the other collaborators in the collaboration session.

10. The method ofclaim 1, wherein the command specifies an object identifier for an object in the drawing document that is modified.

11. The method ofclaim 1, wherein an extensible set of three dimensional modeling tools for modifying the drawing document is supported.

12. A method for accessing a drawing document on a network, comprising:

joining an existing collaboration session comprised of a collaborator on a network, wherein during the collaboration session, collaborators in the collaboration session can work simultaneously across the network on a drawing document stored on a server; and

transmitting, to the server, a first command to modify the drawing document.

13. The method ofclaim 12, further comprising receiving a second command to modify the document from the server wherein the command was originally transmitted from another collaborator.

14. The method ofclaim 12, wherein the command comprises an undo command.

15. The method ofclaim 12, wherein the command comprises an extensible markup language (XML) command.

16. The method ofclaim 12, further comprising displaying a collaboration palette that provides information relating to the collaborators in the collaboration session.

17. The method ofclaim 12, wherein the command is transmitted pursuant to a regularly transmitted command.

18. The method ofclaim 12, wherein the command specifies an object identifier for an object in the drawing document that is modified.

19. The method ofclaim 12, wherein an extensible set of three dimensional modeling tools for modifying the drawing document is supported.

20. An system for collaborating access to a drawing document on a network comprising:

(a) a server connected to a network and having a memory and a data storage device coupled thereto;

(b) a drawing document stored on the server; and

(c) a computer program, performed by the server, the computer program configured to:

(i) receive a request to open the drawing document;

(ii) in response to the request, establishing a collaboration session, wherein during the collaboration session, the computer program permits two or more collaborators to work simultaneously across the network on the drawing document;

(iii) receive a command to modify the drawing document from a first one of the collaborators in the collaboration session; and

(iv) distribute the command to modify the drawing document to other ones of the collaborators in the collaboration session.

21. The system ofclaim 20, wherein the computer program is further configured to maintain a history of modifications to the drawing document.

22. The system ofclaim 21, wherein the history is used to support an undo command.

23. The system ofclaim 21, wherein the history is used to recommunicate modifications to the two or more collaborators.

24. The system ofclaim 20, wherein the computer program is further configured to maintain a record of the collaboration session including name, numbers, and statuses of the two or more collaborators.

25. The system ofclaim 20, wherein the command comprises an extensible markup language (XML) command.

26. The system ofclaim 20, wherein the two or more collaborators all have write-access for the drawing document during the collaboration session.

27. The system ofclaim 20, wherein the command is received in the server from a first collaborator pursuant to a regularly transmitted command.

28. The system ofclaim 20, wherein the computer program is further configured to:

generate an identifier for the command;

distribute the identifier with the command to the other collaborators in the collaboration session.

29. The system ofclaim 20, wherein the command specifies an object identifier for an object in the drawing document that is modified.

30. The system ofclaim 20, wherein the computer program supports an extensible set of three dimensional modeling tools for modifying the drawing document.

31. A system for accessing a drawing document on a network, comprising:

(a) a collaborator connected to a network and having a memory and a data storage device coupled thereto; and

(b) a computer program, performed by the collaborator, the computer program configured to:

(i) join an existing collaboration session comprised of a collaborator on a network, wherein during the collaboration session, collaborators in the collaboration session work simultaneously across the network on a drawing document stored on a server; and

(ii) transmit, to the server, a first command to modify the drawing document.

32. The system ofclaim 31, the computer program further configured to receive a second command to modify the document from the server wherein the command was originally transmitted from another collaborator.

33. The system ofclaim 31, wherein the command comprises an undo command.

34. The system ofclaim 31, wherein the command comprises an extensible markup language (XML) command.

35. The system ofclaim 31, further, wherein the computer program is further configured to display a collaboration palette that provides information relating to the collaborators in the collaboration session.

36. The system ofclaim 31, wherein the command is transmitted pursuant to a regularly transmitted command.

37. The system ofclaim 31, wherein the command specifies an object identifier for an object in the drawing document that is modified.

38. The system ofclaim 31, wherein the computer program supports an extensible set of three dimensional modeling tools for modifying the drawing document.

39. An article of manufacture comprising a program storage medium readable by a computer and embodying one or more instructions executable by the computer to perform a method for collaborating access to a drawing document on a network, the method comprising:

storing a drawing document on a server;

receiving, in the server, a request to open the drawing document;

in response to the request, the server establishing a collaboration session, wherein during the collaboration session, the server permits two or more collaborators to work simultaneously across the network on the drawing document stored on the server;

receiving, in the server, a command to modify the drawing document from a first one of the collaborators in the collaboration session; and

the server distributing the command to modify the drawing document to other ones of the collaborators in the collaboration session.

40. The article of manufacture ofclaim 39, wherein the method further comprises the server maintaining a history of modifications to the drawing document.

41. The article of manufacture ofclaim 40, wherein the history is used to support an undo command.

42. The article of manufacture ofclaim 40, wherein the history is used to recommunicate modifications to the two or more collaborators.

43. The article of manufacture ofclaim 39, wherein the method further comprises the server maintaining a record of the collaboration session including name, numbers, and statuses of the two or more collaborators.

44. The article of manufacture ofclaim 39, wherein the command comprises an extensible markup language (XML) command.

45. The article of manufacture ofclaim 39, wherein the two or more collaborators all have write-access for the drawing document during the collaboration session.

46. The article of manufacture ofclaim 39, wherein the command is received in the server from a first collaborator pursuant to a regularly transmitted command.

47. The article of manufacture ofclaim 39, wherein the method further comprises:

generating an identifier for the command;

distributing the identifier with the command to the other collaborators in the collaboration session.

48. The article of manufacture ofclaim 39, wherein the command specifies an object identifier for an object in the drawing document that is modified.

49. The article of manufacture ofclaim 39, wherein the method further comprises providing an extensible set of three dimensional modeling tools for modifying the drawing document.

50. An article of manufacture comprising a program storage medium readable by a computer and embodying one or more instructions executable by the computer to perform a method for accessing a drawing document on a network, the method comprising:

joining an existing collaboration session comprised of a collaborator on a network, wherein during the collaboration session, collaborators in the collaboration session work simultaneously across the network on a drawing document stored on a server; and

transmitting, to the server, a first command to modify the drawing document.

51. The article of manufacture ofclaim 50, wherein the method further comprises receiving a second command to modify the document from the server wherein the command was originally transmitted from another collaborator.

52. The article of manufacture ofclaim 50, wherein the command comprises an undo command.

53. The article of manufacture ofclaim 50, wherein the command comprises an extensible markup language (XML) command.

54. The article of manufacture ofclaim 50, wherein the method further comprises displaying a collaboration palette that provides information relating to the collaborators in the collaboration session.

55. The article of manufacture ofclaim 50, wherein the command is transmitted pursuant to a regularly transmitted command.

56. The article of manufacture ofclaim 50, wherein the command specifies an object identifier for an object in the drawing document that is modified.

57. The article of manufacture ofclaim 50, wherein the method further comprises providing an extensible set of three dimensional modeling tools for modifying the drawing document.

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