Realtime synchronized document editing by multiple users

• US 9,218,102 B1
• Filed: 01/16/2014
• Issued: 12/22/2015
• Est. Priority Date: 01/08/2009
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Greenspan, David, Iba, Aaron, Zamfirescu-Pereira, John Dalbert
• Primary Examiner(s): NABI, REZA U
• Application Number:
  US14/156,575
• Time in Patent Office: 705 Days
• Field of Search: 715/753
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0481 based on specific properties of the displayed interaction object or a metaphor-based environment, e.g. interaction with desktop elements like windows or icons, or assisted by a cursor's changing behaviour or appearance
• CPC Class Codes: G06F 40/166 Editing, e.g. inserting or deleting
• CPC Class Codes: G06F 40/197 Version control for software G06F8/71

Abstract

Collaborative editing of electronic documents in realtime is provided. A host serves a client code over a network to a plurality of clients that each employ a browser to run the client code. The client code revises the text document locally in response to user input, frequently sends those edits to the host, receives updates from the other clients via the host, and revises the local text document accordingly. Each client, in some embodiments, stores three variables, one for edits not yet reported to the host, one for edits reported by not yet acknowledged, and one for the text document as modified by the acknowledged edits. Updates from the other clients are applied to the three variables according to certain rules. A composition of the three variables yields a version of the text document. The host keeps records of which edits were introduced by which client.

Claims

1. A method comprising:

storing a document as an ordered set of revision records;

receiving, from a first client, a representation of a first changeset specifying one or more changes relative to a first version of the document;

receiving, from a second client, a representation of a second changeset specifying one or more changes relative to the first version of the document;

identifying a revision record for the document, wherein the revision record corresponds to one or more changes that were made to the document prior to receiving the representation of the first changeset and the representation of the second changeset;

generating a third changeset based on a merge of the first changeset and the second changeset, and the revision record;

adding a new revision record that includes the third changeset to an end of the ordered set of revision records;

computing a first follows changeset from the first changeset and the second changeset;

computing a second follows changeset, different from the first follows changeset, from the first changeset and the second changeset;

transmitting the first follows changeset to the first client; and

transmitting the second follows changeset to the second client;

wherein a second version of the document is determined by applying the first and second follows changesets at the first and second clients respectively.

2. The method of claim 1, wherein the document is accessible to a plurality of client computer systems including the first client and the second client.

3. The method of claim 1, wherein each of a plurality of the revision records for the document includes a respective revision number.

4. The method of claim 1, wherein each of a plurality of the revision records for the document includes a respective changeset that specifies at least one addition or deletion of a character from a prior version of the document.

5. The method of claim 1, further comprising:

after receiving the representation of the first changeset, sending an acknowledgement to the first client indicating that the first changeset has been received.

6. An apparatus comprising:

a processor; and

a memory to store computer program instructions, the computer program instructions when executed on the processor cause the processor to perform operations comprising;

storing a document as an ordered set of revision records;

receiving, from a first client, a representation of a first changeset specifying one or more changes relative to a first version of the document;

receiving, from a second client, a representation of a second changeset specifying one or more changes relative to the first version of the document;

identifying a revision record for the document, wherein the revision record corresponds to one or more changes that were made to the document prior to receiving the representation of the first changeset and the representation of the second changeset;

generating a third changeset based on a merge of the first changeset and the second changeset, and the revision record;

adding a new revision record that includes the third changeset to an end of the ordered set of revision record;

computing a first follows changeset from the first changeset and the second changeset;

computing a second follows changeset, different from the first follows changeset, from the first changeset and the second changeset;

transmitting the first follows changeset to the first client; and

transmitting the second follows changeset to the second client;

wherein a second version of the document is determined by applying the first and second follows changesets at the first and second clients respectively.

7. The apparatus of claim 6, wherein the document is accessible to a plurality of client computer systems including the first client and the second client.

8. The apparatus of claim 6, wherein each of a plurality of the revision records for the document includes a respective revision number.

9. The apparatus of claim 6, wherein each of a plurality of the revision records for the document includes a respective changeset that specifies at least one addition or deletion of a character from a prior version of the document.

10. The apparatus of claim 6, the operations further comprising:

after receiving the representation of the first changeset, sending an acknowledgement to the first client indicating that the first changeset has been received.

11. A non-transitory computer readable medium storing computer program instructions, which, when executed on a processor, cause the processor to perform operations comprising:

storing a document as an ordered set of revision records;

receiving, from a first client, a representation of a first changeset specifying one or more changes relative to a first version of the document;

receiving, from a second client, a representation of a second changeset specifying one or more changes relative to the first version of the document;

identifying a revision record for the document, wherein the revision record corresponds to one or more changes that were made to the document prior to receiving the representation of the first changeset and the representation of the second changeset;

generating a third changeset based on a merge of the first changeset and the second changeset, and the revision record;

adding a new revision record that includes the third changeset to an end of the ordered set of revision records;

computing a first follows changeset from the first changeset and the second changeset;

computing a second follows changeset, different from the first follows changeset, from the first changeset and the second changeset;

transmitting the first follows changeset to the first client; and

transmitting the second follows changeset to the second client;

wherein a second version of the document is determined by applying the first and second follows changesets at the first and second clients respectively.

12. The non-transitory computer readable medium of claim 11, wherein the document is accessible to a plurality of client computer systems including the first client and the second client.

13. The non-transitory computer readable medium of claim 11, wherein each of a plurality of the revision records for the document includes a respective revision number.

14. The non-transitory computer readable medium of claim 11, wherein each of a plurality of the revision records for the document includes a respective changeset that specifies at least one addition or deletion of a character from a prior version of the document.

15. The non-transitory computer readable medium of claim 11, the operations further comprising:

after receiving the representation of the first changeset, sending an acknowledgement to the first client indicating that the first changeset has been received.