LaTeX Preview Hashing for Collaborative Editing

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Solution Overview

Problem

Collaborative editing of LaTeX documents is hindered by the need for frequent compilation on a central server, which puts pressure on processing load and network bandwidth, especially when multiple users access the system simultaneously, and existing solutions are limited by hardware restrictions.

Innovation Solution

A method where document content is transmitted to a compile server at determined intervals for compilation, generating hash values for each page, and only producing page previews for pages with non-matching hash values, reducing unnecessary processing and bandwidth usage by avoiding duplicate previews.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If document content is transmitted to a central server for compilation at frequent intervals to enable real-time preview during collaborative editing, then preview responsiveness is improved, but server processing load and network bandwidth consumption increase

Engineering Contradiction:
Improvepreview responsivenessVSAvoidserver processing load
Core Design Contradiction:
SpeedVSLoss of energy

Solution Approach 1:

The system generates hash values for each page of the compiled document in advance and stores them on the client device. When the document is updated, the client compares new hash values with stored ones to identify only the pages that have changed, rather than requesting all pages for preview. This preliminary hashing action enables selective retrieval of only necessary content, reducing server processing load and network bandwidth consumption while maintaining real-time preview responsiveness.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements local caching of hash values on the client device, allowing each client to independently determine which pages have changed without requiring server-side comparison for all pages. This local quality enhancement distributes the computational burden from the central server to individual client devices, reducing overall server processing load while maintaining responsive previews.

Inventive Principle:
Principle #3Local quality

2Reliability

If all pages of a compiled document are transmitted to clients for preview updates, then preview completeness is improved, but network bandwidth consumption increases

Engineering Contradiction:
Improvepreview completenessVSAvoidnetwork bandwidth
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

Hash values for all pages are generated and stored locally on the client device before document updates occur. Upon document modification, the client systematically compares new hash values against stored ones to precisely identify which specific pages have changed. This preliminary hashing enables targeted retrieval of only the necessary page previews, ensuring complete and accurate preview updates while minimizing network bandwidth consumption by transmitting only changed pages rather than all pages.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The document preview system divides the document into individual page segments, each with its own hash value. Instead of treating the document as a single unit requiring complete retransmission, the system segments the update process into page-level operations. Only pages with mismatched hash values (indicating changes) are transmitted to the client, while unchanged pages are locally cached. This segmentation approach maintains preview completeness for all pages while significantly reducing network bandwidth usage.

Inventive Principle:
Principle #1Segmentation

3Productivity

If hash value comparison is implemented to identify changed pages, then processing efficiency is improved, but system complexity increases

Engineering Contradiction:
Improveprocessing efficiencyVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

Hash values serve as an intermediary mechanism between the compiled document content and the preview generation process. Instead of directly comparing entire document contents or requiring complex diff algorithms, the system uses hash values as a simplified mediator that represents each page's content state. The client device systematically compares hash values to identify changed pages, which streamlines the detection process and improves processing efficiency. The added complexity of hash generation and comparison is offset by the substantial reduction in subsequent processing steps.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2972827B1Collaborative editing
Publication Date: 2019.02.27 WRITELATEX
  • EP2972827B1 patent drawingFigure 1
  • EP2972827B1 patent drawingFigure 2

AI summary

Methods are provided for collaborative editing of documents which allow users who are editing source code to see previews of a compiled document as the process of editing continues. During editing, the source code is compiled to provide a compiled document from which previews can be produced. Steps can be taken to ensure that previews are only produced and/or sent to the user for those pages that have been changed since a previous compile. Moreover, a pre-compile checking process may avoid unnecessary attempts to compile incomplete or erroneous source code.