Software Systems Lab Department of Electrical Engineering Technion - Israel Institute of Technology By: David Nasi & Amitay Svetlit Supervisor: Oved Itzhak

Motivation  Conventional text file viewer applications poorly suitable for very large text files (user response time wise).  Conventional text file applications do not provide tools for creating custom search and index.

Project Objectives  A user friendly graphic interface specialized for viewing VLTFs.  Application responsiveness is independent of input file size.  Extensible indexing architecture for employing indexing by arbitrary criteria.

User Interface Design Main Features: Text View Pane Search Results Pane Search Bar Go-to-Line Bar Progress Bar Scroll Knob

User Interface Design – Scroll Knob Scrolling over a VLTF using a conventional scroll bar may be very tedious Scroll Knob functionality allows to scroll over the VLTF with adaptive speed The speed is adjusted by a polynomial factor dependant on the distance of the knob from the center

Software Design – Segmentation Basic Concept  Goal:  Create a highly responsive viewer when displaying VLTFs (in the order of GBs).  Challenge:  Simple file access patterns (i.e. reading the entire file upon opening) are unsuitable.  Approach:  Segmentation: Upon opening the VLTF is partitioned to fixed-size segments. The segmentation process maps line numbers to segments in which they are held. Each segment holds only complete lines.

Segmentation - Example Segment #1 Lines: 1…1000Size = ~ 32Kb Segment #2 Lines: 1001…2200 Size = ~ 32Kb Segment #3 Lines:2201…3115 Size = ~ 32Kb Segment #K Lines: ?...?Size = ~ 32Kb

Software Design – Estimation Basic Concept  Goal:  Create a highly responsive viewer when displaying VLTFs (in the order of GBs).  Challenge:  Since segmentation requires reading the entire file, a question arises about the user experience before the file is fully indexed.  Approach:  Using some metrics (average number of lines in a segment) and provide the user with the estimated line with an indication that this is only estimation.

Software Architecture – Three Tier GUI Business Logic Data Structure

Data Structure Layer Responsibilities:  Segmentation Process  Estimation metrics gathering  Serving Business Logic data request

Data Structure Layer - Asynchronous Request Handling  Queue of Read Requests from the Business Logic  No duplicate segment requests are handled  The requests are handled in a FIFO order  Each request is processed on a separate thread  A callback to the Business Logic transferring the data and meta data for analyzing it - sessionless principle

Business Logic Layer Responsibilities:  Receives read request from the GUI  Serves as cache for the GUI layer requests  Sends data requests to the Data Structure  Custom Search and Index capabilities

Custom Search & Index Capabilities  We provide the developers with an abstract class of a searcher  Through implementing this class it’s possible to: 1. Construct a custom index 2. Interconnect with the GUI performing arbitrary search requests

Choosing a Custom Searcher

Search Progress

GUI Read Requests Handling  As a result of the paging work being done on separate threads library functions are used in order to update the GUI controls  Race Condition between different requests is handled by assigning a time stamp ID to each request

Design Components

Class Overview

End  Many thanks to our dedicated supervisor, Oved Itzhak for his great help and support  Thanks to the software lab staff for the support (Ilana David and Victor Kulik)