Archive-It Architecture Introduction

April 3, 2006Dan Avery

Internet Archive

Archive-It Components

•Crawling

•User Interface

•Storage

•Playback

•Text Indexing

•Integration

Component Integration

Crawling

•Heritrix ( http://crawler.archive.org/ )

•Java application

•Open source (LGPL)

•Crawls for completeness/depth

•Highly configurable

Crawling - Distributed Crawling•Heritrix Cluster Controller

•Java component - open source - developed by IA

•http://crawler.archive.org/hcc

•Provides proxy access to pool of Heritrix instances through JMX interface

•Provides crawler control and status

•Currently controlling 33 crawler instances on three commodity dual Opterons--upper bound unknown

Archive-It Web Application

• User Interface and Crawl Scheduling

• Gets seed URLs and crawl parameters from users

• Schedules new periodic crawls

• Talks to crawler pool through HCC

• Provides access, search, and crawl history UI

Storage•archive.org ARC repository

•custom Perl system

•simple storage on primary/backup pairs

•monthly MD5 digest verification

•robust, non proprietary file format

•Alexandria (Egypt)/Amsterdam

Access• Internet Archive Wayback

Machine

• Replaying archived web pages since 2001

• Current IA version written in Perl and C, with components distributed across various machines

• Not open source, but open source beta (in Java) available now

Full-Text Indexing

•Nutch (http://nutch.org)

•NutchWAX (http://archive-access.sf.net) additions create and search indexes of stored ARC files

•Standard text search plus link analysis

•can search by date instead of relevance, useful for individual archives

Text Indexing Challenges•Some parts are distributable,

some are not

•Incremental indexing - goal of new crawls in index within 72 hours

•Working on Archive-It usable map/reduce version - July

•In the meantime, a lot of workarounds

Integration•Group of Perl and bash scripts - planning more complex than the execution

•Most components available individually

•Decentralized control, centralized monitoring

•Each component operates almost entirely independently

The Big Picture

Future Challenges

•Crawler trap detection

•Scalability

•Current setup can accommodate 300 partners at current crawling rates

•During pilot we crawled/indexed/stored just over 100,000,000 documents (~4TB) in eight weeks

•More machines can be easily added to storage and crawling clusters

Scalability

•Current Nutch is between versions

•Old version has some non-distributable pieces

•New version is much more distributable and scalable (map/reduce - Hadoop), but not ready for incremental indexing

Looking ahead•After basic UI/archiving/indexing...

•Time-based search UI

•Analyzing archives for research and ongoing collection improvement

•Content classification

•Rate of change

•New site suggestions

http://www.archive-it.org

RLG’s Web Archiving Program•Collaborative collection

development.

•Descriptive metadata for web archives.

•Usability/user studies

•Intellectual property concerns

•Web Archiving 101

•Web archiving services and software