W E B V E V E R I E T

Ravn Webveveriet AS, 2010-10-01

Jan Schreiber <jans@ravn.no>

JavaScript Topic Maps in server environments

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Outline

• JavaScript

• The tmjs Topic Maps engine

• Use Case: A PSI Server

• Outlook

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JavaScript

• JavaScript is LISP with a C-like syntax

• Virtually every personal computer in the world has at least one JavaScript interpreter installed on it and in active use.

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tmjs• A Topic Maps engine

• Written in pure JavaScript

• Full TMDM including Variants

• TMAPI 2.0-based

• In-memory backend, JTM import/export, experimental XTM 2.0 import (requires DOM)

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tmjs• Platform independent: All modern

browsers, mobile devices (iPhone & Android), server-side JavaScript

• Unit tests, CXTM tests (partly) & JSLint validating

• Small changes to TMAPI due to the lack of method overloading

• Syntactic sugar: Supports chaining of TMAPI calls

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Chaining

tm.createTopic().addSubjectIdentifier(foo).

createName('bar').getParent().

createOccurrence(type,'baz').

addScopingTopic(quux);

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tmjs: Outlook• More import/export formats: XTM 2.0, CTM

• Complete TMAPI, add more tests, full CXTM

• Persistence:

• Web SQL Database backend

• Persistent backend for Node (couchdb?)

• Later: Query language

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Use Case: A PSI Server

• Idea: Start the server with a Topic Map and it will serve information about all Subject Identifiers for a given domain

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• Screenshot node-psi-server

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Server-side JavaScript

• 1996: Netscape releases LiveWire as part of Netscape Enterprise Server 2.0

• 2009: Ryan Dahl writes Node

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Node• A framework for low-level network

applications based on Google's V8 engine

• TCP, DNS and HTTP are first-class protocols

• Event-based, asynchronous programming

• All I/O is non-blocking

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result = db_query(db, "SELECT * FROM topic");

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db_query(db, "SELECT * FROM topic", callback);

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db_query(db, "SELECT * FROM topic", callback);

callback = function (err, result) {

// ...

}

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var tm, servername;

// assumes that the TopicMap object tm has been initialized and

// the topic map in question has been imported successfuly.

// servername is set from a command line parameter

http.createServer(function (req, res) {

var url = 'http://'+servername+req.url, loc, topic;

loc = tm.createLocator(url);

topic = tm.getTopicBySubjectIdentifier(loc);

if (topic) {

res.writeHead(200, {'Content-Type': 'text/html'});

// create a page with information about the PSI

} else {

// Not found: create a 404 response

}

res.close();

}).listen(80);

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Use Case: A PSI Server

• More output formats: XHTML, JTM, XTM

• Support for logging, caching, templates

• Configurable list of information elements that are included on generated pages (e.g. dc:description, supertype-subtype)

• PSI black-listing

• subj3ct.com integration

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PSI Server: Observations

• Easy to implement

• It’s really fast: 200+200ms to read the Opera topic map, 1ms to serve a PSI page

• tmjs can be used on server and client side Reuse of application code

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Summary & Outlook

• Server side Topic Maps with JavaScript: possible!

• Asynchronous TMAPI?

• In its current state maybe best suited for low-level applications

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What could it be good for?

• TMRAP, TM REST API

• SDshare

• P2P applications

• DNS servers

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Questions?

Download tmjs now!

http://github.com/jansc/tmjs

Coming soon:

http://github.com/jansc/node-psi-server

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