Ash Alam's Blog

Map Reduce and Parallel DBs

ashalam — Mon, 29 Jun 2009 00:37:53 +0000

In regards to the paper (http://database.cs.brown.edu/sigmod09/) critiquing MapReduce framework, some observations come to mind:

Purpose of MapReduce is to analyze really large-scale non-indexed datasets all at once. RDBMs index their data and therefore are efficient in retrieving results to complex queries (e.g. multi-table joins). Not all datasets are indexed. You can write applications (in Java for instance) to have MapReduce framework do things in a certain way. RDBMs require data massaging and loading and then getting indexed before they are useful in this kind of scenario. MapReduce is free, parallel RDBMs are not. In RDBMs, SQL queries work over structured data, but not all datasets are structured. WWW is abound with unstructured data. MapReduce, on the other hand, does not make this assumption and therefore can work against unstructured data.

MapReduce presents a simple interface for manipulating data: a map and a reduce function written in the language of choice (Java/C/C++/Perl/Python) of a developer. Its real power lies in the Expressivity it brings: it makes the phrasing of really interesting transformations and analytics breathtakingly easy. (http://www.asterdata.com/blog/index.php/2008/08/25/announcing-in-database-mapreduce/)

Funtional vs Procedural vs OO

ashalam — Mon, 29 Jun 2009 00:12:11 +0000

Ref: http://stackoverflow.com/questions/23277/what-is-the-difference-between-procedural-programming-and-functional-programming

Funtional: examples – Haskell, LISP. Functions are first class objects, so pass them around. Order of evaluation is not pre-defined, funtions are executed only when data is needed (lazy evaluation), does not maintain state.

Procedural: examples – C. Step by step, that is order of evaluation is pre-determined, has states (side-effects), data (not talking about SQL data, more like variables) is seperate from logic, can pass around function pointers (not entire function).

OO: emulates real-world with objects that encapsulate data and funtions that operate on data. Maintains state, pass around the entire object.

The most important distinction is whereas procedural programming uses procedures to operate on data structures, object-oriented programming bundles the two together so an “object” operates on its “own” data structure. (http://en.wikipedia.org/wiki/Procedural_programming)

And then:

Functional programming is very different from imperative programming. The most significant differences stem from the fact that functional programming avoids side effects, which are used in imperative programming to implement state and I/O. Pure functional programming disallows side effects completely. (http://en.wikipedia.org/wiki/Functional_programming)

Funtional falls under Declarative programming model.

Procedural and OO fall under Imperative programming model.

Spatial Queries for Sensor Networks

ashalam — Sun, 28 Jun 2009 19:55:29 +0000

Using distributed spatial index. See http://www.cs.ucr.edu/~vana/fp229-soheili.pdf

Using localized vs centralized query mechanism with dynamic attributes for optimization: See http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.5.2338

Classical Regression Model and Why It’s not a Good Fit for Spatial DM

ashalam — Sat, 27 Jun 2009 21:42:13 +0000

Problems applying CRM directly for Spatial Data Mining purposes:

Ref: http://www.spatial.cs.umn.edu/paper_ps/SarMRFBaris.pdf

Protected: Research Challenges in Spatial Data Mining

ashalam — Wed, 24 Jun 2009 03:14:36 +0000

This post is password protected. You must visit the website and enter the password to continue reading.

Policy Interop Diagram

ashalam — Mon, 22 Jun 2009 06:02:50 +0000

Policy Interop Diagram

Exchanging RDF Data w/o XSLT Transformation

ashalam — Mon, 22 Jun 2009 05:58:37 +0000

Semantic web services are a semantic extension to traditional Web services architecture. In this new framework, web agents can interpret communicating messages and perform tasks that in regular Web services would require human intervention. However, because of the popularity and world-wide adoption, majority of the existing web services is based on the traditional XML-based service advertisement, discovery and exchange architecture. The semantic web services diverge from this setup by bringing ontologies in the web services cycle, which incorporates a rich semantic model to allow more intelligent search and composition of web services. The existing service architecture, however is not entirely compatible with the semantic paradigm. As a workaround, a wrapper approach has been proposed where the semantic model accepts the service advertisements (Web Services Description Language) and annotates them with semantic information to enable a semantic-aware processor to make sense of it. Unfortunately, the proposal does not contain a standard mechanism to directly connect to service providers that serve semantic-aware RDF (Resource Description Framework) data without XSLT translations. We suggest a modified approach to include RDF data exchange methods on top of the current architecture.

Powerpoint

Exchanging RDF Data

Secure Storage of Semantic Data

ashalam — Mon, 22 Jun 2009 05:51:33 +0000

Powerpoint

Secure Storage of Semantic Data

Discovery of Annotated Geospatial Information Services

ashalam — Mon, 22 Jun 2009 05:46:36 +0000

Powerpoint:

DAGIS

XACML Tutorial

ashalam — Mon, 22 Jun 2009 05:17:21 +0000

Powerpoint presentations:

XACML

trustworthy-sem-web-classtalk-access-control