Mark's IT Blog

Grid Computing’s week 4 lecture took a security theme covering the Grid Security Infrastructure [GSI], Public key infrastructure , Digital certificates, Mutual authentication, My Proxy and shibboleth.

GSI (see: http://en.wikipedia.org/wiki/Grid_Security_Infrastructure) is an overlay on the transport security protocol (SSL) utilizing asymmetric encryption and the public key infrastructure to acheive:

• Authentication
• Data integrity verification
• Single sign-on
• Inter-organisation decentralized security

All grid entities (user and processes) must have a public key certificate, for more info on public key certificates see: http://en.wikipedia.org/wiki/Public_key_certificate

GSI uses the X.509 standard which included 4 primary pieces of information:

• subject name
• public key
• identity
• digital signature

An illustration of the public key infrastructure process:

Scenario 1 -> privacy, only user can decrypt incoming data

Scenario 2 -> authentication, receivers decrypt data using the sources public key this ensures the data is coming from the correct source

Certificate authorities are required to ensure validity of public and private keys that make the users digital certificate

Unfortunatly I missed the presentation of week 4’s Internet Application Development lecture, I will however make a summary from the note provided. The topics covered were:

• Static vs Dynamic pages
• Development environment for ASP.NET
• IIS virtual directories 

From previous weeks, I seem to keep forgetting the difference between simple and complex types. An easy definition to remember:

In XML Schema, there is a basic difference between complex types which allow elements in their content and may carry attributes, and simple types which cannot have element content and cannot carry attributes.

source: http://www.w3.org/TR/xmlschema-0/

Case study’s fourth seminar analyzed the Functional Requirements Document,  ensuring student have the knowledge to complete task 3.

The main features of a Functional requirements document are:

• • Database design
  • Business Logic Layer design (Best completed using UML in most cases)
  • Interface design
  • System requirements

The purpose of a Functional Requirements document is to reconcile what the client wants and what you plan to build. Once a client signs of on a Functional Requirements document, system design can be completed.

In the tutorial we continued work on our own Functional Requirements doc, after working on it almost all weekend I am still only about halfway through…

Time dedication to this subject was also discussed in the tutorial, I understand there is no exam for the subject so we should be spending more time on it. At present I am spending about 75% of my study time on this subject which is an issue for me. Will try and get most of the work done this week so I can complete other subject assignment next weekend!

Grid Computing, week 3, saw another jam-packed lecture that left me with a great deal of questions. I think this is a good thing as it forces students to do required readings or simply be left behind in the lectures. Unfortunately I have not been keeping up with readings on this subject and am feeling the pressure now.

The lecture focused on a possible real life example of a butterfly grid. When developing such a grid, the key considerations must be identified:

• Latency
• Downtime
• Security (cheating)
• Physical scalability
• Specific stakeholder needs (Production company, vendors, ISP, gamers, etc)

The butterfly grid add 7 major tiers in the architecture… There was no diagram in the lecture to assist in understanding where these layers fit, a simplified representation can be seen above.

The layers listed in the lecture slide were:

• Object Management System [OMS]
• Network Protocol Stack (UPD/IP instead of TCP/IP for reduced latency)
• Gateway Servers
• Daemon Controllers
• Game Servers
• Data Store and Grid Service – existing layers
• Globus Toolkit Services

Some news article relating to butterfly grids from early 2000s:

http://www.gridcomputingplanet.com/news/article.php/1107421/IBM-Butterflynet-Announce-Video-Game-Grid.htm

https://www-304.ibm.com/easyaccess/ukcomms/gclcontent/gcl_xmlid/91353

There is however very little recent  information on Butterfly grids to be found on the web.

Data Communication’s third lecture review in more detail the Physical Layer (Application -> Transport -> Network -> DataLink -> Physical).

Analogue vs Digital

Dataflow transmissions (Simplex, Half Duplex, Full Duplex, Multiplex)

Multiplexing Division methods:

• Frequency Division multiplexing [FDM]
• Time Division multiplexing [TDM]
• Statistical Time Division Multiplexing [STDM]
• Wavelength Division Multiplexing [WDM]

Communication Medias

Physical

• • Twisted Pair Cables
  • Coaxial Cable
  • Fiberoptic
• Wireless
  • Radio
  • Infrared
  • Microwave
  • Satellite

Interestingly, as satellites need to orbit the earth at quite a high distance to maintain stable service (ideally geostationary appx. 36,000kms) the delay due to the speed of light makes fibre optic a much faster option.

Internet Application development week 3 extended on the subject of XML from last week. As we learned the basics in week 1 and the XML schema (.xsd) in week 2, next up was stylesheets (XSLT). Stylesheet start to give evidence to the value of XML in dynamic web design. HTML code can be generated through the ‘transformation of XML files and XSLT files.

Initially this is not very exciting but when considering that style sheet processing can be done on the fly, it present a wide range of possibilities.

Some simple processing can be done in the XSLT, although it must be noted that it is certainly not a fully fledged programming language and is not enjoyable to write in!

A snippet of code from an XSLT doc illustrates this fact:

<td>
 <xsl:variable name="assTot" select="sum(assignments/assignment)"/>
 <xsl:variable name="unitTot" select="sum(assignments/unitTest)"/>
 <xsl:variable name="count" select="count(assignments/assignment) + count(assignments/unitTest)"/>
 
 <xsl:value-of select="format-number((($assTot + $unitTot) div $count), '##0.00')" />
 </td>
 <td>
 <xsl:variable name="assTot" 
 select="sum(/units/unit[unitCode='FIT5432']/class/studentMarks/student[@id=$curID]/assignments/assignment)"/>
 <xsl:variable name="unitTot" 
 select="sum(/units/unit[unitCode='FIT5432']/class/studentMarks/student[@id=$curID]/assignments/unitTest)"/>
 <xsl:variable name="count2" select="count(/units/unit[unitCode='FIT5432']/class/studentMarks/student[@id=$curID]/assignments/assignment) + 
 count(/units/unit[unitCode='FIT5432']/class/studentMarks/student[@id=$curID]/assignments/unitTest)"/>                
 <xsl:value-of select="format-number((($assTot + $unitTot) div $count2), '##0.00')" />
 </td>

After spending a lot of time this week working on the first assignment I feel quite comfortable with the topics covered in the first 3 weeks:

• XML
• XML Schema Language
• XSLT (Extensible Stylesheet Language Transformations)

Case study this week saw a review of some factors that influence the success and failure of projects. Specifically, the myki project undertaken by the Victorian state Gov’t.

There were some Critical Success Factors:

• Top Level Management Support
• Appropriate Training
• Top Level Project Team
• Organizational Change Management
• Implementation team
• Steering Committee

I find it a bit leery to conclude from the point about that to make a project successful it simply must have all of those factors clearly defined. Obviously there have been countless projects succeed before a consulting firm decide to label the common phenomena of successes. With that in mind the causality of the point above on the outcome of the project come into question… are the point above something that can be put in place to help ensure Project success OR will a successful project foster the development of the points above. I imagine that the actual causality is not a one way street but the point is that having a consultant come into your company and pontificate the importance of those dot points is unlikely to provide significant improvements.

From my experience I would argue that critical success factors are:

• Accurate definition of the issue that needs to be solved
• Cohesion amongst all parties involved (achieved through specification document and a single final decision maker)
• Capable individuals
• Macro-management of capable team members
• The ability to remove non-functioning member from the team

The tutorial comprised of group work, meetings and presentations. The next submission is due this comming Thursday.

Week two led my first lecture and tutorial for grid computing. In the lecture there were a great deal acronyms which I did not know. So, to start with here are some of the acronyms explained:

• OGSA: Open Grid Services Architecture – http://en.wikipedia.org/wiki/Open_Grid_Services_Architecture
• WSRF: Web Services Resource Framework – http://en.wikipedia.org/wiki/Web_Services_Resource_Framework
• WSDL: Web Services Description Language – http://en.wikipedia.org/wiki/Web_Services_Description_Language
• SOAP: Simple Object Access Protocol – http://en.wikipedia.org/wiki/Simple_Object_Access_Protocol
• SOA: Service Oriented Architecture – http://en.wikipedia.org/wiki/Service-oriented_architecture
• VO: Virtual Organization – http://en.wikipedia.org/wiki/Virtual_Organization_%28Grid_computing%29

Globus Toolkit Acronyms:

• GRAM: Grid Resource Allocation Manager – http://en.wikipedia.org/wiki/Grid_Resource_Allocation_Manager

VMware Workstation is utilized in this subject over VirtualBox

The tutorial enabled us to create a virtual grid setup. Where were provided with several Knoppix VMware images prepared with Globus Toolkit installed. Booting them up and getting a feel for the environment seemed to be the main point of the tut.

Data communications in week to delved deeper into the Application Layer. Looking specifically at HTTP and SMTP and Application architectures.

The Application Layer can be further segmented into User Interface, Business Logic, Data Access and Data Storage. Clients and servers where defined and three basic architectures:

• Host base architectures (server heavy)
• Client-based architectures (client heavy)
• Client-server architectures (shared)

Client Server architectures are the latest in the application architecture evolution and has give rise to the need for some middleware softwares. Middleware acts as a translator between different varieties of software. Some examples include:

• Distributed Computing Environment (DCE)
• Common Object Request Broker Architecture (CORBA)
• Open Database Connectivity (ODBC)

The client server architecture is still evolving and segmentation of the application layer onto multiple tiers is now being enable by faster connection speeds. This allows for better load balancing and greater extendibility/scalability of services.