Data Communications sixth week was a follow up on the assignment topics:
The lecture was an audio recording which gave us a very nice overview of routing.
Three major types of routing:
Al three are used through the internet.
The recording followed some example of HTTP requests travelling through a network.
Grid computing’s 6th week provided a look into clusters, specifically:
Discussion of a cluster implementation method, Beowulf described how some clusters differ. A key characteristic of clusters is their interconnect technologies, some of the options are:
For a detailed list and comparison: http://en.wikipedia.org/wiki/List_of_device_bandwidths#Local_area_networks
It is also worth noting that latency can become more important than bandwidth is many cluster networks. This would be dependent on the programs running on the cluster.
Internet Application Development week 6, an introduction to C#.
The fist part of the lecture covered the basic data types and operators (most of which are the same as Java). Control structures and operators came next, again these reflected Java very closely.
Internet Application Development week 6, an introduction to C#.
The fist part of the lecture covered the basic data types and operators (most of which are the same as Java). Control structures and operators came next, again these reflected Java very closely.
Collections in the C-Sharp language are again a mirror of the Java language.
Functions are the methods of Java:
1 2 3 4 5 6 7 | string MyFirstFunction(string Name, int Age) { ... ... ... return "Confirmed"; } |
To give a feel for the syntax and a useful tool, the code snippet below draws a table of web server information dynamically.
Week 6 of case study consisted of a lecture and tutorial by Enjoo Lim. The lecture reviewed the basics of Database design which was a nice refresher. Points covered were:
After last semesters assignments going to BCNF is a fairly straight forward operation. From our experience on this assignment it is clear that if you dont get the conceptual model right none of the subsequent stages will go smoothly.
The tutorial gave us some time to work in our teams on the task due the following week. At the time of writing this I am compiling our Functional Specification report. There is a clear difference in the level of each teams memebers submissions, to the level that to attain and even level throughout the report would require redoing entire sections. From doing this assigmnet I have found that Object Oriented modelling for Web sites does not fit the same as for a stand alone java program. I will need to do some research on modelling for web systems.
Data Communication, week 5 was unfortunately a missed class for me due to illness. A summary of the lecture on Network and Transport layers are as follows:
Week 5 of grid computing comprised of a lecture focusing on data transfer protocols for the grid environment. The tutorial returned to the Grid Security Infrastructure [GSI] covered in the previous weeks lecture.
The lecture covered 4 protocols for data transfer within a grid:
GridFTP allows for 3rd party transfers which is the major practical difference apart from transfer speed.
We delved into the methods by which these protocols provide advantages over standard file transfer. One question this raised in my mind was why these protocols aren’t the standard if they are superior. I guess the answer to this question lies in the need for most server to try and limit the amount of bandwidth the provide to individuals.
The first assignment for this subject is due this week, I found the specification a little bit vague and am concerned that my report will not hold enough technical details. The lack of technical detail has revealed that my depth of knowledge for this subject is not very sound so it will be a priority over the mid semester break to get some books and clarify my understanding.
Week 5 of Internet Application Development began our move towards dynamic page development. The topics covered were:
As HTTP has been covered in detail through FIT9020 Data Communications I will skip this topic, noting that it is a stateless protocol. The diagram below illustrates how asp.net pages are processed from HTTP requests:
In week 5 of Case Study we discussed risk. There are a number of risks associated with system development, most stemming from:
Reviewing these risking and mitigating or managing them is critical for the success of system development.
In regards to Project we are working on as a team I am really finding that it is taking too much of my study time for the lesson that working in teams is difficult. At present my main goal for the unit is to pass whilst preventing it from adversely affecting my grades for other subjects.
The Data link Layer was covered in week 4 of Data communications, which was another high detail lecture [All Trains Now Depart Promptly -> Application, Transport, Network, Data Link, Physical] .
Using both Logical Link Control [LLC] and Media Access Control [MAC] the Data Link layer controls when computers transmit data, detects and correct transmission errors and identifies the beginning and end of messages.
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:
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:
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