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David Pennington

Week One is nearly over

Thursday, 4 Feb 2016, 16:45
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I had planned to be well ahead by now but moving apartments put a stop to that. As it is, I have managed to get through to the end of week 2 and have the first ICMA (computer marked assignment) nearly completed. So far I have answered 4 questions correctly and one question that needed a second go. As I have to score 30% in five of the seven ICMAs I am quite pleased.

First reactions? Well, the Python bits are easy. Programming is what I do and the course is well presented through the iPython notebooks. I have had a few issues with data paths and, although I seem to have problems that others aren't getting, I am able to work my way around them. I don't seem to be able to make a CSV/JSON combination that works with CSVLint. My JSON description file won't be recognised by CSVLint. I have tried getting it through JSONLint but I can't even do that. So, that is in abeyance for now. I am having more difficulty with the theoretical parts but then I always thought that I would. It is, after all, 35 years since I have done any studying and my arthritis gives me issues with concentration. Funnily enough, I have no problem concentrating when I am coding. I think that I regard issues there as opportunities rather than as problems and I can keep going. Reading theoretical descriptions - I don't find that as gripping - so I have to work harder at it.

Reading the course description of databases has caused me to go back and think about the databases that I have worked with over the years. It is quite an interesting list.

  1. Linked Lists - I wrote my first database software back in 1980 when I created a Trading Room Front Office package using North Star Basic on a NS Horizon. For this, I wrote software for a series of linked lists that held transactions, exchange rates, dates, etc. all with an active re-use of deleted data spaces. The main problem with this was the fixed data widths.
  2. More Linked Lists. When I retired from the City and started my own software company we switched to UCSD Pascal and a complete re-write of the system. The product was called "Integrated Dealer Support System" (IDSS). To ensure that the database was robust, I got a guy called Mark Woodman to write the linked list code for me. At the time, he was an Open University lecturer (he is now a Professor at Middlesex University).
  3. In 1990, I switched to Visual Smalltalk (VSE) from Digitalk. With this, I wrote a Barrister support package based firstly on VOSS from LogicArts and then using Tensegrity from Polymorphic. These are/were Object Oriented Databases (OODB) that were integrated into the Smalltalk environment.  I went on to incorporate Tensegrity into my Smalltalk based Trading System which was called Powerdesk Trader.
  4. In later years, I have mostly written software for my own use. Between 2004 and 2012, I owned and ran a shop with my wife and daughter. This shop had a very active web site which, eventually when we closed the physical shop, became our main means of transacting business. The web software was based around a database of my own devising. Built using IBM's (latterly Instantiations) Visual Age Smaltalk - VAST - this utilised the built-in high speed directory system within Windows by having individual directories for all of the main database elements - products, users, sales, etc.  Within these directories I used VASTs own object dumper and loader mechanisms to save the various objects directly into their relevant directories with the file names providing the indexing. This worked remarkably well with the performance of the web site matching that of those with much more sophisticated (and expensive) systems.
  5. More recently, I have been building a freight car routing system for my US Outline model railroad. This utilises CSV files for its data. This option allows me to make changes to the data without having to write a lot of data management screens. For instance,when I purchase a new freight car, I can pull up the cars.csv file and add the new details within Excel.
  6. Finally, my serious programming has been for a US based insurance company where I my most recent project was to develop a insurance premium calculator based on normalising risk data for the clients. This gets its data from an MS SqlServer RDBMS.

Wow, that's a lot of variation through the years. It will be interesting to see how I really do cope with all the theoretical stuff, given that I have spent 35 years playing with all of the above!

Tags: model railway, python, smalltalk, tm351
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David Pennington

The course is getting closer

Thursday, 14 Jan 2016, 17:22
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Edited by David Pennington, Thursday, 14 Jan 2016, 19:58

Getting closer meant that I had to get more serious about learning Python. 

I run a web and e-mail server from home. The e-mail server is for the family domain and there are three web sites that are running on the machine as well. I thought that I had put together a reliable setup when I  purchased a brand new Lenovo desktop box running Windows 8 (which was fairly quickly upgraded to Windows 10). However, the box freezes occasionally. I can't find any reason for this so I just have to manage the situation. I find the the Pingdom service, which is supposed to e-mail me when my server goes down isn't as reliable as I need.

I was casting around for another program to write in Python to extend my knowledge of the language so I thought that I would write my own Ping software. Now a ping is something that gets sent to a web address and reports back if the server at that address responds or not. What my software had to do was to regularly connect to the server and, if the server failed to respond, send me an e-mail. There was a few problems with me doing this in Python.

  1. I had no idea how to connect to a web server
  2. I had no idea how to send an e-mail
  3. I had no idea how to log these actions

So, this was going to test my ability to learn the inner details of Python. It was actually easier than I thought. Python has a rich set of libraries so I included the following in my program:

import smtplib
import requests
import time
import configparser
import os
These gave me everything that I needed. I used these libraries and very quickly I had my web checker program running. It runs in the background as a script on my iMac and has now been running for a few weeks without incident. It has shown me how useful Python can be. It would have been a good bit more complicated to do this simple task in Smalltalk - but then there are many things that I have done in Smalltalk that would be nigh on impossible in Python so, whilst I am pleased that I now know how to code in Python, I won't be giving up on Smalltalk anytime soon!

My next progression towards the course is a giant backward step. We have decided to move apartments and the move takes place on 23rd January. We are only moving from one floor to another (the new apartment is much bigger than the existing one) but, for various reasons, we are to lose our broadband internet connection for about 10 days - which covers the date of the start of the course! I am hoping that I can use my iPhone as a router for my iMac in the meantime. As we have a nice 4G signal here, that shouldn't be a hardship.

Lastly, I have quite severe Arthritis in a lot of my body so I have registered, through the OU, as disabled. Following an assessment of my problems, I have been awarded a grant that will provide me with equipment that will help me in my studies. I have difficulty sitting for too long in one position and find concentrating for long periods a trial due to pain levels.  Yesterday, I had a visit from a representative of an Ergonomics company who has carried out an assessment for a new desk, chair and reading aids. It seems that I am to get a desk that is electrically height adjustable, a fully configurable chair, an iPad holding device and a footrest. All of this is designed to get me into the best possible position for sitting at my iMac for extended periods. It seems to take about 6 weeks for this to happen but it does mean that, soon after the course starts, I will be able to get on with more success. My existing hobby room is way to small to take the new desk along with my other stuff so it is good that I am moving to a bigger apartment as the 2nd bedroom in that one is substantially larger than now. I might even have room for a decent model railway - at last!!!

Tags: python, dsa, tm351, smalltalk, model railway
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