What’s my IP address?

Posilan is the hosting company that Pixel8 use for the Trust IV blog and website.
They have a handy (and ad-free) IP checker on their website:

The first one is for conventional browsers.
http://www.posilan.com/ip

The second one is useful in case you don’t have a complex browser.
http://www.posilan.com/ipplain.php

For example in UNIX you could type:

wget http://www.posilan.com/ipplain.php


this downloads a small file to your machine containing your IP address.

V. Handy 🙂

Unzipping files in Powershell scripts

I’ve been working for some time on a project which is deploying a complex application to a client’s servers. This project relies on Powershell scripts to push zip files to servers, unzip those files on the servers and then install the MSI files contained within them. The zip files are frequently large (up to 900MB) and the time taken to unzip the files is causing problems with our automated installation software (Tivoli) due to timeouts.

The scripts are currently unzipped using the Copyhere method.

Simple tests on a Windows 8 PC with 8GB RAM and an 8 core processor although a single SATA hard drive show that this method is “disk intensive” and disk utilisation as viewed in Task Manager “flatlines” at 100% during the extraction.

I spent some time looking at alternatives to the “Copyhere” method to unzip files to reduce the time taken for deployments and reduce the risk of Tivoli timeouts which were affecting the project.

Method

A series of test files were produced using a test utility (FSTFIL.EXE), FSTFIL creates test files made up of random data. These files are difficult to compress due to the fact that they contain little or no “whitespace” or repeating characters, similar to the already compressed MSI files which make up our deployment packages.

Files were created that were 100MB, 200MB, 300MB, 400MB and 500MB. Each of these files were zipped into similar sized ZIP files. As well as this a single large ZIP files containing each of the test files was also created.

Tests were performed to establish the time taken to decompress increasingly large ZIP files.

Test were performed to establish whether alternative decompression (unzip) techniques were faster.

Observations

The effect of filesize on CopyHere unzips

Despite initial observations, after averaging out the time taken to decompress different sized files using the CopyHere method the time taken to decompress increasingly larger files was found to be linear.

CopyHere

The difference between CopyHere and ExtractToDirectory unzips

To do this comparison, two PowerShell scripts were written. Each script unzipped the same file (a 1.5GB ZIP file containing each of the 100MB, 200MB, 300MB, 400MB and 500MB test files described earlier). Each script calculated the elapsed time for each extract, this was recorded for analysis.

Unzips took place alternately using one of the two techniques to ensure that resource utilisation on the test PC was comparable for each test.

ExtractToHere

No detailed performance monitoring was carried out during the first tests, but both CPU and disk utilisation was observed to be higher (seen in Task Manager) when using the CopyHere method.

Conclusion


The ExtractToDirectory method introduced in .Net Framework 4.5 is considerably more efficient when UNZIPPING packages. Assuming that this method is not available, alternative techniques to unzip the packages, possibly including the use of “self extracting .exe” files, the use of RAM disks  or memory-mapped files to remove disk bottlenecks or more modern decompression techniques may reduce the risk of Tivoli timeouts and increase the likelihood of successful deployments.
Powershell scripts used

Scripts

 

 

 

Google Latitude contacts disappeared…now fixed

I’ve used Google Latitude for about four years now and have found the application really useful. For those of you who don’t know, Latitude is an app that you install on your smart phone (it supports Android, Blackberry or iOS) and it keeps track of your location. You can then use this information how you wish. You can share it with friends or family, so that they know where you are in real time, or just use it to maintain a history of where you’ve been. (I find it useful for expense claims when I can’t remember how many miles I’ve done or exactly which day I visited a particular client).

typicalday

About 2 months ago my wife asked why I wasn’t showing up on her list of contacts on her iPhone. I had a look at my own iPhone and saw that I had “no contacts” either. I hadn’t made any changes to my privacy settings and thought it was curious that it affected both me and my wife on multiple devices. (Windows 7 and Windows 8 PCs, multiple different browsers including Chrome) as well as on my iPad and iPhone. As a result of this, I suspected that the problem was with Google.

I tried deleting and adding my wife as a “Latitude contact”. Despite clicking on the invitations that we sent each other and accepting the request to share location information we never appeared in each others contact lists.

Searching for answers I found plenty of discussions on internet forums. Several people had reported that this was due to new privacy settings which coincided with a new release of Google Maps. The only solution seemed to be to log onto an android device and enable location sharing again.

But I  don’t have an Android tablet…..

As an application tester, I’m reasonably au fait with virtualisation, so I had a quick look around the internet and I found this website which contains OVA files with images of Android Tablet devices. These can be used to emulate an Android tablet. http://androvm.org/blog/download/

Android tablet in VMWare Player
Android tablet in VMWare Player

These are the steps that I took to fix my problem

  • I already had VMWare Player on my home PC.
    (Download and install this if you don’t already have a copy)
  • Downloaded a suitable OVA file
  • Open it in VMWare Player, created a new virtual machine
  • Start the VM and “boot up” your Android tablet
  • Choose a country location and go through the basic setup
    (including typing in your google account credentials.)
  • Open the Google Play Store
  • Install Google Maps
  • Once Google Maps is installed, open maps and enable the “Latitude layer”
  • Enable location sharing

Google Maps

Google Maps”Hey presto” almost immediately all your devices will repopulate your friends lists and location sharing will work again.

Latitude screenshot
Latitude screenshot

It looks like the new version of Google Maps for Android has the functionality to enable sharing and accept invitations but this doesn’t work for existing, non-Android users, including those of us using iPhones.

If you’ve deleted friends whilst trying to fix the problem get your friends to send an invitation whilst you’re logged into your “new tablet” and you can accept the invitation and enable location sharing from within the Maps application.