Windows 10 and lein self-install fails on Powershell – Solved

I am starting to learn Clojure and wanted to set up Leiningen on my Windows 10 professional.

Here is how I solved the Windows Security problem that was preventing me from downloading the github zip file needed.

Here is hoping that someone finds this solution helpful.

Using PowerShell running as Administrator, I was having trouble getting my REPL going:

PS C:\> lein repl

C:\Users\{YourUserName}\.lein\self-installs\leiningen-2.8.1-standalone.jar can not be found.
You can try running "lein self-install"
or change LEIN_JAR environment variable
or edit lein.bat to set appropriate LEIN_JAR path.

Next, I tried to command lein to self-install:

PS C:\> lein self-install
Downloading Leiningen now...
Exception calling "DownloadFile" with "2" argument(s): "The request was aborted: Could not create SSL/TLS secure
At line:1 char:145
+ ... che]::DefaultNetworkCredentials; $client.DownloadFile($a, $f)} "https ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : WebException

Failed to download

It is possible that the download failed due to "powershell",
"curl" or "wget"'s inability to retrieve GitHub's security certificate.
The suggestions below do not check certificates, so use this only if
you understand the security implications of not doing so.

The PowerShell failed to download the latest Leiningen version.
Try to use "curl" or "wget" to download Leiningen by setting up
the HTTP_CLIENT environment variable with one of the following

a) set HTTP_CLIENT=wget --no-check-certificate -O
b) set HTTP_CLIENT=curl -f -L -k -o

NOTE: Make sure to *not* add double quotes when setting the value

The suggested fix as you can see deals with getting around our inability to get GitHub’s security certificate.

This is really not the right thing to do from a Security perspective. The real problem as I understand is that GitHub only supports TLS 1.2.

In order for us to use PowerShell with TLS 1.2, I needed to do the following:

  1. In power shell, type in the following to find where your PowerShell profile lives:

    PS C:\> $profile

  2. I went to that location but did not see a file. I ran this test to see if my PowerShell detected a profile file:

    PS C:\> test-path $profile

    False means that the file is not there, but we already knew that right?

  3. Next, I created the PowerShell profile file like so:

    PS C:\> new-item -path $profile -itemtype file -forceDirectory: C:\Users\YourUserName\Documents\WindowsPowerShell

    Mode LastWriteTime Length Name
    ---- ------------- ------ ----
    -a---- 10/27/2018 2:38 PM 0 Microsoft.PowerShell_profile.ps1

  4. Once that command finished casting its spell, I did another test-path:

    PS C:\> test-path $profile

    It sees my profile ps1 script now! Progress is Good.

  5. Next, using Notepad, I opened the Microsoft.PowerShell_profile.ps1 file. It was empty. I added the following line which allows PowerShell to use TLS 1.2 and saved the file:

    [Net.ServicePointManager]::SecurityProtocol = [Net.ServicePointManager]::SecurityProtocol -bor [Net.SecurityProtocolType]::Tls12
  6. With renewed confidence, I tried to command lein to self-install once more:

    PS C:\> lein self-install
    Downloading Leiningen now...
    PS C:\>

    No news is good news. I thought. No error this time. What happened? Did it self-install this time?

  7. The only way to find out was to try running my repl once again, fingers crossed:

    PS C:\> lein repl
    Retrieving org/clojure/tools.nrepl/0.2.12/tools.nrepl-0.2.12.pom from central
    Retrieving org/clojure/pom.contrib/0.1.2/pom.contrib-0.1.2.pom from central
    Retrieving org/sonatype/oss/oss-parent/7/oss-parent-7.pom from central
    Retrieving clojure-complete/clojure-complete/0.2.4/clojure-complete-0.2.4.pom from clojars
    Retrieving org/clojure/tools.nrepl/0.2.12/tools.nrepl-0.2.12.jar from central
    Retrieving clojure-complete/clojure-complete/0.2.4/clojure-complete-0.2.4.jar from clojars
    nREPL server started on port 60194 on host - nrepl://
    REPL-y 0.3.7, nREPL 0.2.12
    Clojure 1.8.0
    Java HotSpot(TM) Client VM 1.8.0_191-b12
    Docs: (doc function-name-here)
    (find-doc "part-of-name-here")
    Source: (source function-name-here)
    Javadoc: (javadoc java-object-or-class-here)
    Exit: Control+D or (exit) or (quit)
    Results: Stored in vars *1, *2, *3, an exception in *e




Now you know how to overcome this problem Take care and Happy coding.



Microsoft Tech Net

Outlook Redemption (Redemption.dll) and Background Threading do not mix.

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We wrapped the Redemption.dll into our own Singleton class and called it OutlookRedemption as you will see in the following code examples.

We have had a couple of situations where emailing from our application stops working or works intermittently and in both of those occurrences, the culprit was using the API in a back ground thread.

ClickOnce Deployment – Deploying multiple versions of the same application

According to Wikipedia, ClickOnce is a Microsoft technology that enables the user base to install and run a Windows Application by clicking a link in a web page. ClickOnce is a component of Microsoft .NET Framework 2.0 and later and it supports deploying applications made with Windows Forms or Windows Presentation Foundation.

ClickOnce attempts to bring the ease of deployment similar to web applications to the Windows user base. ClickOnce aims to solve three common problems with conventional methods of deploying an application:

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Last week I was coding a View that required for me to show two ChekBox controls which were mutually exclusive in the same way that two or more RadioButton controls that belong to the same group would interact.

My problem was that one Boolean property which came from a bit column in the database needed to drive which CheckBox would be checked: “Yes” or “No”.

In this example I attempt to show how to code two mutually exclusive checkboxes while binding to the Boolean property described above:


The Name of the Property in the Code Behind file that we are going to bind to is AddInsurance.

Here is the XAML code:

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In application development there are various situations in which it makes sense to code a class in a manner that it can be created (instantiated) once and used throughout the lifetime of the application. Generally this type of class is called a Singleton object.

When creating and object, CPU cycles are used up during the:

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Include Application Name in Connection Strings

In addition to the SQL Server, Database, User ID and Password, you may want to include the Application Name in your connection string parameters. Application Name is an optional argument, but it can greatly help you to segregate the SQL that your application is executing from any other database calls that are being sent from other applications/processes.

Data Source=myServer;
Initial Catalog=myDB;
User Id=myUsername;
Application Name=myApp;

In example:

The Object-Oriented Thought Process …

Recently I came across a book which was a recommendation from a senior colleague at work. The Object-Oriented Thought Process by Matt Weisfeld. Although the first three chapters can seem a bit basic at first glance, they help to remind ourselves and reset in our minds what a true OO approach to a given problem should be.

Here is the Conclusion for (summary) Chapter 1 – Introduction to OO Concepts: