Automatically Recover Zoom Licenses

Suppose you’ve purchased Zoom licenses for your users. However not everybody is using the services provided by having her/his user type as “Licensed”, instead some of the users can go along just fine with “Basic”. As you don’t want to pay for unused licenses, you don’t buy one for each and every user you have, and rely on assigning licenses to only those people that need it. However if auto-provisioning is enabled, any user automatically logging in will trigger an account to be created in Zoom. At this point you have a problem:

  • If a license is automatically handed out to every newly provisioned user, you’ll eventually run out of licenses and new users will be denied the services offered through one
  • If no license is automatically assigned to newly provisioned users, but instead any new account is provisioned as “Basic”, these won’t be able to use the licensed services

As you want to avoid buying more licenses, you’re left with only one alternative: free up licenses not used. You can go to Admin -> Account Management -> Reports -> Inactive Hosts and see those who haven’t logged in to their account in a specific timeframe and choose to remove their license. There are 2 problems with this approach, at least as of May 2020: 1) you have to process users one by one and 2) the timeframe of the report is limited to 1 month, so trying to get the users not active in the last 3 months is not that straightforward.

Luckily there’s an API that Zoom built, whose details are here that allows automating this process. Read on for how to build a script that leverages it for retrieving user data and for removing licenses for users matching a specific criteria.

TL;DR: Are you looking for a script that automatically identifies the users that haven’t logged in recently and removes their Zoom license ? Jump to the Powershell script.

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Using Microsoft Graph to Modify Excel Files Stored in Sharepoint Online With C#

You just want to modify the content of a few cells in an Excel file stored in Sharepoint Online, using C#. A simple goal. Maybe your experience with Sharepoint APIs is fairly limited, so you spend a while researching. There’s questions over at Stack Overflow, that mention “CSOM”, “REST APIs”, “Graph” and various other cryptic terms, but aside the various limitations with each API, a concise and clear sample proves to be elusive.

TL;DR If you’re in a hurry to get to the sample code, skip right to it.

The goal of this post is to use Microsoft Graph to read and write to an Excel file stored in Sharepoint Online. As the main focus is getting to use Graph against Sharepoint Online just to get to an Excel file, in terms of operating against the file itself we’ll be content with just reading and updating the value of a single cell.

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What Does It Really Mean to Install a NuGet Package In a .NET Core Project Within Visual Studio

You’ve ran into it countless times – you open a C# project in Visual Studio and you get to see “Restoring packages for <project_name>.csproj“:

It takes a few seconds usually, then goes away. You continue working for hours, sometimes days, never to encounter the message again. Then – out of the blue – it’s displayed again. There doesn’t seem to be any logic to when this pops up. You might be cloning a Git repository storing a C# project, and moments after, Visual Studio generates the message. Why is there anything to be restored, as we’ve just cloned the full source code for a C# project ? Or you decide to use a different target framework for your project, and sure enough the message comes again. Why is this so ? Decided to install a NuGet package to your project ? – the operation that will be run will be a “package restore”. What is there to restore as you’ve just installed a single package only ?

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Startup Sequence of a .NET Core App

What happens from the moment you launch a .NET Core application, until the very first managed instruction is executed ? How do we get from the simple act of running an .exe to having the managed code executing as part of a .NET Core application ?

This is what this post sets up to explain in detail, dealing with:

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List vs ArrayList in Azure Functions

You’re using Azure Functions, and need to decide on the types to use in your C# code in order to implement whatever you’re trying to achieve. In today’s world of powerful cloud computing with sometimes cheap or downright free resources, is it worth pondering over the best type to use ? After all, you get 400,000 GB-s for free per month as part of the consumption plan. And the code within this Azure Function will be just a few dozen lines, tops. Would it matter selecting an efficient data structure for your implementation ?

Let’s get specific. Say storing 10 mil numbers is needed each minute as an interim step for further processing. Do you go with ArrayList or List<int> ? Your 2 options below:

Figure 1 – Function execution units for both the ArrayList and the List<int> functions against 10 mil elements, running once each minute

Oh, and you get to pay for the area under the graph of each function. How much does that come to ? Read on.

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Boxing Performance in C# – Versus Generics

Last time we saw that the code that added random numbers to the ArrayList instance was spending 75% of its total time (1,141.5 ms) just doing GC. Computing the other 25%, representing the actual work, gives out about 285 ms. But how can this be, since the time the List<T> code takes – including its own GC activity – is 223 ms ? Is the List<T> implementation really that much efficient, that even with GC activity, it manages to complete faster that the actual time spent doing work in the case of the ArrayList one ? Are generics just that magical ?

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Boxing Performance in C# – Analysis and Benchmark

In the first part of this 3-article series, we’ve found to our astonishment that code based on ArrayList performs a whole lot worse than the same one using List<T>.

In order to understand why this is so, we’ll break up the code in smaller parts, see what these involve under the hood and how much time each takes. We should then be able to pinpoint the operation(s) that have the major contribution to the difference in performance. We’ll do this for both structures, and start with ArrayList in this post.

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Boxing Performance in C# – The Basics

Consider consuming a series of bytes and storing them in memory for future processing. Let’s take the code snippet below:

            const int noNumbers = 10000000;  // 10 mil

            ArrayList numbers = new ArrayList();
            Random random = new Random(1);  // use the same seed as to make
                                            //  benchmarking consistent

            for (int i = 0; i < noNumbers; i++)
            {    
                int currentNumber = random.Next(10);  // generate a non-negative
                                                      //  random number less than 10

                numbers.Add(currentNumber); // BOXING occurs here
            }

Is this code good from a performance standpoint ? Not really, it’s actually quite appalling. Take a look at the running times for the ArrayList snippet above and, for the same exact code, but which uses List instead:

This makes the ArrayList code more than 5 times slower than the List one.

Boxing happens in the first case, but not in the second. This mechanism explains most of the performance difference seen above. Intrigued ? Read on.

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Scan for Specific Parameter Types Within an Assembly’s Types’ Methods in C#

Ever wondered how many methods with a specific signature are contained within an assembly ? Say, how many methods that take at least one parameter of type object are in all the types marked as public within the mscorlib.dll assembly.

(TL;DR: I’m in a real hurry, and need the code to do this really quick ! Where is it ? You’ll find it towards the end of the article, here)

mscorlib.dll is a somewhat challenging example, since this assembly contains all the core types (Byte, Int32, String, etc) plus many more, each with scores of methods. In fact, the types within are so frequently used that the C# compiler will automatically reference this assembly when building your app, unless specifically instructed not to do so (via the /nostdlib switch).

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System.OutOfMemoryException: ‘Exception of type ‘System.OutOfMemoryException’ was thrown’

You’ve just created a Console app in the latest Visual Studio, and wrote some C# code that allocates some non-negligible quantity of memory, say 6 GB. The machine you’re developing has a decent amount of RAM – 16GB – and it’s running 64-bit Windows 10.

You hit F5, but are struck to find the debugger breaking into your code almost immediately and showing:

Figure 1 – Visual Studio breaking into an exception

What’s going on here ? You’re not running some other memory-consuming app. 6 GB surely should have been in reach for your code. The question that this post will set out to answer thus becomes simply: “Why do I get a System.OutOfMemoryException when running my recently created C# app on an idle, 64-bit Windows machine with lots of RAM ?“.

TL;DR (small scroll bar => therefore I deduct a lot of text => I’ve got no time for that, and need the answer now): The default build settings for Visual Studio limit your app’s virtual address space to 4 GB. Go into your project’s Properties, go to Build, and choose Platform target as x64. Build your solution again and you’re done.

Not so fast ! Tell me more about what goes on under the hood: Buckle up, since we’re going for a ride. First we’ll look at a simple example of code that consumes a lot of memory fast, then uncover interesting facts about our problem, hit a “Wait, what ?” moment, learn the fundamentals of virtual memory, find the root cause of our problem then finish with a series of Q&A.

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