El nucleo de la programacion asincrona son los objetos Task y Task<T>. Son compatibles con las palabras clave async y await.

Primero hay que reconocer si el codigo se usa para trabajos enlazados a I/O o si son CPU intensivos.

• Si el codigo “espera” algo como una BBDD o una response de un servidor, es codigo I/O. En este caso hay que usar async y await pero SIN usar Task.Run
• Si el codigo realiza un calculo costoso, es CPU intensivo. Use async y await y genere otro subproceso con Task.run

Async / Await (Operaciones I/O)

La palabra clave importante aqui es await. Lo que hace es suspender la ejecucion del metodo actual y devolver el control hasta que está lista para seguir.

public Task Main()
{
	string contenido = await LeerPaginaWebAsync("http://example.com");
}

public async Task<string> LeerPaginaWebAsync(string url)
{
	using (HttpClient client = new HttpClient())
	{
		return await client.GetStringAsync(url);
	}
}

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Don’t create indexes in every column. This slows things down on insert, delete or update operations.

You may create an index for columns that are common in WHERE, ORDER BY or GROUP BY clauses. You may also consider adding an index in columns that are used to relate other tables JOIN.

Index are best used for big domain fields such as ids, names, surnames. Don’t use them for male/female fields.

A good recommendation is to measure performance time before and after the creation of that index. If your index doesn’t improve performance remove it as it causes overhead.

Reference(s)

https://stackoverflow.com/questions/7744038/decision-when-to-create-index-on-table-column-in-database

UNION

The union sentence is used to accumulate results for two SELECT sentences.

SELECT column1, column2 FROM table1
UNION
SELECT column1, column2 FROM table2

We have the following tables

company1

company2

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Find an exact match of a nested field (note that .keyword has to be added to string fields)

{
  "query": {
    "bool": {
      "must": [
        {
          "term": {
            "metadata.title.keyword": "File test.pdf"
          }
        }
      ]
    }
  },
  "size": 200
}

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These are my posts with knowledge about Azure services and usage.

Azure CosmosDB
Azure CosmosDB query examples

Azure Cloud Functions
Azure Functions - Introduction

(for this post some formulas and menu names are in spanish as my excel and computer are in spanish and excel formulas depend on this).

The formula is:

=AGREGAR(3;3;J:J)-1

The first two parameters are for the function itself. The important one is J:J which marks the column to count. What’s important here is this is not going to count filtered items in tables.

Watch out with headers! If you have headers in your table, add -1 to your formula.

(for this post some formulas and menu names are in spanish as my excel and computer are in spanish and excel formulas depend on this).

Here is how to find and mark differences in unequal, really long lists or tables in Excel. For my example, one list is a partial list from other. Some items are missing and you’ve to find which ones are.

This is the full list.

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Authentication process of verifying an identity. We confirm they’re who they say they are. (username & pwd).

Authorization process of verifying what someone is allowed to do. (Permissions and access control).

Past solutions

From worst one to best one and the problems they originate:

Credential Sharing

The worst one. An App is not able to differentiate between real user access and programmatical access.
Permissions are typically too broad. It also the ability to access more content than it should.

Cookie

We could redirect the user off to the API where they could enter their credentials and get a cookie. This allows an app to access the API.

Dangerous because CSRF attacks. We’ve authorised the whole browser and not the app.

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How to solve the problem “Low disk space on ‘Filesystem root’. The volume has only xMB disk space remaining” when you completely fill a virtual disk in VirtualBox.

(You have to delete all your snapshots first)

Open a cmd terminal and run the following command:

"c:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifymedium  
"c:\Users\mario\VirtualBox VMs\Ubuntu OTAN\Ubuntu OTAN.vdi" --resize 30000

The first path is an executable included with VirtualBox.
The second one is where your VDI actually is. --resize takes the size in MBs.

Open gpartitioner and resize it.

JMeter is a testing tool to simulate thousands of users for web testing purposes. It uses Java Threads for this.

1. JMeter
2. JMeter performance testing

These are my post notes on the course “Mobile Design Course - UX, UI and Design Thinking” from Udemy.

1. Color Theory
2. Typography
3. UI Design
4. UX Design
5. Mobile Design Workflow

Contents from a General UI Design course.

1. Design ground rules
2. Design base properties
3. Design using color and contrast appropiately
4. Design with typography and imagery
5. Creating and simplifying visual cues
6. UI Design Mantras