edg3/experiment_software_csharp_12_net_8 · Datasets at Hugging Face

title stringlengths 3 46	content stringlengths 0 1.6k
2:238	Figure 2.19: Complex drop-down menu
2:239	A similar solution can be implemented with a low computational cost since all the main databases can efficiently select strings that start with a given substring.
2:240	When names are quite complex, when searching for the characters that were typed in by the user, they should be extended inside each item string. This operation cannot be performed efficiently with the usual databases and requires ad hoc data structures, nor can we forget the debouncing aspect that can happen while typing as a performance issue.
2:241	Finally, when we are searching inside descriptions composed of several words, more complex search patterns are needed. This is the case, for instance, with product descriptions. If the chosen database supports full-text search, the system can efficiently search for the occurrence of several words that have been typed by the user inside all the descriptions.
2:242	However, when descriptions are made up of names instead of common words, it might be difficult for the user to remember a few exact names contained in the target description. This happens, for instance, with multi-country company names. In these cases, we need algorithms that find the best match for the character that was typed by the user. Substrings of the string that was typed by the user must be searched in different places of each description. In general, similar algorithms cannot be implemented efficiently with databases based on indexes but require all the descriptions to be loaded in memory and ranked somehow against the string that was typed by the user.
2:243	The most famous algorithm in this class is probably the Levenshtein algorithm, which is used by most spellcheckers to find a word that best fits the one that was mistyped by the user. This algorithm minimizes the Levenshtein distance between the description and the string typed by the user, that is, the minimum number of character removals and additions needed to transform one string into another.
2:244	The Levenshtein algorithm works great but has a very high computational cost. Here, we use a faster algorithm that works well for searching character occurrences in descriptions. Characters typed by the user do not need to occur consecutively in the description but must occur in the same order. Some characters may be missing. Each description is given a penalty that depends on the missing characters and on how far the occurrences of the characters typed by the user are from the others.
2:245	More specifically, the algorithm ranks each description with two numbers:
2:246
2:247	The number of characters typed by the user that occurs in the description: the more characters contained in the description, the higher its rank.
2:248	Each description is given a penalty equal to the total distance among the occurrences of the characters typed by the user in the description.
2:249
2:250	The following screenshot shows how the word Ireland is ranked against the string ilad, which was typed by the user:
2:251
2:252	Figure 2.20: Sample of Levenshtein usage
2:253	The number of occurrences is four, while the total distance between character occurrences is three.
2:254	Once all the descriptions have been rated, they are sorted according to the number of occurrences. Descriptions with the same number of occurrences are sorted according to the lowest penalties. The following is an autocomplete that implements the preceding algorithm:
2:255
2:256	Figure 2.21: Levenshtein algorithm UI experience
2:257	The full class code, along with a test console project, is available in this book’s GitHub repository.
2:258	Selecting from a huge number of items
2:259	Here, huge does not refer to the amount of space needed to store the data but to the difficulty the user has in remembering the features of each item. When an item must be selected from among more than 10,000-100,000 items, there is no hope of finding it by searching for character occurrences inside a description. Here, the user must be driven toward the right item through a hierarchy of categories.
2:260	In this case, several user gestures are needed to perform a single selection. In other words, each selection requires interaction with several input fields. Once it is decided that the selection can’t be done with a single input field, the simplest option is cascading drop-down menus, that is, a chain of drop-down menus whose selection list depends on the values that were selected in the previous drop-down menus.
2:261	For example, if the user needs to select a town located anywhere in the world, we may use the first drop-down menu to select the country, and once the country has been chosen, we may use this choice to populate a second one with all the towns in the selected country. A simple example is as follows:
2:262
2:263	Figure 2.22: Cascading drop-down menu example
2:264	Clearly, each drop-down menu can be replaced by an autocomplete when required due to having a high number of options.
2:265	If making the right selection can be done by intersecting several different hierarchies, cascading drop-down menus become inefficient too, and we need a filter form, as follows:
2:266
2:267	Figure 2.23: Filter form sample
2:268	Now, let us understand interoperability with .NET 6.
2:269	Interoperability with .NET 8
2:270	Since .NET Core, Microsoft has brought to C# developers the ability to deliver their software to various platforms. And you, as a software architect, need to pay attention to this, considering developing for Linux and macOS as a great opportunity to deliver new features to your customers. Therefore, we need to ensure performance and multi-platform support, two common non-functional requirements for many systems.
2:271	Both console applications and web apps designed with .NET 8 in Windows are almost completely compatible with Linux and macOS, too. This means you do not have to build the app again to run it on these platforms.
2:272
2:273	Microsoft offers scripts to help you install .NET on Linux and macOS. You can find them at https://docs.microsoft.com/dotnet/core/tools/dotnet-install-script. Once you have the SDK installed, you just need to call dotnet the same way you do in Windows.
2:274
2:275	However, you must be aware of some features that are not fully compatible with Linux and macOS systems. For instance, no equivalent to the Windows Registry exists in these OSes, and you must develop an alternative yourself. If needed, an encrypted JSON config file can be a good option.
2:276	Another important point is that Linux is case-sensitive, while Windows is not. Please remember this when you work with files. Another important thing is that the Linux path separator is different from the Windows separator. You can use the Path.PathSeparator field and all the other Path class members to ensure your code is multi-platform. Environment.NewLine can also be useful in some situations.
2:277	Besides, you can also adapt your code to the underlying OS by using the runtime checks provided by .NET 8, as follows:
2:278	using System.Runtime.InteropServices;
2:279	if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
2:281	else if(RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
2:283	else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
2:285
2:286	Tip – creating a service in Linux
2:287	There are some good ways to create a service when you are developing on Windows, but how can we get the same result if we are developing for the Linux platform? The following script can be used to encapsulate a command-line .NET 8 app in Linux. The idea is that this service works like a Windows service. This can be useful, considering that most Linux installations are command-line-only and run without a user logged in:
2:288
2:289	The first step is to create a file that will run the command-line app. The name of the app is app.dll, and it is installed in appfolder. The application will be checked every 5,000 milliseconds. This service was created on a CentOS 7 system. Using a Linux terminal, you can type this:
2:290	cat >sample.service<<EOF
2:291	[Unit]
2:292	Description=Your Linux Service
2:293	After=network.target
2:294	[Service]
2:295	ExecStart=/usr/bin/dotnet $(pwd)/appfolder/app.dll 5000
2:296	Restart=on-failure
2:297	[Install]
2:298	WantedBy=multi-user.target
2:299	EOF
2:300
2:301
2:302	Once the file has been created, you must copy the service file to a system location. After that, you must reload the system and enable the service so that it will restart on reboots:
2:303	sudo cp sample.service /lib/systemd/system
2:304	sudo systemctl daemon-reload
2:305	sudo systemctl enable sample
2:306
2:307
2:308	Done! Now, you can start, stop, and check the service using the following commands. The whole input that you need to provide in your command-line app is as follows:
2:309	# Start the service
2:310	sudo systemctl start sample
2:311	# View service status
2:312	sudo systemctl status sample
2:313	# Stop the service
2:314	sudo systemctl stop sample
2:315
2:316
2:317
2:318	Now that we have learned about a few concepts, let us learn how to implement them in our use case.
2:319	Achieving security by design
2:320	As we have seen up to this point in the book, the opportunities and techniques we have for developing software are incredible. If you add all the information you will read about in relation to cloud computing in the next chapters, you will see that the opportunities just increase, as does the complexity involved in maintaining this computing environment.
2:321	As a software architect, you must understand that these opportunities come with many responsibilities. The world has changed a lot in recent years. The second decade of the 21st century has required lots of technology. Apps, social media, Industry 4.0, big data, and artificial intelligence are no longer future objectives but current projects that you will lead and deal with within your daily routine. However, the third decade of our century will require much more attention when it comes to cybersecurity.
2:322	The world now regulates companies that manage personal data. For instance, the GDPR – the General Data Protection Regulation – is mandatory not only for European territory but also for the whole world; it has changed the way software is developed. There are many initiatives comparable to the GDPR that must be added to your glossary of techniques and regulations, considering that the software you design will be impacted by them.
2:323	Security by design must be one of your areas of focus for designing new applications. This subject is huge, and it is not going to be completely covered in this book, but as a software architect, you must understand the necessity of having a specialist in the information security area in your team to guarantee the policies and practices needed to avoid cyber-attacks and maintain the confidentiality, privacy, integrity, authenticity, and availability of the services you architect.
2:324	When it comes to protecting your ASP.NET Core application, it is worth mentioning that the framework has many features to help you out with that. For instance, it includes authentication and authorization patterns. In the OWASP Cheat Sheet Series, you can read about many other .NET practices.
2:325
2:326	The Open Web Application Security Project® (OWASP) is a nonprofit foundation that works to improve the security of software. Check it out at https://owasp.org/.
2:327
2:328	ASP.NET Core also provides features to help us out with the GDPR. Basically, there are APIs and templates to guide you in the implementation of policy declaration and cookie usage consent.
2:329	List of practices for achieving a safe architecture
2:330	The following list of practices related to security certainly does not cover the entirety of the subject. However, these practices will help you, as a software architect, to explore some solutions related to this topic.
2:331	Authentication
2:332	Define an authentication method for your web app. There are many authentication options available nowadays, from ASP.NET Core Identity to external provider authentication methods, such as Facebook or Google. As a software architect, you must consider who the target audience of the application is. It would also be worth considering using Azure Active Directory (AD) as a starting point if you choose to go down this route.
2:333	You may find it useful to design authentication associated with Azure AD, a component for managing the Active Directory of the company you are working for. This alternative is pretty good in some scenarios, especially for internal usage. Azure currently offers Active Directory for usage as B2B (Business to Business) or B2C (Business to Consumer).
2:334	Depending on the scenario of the solution you are building, you might need to implement MFA – Multi-Factor Authentication. The idea of this pattern is to ask for at least two forms of proof of identity before allowing the solution to be used. It is worth mentioning that Azure AD facilitates this for you.
2:335	You may also find it useful to implement authentication to your platform using as basis Microsoft Identity Platform. In this case, the usage of the Microsoft Authentication Library (MSAL) will facilitate your work hugely. Check how to implement it by reading its documentation at https://learn.microsoft.com/en-us/azure/active-directory/develop/msal-overview.
2:336	Do not forget that you must determine an authentication method for the APIs you provide. JSON Web Token is a pretty good pattern, and its usage is totally cross-platform.
2:337	You must determine the authorization model you will use in your web app. There are four model options:
2:338
2:339	Simple, where you just use the [Authorize] attribute in the class or method.
2:340	Role-based, in which you may declare Roles for accessing the Controller you are developing.

2:238

Figure 2.19: Complex drop-down menu

2:239

A similar solution can be implemented with a low computational cost since all the main databases can efficiently select strings that start with a given substring.

2:240

When names are quite complex, when searching for the characters that were typed in by the user, they should be extended inside each item string. This operation cannot be performed efficiently with the usual databases and requires ad hoc data structures, nor can we forget the debouncing aspect that can happen while typing as a performance issue.

2:241

Finally, when we are searching inside descriptions composed of several words, more complex search patterns are needed. This is the case, for instance, with product descriptions. If the chosen database supports full-text search, the system can efficiently search for the occurrence of several words that have been typed by the user inside all the descriptions.

2:242

However, when descriptions are made up of names instead of common words, it might be difficult for the user to remember a few exact names contained in the target description. This happens, for instance, with multi-country company names. In these cases, we need algorithms that find the best match for the character that was typed by the user. Substrings of the string that was typed by the user must be searched in different places of each description. In general, similar algorithms cannot be implemented efficiently with databases based on indexes but require all the descriptions to be loaded in memory and ranked somehow against the string that was typed by the user.

2:243

The most famous algorithm in this class is probably the Levenshtein algorithm, which is used by most spellcheckers to find a word that best fits the one that was mistyped by the user. This algorithm minimizes the Levenshtein distance between the description and the string typed by the user, that is, the minimum number of character removals and additions needed to transform one string into another.

2:244

The Levenshtein algorithm works great but has a very high computational cost. Here, we use a faster algorithm that works well for searching character occurrences in descriptions. Characters typed by the user do not need to occur consecutively in the description but must occur in the same order. Some characters may be missing. Each description is given a penalty that depends on the missing characters and on how far the occurrences of the characters typed by the user are from the others.

2:245

More specifically, the algorithm ranks each description with two numbers:

2:246

2:247

The number of characters typed by the user that occurs in the description: the more characters contained in the description, the higher its rank.

2:248

Each description is given a penalty equal to the total distance among the occurrences of the characters typed by the user in the description.

2:249

2:250

The following screenshot shows how the word Ireland is ranked against the string ilad, which was typed by the user:

2:251

2:252

Figure 2.20: Sample of Levenshtein usage

2:253

The number of occurrences is four, while the total distance between character occurrences is three.

2:254

Once all the descriptions have been rated, they are sorted according to the number of occurrences. Descriptions with the same number of occurrences are sorted according to the lowest penalties. The following is an autocomplete that implements the preceding algorithm:

2:255

2:256

Figure 2.21: Levenshtein algorithm UI experience

2:257

The full class code, along with a test console project, is available in this book’s GitHub repository.

2:258

Selecting from a huge number of items

2:259

Here, huge does not refer to the amount of space needed to store the data but to the difficulty the user has in remembering the features of each item. When an item must be selected from among more than 10,000-100,000 items, there is no hope of finding it by searching for character occurrences inside a description. Here, the user must be driven toward the right item through a hierarchy of categories.

2:260

In this case, several user gestures are needed to perform a single selection. In other words, each selection requires interaction with several input fields. Once it is decided that the selection can’t be done with a single input field, the simplest option is cascading drop-down menus, that is, a chain of drop-down menus whose selection list depends on the values that were selected in the previous drop-down menus.

2:261

For example, if the user needs to select a town located anywhere in the world, we may use the first drop-down menu to select the country, and once the country has been chosen, we may use this choice to populate a second one with all the towns in the selected country. A simple example is as follows:

2:262

2:263

Figure 2.22: Cascading drop-down menu example

2:264

Clearly, each drop-down menu can be replaced by an autocomplete when required due to having a high number of options.

2:265

If making the right selection can be done by intersecting several different hierarchies, cascading drop-down menus become inefficient too, and we need a filter form, as follows:

2:266

2:267

Figure 2.23: Filter form sample

2:268

Now, let us understand interoperability with .NET 6.

2:269

Interoperability with .NET 8

2:270

Since .NET Core, Microsoft has brought to C# developers the ability to deliver their software to various platforms. And you, as a software architect, need to pay attention to this, considering developing for Linux and macOS as a great opportunity to deliver new features to your customers. Therefore, we need to ensure performance and multi-platform support, two common non-functional requirements for many systems.

2:271

Both console applications and web apps designed with .NET 8 in Windows are almost completely compatible with Linux and macOS, too. This means you do not have to build the app again to run it on these platforms.

2:272

2:273

Microsoft offers scripts to help you install .NET on Linux and macOS. You can find them at https://docs.microsoft.com/dotnet/core/tools/dotnet-install-script. Once you have the SDK installed, you just need to call dotnet the same way you do in Windows.

2:274

2:275

However, you must be aware of some features that are not fully compatible with Linux and macOS systems. For instance, no equivalent to the Windows Registry exists in these OSes, and you must develop an alternative yourself. If needed, an encrypted JSON config file can be a good option.

2:276

Another important point is that Linux is case-sensitive, while Windows is not. Please remember this when you work with files. Another important thing is that the Linux path separator is different from the Windows separator. You can use the Path.PathSeparator field and all the other Path class members to ensure your code is multi-platform. Environment.NewLine can also be useful in some situations.

2:277

Besides, you can also adapt your code to the underlying OS by using the runtime checks provided by .NET 8, as follows:

2:278

using System.Runtime.InteropServices;

2:279

if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))

2:281

else if(RuntimeInformation.IsOSPlatform(OSPlatform.Linux))

2:283

else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))

2:285

2:286

Tip – creating a service in Linux

2:287

There are some good ways to create a service when you are developing on Windows, but how can we get the same result if we are developing for the Linux platform? The following script can be used to encapsulate a command-line .NET 8 app in Linux. The idea is that this service works like a Windows service. This can be useful, considering that most Linux installations are command-line-only and run without a user logged in:

2:288

2:289

The first step is to create a file that will run the command-line app. The name of the app is app.dll, and it is installed in appfolder. The application will be checked every 5,000 milliseconds. This service was created on a CentOS 7 system. Using a Linux terminal, you can type this:

2:290

cat >sample.service<<EOF

2:291

[Unit]

2:292

Description=Your Linux Service

2:293

After=network.target

2:294

[Service]

2:295

ExecStart=/usr/bin/dotnet $(pwd)/appfolder/app.dll 5000

2:296

Restart=on-failure

2:297

[Install]

2:298

WantedBy=multi-user.target

2:299

EOF

2:300

2:301

2:302

Once the file has been created, you must copy the service file to a system location. After that, you must reload the system and enable the service so that it will restart on reboots:

2:303

sudo cp sample.service /lib/systemd/system

2:304

sudo systemctl daemon-reload

2:305

sudo systemctl enable sample

2:306

2:307

2:308

Done! Now, you can start, stop, and check the service using the following commands. The whole input that you need to provide in your command-line app is as follows:

2:309

# Start the service

2:310

sudo systemctl start sample

2:311

# View service status

2:312

sudo systemctl status sample

2:313

# Stop the service

2:314

sudo systemctl stop sample

2:315

2:316

2:317

2:318

Now that we have learned about a few concepts, let us learn how to implement them in our use case.

2:319

Achieving security by design

2:320

As we have seen up to this point in the book, the opportunities and techniques we have for developing software are incredible. If you add all the information you will read about in relation to cloud computing in the next chapters, you will see that the opportunities just increase, as does the complexity involved in maintaining this computing environment.

2:321

As a software architect, you must understand that these opportunities come with many responsibilities. The world has changed a lot in recent years. The second decade of the 21st century has required lots of technology. Apps, social media, Industry 4.0, big data, and artificial intelligence are no longer future objectives but current projects that you will lead and deal with within your daily routine. However, the third decade of our century will require much more attention when it comes to cybersecurity.

2:322

The world now regulates companies that manage personal data. For instance, the GDPR – the General Data Protection Regulation – is mandatory not only for European territory but also for the whole world; it has changed the way software is developed. There are many initiatives comparable to the GDPR that must be added to your glossary of techniques and regulations, considering that the software you design will be impacted by them.

2:323

Security by design must be one of your areas of focus for designing new applications. This subject is huge, and it is not going to be completely covered in this book, but as a software architect, you must understand the necessity of having a specialist in the information security area in your team to guarantee the policies and practices needed to avoid cyber-attacks and maintain the confidentiality, privacy, integrity, authenticity, and availability of the services you architect.

2:324

When it comes to protecting your ASP.NET Core application, it is worth mentioning that the framework has many features to help you out with that. For instance, it includes authentication and authorization patterns. In the OWASP Cheat Sheet Series, you can read about many other .NET practices.

2:325

2:326

The Open Web Application Security Project® (OWASP) is a nonprofit foundation that works to improve the security of software. Check it out at https://owasp.org/.

2:327

2:328

ASP.NET Core also provides features to help us out with the GDPR. Basically, there are APIs and templates to guide you in the implementation of policy declaration and cookie usage consent.

2:329

List of practices for achieving a safe architecture

2:330

The following list of practices related to security certainly does not cover the entirety of the subject. However, these practices will help you, as a software architect, to explore some solutions related to this topic.

2:331

Authentication

2:332

Define an authentication method for your web app. There are many authentication options available nowadays, from ASP.NET Core Identity to external provider authentication methods, such as Facebook or Google. As a software architect, you must consider who the target audience of the application is. It would also be worth considering using Azure Active Directory (AD) as a starting point if you choose to go down this route.

2:333

You may find it useful to design authentication associated with Azure AD, a component for managing the Active Directory of the company you are working for. This alternative is pretty good in some scenarios, especially for internal usage. Azure currently offers Active Directory for usage as B2B (Business to Business) or B2C (Business to Consumer).

2:334

Depending on the scenario of the solution you are building, you might need to implement MFA – Multi-Factor Authentication. The idea of this pattern is to ask for at least two forms of proof of identity before allowing the solution to be used. It is worth mentioning that Azure AD facilitates this for you.

2:335

You may also find it useful to implement authentication to your platform using as basis Microsoft Identity Platform. In this case, the usage of the Microsoft Authentication Library (MSAL) will facilitate your work hugely. Check how to implement it by reading its documentation at https://learn.microsoft.com/en-us/azure/active-directory/develop/msal-overview.

2:336

Do not forget that you must determine an authentication method for the APIs you provide. JSON Web Token is a pretty good pattern, and its usage is totally cross-platform.

2:337

You must determine the authorization model you will use in your web app. There are four model options:

2:338

2:339

Simple, where you just use the [Authorize] attribute in the class or method.

2:340

Role-based, in which you may declare Roles for accessing the Controller you are developing.