Sql Injection Basics

[Nickie Koskinen]

Thistutorial shows how to use dependency injection (DI) in .NET. With Microsoft Extensions, DI is managed by adding services and configuring them in an IServiceCollection. The IHost interface exposes the IServiceProvider instance, which acts as a container of all the registered services.

Using either the dotnet new command or an IDE new project wizard, create a new .NET console application named ConsoleDI.Example. Add the Microsoft.Extensions.Hosting NuGet package to the project.

In this example, the Microsoft.Extensions.Hosting NuGet package is required to build and run the app. Some metapackages might contain the Microsoft.Extensions.Hosting package, in which case an explicit package reference isn't required.

In this sample app, you'll learn how dependency injection handles service lifetime. You'll create several interfaces that represent different service lifetimes. Add the following interfaces to the project root directory:

All of the subinterfaces of IReportServiceLifetime explicitly implement the IReportServiceLifetime.Lifetime with a default. For example, IExampleTransientService explicitly implements IReportServiceLifetime.Lifetime with the ServiceLifetime.Transient value.

The example implementations all initialize their Id property with the result of Guid.NewGuid(). Add the following default implementation classes for the various services to the project root directory:

Each implementation is defined as internal sealed and implements its corresponding interface. They're not required to be internal or sealed, however, it's common to treat implementations as internal to avoid leaking implementation types to external consumers. Furthermore, since each type will not be extended, it's marked as sealed. For example, ExampleSingletonService implements IExampleSingletonService.

The ServiceLifetimeReporter defines a constructor that requires each of the aforementioned service interfaces, that is, IExampleTransientService, IExampleScopedService, and IExampleSingletonService. The object exposes a single method that allows the consumer to report on the service with a given lifetimeDetails parameter. When invoked, the ReportServiceLifetimeDetails method logs each service's unique identifier with the service lifetime message. The log messages help to visualize the service lifetime.

Each services.AddLIFETIME extension method adds (and potentially configures) services. We recommend that apps follow this convention. Don't place extension methods in the Microsoft.Extensions.DependencyInjection namespace unless you're authoring an official Microsoft package. Extension methods that are defined within the Microsoft.Extensions.DependencyInjection namespace:

In this sample app, you created several interfaces and corresponding implementations. Each of these services is uniquely identified and paired with a ServiceLifetime. The sample app demonstrates registering service implementations against an interface, and how to register pure classes without backing interfaces. The sample app then demonstrates how dependencies defined as constructor parameters are resolved at run time.

In this article, you create a .NET console app that manually creates a ServiceCollection and corresponding ServiceProvider. You learn how to register services and resolve them using dependency injection (DI). This article uses the Microsoft.Extensions.DependencyInjection NuGet package to demonstrate the basics of DI in .NET.

You need to add the package reference to the Microsoft.Extensions.DependencyInjection in the project file. Regardless of the approach, ensure the project resembles the following XML of the DI.Basics.csproj file:

Dependency injection is a design pattern that allows you to remove hard-coded dependencies and make your application more maintainable and testable. DI is a technique for achieving Inversion of Control (IoC) between classes and their dependencies.

In .NET, DI is managed by adding services and configuring them in an IServiceCollection. After services are registered, as IServiceProvider instance is built by calling the BuildServiceProvider method. The IServiceProvider acts as a container of all the registered services, and it's used to resolve services.

Not all services are created equally. Some services require a new instance each time that the service container gets them (transient), while others should be shared across requests (scoped) or for the entire lifetime of the app (singleton). For more information on service lifetimes, see Service lifetimes.

Likewise, some services only expose a concrete type, while others are expressed as a contract between an interface and an implementation type. You create several variations of services to help demonstrate these concepts.

The FarewellService represents a concrete type, not an interface. It should be declared as public to make it accessible to consumers. Unlike other service implementation types that were declared as internal and sealed, this code demonstrates that not all services need to be interfaces. It also shows that service implementations can be sealed to prevent inheritance and internal to restrict access to the assembly.

If you update the IsEnabled property of the DefaultConsole to false, the Greet and SayGoodbye methods omit writing to the resulting messages to console. A change like this, helps to demonstrate that the IConsole service is injected into the IGreetingService and FarewellService services as a dependency that influences that apps behavior.

These methods are convenience methods that create a ServiceDescriptor instance and add it to the ServiceCollection. The ServiceDescriptor is a simple class that describes a service with its service type, implementation type, and lifetime. It can also desribe implementation factories and instances.

The preceding code is equivalent to how the IConsole service was registered in the ServiceCollection. The Add method is used to add a ServiceDescriptor instance that describes the IConsole service. The static method ServiceDescriptor.Describe delegates to various ServiceDescriptor constructors. Consider the equivalent code for the IGreetingService service:

Insert the needle into your vein with the needle bevel (opening) facing up, at a 15 to 35 degree angle, and always in the direction of the heart. The more perpendicular the needle is to the injection site, the greater chance you have of sticking the needle through the vein instead of into it. (See illustration on following page.)

To dissolve crack: put crack and citric or ascorbic acid (about a pinch to a slab) in the cooker; add plenty of water; mash and mix well. Try to only use as much acid as you need, since extra will dissolve your drugs, and acid can be very hard on your veins.

Because speed is often cut with such dangerous chemicals, it is very important not to miss your shot. Skin-popping speed can be very painful, may cause an abscess, and will take a long time for the body to absorb. If you get the shakes after doing a few shots, it may be helpful to have a friend inject you if you are not using alone. Because the quality of speed varies so dramatically, a tester shot is a good idea.

FEET: As with the hands, the veins in the feet are generally smaller than in other parts of the body, and close to nerves, cartilage, and tendons which you want to avoid hitting when you inject. Because they are farther from the heart than the veins in the hands, arms, and legs, blood circulates more slowly in the foot veins and they therefore require more time for healing and repair. In addition, foot sweat and dirty socks act to prevent wounds from healing and increase the chance of infection from bacteria.

NECK : The jugular vein in the neck is the riskiest place to inject because it lies very close to the carotid artery, a major blood vessel that brings blood directly to the brain. Accidentally hitting the carotid artery could be fatal, and damaging the jugular vein in any way can interfere with blood circulation to the brain.

You always want to inject into a vein and never into an artery. Veins are blood vessels that carry blood from the extremities of the body back to the heart and lungs where it becomes re-oxygenated. Veins have no pulse, and the blood they carry is a deep, dark red because it is low in oxygen. Arteries carry blood rich in oxygen from the lungs and heart to all the other parts of the body. Arteries have a pulse, and the blood in them is bright red and frothy. Arteries are located deeper in the body than veins and so are not visible as many of your veins are.

Most if not all of the infection control and other safety precautions intravenous drug injectors should follow also apply to individuals who inject drugs intramuscularly. Muscle-popping produces much less bleeding than intravenous injection, if any at all, but the risk of transmitting viruses and other blood-borne bacteria as a result of needle-sharing is as serious as it is with intravenous injection. In addition, muscle-poppers are at high risk for abscess formation, especially if what they inject has any particles in it whatsoever. When muscle-popping, it is extremely important to inject only a solution that is as particle-free as possible.

The buttocks, thighs, and upper arms are the three best sites, respectively, for intramuscular injection. The best is in the deltoid, the muscle on your upper, outer arm where your shoulder and your arm meet. If injecting into the butt, mentally divide each cheek into four equal sections and inject into the top right or top left outer section of each cheek. You can also use the front surface of your thighs about six inches above your knee to about six inches below your hip, or the outer surfaces of your upper arms between your shoulder and your elbow. Always be careful to avoid nerves, blood vessels, or bones, and rotate injection sites to avoid bruising, abscess formation, and the like. It is not uncommon for your muscle to be sore for a few days after an injection.

Pull your needle out in the same direction and angle at which you inserted it. Because you injected into a muscle, there should be little if any bleeding. You might want to apply a Band-Aid in any case to prevent infection. Massaging the area lightly for a few minutes will help the drug absorb and reduce the pain.

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