What is the difference between Process and Application Domain in the context of .Net applications?
Multiple application domains can run in one process. Although a thread runs in one context of one application domain at a time, the There is no relationship between the number of application domains and threads. A Web. NET executable host and come to understand the relationship between Win32 processes, application domains, contexts, and threads. In a nutshell, application . In Chapters 14 and 15, you examined the steps taken by the CLR to resolve the the relationship between processes, application domains, and object contexts.
GetProcesses ; Get all instances of a running application by its name: ProcessName; A process can be killed by simply calling Kill on the process instance: Kill ; The Process class offers the static Start method to start a process by an executable name. Before the luxury of multi core systems only one thread could be executed at a time. Multiple threads would have to share processor time. Concurrent thread execution would seemingly be achieved by continuously pausing and resuming each running thread on the system.
Chapter Processes, AppDomains,Contexts, and Threads
In todays world of multi core systems multiple threads can genuinely run simultaneously, however seeing as there can be more threads than processors, the same principle holds true. With multiple threads running on a computer, the processor will give more processor time to threads marked as having a higher priority.
When a Process is started, a default thread is created or spawned which will execute the code associated with the assembly. Thread Members Code can get access to the thread that is running it with the CurrentThread property: CurrentThread; Access to all threads running within a process via the Threads property of a Process instance: Threads; Determine if the thread is still alive; that it has been started and has not terminated normally or aborted: IsAlive; The name of the thread can be set and retrieved with the name property.
Multiple application domains can run in one process. NET code can be checked for type safety and security, the CLR can guarantee that one application domain can run independently of another application domain in the same process. No process switch is required to achieve application isolation.
Application domains can have multiple contexts, but a context exists in only one application domain. Although a thread runs in one context of one application domain at a time, the Threading examples Step 3 and Step 4 demonstrate that a thread can execute in more than one context. One or more threads can run in an application domain at the same time. An object lives in only one context. Each application domain starts with a single thread and one context. Additional threads and contexts are created as needed.
There is no relationship between the number of application domains and threads.
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A Web server might require an application domain for each hosted application that runs in its process. The number of threads in that process would be far fewer, depending on how much actual concurrency the process can support.
To enforce application isolation, code in one application domain cannot make direct calls into the code or even reference resources in another application domain. They must use proxies.
Application Domains and Assemblies Applications are built from one or more assemblies, but each assembly is loaded into an application domain. Each application domain can be unloaded independently of the others, but you cannot unload an individual assembly from an application domain. The assembly will be unloaded when the application domain is unloaded. Unloading an application domain also frees all resource associated with that application domain.
Each process has a default application domain that is created when the process is started. This default domain can only be unloaded when the process shuts down. Applications such as ASP. NET or Internet Explorer critically depend on preventing the various applications that run under it from interfering with each other.
By never loading application code into the default domain, they can ensure that a crashing program will not bring down a host. The AppDomain sample illustrates the use of application domains. This class has static methods for creating and unloading application domains: CreateDomain "CreatedDomain2", 0, 0 ; Unload domain ; While the CreateDomain method is overloaded, one signature illustrates application domain isolation: While we will discuss this in greater detail in Chapter 13, the domain's creator can modify this collection to control the permissions that the executing application domain can have.
The AppDomainSetup parameter specifies setup information about the domain. Among the information specified is the location of the application domain's configuration file and where private assemblies are loaded. Hence, application domains can be configured independently of each other.
Code isolation, setup isolation, and control over security combine to ensure that application domains are independent of each other. AppDomain Events To help in maintaining application isolation, the AppDomain class allows you to set up event handlers for when a domain unloads. First, the name, thread, and context of the default domain is written out. ToString ; We then load and execute an assembly.
This code in this assembly just prints out a string and its domain's name, thread, and context. Notice that it executes in the default domain.The Four Components of Context - UX Design for Mobile Developers
You can pass this ObjectHandle between application domains without loading the metadata associated with the wrapped type. When you want to use the create object instance, you must unwrap it by calling the Unwrap method on the ObjectHandle instance.