**context** provides the capability of obtaining contextual information of an application.
## Context Structure
The OpenHarmony application framework has two models: Feature Ability (FA) model and stage model. Correspondingly, there are two sets of context mechanisms.
**application/BaseContext** is a common context base class, which does not belong to either model. It has only one attribute, **stageMode**, which specifies whether the context is used for the stage model.
The FA model has only one type of context: **app/Context**. Both the application-level context and ability-level context are instances of this type. If an ability-level method is invoked in the application-level context, an error occurs. Therefore, you must pay attention to the actual meaning of the context instance.
The stage model has six types of contexts: **application/Context**, **application/AbilityStageContext**, **application/ExtensionContext**, **application/AbilityContext**, **application/FormExtensionContext**, and **application/ServiceExtensionContext**. For details about these contexts and how to use them, see [Context in the Stage Model](#context-in-the-stage-model).
Only the methods in **app/Context** can be used for the context in the FA model.
The FA model has only one context definition. All capabilities in the context are provided through methods. The context uses these methods to extend the capabilities of the FA.
The stage model has six contexts. The following describes these contexts in detail.
### application/Context
**Overview**
**application/Context** is the base class context that provides basic application information such as **resourceManager**, **applicationInfo**, and **cacheDir**. It also provides basic application methods such as **createBundleContext** and **switchArea**. The application-level context is of the **application/Context** type.
**How to Obtain**
Obtain the context by calling **context.getApplicationContext()** in **AbilityStage**, **Ability**, and **Extension**.
**Example**
```javascript
exportdefaultclassMainAbilityextendsAbility{
onCreate(want,launchParam){
console.log('MainAbility onCreate is called'+want+launchParam);
**application/AbilityStageContext** is the context for the HAP file. In addition to those provided by the base class **application/Context**, this context contains **HapModuleInfo** and **Configuration**.
**How to Obtain**
Obtain the context from the **context** attribute in **AbilityStage**.
In the stage model, each ability has a context attribute.
**Ability** provides methods to manage the ability lifecycle, and **AbilityContext** provides methods to operate abilities (such as **startAbility** and **connectAbility**).
**How to Obtain**
Obtain the context from the **context** attribute in **Ability**.
**Example**
```javascript
exportdefaultclassMainAbilityextendsAbility{
onCreate(want,launchParam){
console.log('MainAbility onCreate is called'+want+launchParam);
varwant={
"bundleName":"com.example.MyApplication",
"abilityName":"ServiceExtAbility",
}
// 1. The context here is of the AbilityContext type.
Unlike the FA model, the stage model separates **Service** from **Ability** and defines a group of **Extension** classes to provide the same capabilities. **Extension** is a base class and does not provide specific service functions. The service party extends the corresponding **Extension** class as required. For example, a Service ability is extended to **ServiceExtensionAbility**, and a form (service widget) is extended to **FormExtensionAbility**.
**ExtensionContext** provides the context for the extension. **ExtensionContext** has the **HapModuleInfo** and **Configuration** attributes.
You can use **globalThis** to obtain the context in the FA model, but not in the stage model. To obtain the context in the stage model, use the **context** attribute in the corresponding component.
**Reason**
In the FA model, each ability instance has a JS VM instance. Therefore, a global ability instance can be obtained from the **global** object of the JS engine. In the stage model, where all the processes of an application share a JS VM instance, there is no global ability instance, and using **globalThis** may cause an error or crash.
