Configure Serviced Components

Configure Serviced Components

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There are specific COM+ services that are used to configure a serviced component and apply them in an application, which are as follows:

1. Initiating the COM+ transactions in an application: A transaction consists of a series of operations, each of which is connected together to form a single unit. A transaction can succeed only when all its tasks have been completed successfully. For performing the application-based tasks, the COM+ uses the transaction model. A transaction can exist in any of the four states at the end of its execution, which are as under:



• Committed state: It is used to occur when all the tasks in a transaction have been successfully executed.



• Disable Commit state: It is used to occur when the component fails to complete its task, and the updates to the transaction are in an inconsistent manner.



• Enable Commit state: It is used to occur when the object has not completed its task, but the updates to the transaction are in a consistent manner.



• Aborted: It is used to occur when there is a transaction failure due to the unsuccessful execution of one of its tasks.


2. The transaction attributes that manage all the transactions depend mainly on the specified requirements. The following are the COM+ transaction attributes.




Attribute	Description
Required	It is used to create a transactional object from a COM+ component. When it is activated, the transactional status of a caller is detected by the Required attribute along with the transactional object.
RequiresNew	It is used to ensure that an object created from the COM+ component participates in a new transaction, and the transactional status of the caller is ignored.
Disabled	It is used when the value of a transaction attribute is disabled, the COM+ ignores the transactional requirements of a component so that the context placement of the object can be determined.
Supported	It is used to ensure that an object created from a COM+ component participates in an existing transaction that can be used to share the transaction of the caller without initiating the transaction of its own.
Not Supported	It is used to ensure that an object created from a COM+ component does not participate in a transaction and the transactional status of the caller is ignored.



3. Enabling the Just-In-Time (JIT) Activation: It is used to create a non-active and context-only object. A client invokes a method when the object is in the non-active state, and after that the runtime creates the full object. When the method call returns, the COM+ service deactivates the object. In turn, the deactivated object releases all resources like locks on data stores. Using the JustInTimeActivation attribute of the System.EnterpriseServices.ServicedComponent class can enable the JIT activation.



4. Using the Loosely Coupled Events Service: It is used to provide the publisher and the subscriber with information as and when required. Therefore, it minimizes the task of continuously polling the server for information. An event class and an event sink both are directly and indirectly derived from the System.EnterpriseServices.ServicedComponent class. Both the classes can use the loosely coupled event service of the COM+.



5. Using the Object Pooling Service: It is used to save the resources that are used during object creation. The objects are created at each method call in a non-pooled environment and on activation the object is extracted from the pool. Similarly, the object is returned to the pool on deactivation. The ObjectPooling attribute is applied to a class in order to configure the object pooling.
   
   
6. Using the Queued Components Service: It is used to invoke as well as to execute the COM+ components. This attribute sets the MaxListenerThreads attribute that is used to specify the maximum number of queued components listener threads and can hold values from 0 to 1000.
   
   
7. Using Object Construction: It is used to write configuration-related information within a class of a service component and the configuration information can be initialized externally. The ConstructionEnabled attribute derived from the System.EnterpriseServices.ServicedComponent class is used to configure the object construction.

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