Model-Oriented Software Architecture 1-model system Reading Notes (1)-adaptive system and microkernel Model

1. Adaptive System

1) the microkernel mode is used in software systems that must be able to meet the requirements of the change system. In this mode, the minimum function core is separated from the extended function and the specific customer part. Microkernel can also be used as a socket to insert into these extensions and coordinate their collaboration.

2) The image mode provides a mechanism to dynamically change the structure and behavior of the software system. It is divided into two parts. A meta-level provides information about the selected system attributes and enables the software to contain the self-report information. A basic level includes applicationsProgramLogic. Its implementation is built on the meta level.

 

2. Micro-core Mode

Condition

1) Applications in your field need to support different but similar application platforms.

2) applications can be grouped by class. Each group uses the same functional core in different ways and needs to simulate existing standards based on the application platform.

3) The core functions of the application platform should be separated from components that occupy the smallest storage space and the processing capability consumed should be as small as possible.

 

Structure

1) Internal Server (internal servers)

2) external server (external servers)

3) Adapter (adapters)

4) client (clients)

5) microkenel)

 

5) microkernel

The microkernel represents the main component of this mode. It implements major services such as communication means or resource processing, and all or part of other components are built on such basic services. Many system-specific accessories are encapsulated in microkernel. It is also responsible for maintaining system resources like processes or files.

 

1) Internal Server

An Internal Server extends the functions provided by the microkernel. It represents an independent component that provides additional functions. The microkernel calls the functions of the internal server through a service request.

One of the design goals should be to make the microkernel as small as possible to reduce storage requirements. Another goal is to provide a fast execution mechanism to reduce service execution time. Therefore, extra and more complex services are implemented by internal servers. When necessary, the microkernel will activate or load them, and it can be considered as an extension of the microkernel. Note that the internal server can only be accessed by the microkernel component.

 

2) External Server

An external server is a component that uses the microkernel to implement its own view based on the application field. Different external servers implement different policies for specific application fields.

The external server displays its functions through an output interface like the microkernel. It receives service requests from client applications by using the communication means provided by the microkernel, and explains these requests, execute the corresponding service and return the result to its client. The implementation of the service depends on the microkernel mechanism. Therefore, the external server needs to access the microkernel programming interface.

 

3) adapter and 4) Client

A client is an application precisely associated with an external server. It only accesses the programming interfaces provided by the external server. If a client needs to directly access its external server interface, each client has to use available communication means to interact with the external server. Each communication with the external server must be hardened to the client.CodeWill lead to many disadvantages:

A. Such a system does not support high scalability.

B. If the external server simulates an existing application platform, the client applications developed for these platforms cannot run without being modified.

To avoid direct dependency, the adapter represents the interface of the client and its external server, allowing the client to access the services of their external server in a portable manner. Once a client requests a service from an external server, the adapter's task is to submit the call to the appropriate server. For this purpose, the adapter uses the communication service provided by the microkernel.

 

Advantages of micro-core Mode

1) portability;

2) adaptability and scalability;

3) policy and mechanism separation.

 

Distributed micro-core

1) scalability;

2) reliability;

3) Transparency.

 

Insufficient

1) performance;

2) Complexity of design and implementation.