Software architecture style arrangement (5 warehouse style 6 copy style ).

 

1. Warehouse Style

In the repository style. There are two different components: the central data structure shows the current state. The independent component is executed on the central data storage. The interaction between the warehouse and the external component is greatly changed in the system.

If a process execution is triggered at a certain time in the input stream, the repository is a traditional database. On the other hand, if the current state of the Central Data Structure triggers the process execution selection, the repository is a blackboard system.

1.1 Database System

Database architecture is the most common form of database style. There are two main types of components: one is the central shared data source, which stores the data status of the current system; the other is multiple independent processing elements, which operate on the data elements.

1.2 hypertext system

Early static web pages were typical hyper-text systems.

1.3 Blackboard System

The blackboard architecture consists of three parts: knowledge source, blackboard, and control. The knowledge source includes several different units for Independent Computing. It provides problem-solving knowledge. The knowledge source responds to changes on the blackboard and only modifies the blackboard. The blackboard is a global database that contains all the states of the domain to be resolved. It is the only medium for knowledge sources to interact with each other. The knowledge source response is controlled by changes in the blackboard status.

The blackboard is usually used in systems that do not have deterministic algorithms for solving problems, such as signal processing, problem planning, compiler optimization, and other software systems.

The software expert module is called the knowledge source [knowledge sources (KSS)]. As with human experts working on the blackboard, each knowledge source provides the specific expert knowledge required by the application.

Blackboard [Blackboard], a shared knowledge base that contains information about problems, some solutions, suggestions, and contributions. The blackboard can be considered as a dynamic "library", which is the contribution of other knowledge sources to the current issue recently "published.

Control Mechanism [control shell] to control the Active Stream of problem solving in the system. Just as avid human experts have to have a host to prevent them from scrambling for chalk, knowledge sources (KSS) also need a mechanism to ensure that they work in the most effective and coherent way. The control shell provides this function.

 

Application

1) Database

2) Signal Processing

3) loosely coupled proxy data shared access

4) Batch Processing System with global database

5) programming and development environment

6) compiler

2. Replication style 2.1: copy a repository (RR)

A replication-based warehouse-style system improves data accessibility by using multiple processes to provide the same service.

And scalability of services ). These scattered server interactions create an "illusion" that only one centralized service is available for the client ". The main examples include distributed file systems such as XMS and remote version control systems such as CVS [www.ic.com.

The main advantage of the RR style is that it improves the user's perceptible performance by reducing the number of normal requests processed.

And support offline operations when the master server is faulty or intentionally roaming offline (intentional roaming off the network ). Here, simplicity is uncertain, because the RR style allows components that do not care about the network-unaware to transparently operate on local replication data, compensating for the complexity caused by replication. Maintaining consistency is the main focus of the RR style.

2.2 Cache)

A variant of the replication repository style is the cache style: copy the results of individual requests so that they can be duplicated by subsequent requests.

. This type of replication most often occurs when the potential dataset is far beyond the capacity of a single client, for example, in

Www. Lazy replication can be executed: when a request's response data that has not been cached is replicated, based on the referenced locality of reference and commonality of interest ), copy useful data items to the cache for reuse later. You can also execute active replication to obtain data items that can be cached in advance based on the predicted request.

Compared with the replication repository style, the cache style has fewer improvements to the user's perceived performance, because there will be more requests that do not hit the cache, only recently accessed data can be used offline. On the other hand, the cache style is implemented.

It is much easier, and there is no need to copy the warehouse style so much processing and storage, because only when the data is requested

Data transmission, so the cache style is more efficient. Cache style when combined with client-stateless sserver style becomes a network-based architecture style