Differences in architecture, artifacts, components, frameworks, middleware

What is middleware ?

A definition given by IDC: Middleware is an independent system software or service program, distributed applications use this software to share resources between different technologies, middleware is located on the client server's operating system, managing computing resources and network communication.

As you can see from these definitions, :

• Middleware is a kind of software, not a software;

• Middleware not only realizes interconnection, but also realizes interoperability between applications;

• Middleware is based on distributed processing software, the most prominent feature is its network communication functions.

What is Web Services?

Web services are modular applications that can be described, published, positioned, and invoked through the Web. WEB services can perform any function, from simple requests to complex business processes. Once Web services is deployed, other applications or Web services can discover and invoke the deployed service.

WEB services are invoked through Simple Object Access Protocol (PROTOCOL,SOAP). SOAP is a lightweight message protocol that allows any type of object written in any language to communicate with each other on any platform. SOAP messages are encoded in Extensible Markup Language (XML) and are typically transmitted over HTTP. Unlike other distributed computing technologies, WEB services are loosely coupled and can dynamically locate and interact with other components that provide services on the Internet.

WEB Services uses an XML message such as a SOAP message to invoke it through a well-defined message exchange pattern. The Web Services Description Language (WSDL) document defines the message exchange pattern by describing the data necessary to invoke the service.

Component

In short, a component is an object. The C + + Builder is called a component, and Delphi is called a part, and the control is called in Visual Basic.

A component is a simple encapsulation of data and methods. In C + + Builder, a component is a specific object derived from the Tcomponent. Components can have their own properties and methods. property is a simple visitor to the component data. The method is a simple and visible feature of the component.

Components are the most exciting part of the C + + Builder environment. Using components enables drag-and-drop programming, fast property processing, and real object-oriented design. The VCL and CLX components are the core of the C + + Builder system.

1 , Component Application

When using off-the-shelf components to develop applications, components work in two modes: design tenses and run-time tenses.

In design tenses, components are displayed in a form under the C + + Builder forms editor. In design tenses, a component's method cannot be invoked, the component cannot interoperate directly with the end user, nor does it need to implement the full functionality of the component.

In the running state, the component works in an application that is actually running. The component must correctly represent itself, it needs to handle the invocation of the method and implement the effective synergy with other components.

All the components in the design tense are visible in the form, but not necessarily in the running tense. such as Ttable, Tquery and Tdataset are not visible in the running tense, but they all accomplish important functions.

2 , Component Creation

Creating components is the design of a new component.

Designing components is a heavy task. There are great differences between the development of the component and the visualization program of using the component, which requires the programmer to be familiar with the original VCL class library structure and proficient in object-oriented programming.

Designing components is a hard task. For the developer of the component, the component is pure code. The development of a component is not a visual development process, but rather a rigorous code-making effort with C + + or Object Pascal. In fact, creating new components brings us back to the age of traditional development tools. Although this is a complex process, but also a permanent process.

The biggest significance of creating components is to encapsulate repetitive work, followed by the ability to augment existing components.

The component creation process includes design, development, debugging (so-called 3D ' s) work, and then the use of components.

The three key elements that a component developer should master are attributes, events, and methods.

Patterns, that is, pattern. In fact, is to solve a certain type of problem methodology. You have summed up the method of solving some kind of problem to the theoretical height, that is the pattern.