Middleware is a technology system that has gradually grown with the development of network applications. The initial driving force for the development of middleware was the need for a common standard application development platform to shield the environment and API differences between different operating systems, which is called middleware, the "middle" layer between operating systems and application programs. But with the demand for network applications, addressing issues such as network communication, security, transaction performance, transmission reliability, semantic parsing, and integration of data and applications between different systems has become a more important driving factor for middleware. Therefore, various functional middleware technologies and products have emerged to solve network applications, such as transaction middleware, message middleware, and integration middleware.

Nowadays, middleware has become an essential tool for the development, integration, deployment, operation, and management of network application systems. Due to the involvement of middleware technology in various aspects of network applications, covering various aspects such as basic communication, data access, and application integration, middleware technology presents diverse development characteristics.

Traditional middleware has achieved great success in supporting enterprise computing and information resource sharing in relatively closed, static, stable, and controllable enterprise network environments. However, under the impact of network technology represented by the open, dynamic, and ever-changing Internet in the new era, it still reveals its inherent limitations, such as more specialized functions and significant heterogeneity between products and technologies, The ability to integrate and work together across the Internet is insufficient, and the rigid infrastructure lacks the ability to respond to demand, etc., which is insufficient in the face of the huge challenges brought by Internet computing. The era requires new technological changes.

The development direction of middleware technology will focus on eliminating information silo, promoting borderless information flow, supporting complex application systems in an open, dynamic and changeable Internet environment, and realizing the integration, collaboration and comprehensive utilization of various autonomous information resources (computing resources, data resources, service resources, software resources) distributed on the Internet in a simple, standard, fast, flexible, reliable, efficient and low-cost manner, Improve the business agility of the organization's IT infrastructure, reduce overall operation and maintenance costs, and promote the matching between IT and business. Middleware technology is showing many new and important development trends such as commercialization, service-oriented, integration, virtualization, and so on.

1. Business oriented: Middleware is becoming thicker and wider

The essential feature of middleware is the abstraction of the computing environment and the condensation of application commonalities. Over the past decade, the development of middleware has mostly focused on the abstraction of computing environments. The current middleware can provide various application services in different operating systems and network environments.

Middleware widens and thickens

More and more network applications will be abstracted into standard platform services and added to middleware, becoming important technical features.

Business oriented represents the development trend of middleware in supporting complex business, that is, from bottom-up technology driven to more top-down application layer business driven, condensing more applications and business models, and supporting open multi-party collaboration and on-demand integration capabilities for complex business.

As is well known, for organizations, effective management and utilization of information through IT is a key factor in their business success, and IT serves the business. As one of the core infrastructure of enterprise computing, middleware technology is not enough to focus solely on the technology itself, especially in the current trend of globalization for survival and development. The effective support of IT information systems and their infrastructure for strategy and business is crucial. Therefore, as a refinement of commonality, middleware should not only start from the underlying technology and abstract the characteristics of commonality into the middle layer, but also focus more on the business level, driving the continuous evolution of its own capabilities according to business needs. That is, the constantly emerging new business needs drive the continuous evolution of application patterns and information system capabilities, and thus require middleware to continuously refine more business commonalities, Provide targeted support mechanisms. In recent years, this demand trend has become increasingly evident, with more and more business and application patterns being continuously abstracted into the level of middleware, such as business process flow, business models, business rules, interactive applications, etc. The result is that middleware has more and more condensed common functions. From a visual perspective, one of the development trends of middleware is becoming increasingly "thick".

In addition, driven by new technologies represented by the Internet, with the pace of globalization and the rapid development of national economy and information construction, the breadth, depth, and frequency of business cooperation and resource sharing between enterprises and governments are constantly expanding. Enterprise competition itself has evolved from simple individual behavior to fierce competition at the level of the industrial chain, The construction of e-commerce also shows a trend of development from the edge to the depth. Enterprise informatization When ERP breaks the internal boundaries of the enterprise and forms a borderless information flow within the enterprise, the whole process e-commerce will realize the interconnection of enterprises, partners, suppliers and customers, break the boundaries between enterprises, and form a borderless information flow between cross industries/organizations/departments. Complex business collaboration often needs to optimize the original fragmented business processes (manual/automatic) and information into an integrated environment, Multiple business entities conduct open, flexible and reliable information exchange and interoperability based on the extensive connectivity provided by the Internet, realize business collaboration among enterprises, respond to changes in time and effectively support the delivery of business strategies, thus quickly forming new competitive advantages. Therefore, from the perspective of supporting complex business collaboration and integration based on extensive internet connectivity, another development trend of middleware is becoming increasingly "wide".

2. Service oriented: Middleware will be service-oriented and easy to integrate

Service oriented represents the development trend of middleware in improving the business agility of IT infrastructure, which supports standardized abstraction and capability provision of internet-based data storage, software, and service resources, bridges the technological heterogeneity between different business platforms, and provides the ability to flexibly organize business on demand, closely matching IT with business, and enhancing organizational business agility.

The fundamental pain point for enterprises lies in the sharp contradiction between their volatile business and rigid IT infrastructure. The variability of business is an inevitable result of enterprises attempting to maximize profits through business differentiation, and is a product of fierce market competition. The problem is that companies often find that business needs to change, but IT cannot respond quickly. Why? The fundamental reason is that there are serious issues in the most important software development technology that have not been resolved.

To solve these problems, the essence of technology is the internal mechanism of software technology such as reuse, loose coupling, interoperability (standard), etc. Software reuse, that is, software reuse, also called reuse, refers to the repeated use of the same thing without modification or slight change. From the perspective of the development of software reuse technology, it is to continuously improve the level of abstraction and expand the scope of reuse. The earliest reuse technology was subroutines, which were invented by people and could be reused between different systems. However, subroutines are the most primitive form of reuse, as this reuse scope is within an executable program, with static development time reuse. If a subroutine is modified, it means that all programs that call this subroutine must be recompiled, tested, and published.

Extract common problems in the construction of distributed systems, encapsulate their resolution mechanisms, and provide a simple and unified interface externally, thereby reducing the difficulty and workload of developers in solving these common problems. Therefore, one of its significant features is a bottom-up technology orientation, which typically abstracts and encapsulates basic software capabilities such as operating systems, networks, programming languages, etc. Its focus is mainly on the technical details of building distributed applications.

Reuse Objects

Reuse scope

subroutine

Reuse within an executable program during static development

Components (DLL, Com, etc.)

Intrasystem reuse, dynamic runtime reuse

Enterprise Object Components (Com+,. NET, EJBs, etc.)

Reuse within enterprise networks and between different systems

service

<(such as WebService, SCA/SDO)

Global reuse between different enterprises, dynamically configurable

To solve this problem, components (or controls) were invented, such as DLL components under the MS operating system. Components elevate reuse to a higher level because they can be reused within a system (the same operating system) and are dynamic and runtime reusable. This way, components can develop independently, reducing the coupling between components and their callers.

In order to solve the reuse of components between distributed network computing, people have invented enterprise object components, such as (Com+,. NET, EJBs, etc.), or distributed components. Through remote object proxy, achieve reuse within the enterprise network and between different systems.

The core of traditional middleware is the management of component objects. However, distributed components also heavily rely on their controlled environment. Due to the significant heterogeneity between component implementation and operational support technologies, components designed and implemented by different technologies cannot be directly assembled and reused.

The important development trend of modern middleware is centered around services, such as WebService, SCA/SDO, etc. Through services, or service components, a higher level of reuse, decoupling and interoperability can be achieved, that is, SOA architecture middleware.

Because services are reused through standard encapsulation, assembly, orchestration, and reorganization between service components. And this kind of reuse can be reused between different enterprises globally, reaching the highest level of reuse, and is dynamically configurable.

SOA architecture is loosely coupled, and the decoupling process of middleware has also reached its final stage. Traditional software couples the core three parts of the software, including network connectivity, data conversion, and business logic, into a single piece of software, making it difficult for the software to adapt to changes. Distributed object technology separates connection logic, while message middleware asynchronously processes connection logic, increasing greater flexibility. Message brokers and some distributed object middleware have also separated data transformation. The SOA architecture, through the encapsulation of services, achieves complete decoupling of business logic from network connectivity, data transformation, and so on.

The Continuous Decoupling Process of Software Technology

The Continuous Decoupling Process of Software Technology

There are also problems with software interoperability technology. The unprecedented openness of the Internet means that each node can adopt different middleware technologies, and the technical details are constrained by privatization. There is no unified standard for component models and architectures, which leads to the huge heterogeneity of the middleware platform itself in component description, publishing, discovery, invocation, interoperability protocols and data transmission. The result of various adverse technical constraints is that software systems become difficult to interact with across the internet, ultimately resulting in difficulty in flexible and rapid business integration and restructuring across enterprises/departments.

In terms of interoperability of software, traditional middleware only realizes access interoperability, that is, interoperability between similar systems is achieved through standardized APIs, while connection interoperability still depends on specific access protocols, such as JAVA using RMI, CORBA using IIOP, etc. SOA realizes connection interoperability through standard SOAP protocol that supports Internet and is independent of operating system. Moreover, the service encapsulation adopts XML protocol and has the characteristics of self parsing and customization. In this way, SOA based middleware can also realize semantic interoperability.

Service based middleware

Therefore, the next generation of middleware will optimize the software model, structure, interoperability and development methods in four aspects:

Model: Elastic granularity of component models refers to the implementation of reusable components with higher structural independence, content self inclusion, and business integrity through component models with higher levels of abstraction, namely services. And on the basis of fine-grained services, a coarser grained service encapsulation method is provided, that is, business level encapsulation, forming business components, which can achieve the ability of full lifecycle enterprise modeling from component models to business models.

Structure: Loosening the structure, that is, completely separating the service description and service function implementation, as well as the users and providers of the service, in order to avoid the common technical, organizational, and time constraints during the construction and integration of distributed application systems.

Interoperability: the standardization of interaction process, that is, the standardized definition of interoperability related content, such as service encapsulation, description, publishing, discovery, invocation and other contracts, communication protocols, data exchange formats, and so on. Finally, access interoperability, connection interoperability and semantic interoperability are realized.

Development integration method: The construction method of application systems has shifted from code writing to mainly providing and improving more complex business logic on demand through quick combination and arrangement of services, greatly simplifying and accelerating the construction and reconstruction process of application systems.

In short, service-oriented reflects the development trend of middleware in terms of complete business reuse and flexible business organization, with the core goal of improving the business agility of IT infrastructure. Therefore, middleware will become the main implementation platform for SOA.

3. Integration: Easy for platform evolution, development, and management

Integration represents the trend of integrating and integrating a wide range of middleware products with relatively single functions, forming a unified internet computing platform.

Traditional middleware products have formed various specialized middleware products based on their respective problem domains, such as transaction middleware, application server, message middleware, integration middleware, etc. With the development of information technology, different types and manufacturers of middleware products run simultaneously on the Internet, jointly forming the infrastructure of large-scale critical network application systems. These core critical business applications involve a wide range of functional requirements, and a single functional middleware product is no longer sufficient to fully meet all requirements. Customers need an open integrated middleware platform to better adapt to the open, dynamic, and ever-changing characteristics of the Internet computing environment. Therefore, a wide variety of middleware products inevitably need to be integrated.

In the trend of integration, the various middleware sub products included in the future integrated unified middleware platform together form an interrelated organic whole. This "integration" is not simply a patchwork, but a deep integration, which is reflected in the following aspects:

3.1. Unified kernel product architecture, easy to evolve

An integrated unified middleware platform must have good scalability and a more effective application environment. The use of microkernel design is an important foundation for building a unified middleware platform with flexible pluggable middleware products.

The integration of a unified middleware platform requires the integration of multiple middleware products, so its internal functions are inevitably large and complex. In order to reduce complexity and improve scalability, the microkernel ization of its internal structure will be an inevitable trend. The microkernel is responsible for coordinating the functions of multiple middleware products, and through the microkernel system, the complexity of the platform's internal interfaces can be reduced, achieving a more robust structure, And provide more stable and efficient runtime performance. The use of flexible microkernel design, the addition of new middleware products, and the abandonment of old middleware products can all be carried out very conveniently without the need for fundamental changes to the entire platform system.

Unified middleware microkernel

The microkernel will provide the most core thread services, communication services, resource services, and transaction services of middleware. The dynamic componentization middleware structure of the microkernel is a very important technical route for the integration and development of middleware.

Currently, many traditional middleware