Application Research and Challenges of Message Middleware in Data Exchange
Abstract: Briefly introduces the application of message middleware in data exchange, and discusses the challenges and countermeasures faced by the middle of the message: the size of the transmitted message is not limited; At the same time, it supports multiple operating systems such as Windows 2000 / nt / 98 / ME, And can make full use of the performance of different operating systems through configuration; realize the rollback and submission of message queue operations, so that the message can be multi-level receipt; provide MQ Clinent API in the form of COM.
Keywords: data exchange message middleware message queue COM
The continuous innovation of computer technology has brought about a new wave of information development. People feel the benefits of computer and network technology, so the demand for electronic and information applications is becoming more and more urgent. With its strong penetration, information technology has penetrated into all aspects of social and economic life. In fields such as commercial finance, electronic data exchange is being widely used as a new business method.
EDI (Electronic Data Interchange) is a computer application technology. According to the agreement reached in advance, the information is formatted according to a certain standard, and the formatted data is transferred between its computer systems through the computer communication network. Exchange and automatic processing. As part of computer communication technology, EDI can be used in various economic sectors such as manufacturing, transportation, retail, and health care and government.
Message Queue Middleware MOM (Message-Oriented Middleware) is a kind of specific middleware, which uses efficient and reliable message delivery mechanism for platform-independent data exchange, and integrates distributed systems based on data communication.
1 Research and application status of data exchange
1.1 Current status and trends of international development
Western developed countries have generally adopted EDI. According to statistics, there were more than 100,000 companies using EDI in the world at the end of 1992, and 400,000 in 1995. As early as the early 1960s, the United States applied EDI in roads, railways, maritime transportation, and air transport, and it has also been growing at a rate of 100% per year; Western European countries have applied EDI to automotive, chemical, electronics, transportation, insurance, distribution, retail industries China; Japan has widely used EDI in sales, trade, transportation, and manufacturing; Singapore claims that 95% of its trade is realized with EDI. It is reported that the US government and the customs of most countries in the European Community have announced that since 1992, EDI will be used to export customs services. If EDI is not used, the procedures will be postponed or no longer selected as trading partners.
In 1996, six Asian countries and regions (China, Japan, India, Malaysia, the Philippines, and Taiwan Province of China) reached an agreement to jointly develop an EDI system to enable these countries and regions to collect import and export data in real time during the import and export process , Effectively manage customers, reduce customs declaration errors. This will undoubtedly speed up the process of EDI construction in Asian countries.
In Europe, some large companies, including supermarket chains, have begun to impose sanctions (discrimination policies on prices, processing times, and payment methods) for suppliers who do not open EDI.
The Singapore Trade Development Council announced that from January 1, 1999, all import and export trade must be declared by EDI.
The import and export declaration counters in Hong Kong have been fully closed since 2000, and all import and export declarations must go through EDI.
The development trend of EDI:
(1) The industries applying EDI will increase;
(2) Integration of EDI and other information transmission technologies and systems;
(3) EDI technology will be impacted by the Internet.
1.2 Domestic development status
China has also begun to pay attention to and popularize EDI technology, and grasp the foundation and pilots during the "Eighth Five-Year Plan"; the China Trade Network has been established during the "Ninth Five-Year Plan" to realize the major connectivity with the international trade network as soon as possible and fully implement EDI.
In recent years, domestic software companies such as Founder, ChinaSoft, Qihong Technology, and Nantong have developed rapidly in terms of data exchange platforms.
Founder Digital Corporation proposed a cross-regional and cross-departmental application technology framework for information resource integration in 2002, for services across multiple government machines, intelligent business implementation of supervision, and data between different business systems of multiple departments within the same institution The integration provides a safe information exchange platform for effective conversion and communication-Founder Yichang InfoHub.
The information system of Founder Yichang InfoHub's secure information exchange platform provides terminal nodes with safe and reliable message transmission. It uses the message structure based on XML technology to express, store and transmit information. The message content encapsulated in the message structure may be information in XML format, information in EDI format, or information in a format defined by the user.
The "Administrative Management and Monitoring Assessment System" jointly developed by ChinaSoft Network Technology Co., Ltd. and the Henan State Taxation Bureau filled the gap of the national office software.
Based on this foundation, Chinasoft established a system framework, and through the perfect combination of technical framework and functional framework, the functions were continuously expanded and perfected, and the "Administrative Management and Monitoring Assessment System" was completed. The system has been comprehensively promoted and truthful in the Zhumadian State Taxation Bureau, and has contributed to the improvement of the level and quality of tax industry administration.
Qihong Technology's electronic data exchange platform not only provides a basic development platform for software developers committed to providing data exchange and system integration functions, but also can be directly applied to the construction of various industries and government public basic data exchange platforms.
2 Existing problems and solutions
The current EDI technology needs to solve the following problems:
(1) Network communication transmission standard: to solve the information exchange under special-shaped machine and special-shaped network environment;
(2) Standardization of transaction business format: both transaction parties must use the same transaction file format;
(3) Standardization of language and writing: Both parties to the transaction should use mutually understood language to exchange;
(4) The establishment and management standards of EDI center;
(5) Authority and legitimacy;
(6) Security and confidentiality.
With the deepening of the application of EDI technology, people have realized that users will no longer adopt large and rigid general products, and they will implement personalized IT solutions through component integration. Gartner, an authoritative market research and consulting agency, pointed out that by 2005, at least 70% of new application software will be developed based on architecture in a componentized manner.
All of this determines that the complex and rigid coding software system will replace flexible component integrated software system. The middleware (Middleware) technology provides an integrated platform for component-based application software to achieve resource sharing.
3 Middleware technology
Middleware, which started in the early 1990s, is a general term for a class of software. It realizes network interconnection and interoperability between applications. It is also called the three basic software with the operating system and database. Located between the operating system and the application system, it is an independent system software or service program. The application software uses this software to achieve resource sharing between different platforms and different application environments.
Middleware is a common service between the platform (hardware and operating system) and applications. As shown in Figure 1, these services have standard program interfaces and protocols. For different operating systems and hardware platforms, they can have multiple implementations that conform to interface and protocol specifications.
The scope of middleware is very wide, and a variety of distinctive middleware products have emerged for different application needs. Based on the different purposes and implementation mechanisms, the platform is divided into the following host categories: message queue middleware, distributed object-oriented middleware and transaction processing middleware.
Message queue service is a form of loosely coupled distributed application integration. The sender sends the message to the message server, and the message server stores the message in several queues, and then forwards the message to the receiver when appropriate. In this mode, sending and receiving are asynchronous, and the sender does not need to wait; the life cycle of the two may not be the same; the receiver may not run when sending a message, and the sender may not run when receiving a message; one-to-many communication : There can be multiple recipients for a message.
The most important function of message queue middleware is to provide reliable message communication means in time. In order to complete the reliable transmission of messages, under normal circumstances, the use of queues for message management, that is to say, when data transmission is often carried out, the data is divided into several messages according to the user-defined size and placed in the message queue. Send or receive messages in synchronous or asynchronous communication mode.
In the current message system engineering, for the consideration of function, security, reliability, etc., a large number of network devices using routers, switches, and firewalls, or the use of network technologies such as clusters and dual-machine hot backup, are becoming increasingly complicated. In order to meet the requirements of network use, middleware products can usually be deployed in multiple ways, so as to build a one-to-one, one-to-many, many-to-one, and many-to-many tree network structure between systems to configure the system. And management is greatly simplified, while also meeting the system data transmission requirements.
The cross-platform capability of message transmission middleware is also an important indicator of middleware. In order to meet the data communication requirements of heterogeneous platforms, message transmission is encapsulated using standard IP packets, so middleware products can achieve true cross-platform data communication. In addition, message transmission middleware usually provides rich API function interfaces, which can support standard C / C ++, Microsoft Visual C ++, Microsoft Visual Basic, Borland C, PowerZBuilder, Java and other development languages, especially for standard C / C ++ and Java 'S support facilitates application development on different application platforms, while actually enhancing the cross-platform capabilities of message transmission middleware.
The message queue service system is to apply the message middleware technology to a service program between the platform (hardware and operating system) and the application in practice.
Message queuing is an asynchronous transmission mode that enables mutual communication between multiple different applications. Applications that communicate with each other can be distributed on the same machine, or they can be distributed anywhere in the connected network space. The implementation principle is: the sender of the message puts the information he wants to send into a container (Message), and then saves it to a message queue (Message Queue) in a system common space; local or remote message reception The program then takes the message sent to it from the queue for processing.
There are two important concepts in the messaging mechanism. One is the message and the other is the queue. A message is information that needs to be communicated by both parties in a communication. It can be a variety of media, such as text, sound, images, and so on. The final understanding of the message is agreed in advance for both parties to the message delivery. The advantage of this is that one is equivalent to simple encryption of the data, and the other is to use the format defined by you to save the amount of communication. The message can contain the identity of the sender and the recipient, so that only the user who refers to the irregular user can see the information only delivered to him and return a receipt of whether the operation was successful. The message may also contain a time stamp, so that the receiver can process certain time-related applications. The message can also contain an expiration time, which indicates that if the message has not arrived within the specified time, it will be invalidated. This is mainly used for applications that are more closely related to time.
The message queue is a common storage space for sending and receiving messages, and can exist in memory or in physical files. Messages can be sent in two ways, namely express and recoverable. The difference between them is that for the rapid delivery of messages, the message is placed in memory instead of on the physical disk. Obtain higher processing power; recoverable mode writes messages to the physical disk at each step of the transmission process to obtain better fault recovery capacity. The message queue can be placed on the machine where the sender and receiver are located, or it can be placed separately on another machine. It is precisely because of the flexibility of the message queue placement method that the reliability of the message delivery mechanism is formed. When the machine holding the message queue fails and restarts, the messages sent in recoverable mode can be restored to the state before the failure, and the messages sent by express delivery are lost. On the other hand, with the message passing mechanism, the sender must no longer worry about non-essential factors such as whether the receiver is started or whether a failure has occurred. As long as the message is successfully sent, it can be considered that the processing is complete, but in fact the other party may not even turn on, or It may be the next day when it is completed.
The benefits of using message queue technology are: Because it is asynchronous communication, neither the sender nor the receiver can execute the remaining code without waiting for the other party to return a successful message, thus greatly improving the transaction processing ability; when the information is transmitted In the process, the information sending mechanism has a certain function of fault recovery capability; the message passing mechanism makes it possible for both parties of the message communication to have different physical platforms.
Message queues are divided into user creation queues and system queues. User queues are divided into:
(1) The "public queue" is copied and transmitted in the entire "message queue" network that can transmit messages, and may be accessed by all sites connected by the network.
(2) "Dedicated queues" are not released in the entire network. Instead, they are only available on the local computer where they reside. Private queues can only be accessed by applications that know the full path name or label of the queue.
(3) The "management queue" contains a message confirming the receipt of the message sent in the given "message queue" network. Specifies the management queue that you want the MessageQueue component to use.
(4) "Response queue" contains the response message returned to the sending application when the target application receives the message. Specify the response queue that you want the MessageQueue component to use.
The system queue is divided into:
(1) "Diary Queue" optionally stores copies of sent messages and copies of messages removed from the queue.
(2) The "dead letter queue" stores copies of messages that cannot be delivered or have expired.
(3) "Dedicated system queue" is a series of dedicated queues for management and notification messages required by the storage system to perform message processing operations.
There are many similarities between message queues and e-mails. They all contain multiple attributes for storing messages. The message types indicate the addresses of the sender and the receiver; however, their use is very different: the sending of the message queue The receiver and receiver are applications, while the sender and receiver of e-mail are usually people.
Figure 2 is the architecture of the message queue application.
Typical MOM systems are: IBM's MQSeries, Microsoft's MSMQ, etc.
Microsoft Message Middleware MSMQ can implement a push-type business transmission environment between applications, and can establish reliable applications even on networks with low reliability. It has the characteristics of easy to use and highly integrated application.
Because it fully supports COM, dynamic target service architecture and main built-in centralized system management, MSMQ has become the most easy-to-use, headquartered and managed message queue product on Windows 2000 server. It provides comprehensive message queuing functions, such as reliable and strong message delivery, message routing based on overhead, and full support for transaction processing. MSMQ provides close interoperability with Mqseries through Microsoft's MSMQ-MQ series bridge, and also provides connections to other message queue products through leve18 system products.
But its shortcomings are: it requires NT4.0 or higher, MQ1.0 is based on SQL, and its performance is low and unstable. After the WINDOWS2000 version, it began to be practical, but it can only develop development systems below the county level, and the development system level has received certain restrictions.
IBM's MQSeries middleware products provide a flexible, fast, and easy-to-use solution for implementing communication between programs in a distributed environment in the form of message queues. This kind of message exchange has nothing to do with hardware and operating system, and can guarantee that data will not be lost or copied.
MQSeries provides a series of functions to integrate the system to provide fast, reliable and consistent access to information within the system. MQSeries provides application-to-application side connections in the communication mode of message processing and message queuing. The development of No. 7 signaling monitoring system based on the communication middleware MQSeries can ensure the reliability and security of information communication, and at the same time shorten the development time and win the market for the enterprise.
IBM's Mqserices series has a high market share and stable performance, but the development system is expensive, and its use in China's general companies, enterprises and other units is subject to certain restrictions.
CNT (CSS Network Technology) MQ Service is a distributed message queuing service system developed by ChinaSoft Network Technology Co., Ltd. It is a message queuing service system based on the Windows system platform, which better solves the problems of the current message queuing service system. Defects and deficiencies.
4 Challenges faced by messaging middleware
In the message queue service system, the reliability of message transmission and the size of messages are subject to certain restrictions. At present, the message middleware products of Microsoft and IBM have certain restrictions on the size and capacity of messages. Message middleware will be developed in the future , Will develop in the direction of unlimited message size and capacity transmission. You can use the split and assembly technology to realize that the entire system has no restrictions on the size and capacity of the transmitted message.
In order to ensure that the reliability of message transmission is high enough, the message middleware will use the message multi-level receipt technology, so that the message can be rolled back and can be regretted. When the message is extracted from the queue, it is temporarily stored in the cache area, even if it is broken Electricity can also ensure reliable transmission of messages without delay and loss.
It is another technical difficulty for the message queue service system to handle high concurrent services. The server has been continuously improving from 5 concurrent tasks to 16 concurrent tasks, and then to 2000 concurrent tasks. Using the asynchronous I / O mechanism to handle the correct relationship between processes and threads is another key technology of the message queue service system.
Providing MQ Client API in the form of COM is a requirement of the current message queue service system. The component interface of the API facing the process function will bring certain troubles in the use process. The use of the COM object-oriented component interface has a great advantage over the use of the API component interface. A series of tedious processes such as defining functions, attaching attachments, and setting priorities can be reduced.
5 Application Prospect of Message Middleware
With the development of message middleware applications, the application prospects of message middleware will be more and more broad, and will break away from the scope of data transmission and become a new application mode; use message-driven to make asynchronization more reasonable and optimized; use message queue It is also a good idea to implement the load balancing mechanism; at present, various message queue service systems all use their own transmission protocols, and future development trends will have common transmission protocols.
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