Why do large websites use PHP at the front end and Java at the back end?

First of all, why PHP and Java, but not others. This has a lot to do with their active open source community, being suitable for Web development, running in Linux environment and unified management in operation and maintenance.

Although the market share. Net is not low, but due to the license fees of Windows and SQL Server, the open source community is not active, and other issues are relatively less considered. The languages suitable for Web development in TIOBE TOP 10 also include Python Perl Ruby, among which Perl is a thing of the past, and many applications are mainly in the field of server scripts, so it is impossible to never return on the Web. Python has been on the rise recently, but just considering that there are few documents and it is relatively difficult to recruit, it is basically doomed that it will not be the mainstream choice for large websites for the time being. Not to mention Ruby.

Look at the differences between the two languages. PHP is flexible, easy to use, easy to modify and quick to publish. Its disadvantage is easy to make mistakes (such as spelling mistakes, SQL injection, upload execution, etc.). ), low execution efficiency and lack of global cache. The advantages of Java are stability and reliability, high running efficiency (especially after JIT), and not easy to make mistakes (strong typing, precompiling, exception interception, etc.). ). The disadvantage is that the efficiency of development and release is relatively low. Although excellent engineers can change the above problems to a certain extent, in general, where will there be a dream team with as many experts as dogs?

Then, from the hierarchical structure of MVC, in the development cycle of general website projects, the most frequent requirements for changes and adjustments are views, followed by controllers, and finally models. This is very understandable. Who has nothing to do to change the data structure every day? Every time the version is upgraded, the control structure will be changed more or less. Jing, when have you not changed BU, PM and UED for two days? Probably a collective annual leave.

Third, the communication between them. At present, RPC technology is mature enough. Whether it is Web Service/Hessian/RESTful API, developers can focus on functional development without thinking too much about the differences between heterogeneous platforms and the details of communication. This means that the scheme of using two languages at the same time in large companies will not introduce too much complexity and workload. Of course, the lower limit of the amount of documents has increased a lot, but in fact, most teams like it: don't say that documents are important every day but you don't have time. If you don't write, how can other colleagues cooperate?

Generally speaking, close to the user's front end, using PHP can complete frequent and trivial updates of the front end more quickly, and cope with the changes of various needs freely. The structural adjustment of the page, the basic verification of user input, and the simple logic only related to user interaction are all suitable for PHP development, and even the page changes can be migrated to the front-end team through template technology such as Smarty. Basic business logic and data update are developed in Java, which can effectively improve reusability, improve performance and throughput, and avoid security problems. However, the slight decrease of development efficiency is in exchange for the improvement of maintainability, and the slow release speed is not a problem, because usually the adjustment of basic business logic is always revised as a whole, and it can only be released after layer-by-layer testing and confirmation.

Therefore, large-scale websites use PHP at the front end and Java at the back end, which is easy to recruit and maintain, and the system has high stability and even greatly increased security. Code reuse and document integrity have also been improved. With the above benefits at your fingertips, it is not a problem at all to require architects to have a broader knowledge pedigree.

Well, the next classmate added a good question. Why not use PHP or just Java? I mentioned this a little bit, but it was deleted before it was released, because the question is why PHP+Java. In fact, many companies, especially small and medium-sized companies, prefer to use a single language in order to ensure that the team organization is not too complicated.

In fact, a single solution can be isolated, and PHP can also provide services, but the performance problem is often a problem of algorithm and architecture rather than language differences. Such as speed or JSTL is also a good isolation scheme.

However, as we all know, reality is often much more skinny than ideal. Under high pressure, these schemes will expose many problems and reflect the advantages of bilingualism. These are actually mentioned above, and some points that are difficult to change are detailed:

1. Due to the characteristics of its dynamic scripting language, PHP, including classes, functions and constants, needs to be executed repeatedly in each request cycle to establish the running environment. Sacrifice compilation quality to ensure parsing speed; FastCGI is used, but only processes are reused to process requests to reduce fork overhead, and no other languages are used. After initialization, data is obtained through the interface of FastCGI and returned through the corresponding interface. It is almost impossible to restore Java. It was even worse at first, and now I am driving a JIT sports car. More importantly, the lack of support for system-level data sharing makes it necessary to use extensions or middleware to reuse the core data after one-time initialization.

It is so easy to make mistakes in 2.PHP that it is difficult to find them. Even if you use Zend Studio, which is essentially from official website, you can't change the fact that you must have enough experience, be rigorous enough and be responsible for QA in order to ensure the high quality of your program. Huang Shang of Taobao once joked about IDE. The reason behind the joke "lack of middleware" has been greatly improved in recent years, mainly because the support of many middleware has become more extensive, which has benefited PHP a lot, but the development is actually in the C and Java communities. Performance and error-prone are technical difficulties brought by language characteristics, and they are also the necessary price of flexibility and rapidity. It is difficult to expect fundamental improvement.

There are also JSTL, Velocity and Freemaker in 3.Java, but compared with PHP's flexible and powerful dynamic ability, rich functions and class libraries, easy learning costs and outrageous documents, it's just slag! JSTL has been changed, so we need to restart the context. Velocity should be restarted regardless of the cache. Velocity cache performance is low, is there anything? Even if these are not important, is it necessary to restart the action after adjusting a data validation rule?

All right, that's it.

In practical work, performance problems can be solved by good architecture, and error-prone problems can be solved by framework, specification and comprehensive testing. Middleware has few choices, but it actually has everything. Java has many solutions to consider, not to mention OSGi and so on. Even the policy of deleting nodes and restarting them after completion can work.

So, you will see many technical teams with a single language. What really considers this problem is more the characteristics and accumulation of the team itself. Bilingual people know why they use these, but don't know how to go their own way. Finally, if you don't know why you want to use the bilingual scheme, you don't have to consider it.

Piggy, writing programs is very interesting.

The biggest advantage of back-end java lies in the huge ecological environment. Java has a ready-made solution to any problem you want to solve. Moreover, compared with other languages, the jvm-based solution is the best in terms of operating efficiency and operation and maintenance cost on average (the ability of operation and maintenance personnel is not discussed here, just assuming that our operation and maintenance is only at an average level), so the back end naturally tends to java, no matter what the front end uses.

As for the front end, the biggest problem is that the UI of a website changes quite frequently, such as traditional java-based development scheme, jsp tag library, freemaker and velocity. . . . How do you want the front-end to modify and debug? How can they understand without special study? Moreover, the development mode of java has always been MVC, and the back-end and front-end are too closely combined. Basically, it is difficult for the front end to work freely in the ui layer. On the other hand, the front-end solution based on PHP, at least the front-end can understand and debug, which is a great productivity liberation. It is said that the back-end java can do rest services, and all the dynamic codes of the front-end are handed over to the front-end engineers. For them, the most comfortable dynamic web page solution is naturally PHP, which is determined by historical precipitation. No one can change it. No matter how much you despise PHP, including myself, I still don't like PHP. As many people answered above, PHP is fast. Where's fast? What did PM say to change? 10 was changed at the front end and released 30 minutes later. Send the task to the back-end engineer? Then wait slowly. . .