Shulou(Shulou.com)06/01 Report--

This article shows you how Node compares to Java as a backend server. The content is concise and easy to understand. It will definitely make you shine. I hope you can gain something from the detailed introduction of this article.

What exactly is Node.js? Is it a new language or a new framework, a new tool or just a simple JavaScript file?

runtime environment

Java is known to have a runtime environment called JRE that enables Java programs to run smoothly. JRE has a virtual machine called JVM. The JVM has many components, such as garbage collector (GC), just-in-time (JIT) compiler, interpreter, class loader, thread manager, exception handler, for performing different tasks at different times. JRE also has a series of libraries to help Java programs run at time.

Why are we suddenly involved in the JRE runtime environment, in fact, it is to compare with node, Node is not a language, nor a framework, nor a tool, it is a runtime environment for running JavaScript applications. Node.js has a virtual machine called JavaScript Virtual Machine. It generates machine code for JavaScript-based applications to enable it on different platforms. This virtual machine is Google's V8 engine and has major components such as JIT and GC for task execution, runtime compilation, and memory management, respectively.

development potential

Judging the development potential of Java and node may have to start from the ecological community and support library behind it, but the traditional system with Java as the core is naturally inferior to the new force such as node. In short, Java is mature and huge, and node is fast and active. Java its functionality and practicality naturally needless to say, but java contains a lot of sample code, disturbing the program ape wants to express the intention, not as good as java one of the three frameworks of spring, program ape in the use of spring servlet, data persistence, and make up the underlying things of the system, spring framework has been packaged to help you deal with all this, we only need to focus on writing business layer code enough. But in Spring, subsystem by subsystem, you make the slightest mistake and it punishes you with an exception that crashes you. And then you might see a huge anomaly. It contains a well-packaged method that you don't know about, and Spring does a lot of work to implement the functionality of the code. This level of abstraction obviously requires a lot of logic, and a long exception message isn't necessarily a bad thing; it points to a symptom: how much memory and performance overhead does it cost? How is Spring executed? Frameworks need to parse method names, guess programmer intent, build something like an abstract syntax tree, generate SQL, and so on. How much is the extra cost of these things? So using java to mask complexity doesn't simplify it, it just makes the system more complex. Java's strict type checking allows Java to help you avoid many types of bugs because bad code doesn't compile. The downside of Java's strong typing is too much boilerplate code. Programmers need to keep converting, spend more time writing accurate code, use more boilerplate code, and try to catch errors early and correct them.

Node.js is the opposite. Threads lead to more complex systems. So Node.js uses a lightweight, single-threaded system that takes advantage of js anonymous functions for asynchronous callbacks, and you simply use anonymous functions, i.e. closures. No need to search for the correct abstract interface, just write down the business code, no redundancy. This is the best thing about using Node.js, but asynchronous callbacks naturally present an urgent problem: callback traps.

In Node.js, it's easy to fall into the trap of callback functions while nesting them, and each level of nesting makes the code more complex, making error handling and result handling more difficult. A related problem is that the js language doesn't help programmers express asynchronous execution properly. Some libraries actually use Promise to simplify asynchronous operations, but it seems that we simplify the problem, but in fact the code level is more complicated, Promise uses a lot of boilerplate code, masking the programmer's true intention. Node.js supports ES5 and ES6, and callback functions can be rewritten with async/await functions. It's the same asynchronous structure, but written using the normal loop structure. Errors and consequences are handled naturally, code is easier to understand, easier to write, and the programmer's intent is also easier to understand. Callback traps are not solved in a way that masks complexity. Instead, language and paradigm changes address callback traps, as well as excessive boilerplate code. With async functions, the code is even more beautiful. Simplistic solution that turns the disadvantages of Node.js into advantages.

But JavaScript is loosely typed. And you don't get errors when you write code. Many types don't need to be defined and usually don't need to be converted. Therefore, the code is clearer and easier to read, but there is a risk of missing coding errors. Only when compiling will you check whether there are problems in your syntax and logic. Therefore, in Node.js, in order to better debug bugs, node supports dividing the program into different modules. Because there are modules, the scope of errors will be reduced to a certain range, making Node.js modules easier to test.

package management

One of the most important problems with java is that there is no unified package management system. Some people may say Maven to me. But in terms of purpose, ease of use, and functionality, Maven is a world away from Node.js package management system. npm is the package management tool provided by Node.js officially. It has become the standard publishing platform for Node.js packages, which is used for publishing, propagation and dependency control of Node.js packages. Npm provides command-line tools that allow you to download, install, upgrade, delete packages easily, and also allow you to publish and maintain packages as a developer. The best part is that the npm codebase is not only available to Node.js, but also to front-end engineers. All front-end JavaScript libraries exist as npm packages. Many front-end tools such as Webpack are written in Node.js.

performance

Java uses HotSpot, a super virtual machine that uses a multibyte compilation strategy. It detects frequently executed code, and the more times a piece of code is executed, the more optimizations are applied. HotSpot performance is therefore relatively fast. Node underlying choice with c++ and v8 engine to implement, node.js event-driven mechanism, which means that in the face of large-scale http requests, node.js is done by event-driven, the performance part is not to worry about, and very good. And, thanks to improvements in the V8 engine, every release of Node.js brings a huge performance boost.

Although Node has extremely high performance for highly concurrent applications, Node.js also has its own shortcomings:

Node is not suitable for CPU-intensive applications, because if CPU-intensive applications have long-term operations, they are not as good as large loops, which will cause CPU time slices to be released, causing all subsequent IO operations to be suspended.

And Node only supports single-core CPU, which cannot fully utilize CPU resources.

Low reliability, once a link in the code crashes, it will cause the entire system to crash, because Node uses a single process.

Node's open source component library is uneven in quality, updates quickly, and is not backward compatible.

In fact, Node.js as a backend can achieve almost all applications, but when we choose to consider more is not suitable for Node.

What's the difference between Node and Java as back-end servers? Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserves, please pay attention to the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.