1. Software development
Software development is the process of building a software system or a software part of the system according to user requirements.
Software is generally implemented using some programming language. Usually, software development tools can be used for development. Software is divided into system software and application software, and not only includes programs that can run on computers, but files related to these programs are generally considered to be part of the software.
1.1 System software
System software refers to the system that controls and coordinates computers and external devices, and supports the development and operation of application software. It is a collection of various programs without user intervention. The main function is to schedule, monitor and maintain computer systems; it is responsible for managing various Independent hardware allows them to work in harmony. System software enables computer users and other software to treat the computer as a whole without concern for how the underlying individual pieces of hardware work.
Generally speaking, system software includes an operating system and a series of basic tools (such as compilers, database management, memory formatting, file system management, user authentication, driver management, network connection, etc.), which are tools that support computer systems. That part of the software that functions properly and implements the user's actions.
System software is generally carried along with the computer system when it is purchased, and can also be installed separately as needed.
1.2 Application software
Application software (Application) corresponds to system software, and is a collection of various programming languages that users can use, as well as application programs compiled in various programming languages.
Application software is the part of software provided to meet the application needs of users in different fields and problems. It can broaden the application fields of computer systems and amplify the functions of hardware.
1.3 Human-computer interaction mode
Graphical User Interface GUI (Graphical User Interface GUI) is simple and intuitive, easy for users to accept, and easy to operate.
Command Line Interface CLI: You need a console to enter specific instructions to let the computer complete some operations. It is more troublesome, and some commands need to be recorded.
2. Software structure mode
2.1 C/S structure
Server-client, namely Client-Server (C/S) structure. The C/S structure usually adopts a two-tier structure. The server is responsible for data management, and the client is responsible for completing the interactive tasks with users.
In the C/S structure, the application program is divided into two parts: the server part and the client part. The server part is the information and functions shared by multiple users, and performs background services, such as controlling the operation of the shared database; function, and can freely switch between subroutines.
The C/S structure is very mature in technology, and its main features are strong interactivity, safe access mode, fast response speed, and favorable processing of large amounts of data. However, the C/S structure lacks versatility, and system maintenance and upgrades require redesign and development, which increases the difficulty of maintenance and management, and further data expansion is more difficult, so the C/S structure is limited to small LANs.
2.2 B/S structure
The B/S architecture is the browser and server architecture model, which is a change or improved architecture of the C/S architecture with the rise of Internet technology.
Under this architecture, the user interface is realized through the WWW browser, and a very small part of the business logic is realized on the front end (Browser), but the main business logic is realized on the server side (Server), forming a so-called three-tier structure.
The B/S architecture is a network architecture model after the rise of the WEB, and the WEB browser is the most important application software on the client side. This mode unifies the client, concentrates the core part of system function realization on the server, and simplifies the development, maintenance and use of the system. Just install a browser (Browser) on the client computer, such as Netscape Navigator or Internet Explorer, and install Oracle, Sybase, Informix or SQL Server and other databases on the server. The browser interacts with the database through the Web Server. This greatly simplifies the client computer load, reduces the cost and workload of system maintenance and upgrades, and reduces the total cost of ownership (TCO) for users.
3. Development of application software
In the era when the operating system was still a text interface, the main functions of people using computers were word processing and calculation, and there was no entertainment. Playing games is all in the form of characters: you enter a command, and then the computer displays a text or number on the black and white interface to indicate the result, which is not fun to think about.
In the late 1990s, the country began to use the Internet. At that time, we used telephone lines to surf the Internet, and the network speed was very slow, about 16-256 kilobytes (K). Now we all use megabytes (M), and the difference between them is 1000 times.
From the numbers, we can see how slow the Internet speed was at that time. But at that time, everyone didn't feel slow, why? Because at that time, people could only read news when surfing the Internet, and at the beginning, all the news was text news, and there were no pictures. Later, as the Internet speed became faster, there were pictures in the news, unlike now, in the news There are videos.
I remember that the browser at that time also had a function of not displaying pictures, but only displaying text, which can reduce traffic and increase display speed.
So around 2000, many websites appeared, which specialize in displaying news, such as Sohu, Sina, Yahoo, NetEase and so on. Everyone surfs the Internet, apart from reading the news, there is nothing else to do.
At this time, the game rises. But it is also a stand-alone version of the game, do not need to be connected to the Internet. The development of games has also spawned a large number of computer users, and the number of people using computers has expanded, and it has become more and more interesting.
Around 2002, it was the trough of the Internet. Because of the enthusiasm of everyone in the past few years, various investments and companies have invested in the Internet, but there is nothing else to do except for the news website. There is no content, no application, and we do it. Just look at the news, wondering what else to do on the Internet? So everyone thinks that the Internet is a bubble and withdraws one after another.
When Ma Yun first started his business, he also started the enterprise yellow pages, similar to enterprise information query websites, which also ended in failure.
The SARS in 2003 can be said to have greatly promoted Internet applications from another aspect. Everyone can't go out, neither go to work nor go shopping, so what are you doing? Can only play at home. At this time, Taobao appeared. Everyone can go shopping at home. SARS greatly promoted the use of Taobao.
At the beginning, Taobao was only limited to the purchase of certain commodities, but now, as everyone has seen, it is almost omnipotent.
I have talked so much with you, but I actually want to say: There are many industries in this society, and now the Internet has been integrated into all walks of life in this society, and there is no industry that does not involve the Internet.
All future enterprises will be Internet enterprises, and enterprises that do not use the Internet will inevitably be eliminated. Why? The Internet is actually a tool, a platform, which can greatly reduce the distance between people, reduce communication costs, and improve communication efficiency.
When we were in school in the 1990s, we all relied on writing letters to communicate with each other, and it took several months to go back and forth. The question you wrote in this letter, wait for the other party to answer, and several months have passed since you received the reply, and you have forgotten what the question was in the last letter.
Now, it's almost all real-time communication. So the Internet is a tool, a tool with advanced productivity. Everyone else is using the Internet to improve productivity, but if you don’t use it, you will fall behind and get beaten! For example: It's like when we go to Beijing, everyone takes the high-speed rail, but you have to take the bus and take the national highway. Do you think you can beat others?
Therefore, future enterprises will be Internet enterprises, and all enterprises will and must use the Internet. The Internet touches every aspect of us.
Now the Internet has solved our shopping, catering, and will further involve finance, education, and medical care in the future. The next step is to focus on smart devices, driverless cars, and so on.
In fact, the development of the Internet in our country has surpassed that of developed countries in Europe and America. We can now go out with only our mobile phones, not even our wallets. This is not possible in Europe and America.
With the popularity of Internet applications, more and more software developers will be needed. Because all functions need software to complete, hardware without software is useless. For example, a laptop is basically useless without software installed.
Therefore, the demand for software talents will increase! This is the development of science and technology, the requirement of the times, the trend of the development of human society, and an inevitable trend, not a flash in the pan.
This also explains why the Prime Minister proposed "Internet +" and regarded the Internet as a national strategy. Simply put, "Internet +" is to use the Internet to transform all industries and transform all enterprises.
In this case, will the demand for Internet development talents be small?
4. Java application level
The first point: the third-party trading system. Answer: The use of Java is widely used in the financial industry. The service software of many banks and securities, as well as the trading platform Murex, are all written in Java, and are connected to many bank front desks to provide services.
The second point: website construction. Java occupies a large share in the field of website development with its powerful front-end capabilities and various powerful frameworks. And we can use many different frameworks to create web projects. Websites of government agencies, hospitals, insurance and many others are developed based on Java.
The third point: mobile Internet applications. It can be said that another powerful field of Java is the Android system and mobile apps. When you turn on the phone, any app application is written in Java.
The fourth point: big data technology. Java big data can be said to be a relatively hot profession now, and the salary starts from 10,000 yuan, but the requirements of Java big data are relatively high, and education is also more important. If you learn well in this area, it is relatively easy to find a job.
The fifth point: the field of embedded development. Several products have brought the high productivity of the extensive Java Standard Edition library to the embedded development arena. About 5 to 7 years after Java entered the territory of embedded systems, Java products for hard real-time and deeply embedded systems have shown a scene full of vitality.
