What do programmers often mean by API? What are the API types?

Programmers often say API What does that mean? ？API What are the types ？

API What does that mean ？ By definition ,API(Application Programming Interface), Chinese translation is an application programming interface , Are some predefined functions , The goal is to provide applications and developers with the ability to access a set of routines based on certain software or hardware , Without access to the source code , Or understand the details of the internal working mechanism .

Some companies will package programs , If you take out some functions in the database application and package them into a function , You just need to call the function , You can realize some functions —— And the encapsulated function , It's called API, When you use it, you only need to call the interface for you （API） That's all right. , Like input and output , Function function ,Java Inside math class ,system class ,object class ,Arrays class ,Date class ,Simple Date Format Various functions encapsulated in the class .

 
API The type of

Remote procedure call （RPC）：

Remote procedure call protocol , A way to request services from a remote computer over a network , You don't need to know the protocols of the underlying network technology .RPC It assumes the existence of certain agreements , for example TPC/UDP etc. , Carry information data between communication programs . stay OSI In the seven layer network model ,RPC Across the transport and application layers ,RPC Make development , Applications, including network distributed multiprogramming, are easier . By acting on a shared data buffer （ Or task ） Realize the communication between programs .

Standard query language （SQL）：

A language that operates databases , Including creating databases 、 Delete database 、 Query log 、 Modify the record 、 Add fields, etc .SQL  Although it is a kind of being  ANSI  Standardized language , But it has many different implementations . It is a standard query language for accessing data , Realize data sharing between application programs through general database .

File transfer ：

File transfer realizes data sharing between applications by sending format files .

Information delivery ：

Small formatted information between loosely or tightly coupled applications , Data sharing is realized through direct communication between programs .

Currently applied to API The criteria include ANSI standard SQL API. In addition, some other standards are still being developed .API Can be applied to all computer platforms and operating systems . these API Connecting data in different formats （ Such as shared data buffer 、 database structure 、 File framework ）. Each data format requires different data commands and parameters to achieve correct data communication , But there are also different types of errors . therefore , In addition to the knowledge required to perform data sharing tasks , These types of API Many network parameter problems and possible error conditions have to be solved , That is, every application must know whether it has strong performance to support the communication between programs .

On the contrary, because of this API Only one information format , So information delivery in this case API Only small commands are available 、 A subset of network parameters and error conditions . Because of that , deliver API This method greatly reduces the complexity of the system , So when an application needs to share data through multiple platforms , Using information delivery API Type is the ideal choice . namely API Data interface is a kind of middleware , It can provide data sharing for different platforms . For example, next second data supports connection to relational databases 、 Big data storage 、SaaS、API、IoT Data such as , And do daily updates , Through the enterprise ERP System and sales system , Let enterprises get rid of Excel Table and IT report form , Realize real-time monitoring of data on different platforms , Reduce reporting , Enterprises can react quickly to data .


API Interface with graphical user （GUI） Or command interface has distinct The difference ：API An interface is an operating system or program interface , The latter two belong to the direct user interface . Sometimes the company will API As its public open system . in other words , The company develops its own system interface standards , When you need to perform system integration 、 Customization and application operations , All members of the company can call the source code through the interface standard , The interface standard is called open API.