Flexible combination of applications is a false proposition that has existed for 40 years

1995-1999 In between , Particularly popular components DNA The word , It is said that the flexible combination of applications can be achieved . How fascinating this vision is .

But the components DNA How did this concept come about 、 How did it evolve , Only then can we know what problem it actually solves .

I am from 90 years CORBA From the times , Let me tell you about this historical evolution .

（1）1984 Year is a magical year

1984 year ,Sun The company's is Unix In the system RPC（ Remote procedure call ）, Used to support calls between heterogeneous distributed systems .

1984 year , An Indian guy broke into the United States , Invented a distributed messaging middleware , That's what happened TIBCO company .

1984 year , Bell Labs developed distributed transaction middleware ：Tuxedo.

（2） Let's just talk about RPC

RPC There are several core elements ：

1、Proxy/Stub Mechanism

2、 Registration and discovery basic services

3、IDL Interface description language

4、 Network transmission ：TCP/IP Network communication protocol 、 Transmit binary

（3） We have to mention CORBA

1990 Year by year IBM、HP、Novell And other companies jointly formulated CORBA standard , Is to put RPC From UNIX It is extracted separately from the operating system . It should be said that from now on , The real middleware market is formed .

CORBA Is a big integrator ：

1、ORB（ Object request proxy implementation ）

2、 Name registration and discovery basic services （ This and RPC No difference ）

3、IDL Interface description language （ This and RPC No difference ）

4、IIOP Application call protocol （ This is a comparison RPC New application layer protocol ）

5、 Network transmission ：Http/s、XML Text

And then mixed with the message services that existed in the past 、 Business services , This constitutes CORBA The system of .

CORBA Also trying to solve the object lifecycle service （ Such as the establishment of objects 、 The destruction 、 clone 、 Pooling, etc ）, But it has not been solved well , It's got COM/EJB Component era , To better solve the life cycle service .

（4） Let's talk about WebService

2001 year ,W3C The organization released WebService technical standard ：

1、

2、UDDI Registration and discovery basic services

3、WSDL Interface description language

4、SOAP Application call protocol

5、 Network transmission ：Http/s、XML Text

In fact, you can know at a glance , This is it. 1984 year RPC Improvements on the Internet

（5）SOA And micro services have to be mentioned

Many people put SOA and WebService Mix it up .

Actually SOA The core of is three elements ：

SCA： Service oriented components

SDO： Service data objects

BPEL： Business logic execution language

But none of these three things has caught on .

and SOA What people know is ：ESB, Enterprise service bus . Actually, enterprise service bus , The core is WebService Those four elements .

These four core elements , It has also evolved in the era of microservices ：

1、 Registration and discovery basic services , It evolved into API Gateway middleware （ Solve internal and external problems ） And microservice middleware （ Solve the internal ）

2、WSDL Interface description language （ This has not changed for decades ）

3、SOAP Application call protocol , Now everyone uses RESTFul 了

4、 Network transmission ：Http/s、JSON Text

（6） Let's talk about other middleware

Except what we said at the beginning 1984 Produced in ：RPC middleware 、 Message middleware 、 Transaction middleware . Later, two middleware came into being .

One is with the emergence of the Internet , Produced Web middleware , Such as Apache Server. similar Tomcat Handle JSP Web page , Also calculate Web The category of middleware .

One is component container middleware . This was first in 1995 Microsoft released DCOM It comes into being when , Later, it evolved to COM+、.NET. stay Java system , stay 1997 Year of J2EE The technical system has also been realized , This is it. EJB Component container middleware . later , Component container middleware has also evolved to NO EJB、SOA In the era of Cloud Foundry Bundle Containers , And containers in the era of microservices . Now it is popular based on WASM The container of Technology .

（7） summary

in other words ： The core of middleware is to solve the technical support that can be invoked between distributed applications .

If you don't have a headache for distributed applications , Then it's useless for you to use this set .

If you want to use this technology to solve how applications can be flexibly combined , Then you are really wrong .