Undesratnd Docker Useful for Legacy Programmers

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You can ask a question as ” Hey I am mainframe programmer, and I do not know about Docker, can you tell me about it?” Not only you, but there are many others like you.

I have written this post to make it useful for mainframe developers.

The Mainframe

In Mainframe, you can install software, build applications, and deploy into production. These are possible within the mainframe, and you cannot run these applications in another machine.

How it works

  • The mainframe has a limitation, only it allows compatible software for Zos. 
  • You need to develop in and deploy there.
  • You cannot create distributable platforms.

The distributable means,

A platform developed once, and shippable to any device. One best example is,  a docker image you can use it on PC, the cloud, data center or a virtual machine.

Docker image
Docker image

Where the Docker comes into the picture

Docker Image

In simple terms, packaging all the required software in one application is called Docker image. It is also called a portable platform.

Docker image vs container

  • Docker images created from docker file
  • Docker images stored in Docker registry (Docker hub)
  • Docker images can be downloaded with PULL command
  • Docker images are not executable
  • Docker container create from images

Why Docker You Need

  1. You can create a Docker Image and use it on any device or platform.
  2. Docker image is an executable platform
  3. Using Dockerfile you can create Docker Image. The Dockerfile is not executable.

Docker Vs Virtual Machine

You may ask a question when the virtual machine is there why Docker is needed. 

  • Docker image run in a Docker container. You can install “n” number of containers in one operating system (os).
  • Virtual machine runs on a separate guest OS.
  • Docker container has its own file system. All the containers work independently. 
  • Possible that Docker containers can communicate with each other.