What Zowe is and how it connects

Why Zowe exists

For decades the only way to work on z/OS was a 3270 terminal running TSO and ISPF. It works, but new developers arrive knowing VS Code, terminals, scripts and Git, and the green screen is hard to automate. Zowe was started in 2018 under the Open Mainframe Project, part of the Linux Foundation, so that the mainframe could be driven by the same kind of tools as any other server. IBM, Broadcom, Rocket Software and others contribute to it, and the code is open source.

Zowe does not replace ISPF. Many experienced people use both: ISPF for quick browsing and utilities, Zowe tools when they want an editor with search, side-by-side compare, or scripting.

The main pieces

An important point that confuses people: you can use Zowe Explorer and the Zowe CLI without installing the Zowe server components at all. All they need is a REST service on z/OS that understands requests such as 'list these datasets' or 'submit this job'. At most sites that service is z/OSMF.

z/OSMF as the back end

z/OSMF (z/OS Management Facility) is part of z/OS. It runs as started tasks on a Liberty web server and provides REST interfaces for files, jobs and system tasks. When you click a dataset in VS Code, Zowe Explorer sends an HTTPS request to z/OSMF, which reads the dataset with your user ID and sends the content back.

Because every request runs under your own identity, RACF (or ACF2 or Top Secret) checks it exactly as it would in TSO. Zowe gives you no extra authority. If you cannot read a dataset in ISPF, you cannot read it in VS Code either.

Profiles and the team configuration

Zowe needs to know the host name, port and how to sign on. Since Zowe version 2 this is kept in a team configuration file called zowe.config.json. It holds profiles: a z/OSMF profile for the REST connection, a base profile with shared values, and optionally SSH or TSO profiles. A team can keep the shared file in a project folder or Git repository, and each person keeps their own overrides in zowe.config.user.json.

{
  "profiles": {
    "lpar1": {
      "properties": { "host": "mvs1.example.com" },
      "profiles": {
        "zosmf": { "type": "zosmf", "properties": { "port": 443 } }
      },
      "secure": ["user", "password"]
    }
  },
  "defaults": { "zosmf": "lpar1.zosmf" }
}

The secure array lists properties that must not be written to the file. Zowe stores them in the operating system's credential store instead (Windows Credential Manager, macOS Keychain or a Linux keyring).

Common first-day problems

zowe zosmf check status is a quick way to test the connection from the CLI: if it works, the profile, network and sign-on are all correct.