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Connect/Web

z/OS  ·  z/Linux  ·  Linux x86  ·  Windows  ·  macOS

< 100 MB

Resident
Memory

~50 ms

3270 Connect
Time

25

AI Agent Tools
Day One

4

CGI Scripting
Languages

z/OS Native Web Server

Mainframe access without the Java stack.

One compiled binary. Browser-based 3270 sessions, z/OSMF-compatible REST APIs, static file serving, CGI scripting in REXX, Java, Python, and PHP — plus first-class AI agent integration. No JVM, no application server, no external dependencies.

Features

Everything your team needs — one binary

Connect/Web hosts multiple components and capabilities under a single configurable webroot. Each component has its own REST API and browser UI, sharing one TLS endpoint, one process, one install.

Agentic 3270 / Web Access

Connect/3270

Native z/OS 3270 automation via MCP and REST API — enabling AI agents to drive mainframe applications through natural language prompts, screen data inference, and scriptable workflows. Human access is also available directly in any standard web browser with no emulator, Java, plug-ins, or middleware required.

  • MCP endpoint for AI agent and LLM integration
  • REST API for natural language prompt-driven 3270 automation and AI inference
  • Web browser access with ~110 ms screen updates, no polling

Browser AI interface

Web Chat UI

A browser-accessible AI chat interface hosted directly on z/OS via Connect/Web. Prompt development, ad-hoc inference queries, and model exploration — from any browser, with no desktop client or VPN required.

  • Hosted on z/OS — no external service required
  • Connects to Connect/AI inference pipeline
  • Accessible from any browser — no install

Web content and scripting

Static Serving + CGI

Connect/Web is a full-featured z/OS web server — it serves static HTML, CSS, JS, and images, and supports CGI scripting in four languages including the mainframe-native REXX.

  • Static file serving from any configured webroot
  • CGI: REXX, Java, Python, PHP
  • Existing REXX tooling runs unmodified
  • Customisable landing page and product UIs

Datasets and USS files

Connect/Files

z/OSMF-compatible REST API for sequential datasets, PDS members, and USS files. Uses Dignus C standard I/O directly. Stateless per request, SAF-gated throughout.

  • Read, write, delete datasets and PDS members
  • Full USS path access — read, write, delete
  • All endpoints mirrored at /zosmf/restfiles/

Jobs and spool

Connect/JES

z/OSMF-compatible REST API for JES. Stateless per request — every call queries JES directly through SAPI, gated by the calling user’s SAF authority. No daemon, no broker.

  • List, submit, delete jobs and read spool files
  • All endpoints mirrored at /zosmf/restjobs/
  • Live spool tail via WebSocket phase 2
  • Job event push — state transitions phase 2

AI gateway

planned
Connect/AI

A streaming proxy to Claude, OpenAI, or customer-deployed LLMs compiled into Connect/Web. Calls 3270, JES, and Files natively using the same WebSocket framing already in production.

  • Chat surface embedded in Connect/Web
  • Native calls to all Connect products — no loopback
  • Streaming responses to the browser

Web Server Capabilities

A complete z/OS web server — static, scripted, and dynamic

Connect/Web is a full-featured web server, not just a REST gateway. It serves static content, processes Server-Side Includes, and executes CGI scripts in four languages — giving teams a range of options from lightweight page assembly to full application logic, all without a separate server process.

HTML, CSS, JS, images

Static file serving

Each site has its own configurable webroot. HTML, CSS, JavaScript, and images are served directly — no middleware, no build step required. Product UIs and the landing page are plain static files, fully replaceable with customer branding.

  • Per-site webroot — fully customer-controlled
  • Customisable landing page linking to enabled products
  • All Connect product UIs are plain HTML/CSS/JS
  • Replace or skin any page without touching code

SSI directives in HTML

Server-Side Includes

SSI lets pages include dynamic fragments without a CGI script. Common headers, footers, navigation, and runtime values are assembled server-side before delivery — keeping static pages DRY without the overhead of full scripting.

  • Standard SSI directives: include, echo, if, set
  • Include shared headers, footers, and nav fragments
  • Echo server variables and environment values inline
  • Conditional output — show content by context
  • Combine with CGI output for mixed-mode pages

REXX · Java · Python · PHP

CGI scripting

Full CGI support for application logic — form processing, z/OS data queries, job submission, and dynamic JSON output. Scripts run as the authenticated user under SAF. Existing REXX execs run without modification.

  • Four languages — including mainframe-native REXX
  • SAF-gated: scripts execute as the calling user
  • Existing REXX tooling runs unmodified
  • Python and PHP for new development
  • Java CGI without a full application server
REXXMainframe-native — runs unmodified
JavaNo application server required
PythonModern scripting and data processing
PHPWeb-native development on z/OS

Compatibility

Drop-in z/OSMF replacement

Every Connect/Web REST endpoint is mounted under both a native path and the IBM z/OSMF REST path. Existing tooling keeps working with a single base-URL change — no code changes, no migration project.

Tool What changes Result
Zowe CLI Base URL only Works immediately
Jenkins z/OSMF plugin Base URL only Works immediately
In-house Python/Java clients Base URL only Works immediately
Custom REST scripts Base URL only Works immediately

Streaming and push endpoints are purely additive — existing calls are unaffected.

“We pointed Zowe CLI at Connect/Web on a Friday afternoon. Everything worked before we left for the weekend.”

— z/OS platform architect

How it works

Each handler is registered once under both paths. A canonicalization step rewrites the z/OSMF path to its native equivalent — single source of truth, two URLs, no duplicated logic.

Performance

Native C vs the Java stack

z/OSMF runs on WebSphere Liberty — a genuinely good engineering choice within the Java ecosystem. Connect/Web doesn’t run Java at all.

Layer z/OSMF on Liberty Connect/Web
Language Java C — compiled native
Runtime JVM + WebSphere Liberty BSD sockets, z/OS APIs
Cold start Seconds to a minute Milliseconds
Resident memory 1–2 GB (IBM recommends REGION=4G) < 100 MB
Garbage collection Yes — tunable, but present None
Latency variance Subject to GC pauses Sub-millisecond
z/OS interface JNI shims to z/OS APIs Direct — SAPI, Dignus C I/O

The win isn’t “Liberty is slow.” It’s “we don’t run Java at all.” For z/OS shops that standardise on compiled native tooling, Connect/Web is a natural fit: no JVM in the operations playbook, no Java runtime in the LPAR.

AI Integration

First-class AI agent access to z/OS

Connect/Web exposes its full surface to AI agents through the Model Context Protocol (MCP) — one protocol, two transports. 25 tools across JES, Files, and Connect/3270 are available to any MCP-speaking agent.

jes_jobs_list jes_submit jes_file_records files_ds_read files_ds_write files_fs_read c3270_connect c3270_read c3270_screen + 16 more

Claude Code (stdio)

Register d21mcp once — tools available in every project session. Ask in natural language; the agent calls the right tools automatically.

Claude.ai enterprise (HTTP MCP)

Add the /mcp/ endpoint as a Custom Integration. All 25 tools appear in every team member’s browser session — no CLI install required.

Set up in one command

claude mcp add d21mcp /d21lib/bin/d21mcp \
  --env D21_CONNECTWEB_URL=\
  https://connectweb.example.com

Then ask naturally:

“What JES jobs are currently running?”

“Open a 3270 session and get me to SDSF DA.”

“Read SYS1.PARMLIB(EASY500) and summarise the key settings.”

Who It's For

Built for every team that touches z/OS

From operators running batch to developers building CGI applications — Connect/Web reduces friction at every layer of the z/OS stack.

Operators

Browser 3270 access from any device. No emulator install, no firewall rule for raw TN3270 ports.

Systems programmers

Read and write PARMMLIB members, datasets, and USS files via REST. Expose tooling as CGI with existing REXX.

DevOps teams

Submit JCL, stream spool output, and handle job events. Zowe CLI and Jenkins keep working unchanged.

Web developers

Build z/OS-integrated web apps in Python, PHP, Java, or REXX — without standing up a separate application server.

AI engineers

25 MCP tools let AI agents reason over z/OS data and drive 3270 sessions — no custom integration code.

Platform architects

Replace z/OSMF's 1–2 GB footprint with tens of MB. No JVM to license, patch, or operate.

Deployment

Simple by design

No install wizard, no application server, no Java runtime. A single binary, a config file, and a webroot.

Single binary

Installs to /d21lib/bin/ on z/OS USS. Started with d21zip —webserver.

TLS included

Terminated natively via d21tls. No reverse proxy required.

Multi-site

Dev and prod from one process — separate webroots, ports, and TLS certs per site.

Flexible CGI

REXX, Java, Python, and PHP CGI configured per site. Existing scripts run without modification.

Multiplatform CLI

d21mcp ships for macOS, Linux, Windows, and z/OS USS — MCP works from any developer laptop.

Resources

Learn more about features

Use cases

Connect/MP › Connect/Web

Use Cases

z/OS  ·  z/Linux  ·  Linux x86  ·  Windows  ·  macOS

Operations

Operator — JES admin on any device

Remote access without a desktop emulator

A team member needs to check a TSO session from a laptop that has no 3270 emulator installed. They open a browser, navigate to Connect/3270, and are at an ISPF panel in under a second.

  1. Open Connect/3270 from any browser
  2. Select host, enter credentials
  3. Full TN3270E session — PF keys, PA keys, hidden fields
  4. Multiple tabs = multiple concurrent sessions
Connect/3270 no install WebSocket

Batch operations team

Monitor and triage batch jobs

An operator needs to check whether overnight batch completed, read JESYSMSG for a failed job, and purge it — all without opening z/OSMF or an ISPF session.

  1. GET /jes/jobs?owner=BATCH&status=OUTPUT
  2. Drill into failed job — read spool files
  3. DELETE /jes/jobs/{name}/{id} to purge
  4. Phase 2: tail live spool as job runs via WebSocket
Connect/JES REST z/OSMF compatible

Systems programmer

Edit a JCL procedure or config dataset

A sysprog needs to quickly update a PARMLIB member during an incident. They PUT the updated content directly via the Files API — no ISPF, no FTP, no file transfer tool.

  1. GET /files/ds/SYS1.PARMLIB(IESYS00)
  2. Edit content locally or in a script
  3. PUT /files/ds/SYS1.PARMLIB(IESYS00)
Connect/Files PDS member REST

Automation & CI/CD

DevOps / pipeline engineer

Migrate existing z/OSMF automation

A team running Zowe CLI or a Jenkins z/OSMF plugin wants to move off z/OSMF without rewriting pipelines. They change one base URL — everything else keeps working.

  1. Point Zowe CLI or Jenkins at Connect/Web base URL
  2. All /zosmf/restjobs/ and /zosmf/restfiles/ paths resolve automatically
  3. No code changes, no new client libraries
  4. Gain streaming/push endpoints as an additive bonus
z/OSMF drop-in Zowe CLI Jenkins

CI/CD pipeline

Submit JCL and stream output in one round trip

A deployment pipeline submits a JCL job and needs to know immediately when it completes — without polling. One request submits and streams JESYSMSG back as the job runs.

  1. PUT /jes/jobs with JCL in body — get jobid back
  2. WebSocket stream opens, JESYSMSG records
  3. Stream closes on job completion — pipeline continues
Connect/JES streamed submit phase 2

Automation / AI engineer

Automate a 3270 logon flow

A team has a legacy application only accessible through ISPF panels. They write a JSON macro to log on, navigate to the app, extract data, and log off — no screen-scraping library needed.

  1. Use bundled TSO logon macro as a starting point
  2. Add find-by-label steps for panel navigation
  3. Variable substitution keeps credentials out of the script
  4. Run via c3270_run from any MCP client
Connect/3270 macros JSON

AI-Assisted Mainframe Work

Developer using Claude Code

Ask an AI agent to investigate a failed job

A developer types a natural-language question. Claude Code calls Connect/MCP tools automatically — no curl, no JSON-RPC — and returns a plain-English summary with the relevant spool output.

  1. “Why did job PAYROLL1 fail last night?”
  2. Agent calls jes_jobs_list, jes_files_list, jes_files_read
  3. Summarises JESYSMSG and pinpoints the abend
Connect/MCP Claude Code JES

Developer unfamiliar with ISPF

Navigate ISPF via natural language

A developer new to z/OS needs to reach SDSF but doesn’t know ISPF panel navigation. They describe what they want; the agent drives the 3270 session using the bundled macro library.

  1. “Open a TN3270 session and get me to SDSF DA”
  2. Agent calls c3270_connect with TSO logon macro
  3. Agent calls c3270_screen and returns the panel
Connect/MCP Connect/3270 Claude Code

Team using Claude.ai enterprise

Mainframe access from Claude.ai web

An enterprise team connects Connect/Web’s HTTP MCP endpoint as a Custom Integration in Claude.ai. All 25 tools are available to every team member in the browser — no CLI install required.

  1. Admin adds /mcp/ URL as a Custom Integration
  2. Tools appear in all team members’ Claude.ai sessions
  3. Auth via TLS + bearer / SSO in front of Connect/Web
Connect/MCP Claude.ai remote MCP

Platform & Deployment

z/OS capacity planner

Replace z/OSMF to reclaim LPAR memory

A shop running z/OSMF with 1–2 GB resident pages wants to recover that memory. Connect/Web handles the same REST surface at tens of MB, with no JVM in the operations playbook.

native C no JVM low footprint

z/OS platform admin

Run isolated dev and prod environments

One Connect/Web binary serves a dev site on port 8080 and a prod site on port 443 with separate webroots, TLS certificates, and feature flags — no second process, no second install.

multi-site single binary TLS

Connect/MP › Connect/Web

Features

z/OS  ·  z/Linux  ·  Linux x86  ·  Windows  ·  macOS

Key Features

Many of the world's top mainframe installations are using Connect/MP every day to simplify and accelerate mainframe file exchange, across the Enterprise and beyond.

Connect/Web  ·  Data 21

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Data 21

About Data 21

Founded in 1980, Data 21 Inc. is a veteran-owned enterprise software company headquartered in California. For over 45 years, we have delivered innovative, reliable, high-performance mainframe-centric solutions that power today’s connected enterprise.

Our software is embedded in the critical daily operations of hundreds of enterprises worldwide — a testament to our commitment to exceptional engineering and long-term client success. We don’t just support our customers; we evolve alongside them.

At Data 21, the mainframe isn’t a legacy constraint — it’s a strategic foundation.

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