Do you still rely on AS400/iSeries systems and want to incorporate artificial intelligence without migrating your entire core? With AS400/iSeries MCP Server, our new open‑source product, you can now connect AI agents directly to IBM i systems—moving beyond green screens and enabling conversational flows.
If there’s something we’ve learned since founding Abstracta, it’s that innovation doesn’t always mean breaking away from what already works. For instance, in banking, IBM i systems like AS400 or iSeries remain both reliable and powerful.
However, in many organizations, their use is still limited to traditional setups, with inflexible interfaces and workflows that don’t easily connect with current technologies.
As expectations around technology quality grow and IT teams look to automate processes with artificial intelligence, these environments become a friction point.
Our AS400/iSeries MCP Server was created as a response to that tension. This open-source server enables AI agents to interact directly with IBM i systems, without replacing the core or rewriting existing logic.
Need help creating a custom AI agent?
Explore our AI Agent Development Services and schedule a meeting with our team.
What are AS400, iSeries, and IBM i?
The terms AS400, iSeries, and IBM i refer to successive generations of IBM midrange systems that remain critical in banking, logistics, and insurance. Despite name changes, these systems share architecture based on Power Systems and run the IBM i operating system.
- AS400 debuted in 1988.
- iSeries emerged in the 2000s as its evolution.
- IBM i is the current name of the operating system.
Although reliable, these environments pose integration challenges due to their text-based interface—known as the green screen—which limits seamless interaction with modern technologies.
The Challenge: Modernize Without Disruption
Most banks operate with a combination of new technologies and legacy systems. In this setup, AS400 or iSeries environments often hold critical information, consolidated transactional logic, and key business processes.
Migrating this ecosystem entirely is costly, risky, and slow—all while business units demand greater agility. IT teams must expose data, automate tasks, and develop fresh experiences quickly. And that’s where the conflict arises: how can a chatbot or a modern app interact with a system that only responds through a text terminal?
AS400/iSeries MCP Server makes it possible to overcome that barrier without disrupting the original system. How? By connecting the existing with the new through conversational flows built on technical structures that previously only specialists could operate.
What is AS400/iSeries MCP Server?
AS400/iSeries MCP Server is a modular server that acts as an interface between IBM i systems and modern AI-based tools. It was designed to integrate with terminal protocols such as TN5250, TN3270, and VT420, modeling interactions through structured YAML files.
As an open‑source tool, it exposes the business logic contained in AS400/iSeries through tools compatible with AI agents, testing flows, conversational assistants, and automation platforms.
What Is It For?
With AS400/iSeries MCP Server, you can:
- Let an AI agent query, update, or enter data directly into IBM i.
- Execute full transactions that previously required human intervention at a terminal.
- Integrate services such as conversational assistants, decision engines, or automated processes with flows that translate into actions within the legacy environment.
The product translates the structured language of these systems into an interface that is more understandable and flexible—without touching the core or compromising its integrity.
What Problem Does It Solve?
Institutions like banks and insurers depend on AS400/iSeries for critical operations, but their interfaces weren’t built for modern APIs or language models. This leads to:
- Difficulty exposing business‑useful data in real time
- Dependence on technical specialists skilled in 5250 or 3270 terminals.
- Slowness in scaling new solutions on an architecture that is robust but closed.
AS400/iSeries MCP Server bridges this gap by offering a translation layer between AI agents and legacy systems—boosting innovation without requiring complex migrations or duplicated efforts.
AS400/iSeries MCP Server is already available on GitHub.
Access the repository here.
Typical Use Cases
Automate login to TN5250 or TN3270 terminals
The AS400/iSeries MCP Server lets you define a YAML flow that fills in the username and password fields and sends a confirmation key. This flow mirrors the manual input a human operator performs, with higher speed and no errors.
Run flows with YAML
Each YAML file can represent a complete transaction, from data entry through command execution. This allows you to operate on legacy logic as if you were interacting with an API, without changing the original system.
Integrate chatbots with IBM i systems
A chatbot can receive a user’s instruction and, through the MCP server, execute the corresponding action in the AS400 environment. This supports conversational experiences with real data without exposing technical complexities.
Simulate sessions with Wiresham
Wiresham lets you record real sessions over RTE and replay them in test environments. This way, you can replicate cases without a direct connection to the mainframe, analyze errors, or document critical flows.
Technical Overview
How AS400/iSeries MCP Server works technically
The server runs on Java 21 and can be used in two modes:
- SSE mode (default):
java -jar target/rte-mcp-server-0.0.1-SNAPSHOT.jar - STDIO mode (alternative):
java -jar –Dspring.ai.mcp.server.stdio=true rte-mcp-server-0.0.1-SNAPSHOT.jar
You can extend its capabilities by implementing custom tools based on the RteUtils class, which provides the core functionality for the implementation. To create these features, you just need to implement a class with the @Service annotation and add the methods you want to expose using the @Tool annotation. These methods define how the agent interacts with the IBM i environment.
Define Flows with YAML
YAML files describe each RTE session step, including:
- Server configuration
- Screen actions
- Confirmation keys
config:
server: localhost
port: 2324
protocol: TN5250
terminalType: 'IBM-3477-FC: 27x132'
sslType: None steps:
- actions:
- label: User
input: TESTUSR
- label: Password
input: TESTPSW
attentionKey: ENTER This makes it possible to define complex flows in just a few steps, reusable and readable by other systems.
As an example, below we share a flow executed by Claude in the terminal emulator when asked to use the mcp command, an internal protocol (Model Context Protocol) that enables secure connections between the model and external systems.
Supported Protocols and Terminals
Supported Protocols and Terminals
The server supports multiple IBM protocols and commonly used terminals:
| Protocol | Compatible terminals |
| TN5250 | IBM-3477-FC, IBM-3179-2 |
| TN3270 | IBM-3278-M2, M3, M4, M5 (and E variants) |
| VT420 | VT420-7 |
It is possible to enable encryption with None, TLS, or SSLv3.
What Does This Product Bring to Abstracta?
AS400/iSeries MCP Server reflects Abstracta’s clear vision: accelerate modernization without dismantling what works. Through this product, we:
- Reinforce our role as a strategic ally in digital transformation
- Enable AI adoption across legacy infrastructure industries
- Deliver an open, practical, and scalable tool
Conclusion
AS400/iSeries MCP Server doesn’t replace your legacy system—it transforms it into an AI-ready platform. It connects your critical infrastructure with modern conversational flows and conversational agents—without touching your core.
Want to try it out? Download the project, set up your first flow, and reach out to us to move forward with modernization.
How We Can Help You
With nearly 2 decades of experience and a global presence, Abstracta is a leading technology solutions company with offices in the United States, Chile, Colombia, and Uruguay. We specialize in software development, AI-driven innovations & copilots, and end-to-end software testing services.
We believe that actively bonding ties propels us further and helps us enhance our clients’ software. That’s why we’ve forged robust partnerships with industry leaders like Microsoft, Datadog, Tricentis, Perforce BlazeMeter, Saucelab, and PractiTest.
Our holistic approach enables us to support you across the entire software development life cycle.
Explore our Performance Testing Services and contact us to grow your business!
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