For organizations with IBM mainframes or IBM i systems, Microsoft’s December 2025 announcements changed the planning horizon. Alongside the end of life of BizTalk Server, Microsoft announced Host Integration Server 2028 as a standalone product – the first time in more than twenty years that HIS is not tied to BizTalk. If your integration landscape talks to CICS, IMS, DB2 or host files today, you now have a decision to make about where that connectivity lives for the next decade. This guide lays out the dates, the options and an approach to choosing between them.
What Host Integration Server does
Host Integration Server connects IBM mainframe and midrange systems with applications and services on the Microsoft platform. Its capabilities fall into a few areas:
- Network integration – SNA gateway services for host networks that still use SNA.
- Data integration – access to DB2 and other host data sources from .NET and SQL Server.
- Application integration – calling CICS and IMS transactions from Windows applications.
- Messaging integration – connectivity with IBM MQ.
- Security integration – mapping Windows identities to host credentials.
Many organizations use only one or two of these areas, usually through BizTalk adapters. Knowing exactly which ones you use is the first step of any plan.
The dates that frame your plan
| Item | Date |
|---|---|
| BizTalk Server end of life and HIS 2028 announced | December 16, 2025 |
| HIS 2020 mainstream support ends (extended from July 2025) | July 11, 2028 |
| HIS 2020 extended support ends | July 9, 2030 |
| HIS 2028 general availability (planned) | Reported as planned for September 2027; an early adopter program is available |
Treat the HIS 2028 date as a plan, not a commitment, and check Microsoft’s lifecycle pages before you lock budgets to it.
Four options
| Option | When it fits | Main risk |
|---|---|---|
| 1. Stay on HIS 2020 for now | Stable estate, limited change, mainframe itself has a known end date | Running out of support while the host is still critical |
| 2. Upgrade to standalone HIS 2028 | You need SNA, deep host security integration or HIS features without a cloud equivalent | Planning around a GA date that may move; still a server product to operate |
| 3. Move to Azure Logic Apps Standard host connectors | Host access is mainly TCP/IP-based CICS, IMS, DB2, MQ or host files, and integration is moving to Azure anyway | Network path to the data center and performance under host transaction volumes |
| 4. Hybrid: Logic Apps on your own infrastructure | Data must stay on premises or latency to the host must be minimal | Operating a Kubernetes-based runtime |
Option 3 builds on Microsoft’s work to bring host integration technologies into Logic Apps Standard as built-in connectors for scenarios such as CICS, IMS, 3270 screens, host files, DB2 and IBM MQ, with tooling to generate the metadata that describes host programs and data layouts. For option 4, see running Logic Apps hybrid on an RKE2 Kubernetes cluster.
How to decide: an inventory first
Before choosing an option, inventory every host interaction. For each one, record:
- Protocol – TCP/IP or SNA. SNA-dependent interfaces need an SNA-capable gateway, which narrows the options considerably.
- Interaction type – transaction call (CICS/IMS), screen (3270/5250), data access (DB2, files) or messaging (MQ).
- Volume and latency – peak transactions per second and acceptable response times. Host-heavy batch windows deserve special attention.
- Data conversion – code pages, packed decimals and copybook structures. Conversion bugs are the classic source of silent data corruption in host migrations.
- Transaction semantics – whether the interface relies on two-phase commit or other host transaction behaviour.
- Security – how identities map to host credentials (RACF, ACF2, Top Secret) and who owns that mapping.
- Owner and future – is the host application itself being replaced, and when?
The last question is often decisive. If the mainframe application will be retired in 2029, a short bridge on HIS 2020 or 2028 may be cheaper than re-platforming the integration twice.
A migration approach that limits risk
- Separate the host adapter from the integration logic. Whatever platform you choose, put host access behind a small, well-defined interface – an API or a message contract – so the rest of the landscape does not depend on HIS specifics.
- Migrate by interaction type, starting with read-only data access, then messaging, then transactional calls.
- Run in parallel and compare results field by field, especially numeric and date fields after code page conversion.
- Load test against the host with production-like volumes; mainframe capacity is shared and expensive.
- Plan BizTalk decommissioning in the same program. HIS questions rarely exist without BizTalk questions; see Integration Account modernization and flat file schema generation for BizTalk modernization.
Checklist
- Inventory of host interactions with protocol, type, volume, conversion and security details.
- Decision per interaction: stay, HIS 2028, Logic Apps connectors or hybrid.
- Support dates for HIS 2020 and BizTalk mapped against the program timeline.
- Host access isolated behind stable interfaces.
- Parallel run and load test planned with the host team.
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