SNA Server Changes with the Times

SNA Server, an original member of the BackOffice Suite, has matured. From the commando charged with breaking down the barriers of entry in large shops, it has grown to a tool that serves as a PC-to-SNA gateway and as a true application integration engine.

SNA Server 4.0, launched one year ago, was a big step in this progression. More recently, Service Pack 2, still in beta release as this article went to print, raised SNA’s capability higher, particularly for mainframe application integration.

At the most sophisticated level, SNA Server can participate as a peer in a mainframe CICS two-phase commit transactional environment, and can propagate messages from mainframe applications to NT applications, and vice versa.

As recently as version 3.0, SNA Server was positioned as a gateway product. "SNA Server was primarily about preservation of investment," says Kevin Kean, group product manager for Windows communication products at Microsoft. Now, explains Kean, "SNA Server is moving from being a gateway to being a gateway and an applications integration platform. The ability to move transactions across asynchronous messaging is something people have talked about for a long time."

Version 4.0 includes several new capabilities, but key among them is the COM Transaction Integrator (COMTI), which was developed under the code name Cedar. COMTI allows development of Microsoft Transaction Server components using existing mainframe application programs in a drag-and-drop environment.

Critics contend that COMTI has shortcomings, including a reliance on prior modification of a CICS application to support IBM’s external call interface specification, which is a prerequisite before using COMTI. Also on the minus side is its reliance on Windows NT: Once an NT application has been integrated with a mainframe application, the mainframe can become dependent on the uptime and reliability of MTS, or NT itself.

Also new to version 4.0 is an OLE DB provider for AS/400 and VSAM systems, known as "Thor" during development. The SP2 update adds support for two-phase commit for IMS version 6, COMTI support for User-Defined Types, and a Microsoft Message Queue Server to IBM MQSeries bridge, which helps ease asynchronous message passing between disparate systems and applications running on both sides of the bridge.

Although many of these benefits are only helpful to users interested in integrating Windows NT applications with mainframe and AS/400 applications, SP2 adds TCP/IP support that could be of value to users running SNA Server 3.0. The TCP/IP support is limited, but is available for both ODBC drivers and OLE DB data providers, and for COMTI connectivity for CICS and IMS.

Despite gains in application integration facilities, SNA Server’s Web integration capabilities remain weak. "The big hole for [Microsoft] has been in the Web space," says Cindy Borovick, research manager at International Data Corp. ( "They have gone out into Web integration through IIS, but they have not specifically announced Web TN3270."

As expected, third-party vendors have filled in the missing pieces. In this case, long-time Microsoft partners such as Attachmate Corp. (, Wall Data Inc. ( and WRQ Inc. ( have solved the TN3270 problem for many users.

During 1998, Microsoft seemed to de-emphasized its marketing push on SNA Server. Borovick confirms this trend, and attributes it to Microsoft facing a more difficult sales cycle for customers considering SNA Server on a stand-alone basis. "[Microsoft is] seeing a tremendous amount of competition in price as customers migrate to an IP infrastructure. That’s a price curve Microsoft isn’t on." She notes that efforts by IBM Corp. and Cisco Systems Inc. are creating a competitive environment for SNA Server.

During 1999, Microsoft plans to continue to drive the capabilities of SNA Server as an application integration tool. "We’re expanding the idea of connectivity, rather than narrowing it," Kean says. "[Are we] moving SNA Server from being primarily a gateway to being a gateway/applications integration platform? You bet."

Part of the application integration initiative will include the rebranding and repositioning of SNA Server. Sources close to Microsoft say a relaunch had been planned for the fourth quarter of last year, but was delayed. The plan now appears to be on track for this quarter. One of the possible new names includes Host Interoperability Server. The relaunch is expected to add Web-to-host connectivity capabilities as well.

IDC’s Borovick says, looking ahead, SNA Server remains a key technology for Microsoft. "[SNA Server] still has a place in getting Microsoft into accounts they couldn’t get into from a data center perspective. I would look for Microsoft to make announcements from a scalability perspective as well as bringing solutions to customers so they can integrate the mainframe with the Web. They’ve ignored it too long."

SNA Server 4.0 New Features:

  • OLE DB Provider for DB2/400 and VSAM
  • COM Transaction Integrator
  • VSAM File transfer service
  • PU Passthrough support
  • SNA Session Level Compression
  • LU level security for LU 6.2 and LUA LUs
  • Bulk migration tool
  • MMC Snap-in to manage SNA Servers
  • How Service Pack 2 Adds to SNA Server 4.0:

    • Two-phase commit for IMS version 6
    • COMTI User Defined Type Support
    • OLE DB Provider for AS/400 and VSAM over TCP/IP
    • ODBC driver for DB2 over TCP/IP
    • OLE DB Provider for DB2
    • MSMQ-MQSeries bridge