Bring your legacy systems to the forefront of e-business
Organizations that have legacy systems (e.g., IBM mainframes, AS/400 minicomputers) have long used SNA gateways to connect their Windows PC networks to these legacy systems. A traditional SNA gateway eliminates the need for dumb terminals connected with coaxial cable to mainframes and lets a Windows computer running terminal-emulation software (e.g., a 3270 client) in an IP or IPX network access mainframe and AS/400 hosts in an SNA network.
As Windows NT made its way into large corporations, Microsoft realized the importance of integrating Windows with mainframe and AS/400 hosts. Microsoft delivered SNA Server, an SNA gateway for NT. Since the product's first release, Microsoft has incorporated several integration tools (OLE DB Provider for AS/400 and Virtual Storage Access Method—VSAM, COM Transaction Integrator—COMTI, and Microsoft Message Queue Server—MSMQMQSeries Bridge) into SNA Server and its service packs. These tools let organizations seamlessly integrate their Windows applications with mainframe and AS/400 data and applications. This ability eases business-software development and reduces implementation costs by preserving existing legacy systems and applications. The integration tools also help integrate legacy systems into the modern world of the Internet and e-commerce. (The sidebar "E-Commerce and HIS 2000" provides an example of this integration.)
When Microsoft was developing a version of SNA Server (formerly code-named Babylon) for Windows 2000, the company determined that SNA Server wasn't an appropriate name for the new product. Instead of using SNA Server 5.0 or SNA Server 2000, Microsoft named the new product Host Integration Server (HIS) 2000 to better reflect the product's features. HIS works not only with mainframe and AS/400 systems running SNA but also with mainframe, AS/400, and UNIX systems running TCP/IP. HIS 2000 delivers a comprehensive set of host-integration tools—including those in SNA Server 4.0 and its service packs—the traditional SNA gateway service, and new features.
Integration
HIS offers three types of host integration: network integration, data integration, and application integration. Network integration provides a traditional SNA gateway service and host security integration. The SNA gateway service glues IP and SNA networks together and lets native 3270/5250, TN3270/5250, and Advanced Program-to-Program Communications (APPC)/CICS clients access mainframe and AS/400 hosts from Windows PCs and print host data on LAN printers. The host security integration maps domain accounts to host accounts, letting users employ single sign-on (SSO) functionality for Active Directory (AD) or NT domains and mainframe or AS/400 systems. Host security integration also supports automatic one-way password synchronization from AD or NT domains to AS/400 systems and mainframes. Two-way password synchronization requires third-party support. Network integration also supports RAS over SNA.
Data integration includes data access and heterogeneous replication. Data access integration provides OLE DB Provider for AS/400 and VSAM, OLE DB Provider for DB2, ODBC Driver for DB2, AS/400 Data Queues, Host File Transfer, and Shared Folders Gateway. HIS 2000 also supports APPC file transfer protocol (AFTP). Table 1 details each component's functionality. The heterogeneous-replication features work with Microsoft SQL Server 2000 to provide a process for copying and distributing data from one database to another in a distributed-computing environment and synchronizing databases for redundancy and consistency.
Application integration involves COMTI and MSMQ-MQSeries Bridge. COMTI lets component services in Win2K and Microsoft Transaction Server (MTS) in NT invoke and execute CICS and Information Management System (IMS) transaction programs (TPs) in mainframes as if the TPs were COM+ or COM components. COMTI can automatically build a COM+ or COM component from the COBOL data declaration of mainframe applications. COMTI delivers mainframe data to Windows without rewriting mainframe applications and ensures highly reliable synchronous communication between Windows and mainframes through the transaction support. (For more information about COMTI, see "Related Articles in Previous Issues.")
MSMQ-MQSeries Bridge provides asynchronous communication between Windows applications and mainframe applications. MSMQ, Microsoft's message queue service, uses a store-and-forward queuing system in a Windows network to provide high-reliability and high-availability asynchronous communication between Windows applications. (To learn more about MSMQ, see "Related Articles in Previous Issues.") MQSeries is IBM's message queue service for mainframes and other platforms (e.g., NT, UNIX). MSMQ-MQSeries Bridge links the incompatible MSMQ and MQSeries queuing systems, translates the systems' data formats, and lets MSMQ and MQSeries applications transparently communicate.
Among the three integration types, network integration is the fundamental type that organizations use to provide IP and SNA connectivity and conversion for terminal-emulation software and data- or application-integration tools. In addition to SNA communication, HIS 2000 lets a data- or application-integration tool use TCP/IP to interact with a mainframe or AS/400 host. For example, a COMTI application can use a CICS and IMS over TCP/IP remote environment to use TCP/IP to talk to mainframes directly rather than use SNA. In this scenario, the data- or application-integration tool doesn't need network integration. However, if a DB2 or COMTI data- or application-integration tool uses the SSO feature for application security and two-phase commit (2PC) for high-reliability transactions in OLE DB, that tool still requires network integration.
New Features
The features that I've discussed so far are available in SNA Server 4.0 and its service packs (except heterogeneous replication in data integration). In addition to this functionality, HIS 2000 offers several important new features and enhancements.
For Win2K network integration, HIS 2000 uses AD for user authentication and SNA service location. To maintain user-credential information for SSO and password synchronization and improve security and scalability, HIS 2000 replaces SNA Server's flat file database with Microsoft Data Engine (MSDE) from SQL Server 2000. HIS 2000 supports Resource Access Control Facility (RACF), Advanced Communications Function (ACF)/2, and Top Secret for one-way password synchronization to mainframes. The new 3270 client in HIS 2000 lets users open as many sessions as they want, whereas the 3270 client in earlier versions allows only one open session. HIS 2000 supports as many as 4096 printer sessions in its host print service; SNA Server 4.0 supports a maximum of only 1024 printer sessions. In addition, the new version includes an LU6.2 load-balancing and hot-backup mechanism.
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