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Low-maintenance links to legacy systems
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How to choose which of the three types of Web-to-host connectivity tools is best for you.
Gone are the days when you needed custom hardware and proprietary software to connect a PC to a host. The latest generation of Web-to-host connectivity tools provides an ideal way to link users to legacy systems.
Working through a Web browser, Web-to-host applications offer ubiquitous access, ease of use and simple deployment and maintenance. The Web server acts as middleware between the browser and the host application, greatly simplifying connectivity.
Terminal emulation is nothing new, but until now the task has been difficult. In the early days, the solution required expensive hardware and software. Today's SNA gateways are an improvement, but deployment is still somewhat complex. And dial-up pools, remote access servers and the like make it nearly impossible to connect remote PC users to a host.
Web-to-host connectivity tools remove most of the drudgery from host access implementation by obviating the need to connect each client to an SNA gateway. Users simply connect to the World Wide Web server via a browser, and the Web server connects to a host gateway on their behalf.
Some of the Web-to-host products offer a pure HTML solution, while others use browser components such as ActiveX or Java. Because Java implementations vary from browser to browser and Internet Explorer is the only browser with native support for ActiveX components, pure HTML solutions are a better choice if you support a mix of browsers.
Some Web-to-host connectivity tools let you customize the interface using programmable server technology such as Common Gateway Interface, Active Server Pages or JavaScript. Java applets and ActiveX components only become essential when you get into more sophisticated functionality, such as customizing or redesigning the view of the host application. Many products offer a choice of pure HTML or component-based solutions, so you can mix and match what works best for you.
Although screen scrapers don't get much respect, nothing beats these plain Janes when it comes to quick deployment and instant user familiarity. Most of the products on the chart are screen scrapers, including such popular choices as Attachmate Corp.'s Attachmate HostView Server and IBM Corp.'s eNetwork Host-On-Demand.
The second option is a customizable screen scraper, which uses features such as text boxes and command buttons to dress up screens and make them look more Windows-like. These tools often support some form of templates that let you use HTML and scripting languages to better control an application's appearance. Products such as Eicon Technology Corp.'s Aviva and OpenConnect Systems, Inc.'s OC://WebConnect Pro fall into this category.
Customizable screen scrapers are a good choice if you're deploying a new host application to users who are familiar with Windows. The products also serve as effective steppingstones in a migration to a Windows platform.
The third group of tools is really intended for creating new interfaces to a host application. These development tools provide low-level API access and/or programmable components for building custom front-end applications as replacements for traditional terminal emulation software. For example, tools such as Bluestone Software, Inc.'s Sapphire/Web and Dynamic Information Systems Corp. let you build Web-based front ends to mainframe applications. This type of product makes sense if you're planning long-term re-engineering of your host applications.
This is good and bad. The application probably uses the latest technology, and the manufacturer should be very responsive to your needs. However, a small start-up with few customers and a single product is inevitably fragile. If the vendor were to go under, is the solution still a viable choice? What kind of support and upgrades do you need?
A few big companies also are represented in the chart. Large firms making Web-based products tend to adapt existing applications using the minimum amount of Web technology required to make it work. However, that's not the case with the vendors in this chart.
For instance, IBM did a good job adapting eNetwork Host-On-Demand to the Web. The firm has wholeheartedly embraced Web technology, focusing primarily on Java-based development. To top it off, the host application you're accessing is probably an IBM application running on IBM hardware.
Host-On-Demand runs on IBM's eNetwork Communications Server, which is fundamentally an SNA gateway. The first release of eNetwork Host-On-Demand is available free to anyone who buys eNetwork Communications Server. This first version only supports 3270 emulation, but there's no beating the price if that's all you need. As you'll see on the product comparison chart, Release 2 of eNetwork Host-On-Demand has more extensive emulation support.
Novell, Inc.'s IntranetWare HostPublisher links NetWare for SAA and Novell Web Server. In fact, Novell Web Server 3.1 is bundled with IntranetWare HostPublisher. Novell shops will enjoy HostPublisher's integration with Novell Directory Services (NDS). The combination of NDS and Secure Sockets Layer provides great security for Internet-based users with little effort.
Cisco Systems, Inc. is likewise in the Web-to-host connectivity game, although you won't see the company listed on the chart. Cisco resells OpenConnect Systems, Inc.'s OC://WebConnect Pro. That product is listed, but we decided not to duplicate all the information on it under the Cisco name.
It's important to note that none of the Web-to-host connectivity tools featured in this Buyer's Guide requires modifications to your network or existing applications. Each of the products listed in the chart provides accessto multiple hosts on multiple servers.
Web-to-host connectivity tools offer such compelling advantages that it's debatable whether deploying traditional host clients makes sense at all. Thanks to the compelling advantage of Web-to-host connectivity tools, terminal emulation software may be a dying breed. RELATED LINKS
Review: Web-to-host connectivity tools
Network World, 4/27/98.
Working through a Web browser, Web-to-host applications offer ubiquitous access, ease of use and simple deployment and maintenance. The Web server acts as middleware between the browser and the host application, greatly simplifying connectivity.
Terminal emulation is nothing new, but until now the task has been difficult. In the early days, the solution required expensive hardware and software. Today's SNA gateways are an improvement, but deployment is still somewhat complex. And dial-up pools, remote access servers and the like make it nearly impossible to connect remote PC users to a host.
Web-to-host connectivity tools remove most of the drudgery from host access implementation by obviating the need to connect each client to an SNA gateway. Users simply connect to the World Wide Web server via a browser, and the Web server connects to a host gateway on their behalf.
Some of the Web-to-host products offer a pure HTML solution, while others use browser components such as ActiveX or Java. Because Java implementations vary from browser to browser and Internet Explorer is the only browser with native support for ActiveX components, pure HTML solutions are a better choice if you support a mix of browsers.
Some Web-to-host connectivity tools let you customize the interface using programmable server technology such as Common Gateway Interface, Active Server Pages or JavaScript. Java applets and ActiveX components only become essential when you get into more sophisticated functionality, such as customizing or redesigning the view of the host application. Many products offer a choice of pure HTML or component-based solutions, so you can mix and match what works best for you.
Pigeonholing products
You can group Web-to-host connectivity tools into roughly three categories. The original option, and still the most popular, is the screen scraper. These products essentially reproduce the host screen in a browser window right down to the green-on-black window.Although screen scrapers don't get much respect, nothing beats these plain Janes when it comes to quick deployment and instant user familiarity. Most of the products on the chart are screen scrapers, including such popular choices as Attachmate Corp.'s Attachmate HostView Server and IBM Corp.'s eNetwork Host-On-Demand.
The second option is a customizable screen scraper, which uses features such as text boxes and command buttons to dress up screens and make them look more Windows-like. These tools often support some form of templates that let you use HTML and scripting languages to better control an application's appearance. Products such as Eicon Technology Corp.'s Aviva and OpenConnect Systems, Inc.'s OC://WebConnect Pro fall into this category.
Customizable screen scrapers are a good choice if you're deploying a new host application to users who are familiar with Windows. The products also serve as effective steppingstones in a migration to a Windows platform.
The third group of tools is really intended for creating new interfaces to a host application. These development tools provide low-level API access and/or programmable components for building custom front-end applications as replacements for traditional terminal emulation software. For example, tools such as Bluestone Software, Inc.'s Sapphire/Web and Dynamic Information Systems Corp. let you build Web-based front ends to mainframe applications. This type of product makes sense if you're planning long-term re-engineering of your host applications.
Vendors big and small
As is typical of the Web application market, many of the Web-to-host connectivity products come from tiny companies. In some cases, the product may even be the only one the vendor offers.This is good and bad. The application probably uses the latest technology, and the manufacturer should be very responsive to your needs. However, a small start-up with few customers and a single product is inevitably fragile. If the vendor were to go under, is the solution still a viable choice? What kind of support and upgrades do you need?
A few big companies also are represented in the chart. Large firms making Web-based products tend to adapt existing applications using the minimum amount of Web technology required to make it work. However, that's not the case with the vendors in this chart.
For instance, IBM did a good job adapting eNetwork Host-On-Demand to the Web. The firm has wholeheartedly embraced Web technology, focusing primarily on Java-based development. To top it off, the host application you're accessing is probably an IBM application running on IBM hardware.
Host-On-Demand runs on IBM's eNetwork Communications Server, which is fundamentally an SNA gateway. The first release of eNetwork Host-On-Demand is available free to anyone who buys eNetwork Communications Server. This first version only supports 3270 emulation, but there's no beating the price if that's all you need. As you'll see on the product comparison chart, Release 2 of eNetwork Host-On-Demand has more extensive emulation support.
Novell, Inc.'s IntranetWare HostPublisher links NetWare for SAA and Novell Web Server. In fact, Novell Web Server 3.1 is bundled with IntranetWare HostPublisher. Novell shops will enjoy HostPublisher's integration with Novell Directory Services (NDS). The combination of NDS and Secure Sockets Layer provides great security for Internet-based users with little effort.
Cisco Systems, Inc. is likewise in the Web-to-host connectivity game, although you won't see the company listed on the chart. Cisco resells OpenConnect Systems, Inc.'s OC://WebConnect Pro. That product is listed, but we decided not to duplicate all the information on it under the Cisco name.
It's important to note that none of the Web-to-host connectivity tools featured in this Buyer's Guide requires modifications to your network or existing applications. Each of the products listed in the chart provides accessto multiple hosts on multiple servers.
Web-to-host connectivity tools offer such compelling advantages that it's debatable whether deploying traditional host clients makes sense at all. Thanks to the compelling advantage of Web-to-host connectivity tools, terminal emulation software may be a dying breed. RELATED LINKS
Review: Web-to-host connectivity tools
Network World, 4/27/98.
Interactive buyer's guide
Find the connectivity tools that match your criteria.
Campbell is a freelance writer and technical analyst in Vancouver. He can be reached at rjc@guh.com.
