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SQL*Net 2 is a sound product that provides the same basic services as SQL*Net 1. Be sure to allow adequate time to properly set up SQL*Net. I have found that it always takes longer than you think it will to set up the SQL*Net configuration files correctly, start the background processes, and complete any upper middleware configurations, such as ODBC. Even after you have done it several times, there seem to be a few quirks with each new type of server or each new network stack on the clients . Oracle provides the SQL*Net Easy Config tool with its MS Windows products that allows you to build the configuration files using a GUI interface.

Net/3

Arriving on the market with the Oracle 8 Server is the next generation of Oracle networking products called Net/3. Notice that in the early days, everything from Oracle had an asterisk in its title (SQL*Net and SQL*Forms, for example). Today, everything has a slash in it (Workgroup/2000, Developer/2000, and Net/3, for example). Net/3 is a worthy successor to SQL*Net 2. From a user perspective, most of the improvements associated with Net/3 are "under the hood" where they are not directly visible. As a matter of fact, Net/3 can coexist with SQL*Net 2 (but not SQL*Net 1) installations and work together exchanging information. A list of the more prominent improvements in Net/3 follows :

• Capability to scale to support a larger number of users
• Capability to centrally access control
• Improvements on balancing the load between processes and tracing the transmission of signals
• Improved capabilities for dealing with multiple communications protocols (TCP/IP and IPX/SPX, for example)
• Convenient, graphical interfaces to set up your network configuration
• Better support for centralized repositories of configuration information (the Oracle Names Server, which functions similarly to a Domain Name Server in the TCP/IP and Internet worlds )

You can use Net/3 very much like you are using SQL*Net 2 today. You can have the TNSNAMES.ORA files, which store the basic configuration information for the network and enable users to connect to a database by typing a simple alias (for example, warehouse). However, what the developers are trying to lead you into is using Net/3 as a more centralized administrative tool using Oracle Names Servers. Here, you run a simple wizard on the client workstation to set up Net/3 to point to the Oracle Names Server, which is a single maintenance point for your Oracle network configuration information. It is here that you will reap the greatest benefits from the new tools.

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ODBC, JDBC, and OLE

Earlier in this chapter, I briefly mentioned ODBC, JDBC, and OLEthree upper middleware package standards. Other vendors have created their own ODBC software packages, because ODBC is a utility that is separate from the basic operating system. I am not familiar with any users who have created their own version of OLE; however, Oracle has created Objects for OLE, which enables you to write software that uses OLE to interface with an Oracle database. JDBC is a standard evolved by Sun and others involved with the Java Web development language. JDBC is conceptually equivalent to ODBC, but it extends to the wider range of platforms in which Java and Web browsers function.

Several differences exist between ODBC and OLE. The biggest is that Oracle supports OLE, and many of the other big database vendors do not. As a result, if you are writing an application that you want to sell to a broad audience with multiple DBMSs, OLE might limit your options. Also, because ODBC is older, you might be able to find more third-party development software to support your development efforts. JDBC typically works only in Web applications (although there are some stand-alone Java applications) and requires you to have a newer Web browser that supports Java.

Most of the folks I have talked to indicate that they found OLE several times faster than ODBC. Some people on the ODBC side might counter that the initial Microsoft ODBC drivers were not as optimized as they could be and that you can increase ODBC performance by a good bit. Some of the OLE concepts (such as launching a small database application from within a word processor or spreadsheet) are very difficult to implement by using ODBC. JDBC, on the other hand, is optimized for Java Web applications, whereas you can use ODBC and OLE for Web applications developed using other programming tools, such as Visual Basic. The choice of middleware product depends on your environment and how the vendors respond to users' demands over time.

One final note is that there is another standard out their that is similar to OLE. OLE is designed to allow applications to cooperate by establishing standards as to how objects (that is, applications) make their functionality ( methods ) available to other applications. A group of vendors, including Oracle, has expressed support for the CORBA (Common Object Request Broker Architecture) standard that performs a function similar to OLE. You may see products in the future from Oracle and third party vendors that use this architecture to accomplish the goals of the upper middleware product.

Other Middleware Vendors

Of course, you might want to consider other middleware vendors. Perhaps you are working with an operating system such as Windows 95 right after it was released, and all the beta test drivers that you were shipped are buggy . You desperately want to get a product out the door,

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and you are searching for that one driver that will enable you to complete the porting of your software package to Windows 95. Also, you might be in a situation in which you are writing an extremely demanding application, and you are pushing to optimize performance whenever possible. In this section, I present a brief overview of some of the middleware vendors on the market to give you a feel for some of the alternatives. After this book goes to press, another vendor might release a great product that could be the one that is right for you. You should perform the usual research steps (vendor search, magazine reviews, and so on) to see what products are available to you.

I'll start the product review with the products from Oracle shown in Figure 55.14. The basic middleware that Oracle provides is the SQL*Net product, which I classify as lower middleware. Oracle also offers its own set of ODBC drivers to compete in the upper middleware market. The Oracle ODBC drivers provide an interface to Oracle databases, so if you are trying to write applications for a wide variety of databases, you still might need to purchase additional ODBC drivers for those other databases. One thing to consider when working with new releases of Oracle is that the Oracle drivers might be more up-to-date than some of the third-party drivers, although the ODBC standard shields you from some of the internal changes that occur in the databases themselves . Oracle also markets its Objects for OLE product to serve as upper middleware for those who want to use OLE.

Figure 55.14.
Middleware products
from Oracle.

Of course, Microsoft wrote both the ODBC and OLE upper middleware standards. The Microsoft development tools come with ODBC drivers and OLE support, in addition to development tools from other third-party vendors. These products compete with the Oracle ODBC drivers and objects for OLE. Microsoft supports networking to its SQL*Server product as part of the operating system, so I guess you could call Microsoft's drivers lower middleware for a non-Oracle database.

Next on the list of representative vendors is Intersolv. I have worked with Intersolv's ODBC drivers. It provides drivers for a range of databases, often before the database vendors come out with their releases. Intersolv also has the distinction of writing the drivers that are provided by some of the other database vendors. Intersolv owns the Q+E product line, which was one of the first tools that enabled you to connect spreadsheets such as Microsoft Excel to remote databases. Again, the main focus for Intersolv is the upper middleware ODBC market.

Last on this short survey of some of the vendors in the middleware market is a British firm called Openlink. Openlink is somewhat unique because it bundles together the functions of upper and lower middleware into a single package. You have to run its products on both the client and the server, but in return, you avoid installing and maintaining a number of lower middleware products. Figure 55.15 shows the basic architecture for Openlink.

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