OVERVIEW
In this white paper, we discuss recent trends in distributed object and Internet computing technologies.
We provide a brief overview of the Common Object Request Broker Architecture, an infrastructure for distributed applications based on distributed objects, and the Internet Inter-ORB Protocol, the CORBA protocol that is emerging as the business application messaging standard for the Internet. We give a technical overview of VisiBroker Object Request Brokers--the ORB implementation adopted by Netscape Communications Corporation, Oracle Corporation, Hitachi and other major corporations--and review the advantages of developing distributed applications with these industry-leading products.
Distributed Object Computing: A Challenge for the '90s
As the old adage goes, "The more things change, the more they stay the same." Businesses in the '90s face many of the same challenges they have faced for decades. Survival or success requires continual improvements in customer service and product quality.
There is perpetual pressure on the bottom line. Technology plays an increasingly important role in creating a competitive edge.
Business cycles continue to shorten. These realities translate into mandates for Information Technology (IT) organizations.
Rapid response is critical to the success of the enterprise. For IT, however, the landscape is filled with obstacles that make rapid response difficult.
In the latter half of the '90s, most central IT organizations are under considerable pressure to deliver more value at lower cost.
Most are struggling to manage complex, heterogeneous environments that incorporate disparate hardware, software, applications, networks, and database systems. Many must integrate legacy systems originally developed ten or twenty years ago with the latest client/server and Internet technologies. Driven by the need to deliver solutions and services faster and more cost-effectively, many IT organizations have had to adopt a tactical, short-term approach and, as a result, are finding it increasingly difficult to be proactive in setting the long-term technical direction for the enterprise.
How Did We Get Here?
The last 15 years have seen much change in how we design, develop, and maintain enterprise information systems.
This period began with monolithic mainframe systems. Each of these systems contained all of its own presentation, business, and data access logic. They could not share data with other systems, and so each had to store a private copy of its data.
Because different systems needed access to the same data, organizations had to store redundant copies on multiple systems.
These monolithic applications were inefficient and costly, and they soon gave way to relational database technology and the client/server model. Made possible by a convergence of technologies--networks, low-cost PCs, graphical user interfaces, and relational databases--client/server computing promised to simplify the development and maintenance of complex applications by separating centralized, monolithic systems into components that could be more easily developed and maintained.
Applications were partitioned into client components, which implemented the application's presentation logic and contained much of the business logic, and server components containing business logic in the form of stored procedures. Data access logic was handled either by the client or the server, depending on the implementation strategy. In the end, many client/server solutions simply created two monolithic systems where there once had been one. Today, it remains difficult to build, maintain, and extend mission-critical client/server applications.
Throughout this period, development teams have had to create the same functionality over and over again. Reusing code was difficult. Usually it meant copying a segment of code, modifying it, and then deploying the modified copy. Over time, a proliferation of similar modules had to be updated and maintained separately. A change to one module had to be propagated to similar modules throughout the enterprise. Because this often proved unmanageable, functional inconsistencies crept into enterprise information systems.
The Distributed Object Revolution
Distributed object technology fundamentally changes all this. Coupled with a powerful communications infrastructure, distributed objects divide today's still monolithic client/server applications into self-managing components, or objects, that can interoperate across disparate networks and operating systems.
The component-based, distributed-object computing model enables IT organizations to build an infrastructure that is adaptive to ongoing change and responsive to market opportunities. In the age of global competition and increasingly narrow market windows, companies that can initiate rapid change--not just respond to it--are better prepared to capitalize on opportunity, and are more likely to succeed.
"By 1997/98, object technology will become the predominant paradigm for conceptualizing, building, and using applications." -- The META Group
Distributed applications provide an opportunity to establish and maintain a competitive advantage by creating a flexible IT infrastructure. However, they also bring new requirements. To operate in today's heterogeneous computing environments, distributed business applications must work on a variety of hardware and software platforms. They must integrate old technology with new and make use of existing infrastructure. Furthermore, suitability for enterprise-class applications calls for capabilities beyond conventional Web-based computing--scalability, high availability, ease of administration, high performance and data integrity.
Since 1989, the Object Management Group, a consortium of platform vendors, ISVs and end-users, has been busy specifying the architecture for an open software bus on which objects written by different vendors can interoperate across networks and operating systems. The OMG is the world's largest software consortium, with over 700 member organizations, and its specifications enjoy broad support throughout the standards community and the software industry. The International Standards Organization (ISO) endorses OMG's standards. OMG standards typically are also endorsed by X/Open as part of the Common Application Environment (CAE) specification.
The CORBA Specification
The focus of the OMG's effort has been to specify the Common Object Request Broker Architecture (CORBA). The CORBA specification describes a software bus, called an Object Request Broker (ORB), that provides an infrastructure for distributed object computing.
It enables client applications to communicate with remote objects, invoking operations either statically or dynamically. In late 1994, the OMG approved the CORBA 2.0 specification, which includes a protocol for ORB interoperability called the Internet Inter-ORB Protocol (IIOP).
A recent survey of IT professionals "concluded that 57.9% are currently developing, or plan to develop mission-critical object-oriented applications over the next 12 months."
-- The Standish Group (9/96)
IIOP is robust, scalable, and transaction-oriented. It runs on top of TCP/IP, requires no special configuration, and is fast becoming the standard for communication between and among distributed objects running on the Internet and enterprise intranets.
Leading vendors of Internet tools, including Netscape and Oracle, have fully embraced IIOP as the basis for future product offerings.
CORBA 2.0 compliant objects are fully interoperable because they use IIOP to communicate.
CORBA Services
The ORB backbone is extended with modular, add-on, system-level services that complement the functionality of the ORB and provide building blocks for business applications. The OMG has defined a set of common object services, including:
- A naming service that enables objects to find each other by name
- An event service that enables objects to subscribe to an event channel and be notified of specific events
- A transaction service that defines transactional disciplines, coordinating two-phase commits among objects
- A security service that provides authentication, authorization, encryption and auditing functions to protect sensitive data and to control user access to applications and services
CORBA services provide functionality that is essential for many enterprise applications. Since developers do not have to implement these core functions in each system, they can focus instead on implementing their own application and business logic.
Benefits of CORBA
The OMG and its members envision a near-term future in which software objects with defined interfaces interoperate across corporate intranets and across the Internet. The benefits for application developers and IT organizations are significant:
- Choice. CORBA is an open solution based on a published specification. It is implemented and supported on a wide variety of hardware and operating system platforms.
- Plug-and-Play Flexibility. A CORBA-compliant software object has a defined interface. All communications go through that interface. Changes to the implementation of the object do not affect other objects, so long as the object's interface remains the same. Developers can code to the defined interface knowing that modifications will not break other parts of the distributed application.
"On average, 70% of the work for developing new applications is spent on building infrastructure, with only 30% focusing on the specific needs for the application to fulfill. A standards-based distributed computing model, such as CORBA, solves this problem by providing a reusable infrastructure that allows developers to focus on the specific business problems at hand."
-- The Standish Group
- Coexistence with Existing Systems. ORB technology protects your investment in existing systems. A legacy application, module, or entry point can be encapsulated in a C++ or Java "wrapper" that defines an interface to the legacy code. Creating such an object wrapper gives the legacy code a CORBA-compliant interface, making it interoperable with other objects in a distributed computing environment.
- Interoperability. CORBA-compliant software objects communicate using the Internet Inter-ORB Protocol (IIOP) and are fully interoperable, even when they are developed by different vendors who have no knowledge of each other's objects. Software bridges enable communications between CORBA-compliant objects and objects developed with Microsoft's ActiveX/DCOM technology. Enterprise IT organizations can select an ORB, CORBA services, and software objects based on the functionality they provide--even if they were developed by different vendors.
- Portability. Software objects that comply with the CORBA standard are portable. That is, objects built on one platform can be deployed on any other supported platform.
The Internet Explosion
As the CORBA 2.0 specification was being developed and finalized, the Internet and the World Wide Web began the phenomenally rapid expansion that continues unabated to this day.
Transcending its roots in government agencies and educational institutions, the Internet has become the most significant new medium for communication between and among businesses, educational and government organizations, and individuals.
Growth of the Internet and enterprise intranets will continue at a rapid pace through at least the end the century, leading to global interconnectedness on a scale unprecedented in the history of computing.
Key Internet Technologies
Several Internet-related developments are particularly significant for enterprise IT and are playing a key role in enabling IT organizations to benefit from distributed-object technologies:
- Java.
An object-oriented programming language developed by Sun Microsystems.
The widespread adoption of the "write once, run anywhere" Java language makes it possible to develop truly platform-independent client applications.
- Java Applet. A small program, written in Java, that travels from the Web server to the requesting client where it then executes. An advantage of Java applets is that IT has more control over what version of an applet runs on any client environment, thereby eliminating the version incompatibilities that exist where application software must be loaded and updated on each client machine. Java applets allow "thin" clients, which are not loaded with large, difficult-to-maintain application software.
- "Smart" Web Browsers.Web browsers on millions of desktop computers can now run applets that communicate and interact with applications running on remote systems elsewhere on the Internet.
"We expect most organizations will realize the impracticality of trying to converge on a single technical architecture, and will recognize that a mixture of technical architectures will be the norm through 2000 and beyond.
For most organizations, this realization will become apparent with the arrival of the Internet."
-- The META Group
- Network Computers. Network computers--like Sun's JavaStation, the "zero administration" NetPC from Intel and Microsoft, and Oracle's NC--promise dramatically lower costs for organizations whose users access server-based software objects from downloadable applets running in a Web browser. (The Gartner Group has estimated the five-year cost of owning and supporting a single Windows PC at $60,000, up 100 percent since 1988; Oracle claims that system administration costs will be 70 percent lower for network computers.)
- Secure Firewalls. Firewalls now provide security for enterprise information systems, making it possible for applications behind the firewall to interact safely with applications running on systems outside the firewall.
In the Internet age, it is no longer possible to think of creating homogeneous computing environments.
Enterprise information systems must be able to communicate and interoperate with applications and systems outside the firewall. In this way, enterprise IT can leverage the Internet by using it as a de facto WAN that links government agencies, businesses, educational institutions, and individuals worldwide.
A New Application Paradigm for the Internet Age
The concurrent revolutions in Internet and distributed object computing are on converging paths.
As a communications framework, the Internet provides an ideal platform for distributed object applications and therefore fosters their growth. At the same time, distributed object technology is improving the quality of Web-based applications, adding value to the Internet and enterprise intranets.
This symbiotic relationship is creating a paradigm shift in the way we conceptualize, design, develop, deploy, and maintain business applications. In the age of the Internet, a new kind of application will predominate--an application built from new and legacy code encapsulated in software objects, running on systems both inside and outside the firewall, and interacting with each other through an Object Request Broker using defined interfaces.
How does this new application work? Figure 3 shows an example--a distributed, Web-based parcel tracking application.
The application lets users check the status of a delivery by entering a parcel tracking number. The user enters the tracking number in a form displayed by a Java applet that runs in the user's Web browser. The Java applet uses the Object Request Broker to communicate with a software object running behind the package delivery company's firewall; this object queries the company's database and returns status information through the ORB to the Java applet, which displays the information for the user.
The parcel-tracking application works as follows:
- In a Web browser, the user enters a URL that points to a page on the package delivery company's Web server maintained outside the enterprise firewall.
- The Web server receives the user request and uses HTTP to return a Web page to the client's browser.
The Web page contains the Java applet that makes up the client component of the distributed parcel tracking system.
- With the Java applet running, the user enters a parcel tracking number, and clicks the "Get Parcel Status" button displayed by the Java applet. The applet sends an IIOP message through the Object Request Broker to a server-side software object (Parcel), invoking the object's GetStatus method and passing the user's parcel tracking number.
The Parcel object queries the enterprise database for the status of the user's parcel.
- Upon receiving query results from the database, the Parcel object returns the results to the client-side Java applet through the Object Request Broker. The applet receives the results and displays them in the user's Web browser.
"Today, there is little doubt that conducting business over the Internet is the direction the world is taking."
-- The Standish Group
The client might be a PC running Windows, a Macintosh, a workstation, a network computer, a handheld personal computer, or even a set-top box such as WebTV. Server objects may be written in Java, C++, COBOL, SmallTalk, or other languages and may include new and legacy code. Objects do not have or need information about each other's implementation details.
They communicate only through their defined interfaces. In the background, transparent to the user, the Object Request Broker manages the communications among the various objects that make up the distributed application. Because they communicate with the objects via IIOP, clients are able to invoke business functionality directly, without going through Web server software and the delays inherent in processing through a CGI script for each user access.
Implications for the Enterprise IT Organization
The new application paradigm has much to offer enterprise IT.
Organizations that move quickly to adopt distributed object computing and embrace the Internet will achieve a substantial edge over their competitors. The benefits include:
- Flexibility to mix and match interoperable software objects from multiple vendors
- Centralized management and administration of software objects
- Lower costs and shorter development schedules resulting from reusable objects and simplified integration of legacy code
- A dramatic reduction in the costs for acquiring, configuring, and maintaining client systems, brought about by storing applications centrally
- The stability of widely supported industry standards, such as CORBA and IIOP, that ensure interoperability, portability, and a wide choice of object vendors
CORBA is simply a specification for a software bus. The suitability of a CORBA-based application for enterprise computing is governed by the implementation of the ORB. Because of their design and completeness, VisiBroker products are recognized as the leading solution for distributed applications. After comparing ORB products, the industry's leading technology vendors--including Netscape, Oracle and Hitachi--have selected VisiBroker for their implementation of CORBA and IIOP.
The VisiBroker Solution
Borland's implementation of the CORBA specification addresses the requirements of organizations wishing to deploy enterprise-class distributed business applications. Borland's VisiBroker product family allows systems developers--both commercial solution providers and enterprise IT organizations--to develop, deploy, and manage distributed object applications. The VisiBroker product family includes:
