If you are a C++ professional (expected to be the one of largest class of developers worldwide) and wondered why there is no standard component model for C++ as J2EE for Java?.

Also, did you wonder how to address the challenges in building application by using software components as contrary to mechanical industry where applications are built by assembly of pre-built components? For example, if there is a problem in an automobile, say problem in brake component, it can be easily replaced by another equivalent working component without affecting the entire assembly. The brake component is readily available and replaced saving the manufacturing time.

Is this possible in software industry? This is a daunting question for all architects,
designers, and developers.

In traditional C++ development, as the number of functional units increases with time, new lines of code to be written also increases. Such dependency is mainly due to inability of the designers and implementers to visualize the systems effectively during its time of inception. As the programmers add more functionality, upgrades etc., the systems tend to become complex and difficult to maintain, very often leading to a stovepipe system. The figure describes the productivity curve for C++ component based development.

It is found that cost of software upgrade/maintenance during entire software life cycle (compassing 8-10 years) is 3-4 times of the cost of initial development (1-2 years). These issues often pose a challenge to the CTOs/CIOs to choose between new developments vs. upgrading an existing system. To large extent, either you totally rewrite your system or you are stuck with your legacy system. There is a very little chance of a partial adoption of the system

The biggest reason for these shortcomings is that though object-oriented approach with C++ changed the way applications were built, but it didn't change the nature of the application themselves as described in the figure below.

Just like structure programming, the object-oriented approach is at the service of the functional developer, not the end user. Moreover, the development using object-oriented approach with C++ allows for only "development-time" reuse i.e. developers could use the pieces designed and coded (classes and objects) by other developers. It didn't address the issues related to assembly and deployment aspects.

Here, is the good news! The new specification from OMG®, CORBA3.0 component model (CCM) supports components in C++ as well as leverages and enables the concept of application development by assembly of prebuilt software components. Note that such a business component is the software implementation (binary) of a single business concept (or business process) and it is treated as unit of deployment.

Now, you can develop standard-based, cross-platform components in C++ with development and deployment environment based on CORBA3.0 Component Model (CCM).

The component based development is a comprehensive approach to software manufacturing. It covers all aspects of software development, from conceiving and building individual components to the cost effective assembly of components into systems. It also provides an excellent way to partition of business domain.

In component based approach, both developers and users have same viewpoint of the application as described below:

The components and assembly are highly visible at runtime. This will help the end user to understand how the software is built, assembled, deployed and evolved. This helps to resolve the limitations posed by object-oriented techniques as mentioned earlier.

The 3-tier component based architecture implemented with configurable C++ CCM components will solve a number of problems that are inherent to rich client architectures. The 100% componentization of the enterprise architecture will support :

• Clear separation of user-interface-control and data presentation from application-logic. Componentization also supports further splitting of "application logic" tier into two parts. Through this separation more clients are able to have access to a wide variety of server applications. The two main advantages for client-applications are: quicker development through the reuse of pre-built business-logic components and a shorter test phase, because the server-components have already been tested.

• In contrast to the 2-tier model, where only data is accessible to the public, business-components can place applications-logic or "services" on the net enabling service-oriented architecture (SOA)

• As a rule, servers are "trusted" systems. Their authorization is simpler than that of thousands of "un-trusted" client-PCs. Data protection and security is simpler to obtain. Therefore it makes sense to run critical business processes that work with security sensitive data, on the server.

• Dynamic load balancing, fail-over: if bottlenecks in terms of performance occur or system failure, the server process can be moved to other servers at runtime.

• Re-definition of the storage strategy won't influence the clients. RDBMS' offer a certain independence from storage details for the clients. However, cases like changing table attributes make it necessary to adapt the client's application. With CCM, even radical changes, like let's say switching form an RDBMS to an OODBS, won't influence the client. In well designed systems, the client still accesses data over a stable and well designed interface which encapsulates all the storage details.

• Change management: of course it's easy and faster to exchange a component on the server than to furnish numerous PCs with new program versions

• It is relatively simple to use wrapping techniques in 3-tier architecture. As implementation changes are transparent from the viewpoint of the client, a forward strategy can be developed to integrate with third-party systems smoothly.

With CCM, next generation C++ applications can adopt component based development to ensure cost reduction and productivity enhancement. The K2 Component Server combines the runtime performance, code size of C++ with the component/container model of CCM. K2 is well suited for addressing the high performance need of engineering applications.

These component-based systems are built for future upgrades, web enabling, integration with legacy systems, service oriented architecture (SOA) etc. The systems with component architecture based on CCM/C++ will reduce the software maintenance cost and ensure software longevity.

CCM vs. J2EE

CCM provides several advanced component features over EJB. In fact, CCM joins together the best of NET and J2EE component models. The table below explains the language support by CCM and J2EE.

Note: * Even FORTRAN, COBOL code could be made available as component using CCM.

CCM overview

CCM supports the framework for component definition, code generation, packaging, assembly and deployment C++ components. It supports four types of C++ components i.e. Session, Service, Process and Entity. It is important to note that C++ components itself are not " executables " anymore i.e. they are DLLs which can only be executed within the CCM server. The figure below describes a component.

There are four types of ports defined in CCM which are explained below:

#	Ports	Definition	Symbol
1.	Facets	Facets are distinct named interfaces provided by the component for client interaction. i.e., Components exposes named interface as surface feature using which other client applications can interact by explicit connection. Using facets a component can give multiple object references.
2.	Receptacles	Receptacles are named connection points that describe the component's ability to use a reference supplied by some external agent. Receptacles make use of the reference provided by the Facets.
3.	Event Source	Event Source are named connection points that emit events of a specified type to one or more interested event consumers, or to an event channel.
4.	Event Sink	Event sink are named connection points into which events of a specified type may be pushed.

Note : The facets and receptacles can be connected together to provide synchronous connections. The emitters (events source) and consumers (event sink) also can be connected together to provide asynchronous connections between two components. The above process of composing components is known as component assembly. The assembly can be achieved using graphical user interface tool that interacts with user to capture assembly information. The tool can be used to deploy the component assembly into a runtime environment, which handles automatic connection of components.

Now, UML 2.0 also supports the component diagrams for business application development. UML 2.0 component diagrams are great for initial architectural modeling efforts as they enable you to model the high-level software components, and more importantly the interfaces to those components. Once the interfaces are defined, and agreed to by the team, it helps in organizing the development effort between subteams.

No other products have CORBA3.0 Component Model capabilities, like K2. K2 provides the technology advantages that customers expect such as support for component-based development, component composability, component reuse savings, and component isolation for architecture integrity.

There are several mission critical applications developed and deployed using C++. K2 CCM enhances the capability of such C++ application further via component architecture. There is growing interest to use CCM for high performance, component solution in domains such as Aerospace, Telecom/Wireless, Banking/Finance and Manufacturing etc. for solving problems related to High Performance Computing (HPC) applications, Workflow applications, large-scale legacy integration and large data volume applications.

The CCM based component architecture will enable application development by "assembly of components". Such applications (i.e. assembly of components) could be further used as a "component" in other applications. So that, the resulting application consists of "assembly of assemblies".

The figure below defines the component architecture for a " Satellite Managed System " consisting of assembly of components where each components is autonomous deployment units.

K2 Component Server provides development & deployment of C++ components in high performance component runtime environment. It also provides QoS capability to meet operational requirements of mission critical applications such as clustering, multi-level fault tolerance, load-balancing, logging etc., ensuring performance, reliability, scalability and high availability.

In addition, K2 provides unified platform for component based development and "integration" supporting both synchronous and asynchronous programming model. Now, the enterprises could integrate their systems by "componentizing" the application around K2 CCM. With K2, enterprises can use component assembly instead of complex "integration" techniques. CCM supports concept called "ports" which are useful for assembly purposes. This makes out of the box integration possible with "K2 Assembly Tool" i.e. no coding is required for making inter-connections between components (written in different languages such as Java, C++ even COBOL) for developing applications supporting both synchronous and asynchronous communications.

The K2 CCM supports a highly reuse-focused development lifecycle throughout all stages of development. When the business component approach is fully applied, a new project should be able to reuse various levels of software artifacts at defined points in the lifecycle. This includes business component system models and business components, including their design models, the source code, the executables (fully tested), and even guides for deployment and use.

The figure below, describes the overall component development process consisting of architecture, design, implementation, assembly and deployment.

Also, this development process ensures testing at different levels such as interfaces, components, assembly etc. Assembly (integration) is no longer planned at the end of the implementation phase, but planned early and be continually managed throughout the development process.

This approach enables high level of concurrency in all phases of development, due to partitioning of the project into business components and the separation of concerns allowed by a strong architecture-centric approach.

The functional specification, analysis, design, implementation, and testing of business components can be done to a large extent independently from each other. For example, the most used (and reused) business components in the system can be fully stabilized, so providing for better quality control from the bottom up. And the application developers will focus entirely on their core competence, developing functional components, while technical developers focus on evolving the technical architecture.

CCM provides the most advanced component and assembly deployment model for C++ components. K2 CCM provides a container based deployment model for C++ components which provides a high performance runtime environment. The "collocation" mechanism is used to improve the performance and predictability of communication among collocated components of the assembly application. The term "collocation" can be treated as a unit of deployment. This unit could be

• "Process collocation" i.e. group of components which have to be deployed on the same CCM server process

• "Host collocation" i.e. group of components that have to be deployed on the same hosts

• "Free" components which are not part of "process collocation" or "host collocation" and could be deployed in any manner

The deployer can group components that are to be deployed on a particular CCM server i.e. process collocation or on a particular node i.e. host collocation. The components may be free or partitioned to a generic set of hosts and processes. As it's clear by definition of collocation, all the components that are part of any collocation definition (deployment unit) must support the target destination, i.e. host (Windows/Linux) or CCM servers or as programming language (C++) etc.. The table summarizes the various collocation (deployment) definitions such as:

#	Collocation Definition	Description
1.	Two prcess collocation and single host collocation In this deployment strategy, all the components of the assembly are put into two process and one host as described in the figure.
2.	Six process collocation and Three hosts collocation In this collocation definition, components of the assembly are put into six processes across three nodes as described in the figure.

The K2 CCM deployment model extends a sophisticated runtime environment to migrate from library based deployment model to container based deployment model.

Organizing the whole development process around components is a powerful mechanism for reducing the complexity and costs for all phases of development. Such a reduction is particularly noticeable in system evolution, since many system changes or corrections affect only a singly component.

In fact, it's quite common for the system built using traditional approaches go through a cycle as described below. A modification request may affect only one module, but implementation of the modification ends up impacting several modules. Sometimes, the entire application needs to be re-deployed.

Using C++/CCM component-based approach, the same cycle becomes as shown below. In this case, the modification usually impacts only the component that is affected by the modification request and it is possible to re-deploy only the impacted component. This is a great benefit that is particularly important for large systems.

CCM supports the concept of ports (such as facets, receptacles, event source and event sinks), which are used for assembly. During an upgrade or replacement of a component in an assembly, assembler uses these ports for configuration without worrying about the underlying implementation.

The "maintenance by parts substitution" is possible to achieve in C++/CCM environment as applications are developed as "assembly of components".

The enterprise-wide use of CCM and K2 will help in realizing the ideas such as "Component Factory" and "Component Repository". The repository can be used to set up an efficient software development capability-the business component factory-and enhance the ability to manufacture quality software at industrial levels quickly and cost-effectively. This will also ensure reusable components for future uses.

In contrast to the 2-tier model, where only data is accessible to the client, component architecture with business-components can place applications-logic or "services" for the client applications.

The component based system is designed and built to ensure software upgrade and maintenance capability. These capabilties include support for dynamically adding new features, web enabling, integration with legacy systems and support for SOA. These are the key factors which will ensure the longevity for component based systems beyond the life of a tradional software system.

Moreover, it will also help in reduced time to market, reduced skills requirements wih enhanced focus of expertise on domain problems.

The CIOs and CTOs of the Fortune Global 2000 companies are finding that K2 CCM based applications is enabling "Reuse" and "Assembly". It is possible for the enterprises to implement the component architecture with C++/CCM for large-scale projects to ensure software longevity and cost reductions.

Is your organization ready to transition to the business component approach to achieve cost-effective software manufacturing?

Write to us if you would like to use component based approach (using C++/CCM) to develop IT facilities for your strategic business needs. Please feel free to ask for a demonstration by our engineers or a prototype. Our team is equipped to help your team with onsite training & mentoring as well as joint-development.

1. Business Component Factory by Peter Herzum and Oliver Sims
   
   
2. CORBA 3.0 fundamentals and Programming by John Siegel
   
   
3. Software Architect Bootcamp by Raphael Malvaeu and Thomas Mowbray
   
   
4. OMG CORBA 3.0 Specification
   
   
5. K2 Component Server white paper