The CORA Model

Introduction

This blog is the first in a series around on the comparion between the CORA model and IBM. In this first part, after introducing IBM, the SOA Reference Architecture of IBM is mapped onto the CORA model.

The history of IBM

The roots of IBM date back the 1880s, decades before the development of electronic computers. The company was formed through a merger of three different companies end was called the Computing Tabulating Recording (CTR) Corporation to be changed into the International Business Machines Corporation in 1924. The company manufactured and sold products ranging from commercial scales and industrial time recorder to meat and cheese slicers, tabulators and punch cards.

The decades between 1939 and 1963 (the ‘Era of Innovation’) the company’s product line expanded significantly. In the eighties IBM introduced personal computers (PCs) collaborating with Intel and Microsoft and local area networks (LAN), which permitted PC users to exchange information and share printers and files within a building or complex. In the nineties the emphazise becam on the need to provide integrated solutions for the company’s customers. Today IBM’s strength lies in its combined expertise in solutions, services, products and technologies.

Vision of IBM

In IBM's view, today's networked economy has created a global business landscape and a mandate for business change. Integrated global economies have opened markets of new opportunity and new sources of skills. The Internet has enabled communication and collaboration across the world and brought with it a new computing model premised on continuous global connection. In that landscape, companies can distribute work and technology anywhere in the world. Given these opportunities, IBM is working with its clients to develop new business designs and technical architectures that allow their businesses the flexibility required to compete in this new landscape.

Architectural views of IBM and CORA scope

The SOA Reference Architecture of IBM/ The Open Group describes a SOA-based layered architecture.

Mapping the SOA Reference Architecture of IBM onto CORA results in the following matrix.

This architecture is described from a service oriented perspective and with an application view. There is no presentation layer or channel within this architecture. The first layer is a Consumer layer where a business process and a service can both be a consumer. The examples in the Consumer layer are a mix of logical (e.g. B2B) and physical (e.g. WSRP) elements. So different types and dimensions are used in this architecture.

Atomic services and composed services are put together in one layer. In the CORA they are separated to emphasize the composite nature. Security, Management and Governance are put in one layer. In the CORA security is explicitly separated in a dedicated layer. The integration layer is also described as a vertical layer but is not detailed further.

The data architecture (information architecture) is described as a vertical layer. According to IBM this is done to emphasis the need to think about data on every layer. CORA explicitly defines a horizontal data layer because of the viewpoint that data is an
important asset of an organization and for separation of responsibilities. The focus of IBM on information architecture is understandable but it seen more as an additional focus area while designing a detailed architecture.

Distinctive from the other mentioned reference architectures the Operational systems layer identifies two application types: Package based and Custom based. This is similar to CORA where in CORA one more application type is mentioned: ‘Legacy’.

As shown the CORA is used as a quality instrument to assess the the SOA Reference Architecture of IBM/The Open Group. The following questions could be raised:

• Why is the Presentation Layer absent? 
• Are layers clustered/separated because of the available IBM software components or are there other reasons?
• How does this layering affect the usage of architecture styles?

For both an Enterprise Architecture and Software Architecture on Enterprise Level it is not possible to use solely the SOA Reference Architecture of IBM as a quality instrument because a common IT landscape consists of a mixture of artchitectural styles. As shown in this assesment at project implementation level the SOA Reference Architecture of IBM can be used to create a Software (or Solution) Architecture only when it is connected to the CORA.

CORA can also be used to asses the IBM software components, regarding separation of responsibilities, decoupling, re-usability, portability and substitutability of elements, by plotting them onto the CORA layers and elements. This will be described in the next blog.