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Enterprise architecture in the age of cloud services
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Enterprise architecture in the age of cloud services
Using a hybrid SaaS, software as a service
Fabio Castiglioni (f.castiglioni@it.ibm.com)
Senior IT Architect
IBM
25 September 2012
This article shows how to use an enterprise architecture to specify requirements for public cloudservice, using a hybrid software as a service (SaaS) example. Enterprise architecture (EA) is akey tool to help cloud customers understand how to take advantage of the new business modelthat is enabled by the technology and how to fit external services into their current applicationsand technical environments. In reading this article, an IT architect will learn how to use EAnotations and IBM Rational System Architect to communicate effectively with business usersand other stakeholders, including the service provider.
Introduction
The idea that a good enterprise architecture (EA) is a key enabler for an effective adoption of aservice-oriented architecture (SOA) has been raised by many years (see the Ibrahim and Longcitation in Resources), and many customers have paid for the absence of an EA "due diligence" atthe price of project failure or half-failure. The architecture big picture, the end-to-end link betweenbusiness processes and IT services, and the day-to-day governance mechanism that come withan established enterprise architecture are all essential elements for an SOA that keeps its promiseof a technology capable of transforming the business and the enterprise.
Now, I can hear your mind buzzing, thinking something like, "I must have opened the wrong article.This was supposed to be about cloud, not SOA."
The fact is that, whether we are discussing cloud or SOA, we are dealing with services.
Saying "services" means that we willingly accept structuring our IT with a granularity that isprobably sub-optimal for the management of the specific problem at hand, and we are also willingto accept to over-engineer some of its components to support an increased level of flexibilityrearrange business operations. (Think about standardizing interfaces, for example. It doesn’thappen for free, and it pays back only when you are actually reusing the function.) This level offlexibility is, in itself, only a means to achieve flexible business processes. Those, in turn, havemeaningful economic returns only if they support flexible, informed business strategies.
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Implementers of a cloud (or a SOA) architecture must have this cause-effect chain well laid outbefore them. Otherwise, their decisions will always miss some key aspect of the problem.
This means that having an enterprise architecture model of the area to be transitioned isperforming the due diligence of identifying business-to-IT relations, dependencies, requirements,and constraints.
In this article we will explore how to represent this model, and how to understand from it whatneeds to be done and why, from the perspective of a Consumer of cloud services. This might bean organization that wants to leverage the cloud technology to inject a new level of flexibility in itsoperations.
Cloud service Consumer scenarios
A Cloud Reference Architecture, like the ones from IBM or the National Institute of Standards andTechnology (NIST) of the United States Department of Commerce, structures the cloud business,starting from the set of involved actors. Each actor has a defined role.
Figure 1. IBM Cloud Reference Architecture, which is similar to the one fromNIST
The IBM reference architecture identifies the following roles:
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The Cloud Service Creator who develops new services to be consumed through the cloudinfrastructure
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The Cloud Service Provider who administers and operates the cloud infrastructure
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The Cloud Service Consumer who uses the services hosted in the cloud infrastructure
NIST lists the following roles instead:
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Cloud Provider (similar to the IBM one)
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Cloud Consumer (same)
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Cloud Auditor who can conduct independent assessment of the cloud services
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Cloud Broker who has the capabilities to intermediate, compose, add value to the services ofthe Provider
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Cloud Carrier who has the capabilities to provide transport services to the Cloud ServiceProvider
As you can see, Provider and Consumer are the central roles. Although the Provider’s businessand IT models are very similar to the ones of a traditional outsourcer, the Consumer is the one thatleverages the innovation capabilities of the cloud the most.
Going back to the IBM Cloud Reference Architecture, the Consumer can choose four classes ofservices:
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Infrastructure services (known as infrastructure as a service, or IaaS) where the Consumeruses services equivalent to a hardware system
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Platform services (PaaS, for platform as a service) where the services are equivalent to acomplete hardware and software infrastructure
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Software services (SaaS, for software as a service) where the Consumer uses a businessapplication
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Business process as a service (sometime referred to as BPaaS) where the Consumerhasoutsourced part of the business processes to an external provider
Provider and Consumer might be two departments in the same company (IT operations and ITdevelopment, for example) that use a private cloud, or two separate business entities, one ofwhich is in the business of providing services through the cloud. The latter is the most interestingcase, because it involves changes in the enterprise business model, not merely in the model ofone of its organizational entities.
Of the four classes of service, this article concentrates on the specific case of the acquisition ofnew business capabilities by using a business application delivered through a cloud service (publicSaaS).
One last point involves the ability of the cloud model to be a "platform." Providing services isthe objective, of course, but the quality of the provided services depends on the technical andbusiness support functions provided by the platform (the two pink boxes in the IBM ReferenceArchitecture).
The IBM Cloud Reference Architecture identifies these support services:
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Service Offering Catalog and Management
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Service Request Management
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Order and Subscription Management
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Contracts and Agreement Management
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Pricing, Metering and Billing
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Customer Account Management
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Rating
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Clearing and Settlement, Accounts Payable, Accounts Receivable
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Service Delivery Catalog
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Service Automation Management
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Change and Configuration Management
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Image Lifecycle Management
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Provisioning
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Incident and Problem Management
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IT Service Level Management
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Monitoring and Event Management
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IT Assets and License Management
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Capacity and Performance Management
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Platform and Virtualization Management
Some of these services clearly support the Providers' business and technical processes, somerequire the participation of the Consumers and might actually be new for them, such as billing forthe payment of the service, correlation of external monitoring information to control the quality ofservice purchased, and so forth.
Note:This article will not focus on them for reasons of space, even if we suggest including their (EA)analysis as part of the technical due diligence for the adoption of any cloud-based service.
The TOGAF framework and the ArchiMate model
The Open Group Architecture Framework (TOGAF) is an enterprise architecture framework. Thedevelopment of TOGAF Version 1 in 1995 was based on the Technical Architecture Frameworkfor Information Management (TAFIM) developed by the US Department of Defense. Central toTOGAF is the Architecture Development Method (ADM), which describes a process in 8+1 phasesto manage the development of an enterprise architecture.
ADM is iterative at three levels: over the whole process, between phases, and within phases. It is ageneric method, and it can be tailored to suit the specific needs of the organization. For example,some US federal agencies that use ADM have developed architecture deliverables specific to theirparticular departmental needs.
ArchiMate, an Open Group Standard, is an open and independent modeling language forenterprise architecture that provides instruments to describe, analyze, and visualize therelationships among business, application and technology domains in an unambiguous way.
Just as an architectural drawing in classical building architecture describes the various aspectsof the construction and use of a building, ArchiMate offers a common language for describing theconstruction and operation of business processes, organizational structures, information flows,IT systems, and technical infrastructure. This insight helps stakeholders to design, assess, andcommunicate the consequences of decisions and changes within and between these businessdomains. (Source: The Open Group)
ArchiMate is organized into three core layers and two extensions.
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Business layer
This layer models the organization structure and the services it produces, business roles andprocesses, and business objects such as products and contracts.
Application layer
It describes application components and their interactions, logical data entities and theirrelationships, and the resulting services offered to the upper (business) layer.
Technology layer
This one models hardware and software systems and the connecting networks, showing howthey translate into services provided to the upper (application) layer.
The AchiMate 2.0 specifications added two extensions to the core layers.
Motivation
Motivational concepts are us