Customers will not in general procure the complete IT DialTone Infrastructure from a single source. No single company has the resources to address the complete needs of any major enterprise. The implication of this, is that the IT DialTone Infrastructure must be an open system, integrated from components delivered by different suppliers which work together because they adhere to common standards where they interact.
Open systems that work depend on
The IT DialTone Architecture is a structure that portrays information about and relationships among all of the elements of the IT DialTone Infrastructure.
Like any architecture, the IT DialTone Architecture comprises three distinct parts, all of which contribute to its value and usability:
The IT DialTone Architecture Reference Model defines a common structure for the collection and dissemination of information relating to the IT DialTone Infrastructure.
The model is designed to be applicable in a broad range of different IT environments and to achieve this needs to be extremely flexible and extensible. For clarity of presentation, the model does indicate some relationships between services, in terms of layering. While this layering is broadly representative of the structure of IT systems, it is not prescriptive and must not be understood to constrain the implementation of any specific system.
Figure 3.1 - The IT DialTone 3-Layer Model
The basic structure of the IT DialTone Architecture is defined by a relatively simple 3 layer model.
The lower level, Communications and Platforms, contains operating system environments and basic network communication capabilities and in particular, the definition o the IT DialTone Core Infrastructure.
The top level, Applications and User Interaction, contains applications and services for the interaction with the end user of the system
The middle layer, Distributed Services, contains the majority of the functionality included within the IT DialTone Infrastructure, the many services needed for the deployment of business applications in a distributed environment.
This 3-layer model is the basis for the full IT DialTone Architecture Reference Model (ARM), which includes a further breakdown of each layer, and the introduction of the concept of Infrastructure and Service Qualities.
Figure 3.2 - The IT DialTone Architecture Reference Model
Platforms define the software interface to the physical computing resources of the system and specifically the execution environment for program binaries.
The IT DialTone Platform defines features which must be accessible in a standard way to IT DialTone services or components in order to guarantee that it is possible to provide those services on that platform and that programs can be loaded and executed.
The platform is typically responsible for all services that are not distributed and for providing access mechanisms that allow applications to invoke such services.
Communications Services interconnect systems and provide the basic mechanisms for the transfer of data.
The IT DialTone Communications Services define both the protocols and data structure for transfer of data, and a set of programming interfaces to enable higher level services and applications to send and receive data. The protocol interface is a transport level protocol, which defines neither the detailed internal structure of packets of data being transferred, nor the specific network media to be used.
The IT DialTone Communications Services define a basic quality of service that is available to all other services and applications, such as reliability and security. It DialTone Distributed Services support the needs of applications which need higher quality of service.
IT DialTone Communications Services are based on the IP protocol and associated definitions.
IT DialTone Distributed Computing Services defines a set of low-level services that implement the distributed computing environments on which all other IT DialTone services depend, including
The IT DialTone Infrastructure supports the deployment and use of distributed applications that are constructed out of separately-developed components, interworking by means of standardized interfaces.
IT DialTone Software Integration Services provide support for software components, and for the definition and implementation of interfaces for interaction between components. In particular, the existence and interoperability of multiple, broadly accepted models for the integration of distributed software components is addressed.
The IT DialTone Information Flow Control Services provide mechanisms for managing the run-time interactions between application components, including
The IT DialTone Location Services enable service consumers to locate required resources.
In addition to traditional hierarchically organized directory and naming services, this will include
The IT DialTone Data Services define functionality to enable applications to store and access data, and to represent data, particularly that originating from other applications, in a form that they can interpret. Data Services includes
Management services provide for the managing of an IT DialTone environment, including the processes, people, and tools needed to manage system resources throughout the environment, in accordance with the management policies of the enterprise.Management Services are key to being able to provide predictable levels of service and data delivery guarantees.
The IT DialTone Management Services define specific services to carry out management tasks on a system which has been designed to be manageable. How system resources should be defined in order to be manageable is defined in the Infrastructure Services and Qualities section of the IT DialTone Architecture.
In general, the purpose of security services in IT are to protect the confidentiality, authenticity, and integrity of data interchanges between enterprises, and to defend organizations’ business information and IT infrastructure against unauthorized and unaccountable internal and external access
The major focus for security within the IT DialTone infrastructure is the provision of interoperable mechanisms which enable the ubiquitous IT DialTone Core Infrastructure to be used to support high value commercial transactions and to convey sensitive information within and between enterprises.
The IT DialTone Security Services define specific services which can be invoked by security-aware applications to achieve an appropriate level of security. A basic level of security for non security-aware applications is defined as part of the IT DialTone Communication Services. Aspects related to the overall securability of the system are addressed in the Infrastructure Services and Qualities section of the IT DialTone Architecture.
IT DialTone Applications includes applications that make use of the IT DialTone Infrastructure. The category is divided into
The IT DialTone Presentation and User Interaction Services define the way that information is displayed on and gathered from a variety of devices, operating properly in a distributed environment encompassing multiple geographies, times zones and audiences, in a way that conveys the intended meaning for humans.
There is a set of pervasive capabilities whose definition and effective control is fundamental to the quality of implementation and operation of the infrastructure and its services. For example, for the management service to be effective, manageability must be a capability of all services and applications.
The set of capabilities that are currently defined in the IT DialTone Reference Model is:
The Open Group Architecture Framework (TOGAF) program has developed an architectural approach to the development and deployment of an enterprise IT strategy.
Figure 3.3 - The Architecture Process
A - Initiation and Framework: The step of committing to the development of an IT strategy and gaining buy-in to the overall program.
B - Baseline Description: A formal analysis of the existing system against the structure of an agreed Architecture Reference Model
C - Target Architecture: The definition of the desired "end point" against the same Architecture Reference Model
D - Opportunities and Solutions: The examination of what solutions exist to meet new needs identified
E - Migration Options: The selection of approach to be adopted from the options that exist
F - Implementation: Implementation of the agreed solution
G - Architecture Maintenance: Making sure that the architecture remains accurate so that it can form the basis for the next cycle
The IT DialTone Architecture Reference Model represents a suitable
structure for use within the process. The information that populates the IT DialTone
Architecture provides the baseline for steps D and E.
The Architecture Process described above is also being used by The Open Group in the execution of its IT DialTone mission and the application of the process results in the population of the IT DialTone Architecture.
Step A results in the selection of the specific business usages that the IT DialTone Infrastructure is designed to support.
Step B results in the recording of information about all relevant agreed standards and products which conform to those standards, classified according to the categories of the Architecture Reference Model.
Step C results in a decomposition of the agreed business usages into technical requirements in each category of the IT DialTone Architecture Reference Model.
Step D results in an analysis of the extent to which the documented technical requirements are met by existing standards and the products that conform to those standards, and provision for vendors to record information about their products which could fill identified gaps.
Step E results in a forward plan for Open Group activities.
The IT DialTone Architecture is populated with information intended to help customers design and deploy systems which make use of the IT DialTone Infrastructure. Ultimately, the architecture will be populated with:
The status of every piece of information which populates the IT DialTone Architecture must be totally clear, if it is to be usable by customers. For each type of information, published procedures will be used to ensure the value of the information recorded.