Cloud Migration of a Legacy IT Estate

There are many things to consider when migrating a legacy IT estate to the cloud. The first though must be what are the motivations and expected benefits. Many organisations have many decades of developed software running on private infrastructure and migration to the cloud is something they think they should do.

Migrating an estate to the cloud incurs a significant cost hurdle as new functions are required just to support migration activities. Often the benefit is minimal as only limited efficiencies can be found from closing (or worse partial closing) of legacy applications and data centres.

What is needed is a target systems architecture aligned to business benefits and vertical product supporting IT Stacks.

The systems architecture should reflect management of intermediary states between internal hosting and public cloud. The management of intermediary estates can easily increase an organizations run cost; for example if Corporation A decides to migrate all of its channels’ IT to a public cloud it will need to build an integration from public to private infrastructure, lease connection between new and old sites, provide a security wrap and identity mgmt function across internal and external clouds and finally support the operations for managing these new systems.

The benefits to support all of these new cloud enablement functions will be high. This does not mean it should never be done but the business must address how benefits like improved time to market will be substantively realised.

A TOGAF business architecture should be included before migrating as migration for the sake of hosting will only ever be a platform change. The balance has to be on how much change your organisation can stomach in a single move. Always consider that the SaaS services you are considering will probably be more configurable than your legacy estate. So don’t fall into the myth of business architecture as business change does not always have to be front loaded.

An Identity Management System in TOGAF: How to Fit IdM to ADM?

The TOGAF Architecture Development Method (ADM) is designed to be sufficiently generic to cover all types of IT programmes. This generalism means that the ADM method can support both organisation and governmental identity management projects. This blog post, as part of a series on identity management in TOGAF, shall cover the best fit of the ADM to a IdM project and will try to answer the following questions:

  • What is the best way to realise Identity Management (capability & project) within TOGAF’s ADM?
  • Is TOGAF a suitable Enterprise Architecture model for something as generic and security conscious as identity management?

What is the best way to realise IdM in ADM? The ADM may be generic but it depends upon co-operation with more specific industry verticals (e.g. TeleManagement Forum (TMF) in telecoms) for a more detailed realisation of a technology architecture. Identity Management is as equally inclusive as TOGAF and hence equally applicable across all industry verticals. TOGAF defines four architecture domains (BDAT): Business, Data, Application, and Technology. And the TOGAF Architecture Development Method describes a process for “deriving an organisation-specific enterprise architecture that addresses business requirements”. As such the ADM requires manipulation to fit your organisation and any specific programmes. In an earlier post in this series (IdM Stakeholders, View and Concerns) I produced a set of building blocks necessary for producing a successful identity management system. For traceability I have mapped these building blocks to the four BDAT architecture domains and to the various phases in the ADM. As part of this mapping I have described which building blocks need for an identity management system to be delivered early.


Building Blocks to be delivered earlier that normal within the TOGAF ADM:

  1. Phase B: Business Architecture & Business Architecture Requirements
  2. Phase C: Information Systems Architecture & Application Architecture: Vendor selection & Component list
    • It is crucially important when working with a technology that may have multiple components to be able to explain each component in terms of its business capabilities.
    • Depending on the software vendor the component names and areas of responsibility will change. For example Oracle & ForgeRock’s definition of Access Management differs.
    • The business case should have already have been completed at this stage but it is important to split out responsibility to each component.
    • The test cases can be promoted at this stage so that both component independent and project overall tests are defined early.
  3. Phase D: Technology Architecture & Technology Architecture: Physical arch & deployment model
    • It is critical to promote the necessary environments for a IdM implementation. These are required for testing and patching and for integrating each individual system to which access will be granted.
    • In a federated architecture working with 3rd parties then for each third party a set of test & contract agreement environments will be needed
    • If the architecture is a partial migration then environments may need to be consolidated
    • As the IdM system is a security component it is recommended to introduce good deployment policies at this stage, for example separation of package naming and deployment.
  4. Phase F: Information Systems Architecture & Technology Architecture: Security Policies
    • Security risks must have been identified and the responsibility for the identity management system must be agreed early
    • If the solution is a migration project then the legacy security policy from implementation must be compared with the organisation’s policies and the ambition for secured systems

Conclusion: Is TOGAF a suitable Enterprise Architecture model for something as generic and security conscious as identity management At an organisational level an identity management programme is normally initiated to provide a business enablement capability (e.g. SSO or Federation), a legal requirement (e.g. Healthcare) and / or a security capability (e.g. reduced DDoS exposure). At a national / government level an identity management projects vary in scope and identity ownership architecture. Austria’s Zentrales Melderegister (ZMR) or Denmark’s Det Centrale Personregister are examples of identity owning identity management projects working to enable access to eGovernment services. The UK Cabinet Office’s Identity Assurance programme has the same goals but externalises the identity lifecycle to trusted identity providers. Furthermore some programmes such as the UK land registry are not immediately concerned with individual identity but have a strong identity management capability encapsulated within a larger data structure. For both organisational & governmental IdM deployments the TOGAF ADM model can be applied. The TOGAF ADM model is designed to provide an organisational enterprise architecture capability. However TOGAF ADM can be applied to just IdM because Identity Management is a sufficiently complex area and the number trusted identity providers increases. The ADM is suitable for an Identity Management programme but overall enterprise architecture should be applied to all organisational data & security capabilities.

An Identity Management System in TOGAF: stakeholders, concerns, views & viewpoints

This article is how I would deliver an Identity Management architecture and implementation in accordance with the Open Group’s TOGAF architecture development method. This post is based on my personal experience as a digital enterprise architect and as a solution architect implementing indenting management, master data management and security systems. I intend this to be part of a series on applying TOGAF and using IdM as an example. In this first post I will only describe the functional capability necessary for an IdM system and will focus on the TOGAF definitions for stakeholder, concern, view and viewpoint.


Firstly the Identity Management (IdM) implementation will be referred to as the TOGAF system. This system has stakeholders who have concerns. The stakeholder has a view of the system which is taken from their viewpoint. These definitions allow a business architecture and architecture building blocks to be created for the identity management system and used as part of the TOGAF ADM.


The non-exhaustive stakeholder list for an IdM system include: system owner (e.g. Business sponsor), system maintainers (e.g. Individuals who manage the solution), user maintainers (e.g. Individuals who manage the users & their permissions within the directory system), security governance (e.g. Individuals who validate and sign off the architecture and the software according to the organisations security principles), system developers (e.g. Individuals responsible for coding, packaging and deploying the system) and project team members (e.g. Individuals responsible for the software delivery and maintenance of the IdM system).

I’ve not described them here but the organisation’s HR function who manage the organisation’s joiners and leavers (also promotions & changes) will be key stakeholders if the IdM system is to be used to manage the employees (potentially both internal and external).

The end-user stakeholder is the most important for an identity management system because their concern will massively influence the software solution. For example it may not be necessary for an organisation to maintain the customer end-user’s credentials these saving the organisation large costs in terms of registration and password reset capabilities. In the case of an eCommerce implementation it may make more sense to trust the OpenID Connect capability of PayPal’s (other authentication providers too) Login with Paypal rather than enforcing a local registration for each customer. Choosing external IdP trust as the identity provider does not remove all of the existing stakeholders because system ownership, system maintenance and security concerns remain valid concerns. The stakeholder list depending upon the solution requires review as part of the ADM process.

Stakeholders can be categorised by type such as corporate, system, end-user and project. I often prefer to avoid type categorisation as the type can quickly become a pseudonym for the stakeholder themselves and as such dilute their importance and the quality of their concern. It is though useful to have a repeatable organisational list of stakeholders as these process are repeatable through multiple organisational software deliveries.


Concerns and requirements are not necessarily synonymous because concerns are conceptually larger groupings of requirements that encapsulate the key interests of the stakeholder. Crucially because a concern is a key interest it determines the acceptance of the system. Acceptance criteria must be made against a specific requirement in order to objectify the sign-off process otherwise the system implementer will be at mercy to the vagaries of emotional acceptance.

For a successful Identity Management system implementation concerns are crucial but thankfully also fairly obvious. For example the security governance stakeholders (naturally the most risk averse people on earth apart from England cricket captains) would have the following concerns: security testing coverage including penetration testing, cryptography, encryption and digital signing concerns, risk management concerns such as password management and policy, assurance, availability and administration concerns.

It is important to capture concerns jointly with the stakeholder but to own the process of concern capture if the actual stakeholder or stakeholder function has not defined previously defined their concerns. It is most likely that the security governance function will have pre-published and regularly maintained documentation covering organisational security policy. I have regularly seen security governance stakeholders try to enforce that internal and external password policies should be the same. For example the security governance function will require a much stronger password management policy than maybe necessary or appropriate for a customer facing website. This is a good example of where security concerns and customer concerns will clash. The best approach here for the enterprising architect is to preposition the customer evangelist for this conflict.


A view is a representation of a system from the perspective of a related set of concerns.  A view consists of architectural documentation (e.g. diagrams, requirements coverage, PowerPoint) showing stakeholders not only how their concerns are being met but also how they are being met. Remember that different stakeholders will have different views of the IdM system such as the security governance team member will have a different view to that of the customer evangelist.

The following are the architectural artefacts that I regularly produce for an identity management system implementation and how I use them to manage concerns (note that these artefacts will be phased and not all are immediately necessary for business stakeholders):

  • Requirements ( I will cover these in more detail later in this series but it is sufficient here to say that identity management is a complex area in which many business owners will have little technical expertise. I advise against over elaboration of technical IdM requirements following a “system shall…” approach and rather focus on the business reasoning for technology and standard selection and also the UX wireframing / mock-ups (depending on the appropriate level of detail) for login & registration processes)
  • Technology standards. Selection and reasoning for standards are pre-solution design prerequisites. What are you protecting and how? Are you SAML, Kerberos, Shibboleth, OAuth, or OpenID Connect? More importantly why and can you explain why?
  • Security policies. Hopefully these will have already been defined in your organisation. If not start immediately.
  • User model diagram for entities & attributes necessary as part of the directory system and identity repository (it is important that the business owner is involved in this stage especially as they often enjoy & appreciate it). This artefact is a key architectural building block for the IdM system and requires regular review if scope changes.
  • User lifecycle processes. This is the cradle to grave information that requires a human architecture to manage and maintain the system. Are you outsourcing or keeping in house? What bits can you split off? How does any of this differ from your existing systems? Have you got business agreement, budget and guarantee that it will be supported?
  • Vendor selection. Do you have a preferred vendor, do you require an RFI / RFP? If yes is your stakeholder list appropriate? Are the captured concerns sufficient to differentiate between vendors.
  • Component list: description of all the various software components involved. This is useful and appreciated especially when certain vendors have balkanised their licensing of IdM components. What & why for each component needs to be succinctly described.
  • Physical architecture & deployment model (preferably in UML) is probably the most important technical architecture artefact in an IdM system deployment. It is critical to know how directory services are being located and exposed to other systems covering authentication and authorisation. If the deployment is a CoTS (most likely as no-one would write this stuff from scratch anymore) product deployment then one of your stakeholders would often be the vendors professional services team and the system implementers concern will be the ratification of this architecture.
  • Sizing & capacity model. These are very difficult to produce as an organisation will ask for as much as possible accord g to budget. It’s obvious to refer to previous models but as identity management maybe a new function or a large master data management driven consolidation then previous models may not apply. I would ask both the vendor and system implementer to help.
  • Test Model. Testing for identity management is complex and critical. At an early stage it may be sufficient to define security policies and encryption / signing technologies. It is important to have all the necessary testing and patching environments available ahead of time. A review of testing tools is as early-mid phase activity.
  • Patching & support model. This is both a pre & post go-live activity. The pre go-live a model is required for how patches are downloaded and applied and tests run. Normally a parallel environment is required. Also licence support guarantees are necessary from the vendor.
  • Architecture roadmap. More importantly a business roadmap is required because identity management is an area that is often degraded to being just an enabler rather than a clear discrete but involved function of your business. If your organisation is conducting a data cleansing exercise through master data management then how exactly does this fit with the identity management roadmap?
  • System delivery roadmap. This is not the enterprise architects ownership but it must encompass the architecture perspective because, for example, if there is a data cleansing / consolidation exercise then the identity management system delivery will often be split between various functions and directory service actions and the component deliveries will need to be spaced out to allow approval and validation steps.

From all of these artefacts different views can be collated to provide a concern compliance model. This can also be used by the architecture board as part of architecture compliance reviews. Always remember to try and start objective if you are producing these artefacts and try to mark your own homework before the architecture governance board marks it for you. Confidence is critical in a security product implementation and it is far easier lost than ever won back.


A viewpoint defines the perspective from which a view is taken. The metaphor given by the Open Group is relationship between viewpoint and view is analogous to that of a template and an instance of the completed template. In my view this does not capture the subjective nature of the stakeholder whose concerns are more than a checklist template. The template analogy does not convey the importance of good documentation and presentation as part of an enterprise architect’s skill set. The viewpoint differs from the concern as it is the stereotype of the stakeholder. The experienced stakeholder will regularly raise concerns that should be raised by other stakeholders. These concerns may need capturing or have already been captured but some can be waived if the relevant stakeholder has provided reason. For this reason the view presented to the stakeholder must be from a viewpoint that mirrors their relevant concern.

views and viewpoints for an identity management system
views and viewpoints for an identity management system

Above I provided a set of the architecture building blocks relevant to an IdM system implementation. Here they are mapped to the relevant viewpoint.

Trade-offs to make between concerns:

It is the role of the enterprise architect to balance competing concerns. The most obvious within an identity management implementation is the competition between identity as an enabler and security as a constraint. The identity management project can quickly end up being responsible for other systems security. This forces the system into being a blanket security provider and always returns an architecture that is as only strong as its perimeter defence. It is therefore important to gain quick business agreement that identity and security are not the same thing and security is a concept for which all organisation stakeholders have to take personal responsibility. This way the identity management system can address the concerns for which it is best suited such as identity management and access provisioning.

ADM Cycle & ordering of architecture artefacts:

The architecture building blocks that are described above are developed in TOGAF between the ADM Phases A through D. I do not specifically disagree with the TOGAF ordering but of all the artefacts produced for an IdM implementation it is the security audit that takes the longest and the physical and deployment architecture that needs to be brought forward where possible.


In TOGAF the primary question the EA needs to answer is does the architecture address all of the concerns of the stakeholders?

Statutory & Contract

You may have a customer with multiple different statutory legal compliance criteria and you may also have a customer with highly specific contractual hosting & data sovereignty NFRs. The latter often comes from the sales guy abandoning the normal contract template on any fear of losing their commission and promising any physical hosting model that the customer could imagine. The sales guy has not brushed up on his data sovereignty & EU safe harbour law and the customer is nervous about externalising any data. So it’s no surprise that you the architect are left to figure out this mess while maintaining some sanity by not spawning stovepipe after stovepipe in any customer territory.

If this keeps happening in your company then no TOGAF enterprise continuum will help you find and train a sales team led organisation on the variances of data sovereignty & safe harbour regulation.