Notes of an IT Architect. Eugeny Shtoltc

so that the described business architecture functions as intended by its creators. The creators of the business architecture are the heads of departments, functional blocks and divisions. They are the ones who know exactly how their departments should work. At the same time, they, too, often do not take it out of their heads, but rely on existing processes, for example, the sales department relies on customer experience that they have received in other companies and to which they are accustomed, or as a result of negotiations. The already formed processes in the business architecture take advantage of the power of IT, but this does not mean that the corporate architect needs to make the IT architecture a mirror image of the business architecture. On the contrary, if several processes have similar requirements, then the IT architecture should unify this, if possible, provide flexibility and scalability in a short time in the wake of changes and growth of the process, as well as offer more efficient ways to solve problems.

      Political architecture (or layer of stakeholders) is a layer of stakeholders, their interests and agreements between them. Using the imperial method, it was found that for an architect it is 50 % important to collect information, another 30 % to negotiate, and only 20 % to a choice of technical solutions. With the availability of information, negotiations are easy and their result can be easily recorded. When looking for data, you need to find various solutions. This is a separate skill – the squeak of alternative solutions on the required data, called divergent thinking. During negotiations, it is important to listen to other people, offer different options, focusing on (sell) the best solutions, and find compromises. On the basis of already available data from a large number of solutions, it is necessary to find the best solution, which usually does not cause difficulties for quiet specialists, since they are accustomed to convergent thinking. For the architect, the main contractor (the main stakeholder) is the owner of the product for whom the architecture is being made. There is only one exception if decisions are made by other stakeholders, and the product owner simply broadcasts these decisions. Other stakeholders: the customer (or owned the product, as its representative), developers (minimization of work, clear setting of tasks, Time2Market), service departments (implementation of their standards), service architect (guaranteed service operation), corporate architect (landscape maintenance). If there is no common language, then either the architect of this area, or the owner of this area, need to escalate. For example, if there is no common language with the service team, you can escalate either to the service owner or to the service architect. If the language is not found with the owner of the service, then it is escalated to the architect of the service, if with the architect of the service, then the owner of this service. If there is no common language with either one or the other, you should ask yourself whose interests you are defending. The customer wants for the business:

      * planned process;

      * minimization of risks;

      * movement towards the goal.

      Business architecture is an enterprise and communication activity. According to TOGAF, it consists of pleased with the architecture, and since they are descriptive, they are often:

      * organizational architecture (business goals, people, roles),

      * product architecture (products, distribution channels, customer journey),

      * process architecture, linking the organizational with the product, as the seller and the buyer processes.

      The user path is called the client path. The path itself is the sequence in which services are used, which can be grouped into products. Service is what the client sees. To provide a service, a business needs to perform certain actions. Such actions that are repeated for different users are called processes, and the logic by which they are provided is business logic. Process is a business view of a relationship with a client. Processes are divided into business processes (for an external client), supporting processes (for an internal client) and control processes (for a company's work). All processes are placed in the process register and constitute the business landscape of the business layer. This layer also operates with other entities, such as needs, presence, and others. Processes themselves consist of a unified set of operations that programs can perform.

      The architect investigates the ability to provide services (called business competencies), that is, the ability to provide the necessary operations with programs and describes them using competency maps. Graphical representations such as BPMN diagrams and structured textual descriptions such as process registers are used to describe processes and how they relate to the applications that implement them. From the processes, the user paths are built, along which the user walks, in turn, it is detailed to the level of the operation with reference to the application interfaces using the technological map, which is necessary for their development. Technological maps structurally detail the description of the process by technological objects and attributes. The process itself contains scripts, operations, roles, data, and the technological map adds API, functions, attributes to them. Thus, linking the operations of the process with the service programs that implement these operations. The routing does not describe the implementation on programs, nor the API – they are points for creating operations. Maps can be designed in various systems such as ARIS.

      IT architecture is divided into:

      * Application architecture – here are the systems and applications that are used in the business layer to implement their processes.

      * Information architecture is a collection of information (data) that is exchanged between people or applications as part of the execution of processes. According to the level of logical abstraction, it is divided into: conceptual, logical and physical levels. It is managed (Data Governance) by artifacts, the main of which is the corporate data model. Data models are of different types, for example: relational, object-oriented, chronological (Time based), NoSQL and others.

      * Integration architecture connects various components of the system and it is these connections that describe the integration architecture.

      * The technical architecture describes the implementation of the previous layers. It itself is also divided into layers, but these layers are not abstractions, but are a technical implementation in relation to the client. These layers are also called a stack, since they are not located from the user of the business layer one by one in a specific order and not a single layer can be skipped, while the layers of architecture describe the architecture in a different way, can be supplemented and changed, but we adhere to the set of layers accepted in TOGAF. So, the stack of WEB-applications consists of:

      ** Application layer – the layer with which users directly interact and which provide processes and is implemented using WEB-interfaces in browsers. Execution of business logic at the level of WEB-interfaces is unacceptable – all work is delegated to the underlying layer.

      ** The network layer ensures the operation of WEB-interfaces in the user's browsers, transmitting data. The upper layer of applications is needed by users who are comfortable using the graphical interface and so that any routine actions are performed for them. The network layer provides communication for server applications such as WEB servers and DBMS.

      ** The hardware layer is represented by runners. These devices can be hardware-based with varying degrees of versatility. For example, a load balancer can be purely hardware, it can be hardware with changeable firmware, it can be software executable on a general purpose computer of the x86 type, it can be launched both directly and in a virtual machine, and in a container – all these are implementation details.

      ** The storage layer is made up of storage devices. These devices can be specialized devices such as IBM DataPower or regular RAID with a control module. The data in it completely describes the state and is the result of work, and the previous layers are only needed to change and provide convenient access to users.

      If necessary, other layers can be implemented, for example:

      * information security layer implemented by the firewall;

      * a layer of basic containers;

      * layer of local fault tolerance (HA) using the example of the Kubernetes layer;

      * containerization layer;

      * virtualization layer;

      * a layer of resilience to failures implemented by load balancers on different DataCenter.

      In