Eugeny Shtoltc
Notes of an IT Architect

About the book

In this book, we will cover the following sections:

* Architecture;

* Solution Architect and microservices;

* View from the height of the business and business architect;

* Corporate architecture;

* Service architect;

* Use in the management of ITIL 4, PMBOOK and COBIT 5;

* Application architect and design patterns;

* DevOps as a component of an architect;

* Architect and basic patterns;

* Corporate data bus;

* Service Oriented Architect;

* Applications in the cloud;

* Infrastructure for the cloud;

* Edge scaling sizes: data centers, cluster, sizes;

* Architect in business processes;

* Waterfall;

* Scrum;

* Kanban;

* Varieties of teams;

* Selection and growth of personnel;

* TeamLead & leading specialist;

* Virtualization;

* Features of development in Windows – Vagrant;

* Containerization;

* Podman and Docker;

* Stacks;

* Languages and paradigms of programming;

* Front-end: single page web applications.

About the author

Now the author holds the position of the Chief Architect of Cloud Native Competencies of the Architecture Department of Sberbank Competence. In this position, the author is engaged in research on the implementation and use of technologies that are already or very soon will become the de facto standard, such as servoless theologies and CloudEvents, and with which he shares with the reader. Also, the author, on a regular basis, evaluates existing systems and those planned for implementation in accordance with their modern standards, for example, CloudNative. About this, in the book, the author talks about the scope and guides the reader to implement them. The author pays special attention to this – finding practical solutions in the formed ecosystem that make life easier for both developers and the support service, while the customer remains interested in them. Employees gain knowledge of current technologies in which problems that are present in obsolete and retired ones have already been solved. This solves the problems of both developers and customers. The author does not dwell on any one technology that he has come across, but gives universal technologies in a systemic and practical form, or introduces the reader to the set of used ones, as the author gives the code in the languages of Go, NodeJS, PHP and Java depending on the relevance. more than 10 years of experience in various fields and in various positions allows us to highlight the relevant and popular ones, as well as undergoing training at Yandex, Sberbank EPAM and receiving many specialized certificates. The author has collected experience, both in domestic and foreign companies, both in startups and in enteprase, both creating his own co-commercial products and working in grocery development and outsourcing, producing streaming products, as well as complex proprietary software solutions… In addition to typing systems and practical help, the author gives an organizational minimum. Internally, the vision will enable work experience in various technical positions such as back-end and full-stack developer, DevOps and Team-Lead, including Software Architect. Experience of work not only as a hired employee allows us to take a look at the organizational level. The author worked both as a hired employee, but also as an individual entrepreneur and an official partner of a large supplier of mass software in Russia and the CIS (Bitrix Technology Partner), making and assembling customized and scalable solutions.

Architecture

GOST R 57100-2016 (docs.cntd.ru/document/1200139542) based on the international standard ISO / IEC / IEEE 42010 defines architecture as "Basic concepts and properties of a system in the environment, embodied in its elements, relationships and specific principles of its project and development". There are quite a few varieties of it, but we will highlight the main ones in terms of abstraction level: Application Architecture, Software Architecture, Solution Architecture and Enterprise architecture. An application architect develops the architecture of the application itself using design patterns and task allocation, and often combines his role with the role of Team-Lead or Lead Developer of Responsible Components (Tex-Lead). Software Architect does the same thing as an application architect, but works with multiple teams to add unification to the technologies they use. This position is often in demand in outsourcing, where there are many projects and there is an opportunity to take the load off Team-Lead so that they communicate more with customers and the team. This position is characterized by requirements for a vacancy in knowledge of the programming language and the main stack used on projects. In such a situation, the architect is limited in his choice of technologies and hiring new employees. Since its inception in 1959, the architect has dealt with the decomposition of the system, the distribution of parts among the developers, and was responsible for the subsequent integration of the developed components into the originally required system. Now the situation has been simplified with the advent of microservices.

An enterprise architect designs interconnections between systems using an enterprise data integration bus, and an application architect designs the systems themselves, decomposing them into applications. The boundaries between applications are determined by the boundaries of use: development, deployment, provision to the vendor. Previously, applications were also combined by technology platforms and technologies, but with the advent of containerization, provisions can contain components created on different platforms, languages and stacks, enclosed in containers. It has also lost its relevance to the formation of boundaries based on the deployment of the application due to the fact that components (containers) are rolled out and are already being tested in the environment of other components. Ideally, a group of micro-services is grouped by function performed by the business and the team that develops it, but often business processes involve common components, which blur the boundaries of applications. This specificity has led to the emergence of a separate specialization – Cloud Solution Architect.

Based on the level of architecture that is supposed to be designed, it is possible to turn from an abstract question – how to become an architect – into a set of requirements necessary for solving a given problem: from purely technical to organizational. So a software architect can delegate all organizational activities to Team Lead and focus purely on the technical description of the structure of the program, and often he is a pure techie and also Tex-Lead, but cannot delegate the technical one in any way. In contrast, the corporate architect can be a non-technical specialist, for example, a director, conducting communication to organize the connections of automated systems and satisfy these systems to the needs of customers. Based on this, one can guess that when asked how they become architects, one can answer that architects before Solution Architect are evolutionary along the technical branch, and corporate, either according to the technical branch, or according to the managerial branch, including business analytics. At the same time, you can become an architect at any number of years.

Solution Architect and microservices

The introduction of microservices begins with a business, when marketing starts doing experiments – requesting features in the form of MVP, then testing in the market, then either rejecting (which is rare) or refining. Improvement is required both after confirmation of the assumption, and erroneous in the form of an adjustment. For the operations department, this means rolling out a huge number of features that were developed in a hurry and can bring down the main application – the monolith. This service tries to run these changes in an isolated environment as a separate functionality, for which it asks the development department to develop them separately – in the form of microservices.

It is necessary to separate two levels of separation: technological and domain. Technological features in the work are the same, since that services, that its components, if it is divided into component parts, are technologically launched and supported in the same way. But, unlike services, which must be minimally interconnected with other services and must provide a specific API and SLA, the components are tightly coupled. The reason for the separation into components is of a technological nature. For example, an online store contains services such as the online storefront itself, payment services, warehouse services, and the online storefront is a service on the CMS Joomla! and a database management system (DBMS) MySQL. Here, the division of the service into its component parts occurred due to different software products written in different programming languages. At the same time, for the customer this is a single service on CMS Joomla! performing a single function of providing an interface for ordering to users online, provided by the hosting as a single service (it will not work separately), can work as a catalog of goods without other services (payment, ordering)… From a technological point of view, the components are services:

* Singles are not functional;

* Strongly connected, as many requests are generated for each request to the CMS;

* Interaction interfaces are complex and varied – not even the API is used here, but the SQL interaction language;

* Strongly connected functionally through a complex technical API – only known to the user supported compatibility of some CMS versions with other DBMS versions.

Dividing a system into microservices begins with an analysis of their boundaries, an analysis of the benefits of separation and the added complexity of a distributed system. It is better to separate microservices when there is a combination of need:

* Technological necessity, for example, a large load that is difficult to withstand without separation, for example, scaling, another type of support (SLA);

* For business, the dedicated service is already a separate and little dependent function – further we will consider the DDD (model-driven design + ubiquitous language) approach to the implementation of microservices;

* Requires change of technology platform.

Microservice meets the following characteristics, according to M. Fowler (martinfowler.com). They can be summarized as:

* 1. Must be a component or service. Each microservice is a complete, full-fledged independent service from the point of view of the developer, system administrator and user. It should be able to be easily replaced with another, both in the developer's code, both in the process of work (should be), and presented to another or removed in the user interface. Failure to fulfill the conditions of interchangeability at different levels lead to one service divided into parts – a distributed monolith;

* 2. Organization of business opportunities;

* 3. Products are not projects;

* 4. Smart endpoints and silly connections. Does not require complex integration with debugged services (the integration of complex systems is handled by a service oriented SOA architecture);

* 5. Decentralized management. This refers to orchestration like Kubernetes, network management like Istio, delivery management like KNative;

* 6. Decentralized data management. Due to the self-sufficiency of the service and independence from others, it must have an independent state – a database, and so that the choice of a database management system is independent – there is its own;

* 7. Automated infrastructure. The process of deployment, scaling and rollbacks should be automated, which allows you to quickly automatically rollback, fix the isolation of the service in the code;

* 8. Provided for refusal to work. To visualize failures, you can look at Jaeger and Prometheus, to localize problems, services must be isolated, represent one single service, which allows you to isolate, limit the harmful effects on other services in case of failure and automate rollback;

* 9. Evolving design. The system grows outgrowths in the form of services – it becomes overgrown with them, while its structure does not need to be changed. Neal Ford and Rebeca Parsons in "Microservices as Evolving Architecture" focus on continuous improvement.

Business and business architect's perspective

Business architecture (Enterprise Architect) is the IT architecture of the entire company. It operates with abstractions and entities at the business level, these are strategies, business processes, services, and the like. The systems and interconnections that support the business are called the IT landscape because it contains many systems that do not form a single whole, connected by the business processes in which they participate and which are not limited by them. The Business Architect (Enterprose Architect) works at this level, adjusting the current landscape to the current needs of the business. Often, for traditional companies that did not develop in the high-tech sphere in the blue ocean, it is attracted when the IT landscape has taken shape and difficulties arise in its development and adaptation to changed conditions, a minimum capable product (MVP) is created in technology startups. The business architect of the corporate IT landscape must solve problems with a low rate of changes (due to the impossibility of local testing, postponing distributed changes, a breakdown claim after rolling distributed changes) – Time To Market, quick adaptations to user expectations – Customer Experience and cost – Cost… The first is tackled by the architect's sequential tidying activities, reducing cohesion and confusion, which simplifies and speeds up the process of making changes and, as in any knowledge-intensive field, where the main cost is the man-hours of workers, reduces the cost. More and more often, the architect is not provided with the requirements, he connects at the earliest stages of their formation, after his capabilities are severely limited. To do this, he needs to actively participate in negotiations and meetings in order to adjust the requirements. Further, to form several possible solutions with different levels of complexity, from simple and fast, but not effective ("solutions on the knee"), through the optimal, and to large-scale and flexible. Further, to form an architectural committee, at which to propose solutions for the choice and adjust the choice towards the optimal one.

Changing the existing architecture can be carried out in three ways: supporting the current one, completely replacing the current one, complementing the current one. Replacing the current one requires a long and lengthy study of the functionality of the current system, then finding out the functionality that is currently in demand and searching for differences between the current functionality and the expected one, after which the cost and development time are calculated. During the presentation, in most cases, a refusal will be received in the development of the system, since the customer does not need a technical update of the existing functionality, but he needs new ones and the correction of the old, and even more so not for the time and funds that were spent on creating the current system. With the consistent improvement of the system, fundamental changes to the system cannot be achieved, since the architecturally different functionality of one part contradicts others and changes in the architectural style are not achieved by successive improvements of the parts due to the complex nature.

The Enterpris Architect strategy implements different company strategies in different ways:

* Growth (scaling) strategy when the market is free – the architecture unifies and debugs processes;

* Strategy of innovation (search for hypotheses by Lean Startup). Creation and delivery of features and testing of hypotheses about the demand for these features are as fast as possible;

* Integration strategy. It is necessary to develop an open, most scalable and versioned API;

* Adaptation strategy. Not a strategy using Agile to adapt to the market;

* Strategy of quick decisions. Consistent changes.

Difference between Architects and Architects (NEW)

In general, the architecture of a fairly large company is called Enterprise Architect. It describes all levels of detail and the entire scope of the company. For any IT architect, IT interacts with the rest of the company's business. For most companies, the business makes money, and IT provides this opportunity, and understanding how this happens and what needs to be changed the task of the corporate architect. To do this, the corporate architect works with two layers that make up the corporate architecture: business architecture and IT architecture. It is very important to understand that in most cases IT is the backing function of the company, and the architect describes the current business architecture of the company and adjusts the IT architecture 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 any case, the number of layers is standardized, those that differ are indicated, so that each layer belongs to a specific info-structural department and an operation department.

Let's pay more attention to the integration architecture, since this is the most critical layer for the architecture. In this layer, connections can be presented both in a graphical form (in the arrows on the diagrams between systems), and in a tabular form – in the form of a description of the supplier, consumer and contract (the supplier's obligations to the contractor). The arrows point from the supplier to the consumer, that is, in the direction of the integration flow, while the service modules are not indicated. Depending on whether the parameters are functional or non-functional, they will be described either by API or SLA. Also, depending on whether the connections are inside or from outside to inside and outside. The first type is more visual, and the second allows you to give more detailed characteristics.

The system itself can be integrated in different ways, such as:

* direct integration (communication via API point-to-point, advantages: minimum overhead, disadvantages: two-way revision of systems is required, complexity of change management, complexity of scaling, no reuse);

* using gateways (communication through the API of an integration layer, such as a queue with a firewall, advantages: minimum overhead, unified API, disadvantages: complexity of change management, complexity of scaling, no reuse);

* Enterprise data bus or enterprise service bus (ESB) provides asynchronous umbrella integration based on the principles of event and service approach (SOA, service-oriented architecture). The corporate data bus is able to flexibly route messages from one service to another. (advantages: unification, reusability due to SOA, replaceability of services due to SOA, disadvantages: an expensive solution in many applications, delivery time from tens of milliseconds);

* Service Mesh, like ESB, is umbrella, but applications do not need to integrate with it, since applications running in a containerized environment immediately receive integration. (microservices, advantage: minimum overhead, not noticeable for application developers);

* Integration file gateways and point-to-point file transfer (file overload). Point-to-point file transfer is the same point-to-point transfer, but it allows you to transfer large data in exchange for the transmission speed (advantage: it is possible to transfer very large amounts of data, high delivery guarantee, weak connectivity of integrated systems, greater control, broadcast mode, disadvantages: transmission speed, possibility of desynchronization, high security requirements). Communication protocols are CIFS (Common Internet File System), NFS (Network File System extends the local file system) and S3 (Simple Storage Service provides access to object storage such as Minio and Ceph) and transfer protocols HTTPS (HTTP + SSL), SFTP (SSH + SSL) and FTPS (FTP + SSL). From the point of view, records can be divided into block (disk) and object (writing to the key-value database: Bucket).

Systems can communicate in various ways:

* integration request (normal synchronous request-response),

* remote procedure call (RPC),

* sending a command to the queue (from the supplier to the consumer directly through the event queue),

* publish-subscribe, Push-Sub (sending events to a common queue, from which groups of events are retrieved from the system in advance, undefined by the provider),

* packet data transmission,

* transferring files to storage,

* streaming data.

The interactions themselves should be described, and preferably unified. To describe functional or non-functional parameters (response time, availability, message size, bandwidth) of interactions between the supplier and the consumer, a Contract is used, which the supplier undertakes to fulfill. Functional parameters are described using the Application Programming Interface (API). Service APIs can be divided into groups based on message format (DTO, JSON, XML, binary) or protocol (HTTP, REST, SOAP). It is important to specify in the API contract: ID, name, version, purpose, template, specification of input and output parameters. The API itself will contain methods (encouraging the consumer to take data, change, allocate, etc.). Parameters passed in a method are described by a method specification, for example, using OpenAPI or Swagger. For many languages, and primarily for the Java language, you can automatically generate a specification for OpenAPI using Swagger by Javadoc annotations (by special comments) in the code. The specification will be displayed in both text formats (JSON and YAML) and graphical. For ease of design, you can use the Swagger Editor (https://swagger.io/tools/swagger-editor/). This helps to organize automated contract testing. In general, the presence of the specification helps to organize API-first development, when the API specification is first written, and already the application code is developed for it, implementing it.