The theory of programming and programming profession.

• Recursion or Iteration
• Logical - based on logical reasoning and use logical operators such as AND, OR, and
• Procedural or Declarative (non-Procedural) - step-by-step procedures OR describe what needs to be done rather than how
• Serial, parallel or distributed
• Deterministic or non-deterministic - with exact decision at every step of the algorithm or solve problems via guessing although typical guesses are made more accurate through the use of heuristics.
• Exact or approximate
• Quantum algorithm

Greedy Method

makes locally optimal choices at each step to find a global optimum solution. It is used in optimization problems where the goal is to find the best solution among a set of possible solutions.

• Search and enumeration - Many problems (such as playing chess) can be modeled as problems on graphs.

Brute-force or exhaustive search

.

Backtracking

multiple solutions are built incrementally and abandoned when it is determined that they cannot lead to a valid full solution.

Divide and conquer

If a problem can be solved by combining optimal solutions to non-overlapping sub-problems. smaller sub-problems, solves them recursively. sorting, searching, and matrix multiplication

• Dynamic Programming (DP) - breaking down a problem into smaller sub-problems and storing the solutions to these sub-problems to avoid redundant computation.

Randomized algorithm

Such algorithms make some choices randomly (or pseudo-randomly).

Reduction of complexity

solving a difficult problem by transforming it into a better-known problem for which we have (hopefully) asymptotically optimal algorithms. also known as transform and conquer.

• Reduction (Transform and Conquer)

Linear Programming

This algorithmic approach involves optimizing a linear objective function subject to linear constraints. case of mathematical programming.

is the problem of finding the best solution from all feasible solutions.

Linear programming - case of Mathematical programming. Searching for optimal solutions to a linear function bound to linear equality and inequality constraints. The constraints of the problem can be used directly in producing the optimal solutions.

Dynamic programming - the optimal solution to a problem can be constructed from optimal solutions to subproblems. subproblems overlap in dynamic programming. dynamic programming reduces the exponential nature of many problems to polynomial complexity.

The greedy method - start with some solution, which may be given or have been constructed in some way, and improve it by making small modifications.

The heuristic method - can be used to find a solution close to the optimal solution in cases where finding the optimal solution is impractical.

• discriminative - SVM, regression
• generative - GDA, Naive Bayes, Generative Adversarial Networks (GANs) and Variational Autoencoders (VAEs).

is a sequence in which each number is the sum of the two preceding ones

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144.

creates golden spiral with golden ratio

• Algebraic form: (1+sqrt(5))/2 = 1.618033988749894
• Continued fraction: 1 + 1/ (1 + 1/ (1 + 1/ … ))

is a mathematical model of computation.

• can be in exactly one of a finite number of states at any given time
• transition - change from one state to another.

• deterministic Turing machines - every state has exactly one transition for each possible input
• probabilistic Turing machines
• non-deterministic Turing machines - input can lead to one, more than one, or no transition for a given state. The powerset construction algorithm can transform any nondeterministic automaton into a (usually more complex) deterministic automaton with identical functionality.
• quantum Turing machines - used to model the effects of a quantum computer
• symmetric Turing machines
• alternating Turing machines

Circuits are defined by:

• logic gates - binary AND and OR gates and unary NOT gates.
• values the gates can produce.

Boolean circuit - mathematical model for combinational digital logic circuits. values in a Boolean circuit are boolean values, and the circuit includes conjunction, disjunction, and negation gates.

Circuit - model of computation in which input values proceed through a sequence of gates, each of which computes a function. Generalization of Boolean circuits.

Quantum circuit - model for quantum computation

MVC

контроллер принимает запросы и влияет на Model и View. View зависит от Model.

(MVP)Model-View-Presenter

MVC где View не зависит от Model, данные передаются от Model через Presenter(Controller).

(MVVM)Model-View-ViewModel

как MVP, только данные привязаны к View и View меняет данные через ViewModel(Controller).

(no term)

Presentation-Abstraction-Control.

Naked objects

domain objects - бизнес логика 2) интерфес прямое представление domain objects 3) interface automatically generated from domain objects.

Hierarchical Model-View-Controller. View-Interactor-Presenter-Entity-Routing (VIPER).

Software bus

shared communication channel facilitates connections and communication between software modules

Single-page application

web app-site dynamically rewriting the current page rather than loading entire new pages from server. All or major resources loaded once. Javascript, XMLHttpRequest, WebSocket, Server-sent events

Event sourcing - entities do not track their internal state by means of direct serialization or object-relational mapping, but by reading and committing events to an event store.

Command Query Responsibility Segregation (CQRS) - separating reading data (a 'query') from writing to data (a 'command') see 9.1.1

Actor-based

Tarant (JavaScript) - "everything is an actor who can send finite amount of messages"

• Decoupling the sender from communications sent
• control structures as patterns of passing messages

(no term)

process calculi (modern actor-based) -

Choreographic programming

Choreographic languages are inspired by security protocol notation (also known as "Alice and Bob" notation)

Multitier programming

for distributed software, tiers to be developed in a single compilation unit

Relativistic programming

Relativistic programming, instead of trying to avoid conflicts between readers and writers or writers and writers, algorithm is designed to tolerate them and get a correct result regardless of the order of events. Non-blocking algorithm - atomic read-modify-write primitives that the hardware must provide, Critical sections are almost always implemented using standard interfaces over these primitives.

Structured concurrency

encapsulation of concurrent threads of execution (here encompassing kernel and userland threads and processes) by way of control flow constructs that have clear entry and exit points. Ensure all spawned threads have completed before exit.

• OpenMP, Swift, Java

Linearizability - результат любого параллельного выполнения (операций) эквивалентен некоторому последовательному выполнению.

an operation (or set of operations) is linearizable if

• The extended list can be re-expressed as a sequential history (is serializable).
• That sequential history is a subset of the original unextended list.

this means that the unmodified list of events is linearizable if and only if its invocations were serializable, but some of the responses of the serial schedule have yet to return.

Linearizability - constrains what outputs are possible when an object is accessed.

линеаризуемость является локальным - если доказана линеаризуемость операций для нескольких программ в отдельности (или для операций работающих с разными объектами одной программы), то программы вместе (операции вместе) также будут линеаризуемы.

линеаризуемость является неблокируемым свойством - В линеаризуемой программе запущенные операции не требуют для своего завершения запуска других операций.

Часто под thread-safety понимают именно линеаризуемость.

way to achieve linearizability

• running groups of primitive operations in a critical section.
• to design a linearizable object using the native atomic primitives provided by the hardware.
• transactional memory abstraction - user marks sequential code that must be run in isolation from other threads. implementation then ensures the code executes atomically. Annotate method with @Transactional

Нелинерализуемая последовательность:

Message Passing

.

Pipelines

Pipelines can be rippin fast but are not suitable for every problem

Event Handling

The popular approach for GUI applications.

Shared State

Use locks and shared memory to shoot yourself in the foot in parallel.

• Channel - synchronous or asynchronous, buffered or not
• Coroutine -
• Futures and promises

shared memory

. Asynchronous concurrent access. locks, semaphores and monitors can be used to avoid these to avoid race conditions.

message passing

can be asynchronous, where a message can be sent before the receiver is ready

Partitioned global address space

middle ground between shared memory and message passing.

Implicit interaction

no process interaction is visible to the programmer

race conditions

работа системы или приложения зависит от того, в каком порядке выполняются части кода. better to avoid race conditions by careful software design.

Task parallelism

classified as MIMD/MPMD or MISD.

Data parallelism

MIMD/SPMD or SIMD.

Stream Parallelism

or pipeline parallelism - focuses on dividing a computation into a sequence of stages, where each stage processes a portion of the input data

Implicit parallelism

reveals nothing to the programmer

Actor model

Asynchronous message passing Task - Erlang, Scala

Bulk synchronous parallel

Shared memory Task

Communicating sequential processes

Synchronous message passing Task - Go

Circuits

Message passing Task

Dataflow

Message passing Task - Tensorflow, Apache Flink

Functional

Message passing Task - Concurrent Haskell, Concurrent ML

LogP machine

Synchronous message passing Not specified

Parallel random access machine

Shared memory Data - CUDA, OpenMP

SPMD PGAS

SPMD PGAS Partitioned global address space Data - Unified Parallel C

Global-view Task parallelism

Partitioned global address space Task Chapel, X10

data contention - read same data by several processes

Use of timestamps on transaction to determine transaction priority:

• Optimistic concurrency control - good for low/rare data contention.
  • Timestamp-based concurrency control
  • Validation-based concurrency control
  • Multiversion concurrency control
    • Snapshot isolation - guarantee that all reads made in a transaction will see a consistent snapshot of the database

Abstract Factory.

The abstract factory pattern is used to provide a client with a set of related or dependant objects. The "family" of objects created by the factory are determined at run-time.

(no term)

То же самое что и Factory Method только их несколько со своим конечным Product.

Builder.

The intent of the Builder design pattern is to separate the construction of a complex object from its representation. By doing so the same construction process can create different representations.

(no term)

- Director, Builder - A,B -> Complex object

(no term)

- java 8 stream pipeline

Factory Method.

The factory pattern is used to replace class constructors, abstracting the process of object generation so that the type of the object instantiated can be determined at run-time

• AbstractCreater: public abstract Product factoryMethod();
• Предоставляющий подклассам (дочерним классам) интерфейс для создания экземпляров некоторого класса. Creator A Creator B.factoryMethod() ->ProductA or B (Product interface)

Prototype.

The prototype pattern is used to instantiate a new object by copying all of the properties of an existing object, creating an independent clone. This practise is particularly useful when the construction of a new object is inefficient.

Singleton.

The singleton pattern ensures that only one object of a particular class is ever created. All further references to objects of the singleton class refer to the same underlying instance.

(no term)

- Singleton.getInstance()

Dependency Injection

a class accepts the objects it requires from an injector instead of creating the objects directly.

Lazy initialization

tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed. For: Many created but rarely used. ex. Singleton.getInstance();

Object pool

avoid expensive acquisition and release of resources by recycling objects that are no longer in use. ex. database connection pool.

Adapter.

The adapter pattern is used to provide a link between two otherwise incompatible types by wrapping the "adaptee" with a class that supports the interface required by the client.

Adaptee - к чему доступ. Adapter.operation() вызывает adaptee.specific operation(). - aggreage in.

Bridge.

The bridge pattern is used to separate the abstract elements of a class from the implementation details, providing the means to replace the implementation details without modifying the abstraction.

Два интерфейса - Abstraction с impl ссылкой и Implementatior. AbstrClass.refinedFunction() - вызывает impl.implementation()

Composite.

The composite pattern is used to create hierarchical, recursive tree structures of related objects where any element of the structure may be accessed and utilised in a standard manner.

Decorator.

The decorator pattern is used to extend or alter the functionality of objects at run-time by wrapping them in an object of a decorator class. This provides a flexible alternative to using inheritance to modify behaviour.

Facade.

The facade pattern is used to define a simplified interface to a more complex subsystem.

Flyweight.

The flyweight pattern is used to reduce the memory and resource usage for complex models containing many hundreds, thousands or hundreds of thousands of similar objects.

Proxy.

The proxy pattern is used to provide a surrogate or placeholder object, which references an underlying object. The proxy provides the same public interface as the underlying subject class, adding a level of indirection by accepting requests from a client object and passing these to the real subject object as necessary.

Chain of Responsibility.

The chain of responsibility pattern is used to process varied requests, each of which may be dealt with by a different handler.

• Abstract class с ссылкой на соседа, и методом, который если нужно вызывает этот же метод соседа
• Назначение - для организации в системе уровней ответственности
• java.util.logging.Logger#log()
• javax.servlet.Filter#doFilter()

Command.

The command pattern is used to express a request, including the call to be made and all of its required parameters, in a command object. The command may then be executed immediately or held for later use.

• Коллекция хранит объекты комманд, Переключатель сохраняет и вызывает требуемую комманду.

Interpreter.

The interpreter pattern is used to define the grammar for instructions that form part of a language or notation, whilst allowing the grammar to be easily extended.

Iterator.

The iterator pattern is used to provide a standard interface for traversing a collection of items in an aggregate object without the need to understand its underlying structure.

Mediator.

The mediator pattern is used to reduce coupling between classes that communicate with each other. Instead of classes communicating directly, and thus requiring knowledge of their implementation, the classes send messages via a mediator object.

Memento.

The memento pattern is used to capture the current state of an object and store it in such a manner that it can be restored at a later time without breaking the rules of encapsulation.

Observer.

is used to allow an object (subject) to publish changes to its state. Other objects(observers) subscribe to be immediately notified of any changes.

• Subject.attach(o)detach(o)notify()- o.update() всех.

State.

The state pattern is used to alter the behaviour of an object as its internal state changes. The pattern allows the class for an object to apparently change at run-time.

Strategy.

The strategy pattern is used to create an interchangeable family of algorithms from which the required process is chosen at run-time.

• Класс стратегии передается параметром в конструктор

Template Method.

The template method pattern is used to define the basic steps of an algorithm and allow the implementation of the individual steps to be changed.

• Абстрактный класс с final методом вызывающим методы из наследника.
• Назначение - фиксация логики общей для группы классов.
• All non-abstract methods of java.io.InputStream, java.io.OutputStream, java.io.Reader and java.io.Writer.
• All non-abstract methods of java.util.AbstractList, java.util.AbstractSet and java.util.AbstractMap.

Visitor.

The visitor pattern is used to separate a relatively complex set of structured data classes from the functionality that may be performed upon the data that they hold.

(no term)

Вместо добавления print(), close() для каждого субклассов, у каждого субкласса создается один метод accept(visitor v){v.visit(this)}.

Thread pool

multiple threads waiting for tasks to be allocated for concurrent execution by the supervising program. Size - tunable parameter of the app. Goal - remove creation and destruction overhead.

Active object

decouples method execution from method invocation. method calls = request list. Недостаток - динамичный код в там где может быть статичный. see ./java#MissingReference

Double-checked locking

to reduce the overhead of acquiring a lock. see ./java#MissingReference

//problem
 public synchronized Helper getHelper() { //lock every time = low performace
        if (helper == null) {
            helper = new Helper();
        }
        return helper;
    }
//solution java 1.5
private volatile Helper helper;
    public Helper getHelper() {
        Helper localRef = helper;
        if (localRef == null) {
            synchronized (this) {
                localRef = helper;
                if (localRef == null) {
                    helper = localRef = new Helper();
                }
            }
        }
        return localRef;
    }

Guarded suspension [səˈspɛnʃən] (or ./java#MissingReference in java)

both a lock to be acquired and a precondition to be satisfied.

(no term)

reentrant - reentrant procedure can be interrupted in the middle of its execution and then safely be called again ("re-entered") before its previous invocations complete execution.

• Testable
• Maintainable
• Changeable
• Easy to Develop
• Easy to Deploy
• Independent

from outside to inside and from specifig to general:

1. (blue) DB, Devices, Web, UI, External Interfaces - Frameworks & Drivers
2. (green) Gateways, Presenters, Controllers - Interface adapters
3. (read) Use Cases - Application Business Rules - which Controller / Gateway to be called for the particular use case
4. (yellow) Entities - Entrprise Business Rules - core-business rules or domain-specific business rules

Interface Adapters:

• Presenters (UI Logic, States)
• Controllers (UI Logic, States) - Interface that holds methods needed by the application which is implemented by Web, Devices or External Interfaces
• Gateways (Interface that holds every CRUD operation performed by the application, implemented by DB)

User ->

• (blue) UI - inputs
• (green) Presenter - input to use case and presents the response as user understandable format
• (red) Translate Use case - which controller / gateway to be called
• (green) Translate Controller - create request to Web (client) and process response for app
• (blue) Web - Gets data from API using HTTP client

Violating 8.5

• Translate Usecase → Translate Controller
• Translate Controller → Web

Solution - Dependency Inversion

• UI -> Presenter (with web interface)-> Use case (with Controller interface) -> Translate Controller -> Web

• (super green) - configuration
• (green) etrypoints - REST API
• (read and yellow) core - Entities, Use cases
• (blue) data providers - Database, file system, network devices

• https://en.wikipedia.org/wiki/Principle_of_least_privilege
• https://en.wikipedia.org/wiki/Discretionary_access_control

statements that change state

• Procedural (early Perl, JavaScript)
• Object-oriented

Command-query separation () principle - every method should either be a command that performs an action, or a query that returns data to the caller, but not both.

• introduce complexity if you want to implement reentrant in concurrent programming.

expresses the logic of a computation without describing its control flow. [kənˈtrəʊl] [fləʊ] - what the program should accomplish without specifying how the program should achieve the result.

Fnctional programming is type of declarative

• if then else
• non-structured - unstructured jumps to labels or instruction addresses. The lines are usually

numbered or may have labels: this allows the flow of execution to jump to any line in the program. (ASM)

Object-Oriented

Modifying a lot of state at once is hard to get correct; encapsulate subsets of state into separate objects and allow limited manipulation of the encapsulated sub-state via methods.

Functional

Modifying state is hard to get correct; keep it at the boundaries and keep logic pure so that it is easier to verify the logic is correct.

Declarative

Modifying state is hard to get correct; use a language to describe how state should be manipulated and allow the machine to determine the steps required.

Imperative

Modifying state is hard to get correct; minimize the number of conceptual layers between how the computer operates and how the code is written.

Monolith

Modifying state distributed among many services is hard to get correct; keep it centralized.

Service-Oriented-Architecture

Modifying all of the state in one service is hard to get correct; distribute it among multiple services.

MicroServices

Modifying any state in a service is hard to get correct; have many services that are primarily stateless.

Adding behavior to existing code (an advice) without modifying the code itself. (increase modularity)

• separation of cross-cutting concerns.
• reflection and metaobject protocols, subject-oriented programming, etc.

cluttering [/ˈklədər/] - загромождение.

breaking down program logic into distinct parts - concerns, cohesive areas of functionality.

cross-cutting concerns or horizontal concerns - Logging, crosscuts all logged classes and methods.

aspects - express cross-cutting concerns in stand-alone modules, can contain:

• advice (code joined to specified points in the program) and inter-type declarations (structural members added to other classes).
• and pointcut is a set of join points, specifies where exactly to apply advice.

• robustness (anarchic scalability)
• independent deployment of components
• large-grain data transfer
• a low entry-barrier for content readers, content authors and developers alike.
• creating a layered architecture to promote caching to reduce user-perceived latency,

• stateless - The server won’t maintain any state between requests from the client.
• endpoints or entry points - the resource identifier (URI) of one or several resources used as starting points

• application-layer (OSI model)
• intermediate network elements
• require reliable protocol like TCP
• since HTTP/1.1 can requse a connection multiple times = HTTP session
• plain-text(ASCII) messages - in urls non-ASCII characters must be percent-encoded.

• <CR><LF> - line separator

  Request

  request line

  e.g., GET /images/logo.png HTTP/1.1

  (no term)

  verb GET POST DELETE PUT

  (no term)

  URI

  (no term)

  HTTP Version

  (no term)

  Header fields - key-value (e.g., Accept-Language: en ) all header fields except Host are optional

  (no term)

  an empty line - only <CR><LF>

  (no term)

  Body - optional

  Response: (e.g., HTTP/1.1 200 OK)

  • Status/Response Code
  • HTTP Version
  • Header - key-value
  • Body - optional

  URI: <protocol>://<service-name>/<ResourceType>/<ResourceID>

  Get user of Id 1: http://localhost:8080/UserManagement/rest/UserService/users/1

POST Starting with HTML 4.0, forms can also submit data in multipart/form-data as defined in RFC 2388

https://en.wikipedia.org/wiki/MIME#Form-Data Content-Transfer-Encoding

In June 1992, MIME (RFC 1341, since made obsolete by RFC 2045) defined a set of methods for representing binary data in formats other than ASCII text format.

Suitable for use with SMTP servers that support the BINARYMIME SMTP extension (RFC 3030): binary – any sequence of octets.

Unlike SOAP-based web services, which have a standard vocabulary to describe the web service interface through WSDL, RESTful web services currently have no such grammar.

• Make the XML schemas available to service consumers and package them with the WAR file.
• Clearly document the expected input, output, and error conditions that may arise as result of invocation.
• or use WADL

PATCH Partially update an existing resourc

client-server

Separating the user interface concerns from the data storage concerns. Resource providers and requesters.

Stateless

no client context being stored on the server between requests. Session state is held in the client.

Cacheability

clients and intermediaries can cache responses. Responses must therefore, implicitly or explicitly, define themselves as cacheable

Layered system

A client cannot ordinarily tell whether it is connected directly to the end server, or to an intermediary along the way.

Code on demand (optional)

Servers can temporarily extend or customize the functionality of a client by transferring executable code. such as JavaScript.

Uniform interface - most important:

Resource identification in requests

The resources themselves are conceptually separate from the representations that are returned to the client.

Resource manipulation through representations

When a client holds a representation of a resource, including any metadata attached, it has enough information to modify or delete the resource.

Self-descriptive messages

For example, which parser to invoke can be specified by a media type.

Hypermedia as the engine of application state (HATEOAS)

As access proceeds, the server responds with text that includes hyperlinks to other actions that are currently available. There is no need for the client to be hard-coded with information regarding the structure or dynamics of the REST service.

• No expensive tools require to interact with the Web service
• Smaller learning curve
• Efficient (SOAP uses XML for all messages, REST can use smaller message formats)
• Fast (no extensive processing required)
• Closer to other Web technologies in design philosophy

• https://blog.restcase.com/rest-api-error-codes-101/
• 400 Bad Request – client sent an invalid request, such as lacking required request body or parameter
• 401 Unauthorized – client failed to authenticate with the server
• 403 Forbidden – client authenticated but does not have permission to access the requested resource
• 404 Not Found – the requested resource does not exist
• 412 Precondition Failed – one or more conditions in the request header fields evaluated to false
• 500 Internal Server Error – a generic error occurred on the server
• 503 Service Unavailable – the requested service is not available
• 415 Unsupported Media Type The request data format is not supported by the server.
• 422 Unprocessable Entity The request data was properly formatted but contained invalid or missing data.
• 429 Too Many Requests - When a request is rejected due to rate limiting
• 410 Gone - Indicates that the resource at this end point is no longer available. Useful as a blanket response for old API versions

good responses

• 200 OK The requested action was successful.
• 201 Created A new resource was created.
• 202 Accepted The request was received, but no modification has been made yet.
• 204 No Content The request was successful, but the response has no content.

code ranges

• 2xx Successful operation
• 3xx Redirection
• 4xx Client error - запрос не принят к обработке, сущности не создаются
• 5xx Server error - техническая ошибка сервера

ex

• 400 - ошибка проверки аргументов запроса или предварительной проверки правил его использования
• 401,403 - авторизация недействительна или не обладает достаточными правилами

https://www.vinaysahni.com/best-practices-for-a-pragmatic-restful-api#restful

Maturity model - framework for measuring an organization's maturity.

• Big data maturity model
• Cybersecurity Maturity Model Certification (CMMC)
• People Capability Maturity Model (PCMM)
• Open Information Security Maturity Model (O-ISM3)

RMS three steps: resource identification (URI), HTTP verbs, and hypermedia controls (e.g. hyperlinks).

RMS - classifies Web APIs based on their adherence and conformity to each of the model's four levels:

• Level 0: The Swamp of POX
  • single URI (typically POST over HTTP)
• Level 1: Resources
  • Introduces resources with URI (still all typically POST)
• Level 2: HTTP verbs

• Level 3: Hypermedia controls or HATEOAS (Hypermedia As The Engine of Application State),

  • GET request to a hotel reservation system might return a number of available rooms along with hypermedia

  links (these would be html hyperlink controls in the early days of the model) allowing the client to book specific rooms.

Request:

GET /room/?customerId=1&date=10-11-2020&hotelCode=ASTORIA HTTP/1.1

Response:

{
   customerId: "1",
   reservations: [{room: "102", checkin: "10-11-2020", checkout: "11-14-2020", price: "100", href: "https://localhost:8080/room/102"}]
}

was created by an industry consortium to standardize REST API descriptions across vendors.

• the Swagger 2.0 specification was renamed the OpenAPI Specification (OAS) and brought under the Open API Initiative.
• OpenAPI Specification comes with a set of opinionated guidelines on how a REST API should be designed
• https://www.openapis.org/

design https://github.com/stickfigure/blog/wiki/How-to-%28and-how-not-to%29-design-REST-APIs

Service granularity

A principle to ensure services have an adequate size and scope. The functionality provided by the service to the user must be relevant.

Roles:

Service provider

It creates a web service and provides its information to the service registry. Each provider debates upon a lot of hows and whys like which service to expose, which to give more importance: security or easy availability, what price to offer the service for and many more.

Service broker, service registry or service repository

Its main functionality is to make the information regarding the web service available to any potential requester. Whoever implements the broker decides the scope of the broker. UDDI no longer active

Service requester/consumer

??

• https://en.wikipedia.org/wiki/Covariance_and_contravariance_(computer_science)

• Планирование(Training)
• Требования(Requirements)
• Проектирование(Design)
• Реализация(Implementation)
• Верификация (Verification)
• Выпуск(Release)
• Реагирование(Response)

• Безопасный дизайн;
• Моделирование угроз;
• Безопасное кодирование;
• Тестирование безопасности;
• Обеспечение приватности.

1. определении и интеграции требований безопасности и конфиденциальности;
2. определении минимально допустимых уровней безопасности и конфиденциальности;
3. оценке безопасности и конфиденциальности, изучении разработки программного обеспечения на основе затрат и нормативных требований.

• https://www.microsoft.com/en-us/securityengineering/sdl/
• https://learn.microsoft.com/en-us/previous-versions/ms995349(v=msdn.10)?redirectedfrom=MSDN

Refinement [rɪ'faɪnmənt]

изысканность; изящество.

Program refinement

verifiable transformation of an abstract (high-level) formal specification into a concrete (low-level) executable program.

functional correctness

for each input it produces an output satisfying the specification

partial correctness

if an answer is returned it will be correct

total correctness

additionally requires that an answer is eventually returned

proof theory

branch of mathematical logic and theoretical computer science. represents proofs as formal mathematical objects, facilitating their analysis by mathematical techniques.

• logic calculi - разные исчисления логики
• formal languages
• automata theory - теории автоматов
• control theory -
• program semantics - формальной семантики
• type systems - системы типов
• type theory - теория типов

when:

• Specification - to give a description of the system to be developed
• Development - as an integrated part of a tool-supported system development process.
• Verification - formal verification is the use of software tools to prove properties of a formal specification, or to prove that a formal model of a system implementation satisfies its specification.

• Level 0: Formal specification may be undertaken and then a program developed from this informally.
• Level 1: Formal development and formal verification
• Level 2: Theorem provers may be used to undertake fully formal machine-checked proofs.

styles of formal methods may be roughly classified as meaning of a system is expressed:

Denotational semantics

in the mathematical theory of domains.

Operational semantics

as a sequence of actions of a (presumably) simpler computational model.

Axiomatic semantics

in terms of preconditions and postconditions which are true before and after the system performs a task, respectively.

Used for simple imperative programming language + concurrency, procedures, jumps, and pointers.

• uses axiomatic techniques to define programming language semantics
• argue about the correctness of programs through assertions known as Hoare triples.

Hoare triple - describes how the execution of a piece of code changes the state

• {P}C{Q}
• P and Q are assertions: precondition and postcondition - formulae in predicate logic.
  • P - describing the condition the function relies on for correct operation
  • Q - describing the condition the function establishes after correctly running
• C is a command
• If we start in a state where P is true and execute S, then S will terminate in a state where Q is true.
• if program variables satisfy the condition P and the program S is executed, then the program variables satisfy the condition Q provided the program terminates.
• We may extend it to total correctness with the additional assertion that the program will terminate when starting at a variable state satisfying P

Hoare logic provides axioms and inference rules. Only partial correctness can be proven.

Hoare Triple is still valid if the precondition is stronger than necessary, but not if it is too weak.

depends on

• set theory
• first order logic - Логика первого порядка -

more focused on refinement - easier to correctly implement a specification written in B

Mechanisms include encapsulation and data locality.

The Rodin Platform is a tool that supports Event-B.

• based on an Eclipse software IDE
• ProB - plug-in for Robin. - Animation and Model-checking of Event-B models; Counterexamples for false proof goals, in particular, proof obligations

cycle of project development :

1. Translation from an informal or semi-formal specification into the Abstract Machine Notation.This step is not machine-checked, so it’s extremely important that this translation can be read and accepted by the “client”.
2. A sequence of (machine-checked) refinements : each version of the software is proved to be consistent with the previous one.
3. Possible translation into some classical programming language : Ada, C, C++.

Разработка через тестирование

• программисты, пишущие больше тестов, склонны быть более продуктивными
• менее связанный дизайн, с простой инициализацией
• четкие и небольшие интерфейсы

Set of practices to test behavior not implementation. test counter - bad input 0 test 1. good input counter current test current+1 may be improved unit testing.

Проблемно-ориентированное проектирование

Domain

A sphere of knowledge (ontology), influence, or activity. The subject area to which the user applies a program is the domain of the software;

Context

the setting in which a word or statement appears that determines its meaning

Model

A system of abstractions that describes selected aspects of a domain and can be used to solve problems related to that domain;

Ubiquitous Language или язык описания

[juːˈbɪkwɪtəs] вездесущий. A language structured around the domain model and used by all team members to connect all the activities of the team with the software.

• используется для единого стиля описания домена и модели.
• used in the domain model and for describing system requirements

Microsoft recommends that it be applied only to complex domains where the model and the linguistic processes provide clear benefits in the communication of complex information, and in the formulation of a common understanding of the domain.

Under domain-driven design, the structure and language of software code (class names, class methods, class variables) should match the business domain.

Most functional tests follow the Arrange-Act-Assert model:

• Arrange, or set up, the conditions for the test
• Act by calling some function or method
• Assert that some end condition is true
• Cleanup (optional)

• Capybara
• Jasmine - for javascript

Syncrhonous queries - is simplier and is better for backend and for client.

Async - requre queue for context of operation with request.

Если бизнес процесс длительный - то лучше асинхронный

ISO/IEC 25000 models:

• Data Quality -
• Quality in Use -
• Product Quality - static and dynamic 8 characteristics

Abstract Pyramid:

1. Process quality - process
2. Inner quality - program
3. Interface quality - program
4. Quality in Use (many contexts) - program products

Metrics models: ISO/IEC 5055, which is compatible with ISO/IEC 25010

• Reliability (Надежность)
• Performance Efficiency (Эффективность работы)
• Security
• Maintainability (Сопровождаемость)

For every metric:

• Description
• justification (обоснование)
• (решение) - How can we increase this metic
• rating scale (Шкала оценки) - ex. ABCD, A(4) good, B(3), C(2) - bad, D(1) - very bad, NA - unknown

Types of metrics: (separately for libraries, and for services)

• Dynamic
• Static
• Experimentic - the new one

Dynamic metrics:

• quantity error-logs entries
• quantity of Incoming Failed
• quantity of Outgoing Failed
• Speed of BD requests
• Speed of release
• Success rate of releases

Static metrics:

• existence of Sonar Issues? with "Critical"?
• Documentation completeness (полнота документации)
• For tests, is PostgreSQL running in Docker for them?
• do tests run in several threads?

YooMoney merics collection software:

• Sonar
• Grafana
• Source code of service itself
• others..

Question of rating scale normalization for every service ……………..

It is much easier to update microservices if "standrad" of the best service exist.

1. Equal instruments: ex. for frontend: Node.JS, NPM, React, Nest.JS.
2. Equal architecture of code:
   1. Tool or framework
   2. One documentation
3. Equal style of code: linter

Tools:

• Service template
• "Automic updater"
• Modernizer - for atomic applying patches to services.

Steps:

1. calc diff from versions
2. create patch on diff: package.json, configs, dependencies

Automatization "Automic updater":

1. Jeninks scan services and calc diff
2. Create task in Jira
3. Try to automatic update and make pull request to Git repository
4. if success: move task in Jira to tesing, test and release to production.

Notes: template update after quartal or at new project only.

• Direct: независимо от версии нет конфликтов
• Backward compatibility - if two version of one service is compatible with environment

steps of update on prod:

1. update one Node "test"
2. update DB
3. allow node "test" 5% of traffic

Problem: Node "test" update DB and old nodes can not read from DB

Solution:

• emulate this on tests, cover this case in autotests

ways simple

• autotests
• swagger-diff
• minimization of difference between versions test-prod
• prepare BD with scripts for rallback imergence

Ways fundamental:

• Контрактное тестирование - методология проверки совместимости двух сервисов
• средства зеркалирования трафика
• Добавление нескольких экземпляров одного сервиса на тестовую среду
• Статический анализ кода на изменения в БД

tools:

• k6 - allow scripts, have RestAPI, have prometheus format
• Gatling - allow scripts, no RestAPI, no prometheus format
• Yandex Tank + pandora - allow scripts, have RestAPI, no prometheus format

Prometheus - defacto standard in keeping and visualization of metrics (event monitoring and alerting)

• exporters - run on monitored host to export local metrics
• central storage
• Alermanager - to trigger alerts based on metrics
• Grafana - for dashboards
• PromQL - query language to create dashboards and alerts.

Victorie Metrics for storage.

• Сущность - из предметной области - Первичны! всегда объектно ориентированный подход
• Атрибуты -
• Действия - действия бизнес процессов над ними

Больше одного слова в наименовании - признак ошибок декомпозиции всегда!

Сущность правила иментования

• в единственном числе
• отражают объекты реального мира тоесть предметной области
• Сущность всегда находится в рамках контекста предметной области (domain)
• ex. Payment, Refund, Card, Wallet

Опасности иерархий

• Вложенная сущнось, действительно ли у нее общее состояние с той в которую она входит. Не может обладать собственным состоянием.
• Нетривиальные зависимости состояния сущностей
• Часто иерархи я является частным представление одного типа клиентов
• Можно сознательно создавать агрегаты (aggregates) но у такой сущности нет собственного состояния и операций

Атрибут правила именования - свойства или факт об объекте

• существительными или прилагательными, НЕ ГЛАГОЛАМИ
• для enum используйте стандартизированные справочники: ISO-4217, ISO-3166, ISO-639
• пример: amount, currency, country, moc, refundable, paid

Действия (операции) - отражает бизнес-процесс, жизненный цикл его сущсности

• действия всегда выполняются над сущностями
• именуются глаголами
• Наименование действия сочетается с наименовантем сущности
• избегать императивов: когда глаголы первичны
• Пример: capture, cancel, suspend, close

Istio, linkerd2, avito-tech/netramesh

Providing observability to your distributed system

1. intercept all TCP traffic

• White-Box
• Black-Box

the names and entry points of the code located within. for OOP: objects they depend on.

• Information fluctuation complexity
• Average level of "information", "surprise", or "uncertainty" inherent in the variable's possible outcomes.
• мера неопределённости некоторой системы (в статистической физике или теории информации), в частности непредсказуемость появления какого-либо символа первичного алфавита
• равна количеству информации на символ передаваемого сообщения.

двоичная энтропия, при отсутствии информационных потерь, рассчитывается по формуле Хартли:

• i = log2(N)
• i - количество информации в каждом символе сообщения
• N — мощность алфавита

• выбор основания логарифма определяет единицу измерения энтропии, принято использовать 2.

  Для случайной величины x, принимающей n независимых случайных значений xi с вероятностями pi (i=1,…,n}, формула Хартли переходит в формулу Шеннона:

• H(x) = − ∑i pi*log2(pi)
• Величина Hi = −log2*pi называется частной энтропией, характеризующей только i-e состояние.
• В общем случае, основание логарифма в определении энтропии может быть любым, большим 1 (так как алфавитом, состоящим только из одного символа, нельзя передавать информацию);
• I total information from N occurrences(алфавита):
• I = − ∑i (N*pi)*log2(pi)
• N*pi - Approximated number that the certain result will come out in N occurrence
• I/N = Entropy
• Entropy is the average(expected) amount of information in a certain event

Примеры:

• Кидание монеты имеет энтропию -2(1/2*log2(1/2)) = log2(2) = 1 бит на одно кидание, 2^1=2 возможных состояний
• У источника генерирующего строку AAA -suminf(log2(1)) = 0, а количество возможных состояний равно: 2^0 = 1
• 4 красных, 2 желтых, 3 зеленых, посчитать этропию выбора шарика
  • 3 варианта событий n=3,
  • -(4/9)*log2(4/9)-(2/9)*log2(2/9)-(3/9)*log2(3/9)=1.53

is a measure of the average number of bits needed to identify an event from a set of possibilities between two probability distributions

• between two probability distributions p p and q q over the same underlying set of events

H(p,q) = - ∑p(x)log(q(x))

The amount of information acquired due to the observation of event i follows from Shannon's solution of the fundamental properties of information:

• I(p) is monotonically decreasing in p: an increase in the probability of an event decreases the information from an observed event
• I(1) = 0
• I(p1·p2) = I(p1) + I(p2): the information learned from independent events is the sum of the information learned from each event.

unordered

• '{}' : Surround in-line keyed branch.
• '? ' : Key indicator.
• key-value: ' k1: v1\n k2: v2\n' - colon MUST be followed by the space
• flow style: '{k1: v1, k2: v2}'
• ? - allow leading #[] ?#key
• True False in several forms
• keep new lines
  • | or > before text
  • "aa\naa\n"
• 123 - integer , 123.0 - float, Yes - boolean
• {{AA}} - something external
• %YAML 1.1 - version
• repeated nodes - & and *
  • k: &target 80 - target is a 80 - copy
  • k2: *target - paste
  • << : *target - paste

hr:  65    # Home runs
avg: 0.278 # Batting average
rbi: 147   # Runs Batted In

# canonical form:
? x
: 1
? y
: 2

american: # dict with list
- Boston Red Sox
- Detroit Tigers
- New York Yankees
national:
- New York Mets
- Chicago Cubs
- Atlanta Braves


# Sequence of Mappings
-
  name: Mark McGwire
  hr:   65
  avg:  0.278
-
  name: Sammy Sosa
  hr:   63
  avg:  0.288

# Compact Nested Mapping
---
# Products purchased
- item    : Super Hoop
  quantity: 1
- item    : Basketball
  quantity: 4
- item    : Big Shoes
  quantity: 1

two stypes:

• plain style (unquoted) - provides no form of escaping
• double-quaoted style - provides escape sequences.
• single-quoted style - useful when escaping is not needed

unicode: "Sosa did fine.\u263A"
control: "\b1998\t1999\t2000\n"
hex esc: "\x0d\x0a is \r\n"

single: '"Howdy!" he cried.'
quoted: ' # Not a ''comment''.'
tie-fighter: '|\-*-/|'
...
# Multi-line Flow Scalars - plain style
---
plain:
  This unquoted scalar
  spans many lines.

quoted: "So does this
  quoted scalar.\n"

two types:

• ("|") - preserve line breaks (ends with an empty or a more-indented line?)
• (">") - line break is folded to a space. Folded newlines are preserved for “more indented” and blank lines.

# ASCII Art
--- |
  \//||\/||
  // ||  ||__


--- >
 Sammy Sosa completed another
 fine season with great stats.

   63 Home Runs
   0.288 Batting Average

 What a year!
---
name: Mark McGwire
accomplishment: >
  Mark set a major league
  home run record in 1998.
stats: |
  65 Home Runs
  0.278 Batting Average

!!binary aGVsbG8= would parse as the bytestring hello.

In order to represent static Python objects like functions or classes, you need to use a complex !!python/name tag. For instance, the function yaml.dump can be represented as

!!python/name:yaml.dump

Similarly, modules are represented using the tag !python/module:

!!python/module:yaml

Any pickleable object can be serialized using the !!python/object tag:

!!python/object:module.Class { attribute: value, ... }

In order to support the pickle protocol, two additional forms of the !!python/object tag are provided:

!!python/object/new:module.Class
args: [argument, ...]
kwds: {key: value, ...}
state: ...
listitems: [item, ...]
dictitems: [key: value, ...]

!!python/object/apply:module.function
args: [argument, ...]
kwds: {key: value, ...}
state: ...
listitems: [item, ...]
dictitems: [key: value, ...]

If only the args field is non-empty, the above records can be shortened:

!!python/object/new:module.Class [argument, ...]

!!python/object/apply:module.function [argument, ...]

Named tag handles must be defined by a %TAG directive before the document.

%TAG !foo! tag:example.com,2015:app/
!foo!bar would then resolve to tag:example.com,2015:app/bar

the URI tags are useful if we are using YAML as a data store for an application we are creating.

YAMLlint - The YAML Validator

https://github.com/devopyio/yamlfmt

require gopkg.in/yaml.v2

• https://gpo.zugaina.org/dev-go/yaml

https://pyyaml.org/wiki/PyYAML

from file:

python -c "import yaml ; f = open('/home/u/a.yml', 'r') ; print(yaml.load(f, yaml.SafeLoader))"

from source code block:

aa:
  - b
  - 'c"as"c'

---
s: asd

"asssss"

asssss

import yaml
for data in yaml.load_all("""
aa:
  - b
  - 'c"as"c'

---
s: asd""", yaml.SafeLoader):
    print(data)

{'aa': ['b', 'c"as"c']}
{'s': 'asd'}

print(zzz)
# import yaml
# for data in yaml.load_all(zzz, yaml.SafeLoader):
    # print(data)

asssss

import yaml

x = yaml.load(zzz, yaml.SafeLoader)
print(x)

• SQL-99 introduced three extensions to the GROUP BY statement: the CUBE, ROLLUP and GROUPING SETS operator.

single line: – at any place

Multi-line Comments: * *

UNKNOWN - special mark which is not TRUE and not FALSE.

null or NULL - value does not exist in the database.

'Fish ' || NULL || 'Chips'   -- Result is NULL
SELECT 10 = NULL       -- Results in Unknown
SELECT NULL OR TRUE   -- Results in True

Effect of Unknown in WHERE clauses - comparison of the i column with Null always returns Unknown

SELECT * FROM t WHERE i = NULL;

'Fish ' || 'Chips'

• взять все записи из первой таблицы, у которых во второй таблицы по внешнему ключу имеют количество

строк больше 2.

SELECT * FROM Customers WHERE EXISTS (
  SELECT CustomerID, COUNT(EmployeeID)
  FROM Orders
  WHERE CustomerID = Customers.CustomerID --обязательное
  GROUP BY CustomerID
  HAVING COUNT(EmployeeID) > 2 )

 SELECT Book.title
 FROM Book
 JOIN Book_author
 ON Book.id = Book_author.fid

 -- or

 SELECT column_list
 FROM table1, table2....
 WHERE table1.column_name =
 table2.column_name;

(INNER) JOIN

пересечение (Equi Join)

LEFT (OUTER) JOIN

пересечение и левая таблица

RIGHT (OUTER) JOIN

FULL (OUTER) JOIN

объединение двух с перечечением по полю. сначала совпадающие, потом где не совпали: сначала левая таблица с null, потом null с правой таблицей

CROSS JOIN

декартово произведение Cartesian product[kɑːˈtiːzɪən] для каждой строки левой таблицы перебирается правая таблица, то же самое что и:

SELECT *
FROM employee, department;

NATURAL JOIN

select * inner join on. will produce two identical columns. Natural - one.

• must have the same number of columns and same order
• columns must also have similar data types
• UNION - distinct
• UNION ALL - all
• INTERSECT - A
• column names in the result-set are usually equal to the column names in the first SELECT

 SELECT column_name(s) FROM table1
 UNION
 SELECT column_name(s) FROM table2;
 UNION ALL
 SELECT column_name(s) FROM table2;

• SELECT DISTINCT CustomerName FROM Sales - недостаток, нельзя с aggregate
• GROUP BY often used with aggregate functions to group by colums
• HAVING - becouse WHERE could no be used with aggregate functions.

     SELECT COUNT(Id), Country
       FROM Customer
      GROUP BY Country
     HAVING COUNT(Id) > 10

SQLite

• INTEGER PRIMARY KEY - 64-bits
• insert (null) OR insert into table (field2) values ('val2');

alg:

• empty = 1
• largest is reached -> random find empty and remember as current ROWID

PostgreSQL

• Integer = 32-bits not autoincrement
• serial = 32-bits, bigserial = 64-bits
• insert into table (field2) values ('val2');

alg nextval()

• empty = 1
• on conflict - mark used = gaps
• DEFAULT any calls to nextval after the sequence has reached its maximum value will return an error

solutions:

1. добавить CYCLE в эквивалент serial

CREATE SEQUENCE tablename_colname_seq CYCLE;
CREATE TABLE tablename (
    colname integer NOT NULL DEFAULT nextval('tablename_colname_seq')
);
ALTER SEQUENCE tablename_colname_seq OWNED BY tablename.colname;

1. JDBC

private int genId() throws SQLException{
                // Generate id
                int id;
                Random r = new Random();
                ResultSet rs;
                do{
                        id = r.nextInt(ID_LENGHT);//16^x-1
                        pstmtGetId.setInt(1, id);
                        rs = pstmtGetId.executeQuery(); //rs is not closed....
                }while(rs.next()); // Check if exist
                return id;
        }

SQL:2016 or ISO/IEC 9075:2016

• SQL/JSON path language (specified in [ISO9075-2])
  • adopts many features of ECMAScript
• in standard SQL JSON strings should be stored in one of the old familiar data types: VARCHAR, CLOB, etc.

• conditions
• loops
• types and variables of those types
• procedures and functions
• triggers ?
• exceptions handling
• PL/SQL collections - arrays
• object-orientation
• stored in the database for reuse by applications

• comment – signle line * * multiline
• identifiers - letter with numbers, $, _, 30-chars. - not case-sensitive
• "delimiters" :
  • +, -, *, /
  • 'aasdas' - character string
  • "customers" - Quoted identifier delimiter
  • := Assignment operator
  • || Concatenation operator
  • = < > <= >= Relational operators
  • <>, ', ~, ^= != - different versions of not equal
  • NOT , AND, OR - logical
• Comparison - result TRUE, FALSE or NULL
  • 'Zara Ali' LIKE 'Zara Ali' - pattern . Used for character, string, or CLOB
  • BETWEEN 5 and 20
  • IN ('a', 'b', 'c')
  • IS NULL - Comparisons involving NULL values always yield NULL.
  • EXISTS - Returns TRUE if a subquery returns at least one row.
  • ANY, SOME - Compares a value to each value in a list or returned by a subquery and yields TRUE if any of the individual comparisons yields TRUE.
  • ALL - Compares a value to each value in a list or returned by a subquery and yields TRUE if all of the individual comparisons yield TRUE.
• Data Types: - has subtypes
  • Scalar - NUMBER, DATE, or BOOLEAN, strings
  • Large Object (LOB) -
    • BFILE - stored in files outside the database - system dependent
    • BLOB - Binary large object in database - 8 to 128 TB
    • CLOB - large blocks of character data - 8 to 128 TB
    • NCLOB - NCHAR data (national character)- 8 to 128 TB
  • Composite - collections and records
  • Reference
  • NULL values represent missing or unknown data and they are not an integer, a character, or any other specific data type - that NULL is not the same as an empty data string or the null character value '\0'
• '' = '

The precedence of operators goes as follows: , <, >, <, >=, <>, !=, ~=, ^=, IS NULL, LIKE, BETWEEN, IN.

DECLARE
   message  varchar2(20):= 'Hello, World!';
BEGIN
   dbms_output.put_line(message);
END;
/ -- for CLI

--varible
variable_name [CONSTANT] datatype [NOT NULL] [:= | DEFAULT initial_value] ;
name varchar2(25); --constrained declaration

--select into clause
declare
  v_authName author.author_last_name%type; --author - table
begin
  select author_last_name into v_authName -- в переменную
  from author
  where author_key = 'A103';

v_author author%rowtype; -- USED LIKE VARRAY - СТРУКТУРА
begin
  select * into v_author
  from author
  where author_key = 'A103';

--IF--
IF (a <= 20) THEN
   c:= c+1;
ELSE
ELSIF( boolean_expression 2) THEN
END IF;
--LOOPS--
LOOP --infinity
   Sequence of statements;
END LOOP;

<< outer_loop >>
FOR i IN 1..3 LOOP -- for
EXIT; CONTINUE; GOTO label;
END loop outer_loop;

WHILE condition LOOP
-- VARRAY
CREATE OR REPLACE TYPE varray_type_name IS VARRAY(n) of <element_type>
type namesarray IS VARRAY(5) OF VARCHAR2(10);
names namesarray;
-- PL/SQL table

VAR[IABLE] [variable [type] ]

DEF[INE] [variable] | [variable = text]

Predefined Variables

• _CONNECT_IDENTIFIER Connection identifier used to make connection, where available.
• _DATE Current date, or a user defined fixed string.
• _EDITOR Specifies the editor used by the EDIT command.
• _O_VERSION Current version of the installed Oracle Database.
• _O_RELEASE Full release number of the installed Oracle Database.
• _PRIVILEGE Privilege level of the current connection.
• _SQLPLUS_RELEASE Full release number of installed SQL*Plus component.
• _USER User name used to make connection.

VARIABLE ret_val NUMBER

exec :ret_val := 'SALES'
EXECUTE DBMS_LOB.FREETEMPORARY(:ret_val)

OPEN :emp_cv FOR SELECT * FROM employees; -- declare as cursor varible

active set - set of rows the cursor holds

• Implicit cursors - name: "sql". UPDATE and DELETE - rows that would be affected. INSERT - what. No need to close.
• Explicit cursors

Attributes:

• sql%FOUND - one or more rows
• sql%NOTFOUND
• sql%ISOPEN - Always returns FALSE for implicit cursors.
• sql%ROWCOUNT

CURSOR cursor_name [ ( [ parameter_1 [, parameter_2 ...] ) ]
      [ RETURN return_specification ]
IS sql_select_statements
[FOR UPDATE [OF [column_list]]; -- lock record for modification

DECLARE
   c_id customers.id%type;
   c_name customerS.No.ame%type;
   c_addr customers.address%type;
   CURSOR c_customers is --declare
      SELECT id, name, address FROM customers;
BEGIN
   OPEN c_customers; --allocate memory
   LOOP
     FETCH c_customers into c_id, c_name, c_addr; --execute SELECT
     EXIT WHEN c_customers%notfound;
     dbms_output.put_line(c_id || ' ' || c_name || ' ' || c_addr);
   END LOOP;
   CLOSE c_customers;
END;

CURSOR c1
IS
  SELECT course_number, instructor
  FROM courses_tbl
  FOR UPDATE OF instructor; -- lock record for modification

• Table-based
• Cursor-based records
• User-defined records

-- Table-based --
DECLARE    customer_rec customers%rowtype;

-- Cursor-based records --
DECLARE
   CURSOR customer_cur is
      SELECT id, name, address
      FROM customers;
   customer_rec customer_cur%rowtype;
BEGIN
   OPEN customer_cur;
   LOOP
      FETCH customer_cur into customer_rec;
      EXIT WHEN customer_cur%notfound;
      DBMS_OUTPUT.put_line(customer_rec.id || ' ' || customer_rec.name);
   END LOOP;
END;
-- User-Defined Records --
TYPE
type_name IS RECORD
  ( field_name1  datatype1  [NOT NULL]  [:= DEFAULT EXPRESSION],
   field_name2   datatype2   [NOT NULL]  [:= DEFAULT EXPRESSION],
   ...
   field_nameN  datatypeN  [NOT NULL]  [:= DEFAULT EXPRESSION);
record-name  type_name;

DECLARE
   type books is record
      (title varchar(50),
      author varchar(50),
      subject varchar(100),
      book_id number);
   book1 books;
   book2 books;
BEGIN
   -- Book 1 specification
   book1.title  := 'C Programming';
   book1.author := 'Nuha Ali ';
   book1.subject := 'C Programming Tutorial';
   book1.book_id := 6495407;

Package specification - interface. all abjects here are public other - private

you can invoke from PL/SQL, SQL, Java, and other programming environments:

• DBMS_ALERT - triggers to alert an application when specific database values change. Ex. to update the value of its investment portfolio as new stock and bond quotes arrive.
• DBMS_OUTPUT - displaying PL/SQL debugging information. You display the information by invoking the procedure GET_LINE or by setting SERVEROUTPUT ON in SQL*Plus
• HTF and HTP - HTF and HTP packages enable your PL/SQL programs to generate HTML tags.
• UTL_FILE - read and write operating system text files
• UTL_HTTP - callouts
• UTL_SMTP
• DBMS_PIPE and DBMS_CONNECTION_POOL

  CREATE OR REPLACE PACKAGE c_package AS
     PRAGMA SERIALLY_REUSABLE; -- memory is returned to the pool cannot be accessed from database triggers or
                               -- other PL/SQL subprograms that are called from SQL statements.  Adds a customer
     PROCEDURE addCustomer(c_id   customers.id%type,
     c_name  customerS.No.ame%type,
     c_age  customers.age%type,
     c_addr customers.address%type,
     c_sal  customers.salary%type);

     -- Removes a customer
     PROCEDURE delCustomer(c_id  customers.id%TYPE);
     --Lists all customers
     PROCEDURE listCustomer; x
  END c_package;
  --Package created.

  CREATE OR REPLACE PACKAGE BODY c_package AS
     PROCEDURE addCustomer(c_id  customers.id%type,
        c_name customerS.No.ame%type,
        c_age  customers.age%type,
        c_addr  customers.address%type,
        c_sal   customers.salary%type)
     IS
     BEGIN
        INSERT INTO customers (id,name,age,address,salary)
           VALUES(c_id, c_name, c_age, c_addr, c_sal);
     END addCustomer;

     PROCEDURE delCustomer(c_id   customers.id%type) IS
     BEGIN
        DELETE FROM customers
        WHERE id = c_id;
     END delCustomer;

     PROCEDURE listCustomer IS
     CURSOR c_customers is
        SELECT  name FROM customers;
     TYPE c_list is TABLE OF customerS.No.ame%type;
     name_list c_list := c_list();
     counter integer :=0;
     BEGIN
        FOR n IN c_customers LOOP
        counter := counter +1;
        name_list.extend;
        name_list(counter) := n.name;
        dbms_output.put_line('Customer(' ||counter|| ')'||name_list(counter));
        END LOOP;
     END listCustomer;

  END c_package;
  --Package body created.

  DECLARE
     code customers.id%type:= 8;
  BEGIN
     c_package.delcustomer(code); -- procedure from package
  END;

  DROP PACKAGE c_package;

A function is same as a procedure except that it returns a value.

May be stand alone or packaged.

Shema level:

• CREATE PROCEDURE / FUNCTION
• DROP PROCEDURE / FUNCTION
• IN - default - by reference.
• OUT - The actual parameter must be variable and it is passed by value.
• IN OUT - by value.
• AS for stand alone?

OVERLOADING

CREATE [OR REPLACE] PROCEDURE procedure_name
[(parameter_name [IN | OUT | IN OUT] type [, ...])]
{IS | AS}
BEGIN
  < procedure_body >
END procedure_name;

EXECUTE greetings;
BEGIN
   greetings;
END;

CREATE [OR REPLACE] FUNCTION function_name
[(parameter_name [IN | OUT | IN OUT] type [, ...])]
RETURN return_datatype
{IS | AS}
BEGIN
   < function_body >
END [function_name];

programs, which are automatically executed or fired when some events occur

• database manipulation (DML) statement (DELETE, INSERT, or UPDATE)
• A database definition (DDL) statement (CREATE, ALTER, or DROP).
• A database operation (SERVERERROR, LOGON, LOGOFF, STARTUP, or SHUTDOWN)
• associated on the table, view, schema, or database

Purpose:

• Generating some derived column values automatically
• Enforcing referential integrity
• Event logging and storing information on table access
• Auditing
• Synchronous replication of tables
• Imposing security authorizations
• Preventing invalid transactions

  CREATE [OR REPLACE ] TRIGGER trigger_name
  {BEFORE | AFTER | INSTEAD OF }   --INSTEAD OF clause is used for creating trigger on a view.
  {INSERT [OR] | UPDATE [OR] | DELETE}  --1 условие
  [OF col_name]  --2
  ON table_name  --3
  [REFERENCING OLD AS o NEW AS n]
  [FOR EACH ROW]  --  for each row, or  table level
  WHEN (condition)  -- for row level - condition for rows for which the trigger would fire
  DECLARE
     Declaration-statements
  BEGIN
     Executable-statements
  EXCEPTION
     Exception-handling-statements
  END;


CREATE OR REPLACE TRIGGER display_salary_changes
BEFORE DELETE OR INSERT OR UPDATE ON customers
FOR EACH ROW
WHEN (NEW.ID > 0)
DECLARE
   sal_diff number;
BEGIN
   sal_diff := :NEW.salary  - :OLD.salary;
   dbms_output.put_line('Old salary: ' || :OLD.salary);
   dbms_output.put_line('New salary: ' || :NEW.salary);
   dbms_output.put_line('Salary difference: ' || sal_diff);
END;

subscript - index.

collection types:

• Index-by tables or Associative array - dynamic- dense - Only in PL/SQL block
• Nested table - dense initially, but it can become sparse when elements are deleted from it
• varray - fixed size

PL/SQL tables:

• index-by tables- key-value - key -integer or string - can be
• the nested tables - can be stored in a database column

build-in operation for collections:

• EXISTS(n) - TRUE if the nth element in a collection exists
• COUNT
• LIMIT
• FIRST
• LAST
• PRIOR(n)
• NEXT(n)
• EXTEND - Appends one null element to a collection
• EXTEND(n)
• EXTEND(n,i) - Appends n copies of the ith element to a collection.
• TRIM - Removes one element from the end of a collection.
• TRIM(n)
• DELETE - Removes all elements from a collection, setting COUNT to 0.
• DELETE(n) - remove nth element
• DELETE(m,n) - Removes all elements in the range m..n

Exceptions:

• COLLECTION_IS_NULL - You try to operate on an atomically null collection.
• NO_DATA_FOUND - element that was deleted
• SUBSCRIPT_BEYOND_COUNT
• SUBSCRIPT_OUTSIDE_LIMIT
• VALUE_ERROR - subscript is null or not convertible to the key type

TYPE type_name IS TABLE OF element_type [NOT NULL] INDEX BY subscript_type;
-- subscript_type - key, element_type - value
table_name type_name; -- table_name - name of Associative array

-- adding elements to the table
   salary_list('Rajnish') := 62000;
   salary_list('Minakshi') := 75000;
   salary_list('Martin') := 100000;
   salary_list('James') := 78000;
-- printing the table
   name := salary_list.FIRST;
   WHILE name IS NOT null LOOP
      dbms_output.put_line
      ('Salary of ' || name || ' is ' || TO_CHAR(salary_list(name)));
      name := salary_list.NEXT(name);
   END LOOP;

-- NESTED
TYPE type_name IS TABLE OF element_type [NOT NULL];
table_name type_name;

DECLARE
   CURSOR c_customers is
      SELECT  name FROM customers;
   TYPE c_list IS TABLE of customerS.No.ame%type;
   name_list c_list := c_list();
   counter integer :=0;
BEGIN
   FOR n IN c_customers LOOP
      counter := counter +1;
      name_list.extend;
      name_list(counter)  := n.name;
      dbms_output.put_line('Customer('||counter||'):'||name_list(counter));
   END LOOP;
END;

• ACCESS_INTO_NULL - when a null object is automatically assigned a value
• CASE_NOT_FOUND - when none of the choices is selected
• COLLECTION_IS_NULL - program attempts to apply collection methods other than EXISTS to an uninitialized nested table or varray
• DUP_VAL_ON_INDEX - column with unique index
• INVALID_CURSOR - closing an unopened cursor
• INVALID_NUMBER - conversion of a character string into a number fails
• LOGIN_DENIED - program attempts to log on to the database with an invalid username or password
• NO_DATA_FOUND - raised when a SELECT INTO statement returns no rows.
• NOT_LOGGED_ON - when a database call is issued without being connected to the database
• PROGRAM_ERROR - PL/SQL has an internal problem
• ROWTYPE_MISMATCH - incompatible data type
• SELF_IS_NULL - member method is invoked, but the instance of the object type was not initialized
• STORAGE_ERROR - PL/SQL ran out of memory or memory was corrupted
• TOO_MANY_ROWS - when a SELECT INTO statement returns more than one row.
• VALUE_ERROR - arithmetic, conversion, truncation, or sizeconstraint error occurs.
• ZERO_DIVIDE - divide a number by zero

DECLARE
   <declarations section>
BEGIN
   <executable command(s)>
   RAISE exception_name;
EXCEPTION
   <exception handling goes here >
   WHEN exception1 THEN
      exception1-handling-statements
   WHEN exception2  THEN
      exception2-handling-statements
   WHEN exception3 THEN
      exception3-handling-statements
   ........
   WHEN others THEN -- others - keyword
      exception3-handling-statements
END;

• automatically starts
• ends when one of the following events take place:
  • COMMIT or a ROLLBACK
  • DDL statement, such as CREATE TABLE
  • DCL statement, such as a GRANT
  • User disconnects from the database.
  • SQL*PLUS exited
  • DML statement fails - ROLLBACK

SAVEPOINT Statement - names and marks the current point in the processing of a transaction. let you roll back part of a transaction

• SAVEPOINT < savepoint_name >;
• ROLLBACK [TO SAVEPOINT < savepoint_name>];
• ROLLBACK;
• SET AUTOCOMMIT ON;
• SET AUTOCOMMIT OFF;

Each user account owns a single schema.

• Tables
• Indexes - indexed row - есть несколько типов индексов
• Partitions - Partitions are pieces of large tables and indexes. Each partition has its own name and may optionally have its own storage characteristics.
• Views - stored queries. metadata
• Sequences - user-created object that can be shared by multiple users to generate integers. Typically, you use sequences to generate primary key values. metadata
• Dimensions - parent-child relationship between columns from the same table. Commonly used to categorize data such as customers, products, and time.
• Synonyms - for another schema object
• PL/SQL subprograms and packages

Тon-schema objects may include:

• user account
• roles
• contexts
• directory objects

SYS and SYSTEM Schemas - SYS and SYSTEM administrative account is automatically created when a database is created. SYS - admin аккаунт. SYS schema stores the base tables and views for the data dictionary - A read-only collection of database tables and views containing reference information about the database, its structures, and its users.

SYSTEM schema stores additional tables and views that display administrative information, and internal tables and views used by various Oracle Database options and tools.

• anonymous block
• procedure
• function
• package specification
• package body
• trigger - stored procedure that Oracle Database invokes automatically whenever a specified event occurs
• type specification
• type body
• library

[ORDER | MAP] MEMBER PROCEDURE | FUNCTION

Member Methods

• Constructors are functions that return a new object as its value. Every object has a system defined constructor method. The name of the constructor is same as the object type.
• MAP - called when we compare two objects a > b = a.map() > b.map()
• ORDER -

CREATE OR REPLACE TYPE customer AS OBJECT
(code number(5),
 name varchar2(30),
 contact_no varchar2(12),
 addr address,
 member procedure display
);

CREATE OR REPLACE TYPE rectangle AS OBJECT
(length number,
 width number,
 member function enlarge( inc number) return rectangle,
 member procedure display,
 map member function measure return number
);
-- Instantiating an Object

DECLARE
   residence address;
BEGIN
   residence := address('103A', 'M.G.Road', 'Jaipur', 'Rajasthan','201301');
END;

CREATE OR REPLACE TYPE BODY rectangle AS
   MEMBER FUNCTION enlarge(inc number) return rectangle IS
   BEGIN
      return rectangle(self.length + inc, self.width + inc);
   END enlarge;
   MEMBER PROCEDURE display IS
   BEGIN
      dbms_output.put_line('Length: '|| length);
      dbms_output.put_line('Width: '|| width);
   END display;
   MAP MEMBER FUNCTION measure return number IS
   BEGIN
      return (sqrt(length*length + width*width));
   END measure;
END;

-- order
CREATE OR REPLACE TYPE rectangle AS OBJECT
(length number,
 width number,
 member procedure display,
 order member function measure(r rectangle) return number
);

• CURRVAL and NEXTVAL sequence_name.CURRVAL sequence_name.NEXTVAL
• LEVEL - SELECT CONNECT BY - to organize rows from a database table into a tree structurex
• ROWID - binary address) of a row in a database table
• ROWNUM - indicating the order in which a row was selected from a table.

<dependency>
                <groupId>org.xerial</groupId>
                <artifactId>sqlite-jdbc</artifactId>
                <version>3.7.2</version>
        </dependency>
Class.forName("org.sqlite.JDBC");

            Connection connection = null;
            try
            {
              // create a database connection
              connection = DriverManager.getConnection("jdbc:sqlite:sample.db");
              Statement statement = connection.createStatement();
              statement.setQueryTimeout(30);  // set timeout to 30 sec.

              statement.executeUpdate("drop table if exists person");
              statement.executeUpdate("create table person (id integer, name string)");

rowid - по умолчанию все таблицы имеют 64 ключ, оптимизированный для сортировки и автоинкрементный https://www.sqlite.org/lang_createtable.html#rowid

create table contact (id INTEGER PRIMARY KEY

id - alias for rowid. вставить запись с автоинкрементом:

insert into contact values(null,

• TEXT as ISO8601 strings ("YYYY-MM-DD HH:MM:SS.SSS").
• REAL as Julian day numbers, the number of days since noon in Greenwich on November 24, 4714 B.C. according to the proleptic Gregorian calendar.
• INTEGER as Unix Time, the number of seconds since 1970-01-01 00:00:00 UTC.

Предположим, первый генерал отправляет второму сообщение «Атакуем завтра в девять часов утра». Отправив посыльного, первый генерал не знает, добрался ли посыльный до второго генерала. Не зная, поддержит ли второй генерал его действия, первый может отложить штурм. Зная это, второй генерал может отправить подтверждающее сообщение «Я получил Ваше сообщение и атакую завтра в девять часов утра». Но это сообщение также может быть перехвачено противником. Зная, что первый генерал не начнёт штурм без подтверждения, второй генерал также может отложить атаку. Первый генерал может отправить сообщение «Я получил Ваше подтверждение о времени начала штурма», но оно также может быть перехвачено. Быстро становится очевидным, что, сколько бы ни было циклов обмена сообщениями, нет способа гарантированно уведомить обоих генералов о том, что их сообщения получены. Таким образом, задача не имеет решения.

часто рассматривается в рамках курса компьютерных сетей

First general can send a marking on each message saying it is message 1, 2, 3 … of n. This method will allow the second general to know how reliable the channel is and send an appropriate number of messages back to ensure a high probability of at least one message being received. each assume: "I have not received an additional message for 200 minutes; either 200 messengers failed to cross the danger zone, or it means the other general has confirmed and committed to the attack and has confidence I will too"

Market Cap - The total market value of a cryptocurrency's circulating supply. It is analogous to the free-float capitalization in the stock market. Market Cap = Current Price x Circulating Supply

rating at 2023-03-30:

• Bitcoin BTC $537,894,522,662
• Ethereum ETH $218,204,943,358
• Tether USDT $79,644,704,771
• BNB BNB $50,011,463,543
• USD Coin USDC $32,849,897,095
• XRP XRP $27,801,186,083
• Cardano ADA $13,114,264,849
• Dogecoin DOGE $10,320,418,090
• Polygon MATIC $9,909,970,844
• Solana SOL $7,895,004,987
• Binance USD BUSD $7,611,302,222

DApps incur gas, that is fees paid to the validators of the block chain, due to the cost of deploying and executing the DApp's smart contracts.

1. operate on their own block chain. Block chains such as Bitcoin and Ethereum can be classified as Type I DApps.
2. operate on the block chain of a Type I DApp. These protocols themselves have tokens that are required for their function.
3. DApps are protocols that operate using the protocols of a Type II DApp. Similar to Type II DApps, Type III DApps also have tokens that are required for their function.

https://ethereum.org/en/developers/docs/dapps/

stake Ether -

• "execution" (Execution Engine, EL client or formerly the Eth1 client) - listens to new transactions broadcasted in the network, executes them in EVM, and holds the latest state and database of all current Ethereum data.

  • Full nodes
  • Archive nodes are nodes that store all of the information that a full node does and builds an archive of

  historical blockchain states.

• "consensus" (Beacon Node, CL client or formerly the Eth2 client) - implements the proof-of-stake consensus algorithm, which enables the network to achieve agreement based on validated data from the execution client.
• Light (nodes? wtf) - low-capacity devices like smartphones - can access the Ethereum blockchain with the same functionality and security guarantees as a full node.

petrruha@yandex.ru

Добрый день! Ссылки на видео в ютуб:

https://youtu.be/hF4958I4XFc 1.2 https://youtu.be/HPDqgao4qNs

https://youtu.be/rEXb09fWX2Y

​​​​​​​https://youtu.be/FuFysH2My68

​​​​​​​https://youtu.be/NRuYrTggyww

​​​​​​​https://youtu.be/IfuvXZ8a3xA

​​​​​​​https://youtu.be/xtwUvmv1m4o

Конспекты и чек-листы https://disk.yandex.ru/d/vqQd6t-4-mtRVA

Так как этот пакет включает контроль выполнения заданий (но это по желанию), выполненные задания присылайте в телеграм по номеру 89205557141 Энтузиазма и впечатляющих результатов Вам в этом путешествии в мир ораторского искусства!

1. перейти на язык оппонента
   • проблему эффективной коммуникации
2. продемонстировать уважение к его требованиям
   • анализу существующих интересов
   • свои интересы следует сформулировать и показать их важность для вас
3. предложить вариант решения проблемы, учитывает интересы оппонента

Участники выбирают сигналы, а не переговоры, как путь наименьшего риска и наименьших обязательств.

• Помните о тех позитивных целях, которые привели вас за стол переговоров.
• наглядно демонстируйте партнеру готовность совместно искать приемлемое для всех решение
• Вовлекайте партнера в процесс выработки решения
• выразите готовность признать точку зрения оппонента.
• Делайте разграничение между участниками и предметом переговоров.
• Сосредоточьтесь на интересах, а не на позициях.
• Разрабатывайте взаимовыгодные варианты.
• Настаивайте на использовании объективных критериев.
• сбить первые требования террористов, чтобы в дальнейшем не следовать их сценарию. Зато последнее требование нужно постараться удовлетворить, тогда террористу психологически будет легче сдаваться. ("спасение лица противника")
• Будьте тверды, говоря о проблеме, но мягки с людьми.
• Станьте на их сторону, Переформулируйте, Постройте золотой мост, Используйте силу для воспитания.
• чаще: "Да, здесь вы правы", "Да, здесь с вами следует согласиться". Это же "да" должно присутствовать и в невербальной форме.

урок Путина: переговоры могут раскрыть планы и упустить эффект неожиданности

Эффективная тактика - завышение требований в начале.

Проблемы переговоров:

• Люди часто говорят непонятно.
• Люди часто не обращают внимания на ваши слова.
• Люди часто понимают не то, что на самом деле было сказано.
• пять возможных барьеров на пути к сотрудничеству: Ваша реакция, Их эмоции, Их позиция, Их неудовлетворенность, Ихсила.
• Люди не любят высказывать свои соображения, но очень любят критиковать чужие.
• люди не идут на уступки, боясь показаться проигравшими. Решения:
  • покажите, что изменились обстоятельства
  • обратитесь за рекомендацией к третьей стороне (общий начальник, общий друг;)
  • укажите на справедливый стандарт

Ошибки:

• Посредник - ненужный человек
• Не я здесь главный
• не оскорблять и не уничтожать что-либо относящееся к против. стороне

например: «я вижу, что тебя это расстраивает» или «похоже, тебя сильно злит, что…». Это поможет человеку почувствовать себя услышанным и выпустить пар, после чего он будет более расположен к дальнейшему диалогу.

1. Смиритесь со всеми исходами, как успешными, так и нет. Если у вас не получится переубедить

конкретного человека — ничего страшного не случится.

1. Помните, что ваш собеседник — человек. Его жизнь уникальна и бесценна. В людях, не

поддерживающих борьбу с войной и диктатурой, слишком легко увидеть монстра и врага. Но с таких позиций разговор не пойдет. Держите в голове, что вы оба — люди, а значит — союзники.

1. Не надейтесь, что тщательно подобранные железные аргументы сразу переубедят собеседника. Если

он не убежденный рационалист, то на подсознательном уровне ценит свои убеждения больше, чем правду. Поэтому процесс будет постепенным. Если вы видитесь редко или единожды — вы максимум посеете зерно. Если это ваш друг или родственник, то будьте готовы переубеждать его месяцами.

1. Ни в коем случае нельзя эмоционировать, тем более — быть агрессивным. Если чувствуете, что не

получится — лучше отложить разговор. Победить безумие можно разумом, но не криками или обвинениями.

1. Найдите точки соприкосновения.

Они гарантировано есть, и их, скорее всего, много. Это может быть ценность жизни, плохое руководство, коррупция или низкие зарплаты. Мы все живем в одной реальности, и проблемы у нас общие. Так вы покажете, что не очень-то уж отличаетесь друг от друга.

1. Попросите собеседника как можно короче и точнее сформулировать его позицию.

"Война плохо, но если бы не мы, то нас", "во всем виновата Америка", "не будь наивным, это просто деньги". Важно, чтобы вы четко поняли эту позицию и чтобы собеседник закрепился на ней, а не плавал. После этого говорите, отталкиваясь именно от нее. Если виновата Америка, то говорим про вину, если "они первые"  — то только про готовящееся нападение и т.д.

1. Спросите у собеседника, какие факты и данные смогли бы убедить его в том, что он ошибся. И

наоборот: какие события в будущем он ожидает увидеть, если верна именно его точка зрения.

Если собеседник не смог ответить — все нормально. Эти вопросы задают себе ученые, когда строят гипотезы, а гипотеза "Путин — хороший" ненаучна. Так вот, если он не смог ответить, вы можете мягко указать на эту странность.

Если же вам четко ответили, то ответ должен задать вектор беседы. Ведь теперь вы знаете, какие подобрать аргументы для разрушения гипотезы собеседника и какой дать другой прогноз на ближайшее будущее. И если сбудется ваш прогноз, а не его, то вы получите еще один хороший аргумент для дальнейшего переубеждения оппонента.

Продолжение инструкции после того, как вы обсудили направление разговора — в следующем, финальном посте!

1. Меньше утверждайте, чаще спрашивайте.

   "А откуда это известно?", "почему ты веришь им?", "это точно именно так работает?" Главное — постараться задавать их искренне, без издевки (хотя она и может напрашиваться). Рано или поздно человек начнет противоречить сам себе, тогда укажите на это. Схема, кстати, работает со всеми, кто верит в чушь с научной и логической точек зрения.

   1. Ссылайтесь на факты, упомянутые кем-то.

   Причем в идеале не "Медузой" и Кацем, а знакомыми. И неважно, если сами знакомые тоже смотрели именно Каца или вообще выдуманные. Здесь и вообще в процессе стоит упоминать, что так же, как вы, думает много людей. В идеале — кумиры или знакомые собеседника, но можно приводить просто уважаемых многими людей.

   1. Если вдруг собеседник сошлется на то, что показания очевидцев, просто знакомых и кумиров —

   ненадежны, поздравляем! Тогда уже можно начать ссылаться на нормальные авторитетные источники. Но только в такой последовательности.

   1. Если собеседник сам спросит вас о чем-то.

   Будьте готовы ответить четко, коротко и убедительно. Особенно проработайте такие частые запросы, как: "Путин Россию поднял", "Россия же не может проиграть", "мы станем сверхдержавой", "в других странах все так же" и "а как ты видишь будущее".

   1. Если собеседник — ваш знакомый, будьте готовы повторять такую беседу много раз. Если нет —

   смиритесь, что, скорее всего, никогда не узнаете, был ли у ваших трудов результат.

   Дополнение:

   Если беседа проходит публично, приводить авторитетные источники стоит вне зависимости от готовности собеседника их принять. А свидетельства знакомых и очевидцев стоит приводить с оговоркой о том, что они не являются вескими свидетельствами.