diff --git a/src/authentication/jwt-refresh-token.strategy.ts b/src/authentication/jwt-refresh-token.strategy.ts
new file mode 100644
index 0000000..abf9006
--- /dev/null
+++ b/src/authentication/jwt-refresh-token.strategy.ts
@@ -0,0 +1,30 @@
+import { ExtractJwt, Strategy } from 'passport-jwt';
+import { PassportStrategy } from '@nestjs/passport';
+import { Injectable } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { Request } from 'express';
+import {UsersService} from "../users/user.service";
+
+@Injectable()
+export class JwtRefreshTokenStrategy extends PassportStrategy(
+  Strategy,
+  'jwt-refresh-token'
+) {
+  constructor(
+    private readonly configService: ConfigService,
+    private readonly userService: UsersService,
+  ) {
+    super({
+      jwtFromRequest: ExtractJwt.fromExtractors([(request: Request) => {
+        return request?.cookies?.Refresh;
+      }]),
+      secretOrKey: configService.get('JWT_REFRESH_TOKEN_SECRET'),
+      passReqToCallback: true,
+    });
+  }
+
+  async validate(request: Request, payload: TokenPayload) {
+    const refreshToken = request.cookies?.Refresh;
+    return this.userService.getUserIfRefreshTokenMatches(refreshToken, payload.userId);
+  }
+}
\ No newline at end of file
diff --git a/src/authentication/jwtRefreshGuard.guard.ts b/src/authentication/jwtRefreshGuard.guard.ts
new file mode 100644
index 0000000..2b7317e
--- /dev/null
+++ b/src/authentication/jwtRefreshGuard.guard.ts
@@ -0,0 +1,5 @@
+import { Injectable } from '@nestjs/common';
+import { AuthGuard } from '@nestjs/passport';
+
+@Injectable()
+export default class JwtRefreshGuard extends AuthGuard('jwt-refresh-token') {}
\ No newline at end of file
diff --git a/src/chat/chat.gateway.ts b/src/chat/chat.gateway.ts
new file mode 100644
index 0000000..1c10f8c
--- /dev/null
+++ b/src/chat/chat.gateway.ts
@@ -0,0 +1,44 @@
+import {
+    ConnectedSocket,
+    MessageBody, OnGatewayConnection,
+    SubscribeMessage,
+    WebSocketGateway,
+    WebSocketServer,
+} from '@nestjs/websockets';
+import {Server, Socket} from 'socket.io';
+import {ChatService} from "./chat.service";
+
+@WebSocketGateway()
+export class ChatGateway implements OnGatewayConnection {
+    @WebSocketServer()
+    server: Server;
+
+    constructor(
+        private readonly chatService: ChatService
+    ) {
+    }
+
+    async handleConnection(socket: Socket) {
+        await this.chatService.getUserFromSocket(socket);
+    }
+
+    @SubscribeMessage('send_message')
+    async listenForMessages(@MessageBody() content: string, @ConnectedSocket() socket: Socket,) {
+        const author = await this.chatService.getUserFromSocket(socket);
+        const message = await this.chatService.saveMessage(content, author);
+        this.server.sockets.emit('receive_message', message);
+        return message;
+    }
+
+    @SubscribeMessage('request_all_messages')
+    async requestAllMessages(
+        @ConnectedSocket() socket: Socket,
+    ) {
+        await this.chatService.getUserFromSocket(socket);
+        const messages = await this.chatService.getAllMessages();
+
+        socket.emit('send_all_messages', messages);
+    }
+
+
+}
\ No newline at end of file
diff --git a/src/chat/chat.service.ts b/src/chat/chat.service.ts
new file mode 100644
index 0000000..17cd034
--- /dev/null
+++ b/src/chat/chat.service.ts
@@ -0,0 +1,47 @@
+import { Injectable } from '@nestjs/common';
+import { AuthenticationService } from '../authentication/authentication.service';
+import { Socket } from 'socket.io';
+import { parse } from 'cookie';
+import { WsException } from '@nestjs/websockets';
+import UserEntity from "../users/entities/user.entity";
+import {InjectRepository} from "@nestjs/typeorm";
+import Message from "./mesage.entity";
+import {Repository} from "typeorm";
+
+@Injectable()
+export class ChatService {
+    constructor(
+        private readonly authenticationService: AuthenticationService,
+        @InjectRepository(Message)
+        private messagesRepository: Repository<Message>,
+    ) {
+    }
+
+    async saveMessage(content: string, author: UserEntity) {
+        const newMessage = this.messagesRepository.create({
+            content,
+            author
+        });
+        await this.messagesRepository.save(newMessage);
+        return newMessage;
+    }
+
+    async getAllMessages() {
+        return this.messagesRepository.find({
+            relations: {
+                author: true,
+            }
+        });
+    }
+
+    async getUserFromSocket(socket: Socket) {
+        const cookie = socket.handshake.headers.cookie;
+        const { Authentication: authenticationToken } = parse(cookie);
+        const user = await this.authenticationService.getUserFromAuthenticationToken(authenticationToken);
+        if (!user) {
+            throw new WsException('Invalid credentials.');
+        }
+        return user;
+    }
+}
+
diff --git a/src/chat/mesage.entity.ts b/src/chat/mesage.entity.ts
new file mode 100644
index 0000000..65912c0
--- /dev/null
+++ b/src/chat/mesage.entity.ts
@@ -0,0 +1,16 @@
+import { Column, Entity, ManyToOne, PrimaryGeneratedColumn } from 'typeorm';
+import User from '../users/entities/user.entity';
+
+@Entity()
+class Message {
+    @PrimaryGeneratedColumn()
+    public id: number;
+
+    @Column()
+    public content: string;
+
+    @ManyToOne(() => User)
+    public author: User;
+}
+
+export default Message;
\ No newline at end of file
diff --git a/src/posts/httpCache.interceptor.ts b/src/posts/httpCache.interceptor.ts
new file mode 100644
index 0000000..4f77122
--- /dev/null
+++ b/src/posts/httpCache.interceptor.ts
@@ -0,0 +1,19 @@
+import { CACHE_KEY_METADATA, CacheInterceptor, } from '@nestjs/cache-manager';
+import {ExecutionContext, Injectable} from "@nestjs/common";
+
+@Injectable()
+export class HttpCacheInterceptor extends CacheInterceptor {
+    trackBy(context: ExecutionContext): string | undefined {
+        const cacheKey = this.reflector.get(
+            CACHE_KEY_METADATA,
+            context.getHandler(),
+        );
+
+        if (cacheKey) {
+            const request = context.switchToHttp().getRequest();
+            return `${cacheKey}-${request._parsedUrl.query}`;
+        }
+
+        return super.trackBy(context);
+    }
+}
\ No newline at end of file
diff --git a/src/posts/postsCacheKey.constant.ts b/src/posts/postsCacheKey.constant.ts
new file mode 100644
index 0000000..78140f6
--- /dev/null
+++ b/src/posts/postsCacheKey.constant.ts
@@ -0,0 +1 @@
+export const GET_POSTS_CACHE_KEY = 'GET_POSTS_CACHE';
\ No newline at end of file
diff --git a/src/posts/postsSearch.service.ts b/src/posts/postsSearch.service.ts
new file mode 100644
index 0000000..4d765b8
--- /dev/null
+++ b/src/posts/postsSearch.service.ts
@@ -0,0 +1,98 @@
+import {Injectable} from '@nestjs/common';
+import {ElasticsearchService} from '@nestjs/elasticsearch';
+import Post from "./entities/post.entity";
+import {PostSearchResult} from "./types/postSearchResult.interface";
+import {PostSearchBody} from "./types/postSearchBody.interface";
+import PostCountResult from "./types/postCountBody.interface";
+
+@Injectable()
+export default class PostsSearchService {
+    index = 'posts';
+
+    constructor(
+        private readonly elasticsearchService: ElasticsearchService
+    ) {
+    }
+
+    async indexPost(post: Post) {
+        return this.elasticsearchService.index<PostSearchBody>({
+            index: this.index,
+            document: {
+                id: post.id,
+                title: post.title,
+                content: post.content,
+                authorId: post.author.id
+            }
+        });
+    }
+
+    async count(query: string, fields: string[]) {
+        const result = await this.elasticsearchService.count({
+            index: this.index,
+            query: {
+                multi_match: {
+                    query,
+                    fields,
+                },
+            },
+        });
+
+        return result.count;
+    }
+
+
+
+    async search(text: string) {
+        const result = await this.elasticsearchService.search<PostSearchResult>({
+            index: this.index,
+            query: {
+                multi_match: {
+                    query: text,
+                    fields: ['title', 'content'],
+                },
+            },
+        });
+
+        const hits = result.hits.hits;
+        return hits.map((item) => item._source);
+    }
+
+
+    async remove(postId: number) {
+        await this.elasticsearchService.deleteByQuery({
+            index: this.index,
+            query: {
+                match: {
+                    id: postId,
+                }
+            }
+
+        })
+    }
+
+    async update(post: Post) {
+        const newBody: PostSearchBody = {
+            id: post.id,
+            title: post.title,
+            content: post.content,
+            authorId: post.author.id
+        };
+
+        const script = Object.entries(newBody).reduce((result, [key, value]) => {
+            return `${result} ctx._source.${key}='${value}';`;
+        }, '');
+
+        await this.elasticsearchService.updateByQuery({
+            index: this.index,
+            query: {
+                match: {
+                    id: post.id,
+                }
+            },
+            script: {
+                source: script
+            }
+        });
+    }
+
+}
\ No newline at end of file
diff --git a/src/posts/types/postCountBody.interface.ts b/src/posts/types/postCountBody.interface.ts
new file mode 100644
index 0000000..19e322f
--- /dev/null
+++ b/src/posts/types/postCountBody.interface.ts
@@ -0,0 +1,5 @@
+interface PostCountResult {
+    count: number;
+}
+
+export default PostCountResult;
\ No newline at end of file
diff --git a/src/posts/types/postSearchBody.interface.ts b/src/posts/types/postSearchBody.interface.ts
new file mode 100644
index 0000000..61dacc3
--- /dev/null
+++ b/src/posts/types/postSearchBody.interface.ts
@@ -0,0 +1,6 @@
+export interface PostSearchBody {
+  id: number,
+  title: string,
+  content: string,
+  authorId: number
+}
\ No newline at end of file
diff --git a/src/posts/types/postSearchResult.interface.ts b/src/posts/types/postSearchResult.interface.ts
new file mode 100644
index 0000000..96a9afb
--- /dev/null
+++ b/src/posts/types/postSearchResult.interface.ts
@@ -0,0 +1,10 @@
+import {PostSearchBody} from "./postSearchBody.interface";
+
+export interface PostSearchResult {
+  hits: {
+    total: number;
+    hits: Array<{
+      _source: PostSearchBody;
+    }>;
+  };
+}
\ No newline at end of file
diff --git a/src/productCategories/productCategory.entity.ts b/src/productCategories/productCategory.entity.ts
new file mode 100644
index 0000000..1c41f4a
--- /dev/null
+++ b/src/productCategories/productCategory.entity.ts
@@ -0,0 +1,19 @@
+import { Column, Entity, PrimaryGeneratedColumn, OneToMany } from 'typeorm';
+import Product from '../products/product.entity';
+
+@Entity()
+class ProductCategory {
+    @PrimaryGeneratedColumn()
+    public id: number;
+
+    @Column()
+    public name: string;
+
+    @OneToMany(
+        () => Product,
+        (product: Product) => product.category,
+    )
+    public products: Product[];
+}
+
+export default ProductCategory;
\ No newline at end of file
diff --git a/src/products/product.entity.ts b/src/products/product.entity.ts
new file mode 100644
index 0000000..9a6587e
--- /dev/null
+++ b/src/products/product.entity.ts
@@ -0,0 +1,23 @@
+import { Column, Entity, PrimaryGeneratedColumn, ManyToOne } from 'typeorm';
+import ProductCategory from '../productCategories/productCategory.entity';
+import { CarProperties } from './types/carProperties.interface';
+import { BookProperties } from './types/bookProperties.interface';
+
+@Entity()
+class Product {
+    @PrimaryGeneratedColumn()
+    public id: number;
+
+    @Column()
+    public name: string;
+
+    @ManyToOne(() => ProductCategory, (category: ProductCategory) => category.products)
+    public category: ProductCategory;
+
+    @Column({
+        type: 'jsonb'
+    })
+    public properties: CarProperties | BookProperties;
+}
+
+export default Product;
\ No newline at end of file
diff --git a/src/products/types/bookProperties.interface.ts b/src/products/types/bookProperties.interface.ts
new file mode 100644
index 0000000..b3dae4e
--- /dev/null
+++ b/src/products/types/bookProperties.interface.ts
@@ -0,0 +1,4 @@
+export interface BookProperties {
+    authors: string[];
+    publicationYear: string;
+}
\ No newline at end of file
diff --git a/src/products/types/carProperties.interface.ts b/src/products/types/carProperties.interface.ts
new file mode 100644
index 0000000..a1c4c28
--- /dev/null
+++ b/src/products/types/carProperties.interface.ts
@@ -0,0 +1,7 @@
+export interface CarProperties {
+    brand: string;
+    engine: {
+        fuel: string;
+        numberOfCylinders: number;
+    }
+}
\ No newline at end of file
diff --git a/src/search/search.module.ts b/src/search/search.module.ts
new file mode 100644
index 0000000..5f5c6d9
--- /dev/null
+++ b/src/search/search.module.ts
@@ -0,0 +1,22 @@
+import { Module } from '@nestjs/common';
+import { ConfigModule, ConfigService } from '@nestjs/config';
+import { ElasticsearchModule } from '@nestjs/elasticsearch';
+
+@Module({
+  imports: [
+    ConfigModule,
+    ElasticsearchModule.registerAsync({
+      imports: [ConfigModule],
+      useFactory: async (configService: ConfigService) => ({
+        node: configService.get<string>('ELASTICSEARCH_NODE'),
+        auth: {
+          username: configService.get<string>('ELASTICSEARCH_USERNAME'),
+          password: configService.get<string>('ELASTICSEARCH_PASSWORD'),
+        }
+      }),
+      inject: [ConfigService],
+    }),
+  ],
+  exports: [ElasticsearchModule]
+})
+export class SearchModule {}
\ No newline at end of file
diff --git a/src/utils/types/paginationParams.ts b/src/utils/types/paginationParams.ts
new file mode 100644
index 0000000..39600b5
--- /dev/null
+++ b/src/utils/types/paginationParams.ts
@@ -0,0 +1,23 @@
+import { IsNumber, Min, IsOptional } from 'class-validator';
+import { Type } from 'class-transformer';
+
+export class PaginationParams {
+
+    @IsOptional()
+    @Type(() => Number)
+    @IsNumber()
+    @Min(1)
+    startId?: number;
+
+    @IsOptional()
+    @Type(() => Number)
+    @IsNumber()
+    @Min(0)
+    offset?: number;
+
+    @IsOptional()
+    @Type(() => Number)
+    @IsNumber()
+    @Min(1)
+    limit?: number;
+}
\ No newline at end of file