1) The document discusses isolation of requests and processes in server architectures. It notes that isolation is important for security, reliability, and avoiding errors propagating between requests. 2) It examines different levels of isolation from physical servers to containers to processes to software contexts. Process-level isolation and microservices architectures are discussed as strategies. 3) Limitations of existing infrastructure approaches are outlined, noting the need for app-level integrity, statefulness, and scalability without vendor lock-in. A "meta serverless" approach is proposed to address these.

1. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
toString().padStart(width) : cell.padEnd(width); }).join(''))).join
}; const proportion = (max, val) => Math.round(val * 100 / max); co
calcProportion = table => { table.sort((row1, row2) => row2[DENSITY
row1[DENSITY_COL]); const maxDensity = table[0][DENSITY_COL]; table
forEach(row => { row.push(proportion(maxDensity, row[DENSITY_COL]))
return table; }; const getDataset = file => { const lines = fs.read
FileSync(file, 'utf8').toString().split('n'); lines.shift(); lines
return lines.map(line => line.split(',')); }; const main = compose
(getDataset, calcProportion, renderTable); const fs = require('fs'
compose = (...funcs) => x => funcs.reduce((x, fn) => fn(x), x); con
DENSITY_COL = 3; const renderTable = table => { const cellWidth = [
8, 8, 18, 6]; return table.map(row => (row.map((cell, i) => { const
= cellWidth[i]; return i ? cell.toString().padStart(width) : cell.p
(width); }).join(''))).join('n'); }; const proportion = (max, val)
Private cloud
without vendor lock
Timur Shemsedinov
github.com/tshemsedinov
Chief Software Architect at Metarhia
Lecturer at Kiev Polytechnic Institute

2. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Serverless Benefits
● Service price? (evangelists told us...)
● Efficiency: Performance? Speed? Latency?
● Easy to test, deploy, maintain?
● Security? Reliability? Flexibility? Quality?
● Quick development?
● Reduces development cost?
● Scalability?

3. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
What we pay for?
We pay for:
● lack of available professionals
● lack of competencies
● lack of available technologies
● lack of funding for our projects
● lack of time

4. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Serverless Disadvantages
● High resource consumption
● Stateless nature
● Interactivity issue (separate solution needed)
● No application integrity
● Development and debug issues
● Deploy and maintain issues
● Vendor lock, not open source

5. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Middleware Madness
router.get('/user/:id', (req, res, next) => {
const id = parseInt(req.params.id);
const query = 'SELECT * FROM users WHERE id = $1';
pool.query(query, [id], (err, data) => {
if (err) throw err;
res.status(200).json(data.rows);
next();
});
});

6. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Code Structure and Patterns
exports.handler = (event, context, callback) => {
const { Client } = require('pg');
const client = new Client();
client.connect();
const id = parseInt(event.pathParameters.id);
const query = 'SELECT * FROM users WHERE id = $1';
client.query(query, [id], (err, data) => {
callback(err, { statusCode: 200,
body: JSON.stringify(data.rows)});
});
};

7. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
What do we want?
async (arg1, arg2, arg3) => {
const [data1, data2] = await Promise.all(
[getData(arg1), getData(arg2)]
);
const data3 = await getData(arg3);
if (!data3) throw new Error('Message');
return await processData(data1, data2, data3);
}

8. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
What do we want?
async (arg1, arg2, arg3) => {
const data1 = await getData(arg1);
if (!data1) throw new Error('Message');
const [data2, data3] = await Promise.all(
[getData(arg2), getData(arg3)]
);
return await processData(data1, data2, data3);
}

9. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Equivalent example
async id => await application.database
.select('users')
.where({ id });

10. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Complex Query
async id => await application.database
.select('users')
.where({ id })
.cache({ timeout: 30000, invalidate: { id })
.projection({
name: ['name', toUpperCase],
age: ['birth', toAge],
place: ['address', getCity, getGeocode],
});

11. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
App Architecture Evolution
● File-server
● Local app + local db
● Client + DBMS
● Three-tier
● Web three-tier
● Web Services
● Cloud functions
Client
App Server
DB Server

12. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Layered Architecture
● Server-side
■ Layered
■ Microservices
■ Serverless
Database
Data Access Layer
Business-logic
API
Network

13. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Layered Architecture
● Client-side
■ UI
○ Components
■ Data
○ AJAX API
○ WebSockets
○ DB Sync

14. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
What do we want?
● Apps consolidation
● Stateful cloud applications
● Interactivity (Websockets, TCP, TLS support)
● No vendor lock
● Private clouds
● Do not overpay for clouds

15. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
How do we achieve this?
● Architecture: layered approach
● Long-lived processes
● We need request isolation
● Open source

16. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Why Isolation?
● Errors, crashes
● Memory leaks and other resources
● Application: data, database connections
● File system and root directory
● OS environment, PID, IPC
● OS Security: users, groups
● Networking: socket descriptors, ports, hosts

17. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Execution Strategy Problems
● Different requests execution should be isolated
from each other for security reasons
● One failed request can kill multiple concurrently
executed in a same process
● It’s hard to associate an error with a request
in JavaScript with it’s asynchronous nature
● Multitenant: apps and organizations in SaaS

18. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Isolation: Physical Server
Hardware
OS
App App

19. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Isolation: Virtualization
Hardware
OS
Hypervisor
OS
App
OS
App
OS
App
OS
App

20. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Isolation: Containerization
Hardware
OS
Containers
App App App App App App App

21. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Microisolation
Hardware
OS
App Server App
App
App
App
App
App
App
App
App
AppAppAppAppApp
AppApp

22. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Isolation Levels (for Node.js)
● Hardware segmentation, Servers
○ Virtual machine (hypervisor)
■ Container (docker)
● Process (node)
○ Thread (worker_threads)
■ Sandbox (vm.createContext, vm.Script)
● Software context (object, closure)

23. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Execution Strategy
1 process, 1 thread, 1 request per thread
1 process, 1 thread, N requests per thread
1 process, N threads, 1 request per thread
1 process, N threads, N requests per thread
N processes, 1 thread, 1 request per thread
N processes, 1 thread, N requests per thread
N processes, N threads, 1 request per thread
N processes, N threads, N requests per thread

24. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Infrastructure Limitations
● Physical non-repeatability
● Shared hosting poor insulation, no control
● Virtualization single server, resource losses
● Containerization single server
● Clusterization stateless, no app level cluster
● Serverless no app level integrity
● Metaserverless integrity, stateful, scalability

25. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
SOA Architecture
DB
API
+
BL
Network
API
+
BL
API
+
BL
API
+
BL
Database
Data Access Layer
Business-logic
API
Network

26. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Microservices Architecture
DB
API
+
BL
Network
API
+
BL
API
+
BL
API
+
BL
Database
Data Access Layer
Business-logic
API
Network
DB DB DB

27. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Serverless Architecture
Database
API
+
BL
Network
API
+
BL
API
+
BL
API
+
BL
Database
Data Access Layer
Business-logic
API
Network

28. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Serverless Architecture
Database
API+BL
Network
Database
Data Access Layer
Business-logic
API
Network
API+BL
API+BL
API+BL
API+BL API+BL API+BL

29. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Serverless Architecture
Database
API+BL
Network
Database
Data Access Layer
Business-logic
API
Network
API+BL
API+BL
API+BL
API+BL API+BL API+BL
API+BL
API+BL API+BL
API+BL
API+BL
API+BL
API+BL
API+BL

30. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Serverless Architecture
Database
API+BL
Network
Database
Data Access Layer
Business-logic
API
Network
API+BL
API+BL
API+BL
API+BL API+BL API+BL
API+BL
API+BL API+BL
API+BL
API+BL
API+BL
API+BL
API+BL
API+BL
API+BL
API+BL
API+BL API+BL
API+BL API+BL API+BL
API+BL API+BL
API+BL
API+BL
API+BL
API+BL
API+BL
API+BL API+BL
API+BL
API+BL

31. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Target Architecture
Network
API
Business-logic
Data Access Layer
Database

32. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
Metaserverless Experiments
● Application is not a separate functions,
application has distributed in-memory state
● Functions can be executed sequentially and
parallely in asynchronous style
● Applications have long life and structure
● Interactivity (Websockets, TCP, TLS support)
● No vendor lock, Private clouds, Open Source

33. const fs = require('fs'); const compose = (...funcs) => x => funcs.
reduce((x, fn) => fn(x), x); const DENSITY_COL = 3; const renderTab
table => { const cellWidth = [18, 10, 8, 8, 18, 6]; return table.ma
=> (row.map((cell, i) => { const width = cellWidth[i]; return i ? c
toString().padStart(width) : cell.padEnd(width); }).join(''))).join
}; const proportion = (max, val) => Math.round(val * 100 / max); co
calcProportion = table => { table.sort((row1, row2) => row2[DENSITY
row1[DENSITY_COL]); const maxDensity = table[0][DENSITY_COL]; table
forEach(row => { row.push(proportion(maxDensity, row[DENSITY_COL]))
return table; }; const getDataset = file => { const lines = fs.read
FileSync(file, 'utf8').toString().split('n'); lines.shift(); lines
return lines.map(line => line.split(',')); }; const main = compose
(getDataset, calcProportion, renderTable); const fs = require('fs'
compose = (...funcs) => x => funcs.reduce((x, fn) => fn(x), x); con
DENSITY_COL = 3; const renderTable = table => { const cellWidth = [
8, 8, 18, 6]; return table.map(row => (row.map((cell, i) => { const
= cellWidth[i]; return i ? cell.toString().padStart(width) : cell.p
(width); }).join(''))).join('n'); }; const proportion = (max, val)
Private cloud
without vendor lock
Timur Shemsedinov
github.com/tshemsedinov
Chief Software Architect at Metarhia
Lecturer at Kiev Polytechnic Institute