diff --git a/examples/basic/server.ts b/examples/basic/server.ts
index 95e1581..1ba6361 100644
--- a/examples/basic/server.ts
+++ b/examples/basic/server.ts
@@ -58,7 +58,7 @@ const backend = app.createBackend({
 	dataSource,
 });
 
-const server = backend.createServer({
+const server = backend.createHttpServer({
 	basePath: '/api'
 });
 
diff --git a/src/app.ts b/src/app.ts
deleted file mode 100644
index e56f55d..0000000
--- a/src/app.ts
+++ /dev/null
@@ -1,67 +0,0 @@
-import * as v from 'valibot';
-import {
-	Resource,
-	Language,
-	MediaType,
-	Charset,
-	ApplicationParams,
-	ApplicationState,
-	FALLBACK_LANGUAGE,
-	FALLBACK_CHARSET, FALLBACK_MEDIA_TYPE,
-} from './common';
-import {BackendBuilder, createBackend, CreateBackendParams} from './backend';
-import {ClientBuilder, createClient, CreateClientParams} from './client';
-
-export interface ApplicationBuilder {
-	mediaType(mediaType: MediaType): this;
-	language(language: Language): this;
-	charset(charset: Charset): this;
-	resource<T extends v.BaseSchema>(resRaw: Resource<T>): this;
-	createBackend(params: Omit<CreateBackendParams, 'app'>): BackendBuilder;
-	createClient(params: Omit<CreateClientParams, 'app'>): ClientBuilder;
-}
-
-export const application = (appParams: ApplicationParams): ApplicationBuilder => {
-	const appState: ApplicationState = {
-		name: appParams.name,
-		resources: new Set<Resource<any>>(),
-		languages: new Set<Language>(),
-		mediaTypes: new Set<MediaType>(),
-		charsets: new Set<Charset>(),
-	};
-
-	appState.languages.add(FALLBACK_LANGUAGE);
-	appState.charsets.add(FALLBACK_CHARSET);
-	appState.mediaTypes.add(FALLBACK_MEDIA_TYPE);
-
-	return {
-		mediaType(serializerPair: MediaType) {
-			appState.mediaTypes.add(serializerPair);
-			return this;
-		},
-		charset(encodingPair: Charset) {
-			appState.charsets.add(encodingPair);
-			return this;
-		},
-		language(language: Language) {
-			appState.languages.add(language);
-			return this;
-		},
-		resource<T extends v.BaseSchema>(resRaw: Resource<T>) {
-			appState.resources.add(resRaw);
-			return this;
-		},
-		createBackend(params: Omit<CreateBackendParams, 'app'>) {
-			return createBackend({
-				...params,
-				app: appState
-			});
-		},
-		createClient(params: Omit<CreateClientParams, 'app'>) {
-			return createClient({
-				...params,
-				app: appState
-			});
-		},
-	};
-};
diff --git a/src/backend/common.ts b/src/backend/common.ts
index 6e30be4..367db64 100644
--- a/src/backend/common.ts
+++ b/src/backend/common.ts
@@ -1,16 +1,21 @@
-import {ApplicationState, Charset, Language, MediaType, Resource} from '../common';
+import {ApplicationState, ContentNegotiation, Resource} from '../common';
 import {BaseDataSource} from '../common/data-source';
+import http from 'http';
 
 export interface BackendState {
 	app: ApplicationState;
 	dataSource: (resource: Resource) => BaseDataSource;
-	cn: {
-		language: Language;
-		charset: Charset;
-		mediaType: MediaType;
-	}
+	cn: ContentNegotiation;
 	showTotalItemCountOnGetCollection: boolean;
 	throws404OnDeletingNotFound: boolean;
 	checksSerializersOnDelete: boolean;
 	showTotalItemCountOnCreateItem: boolean;
 }
+
+export interface RequestContext extends http.IncomingMessage {
+	body?: unknown;
+}
+
+export type RequestDecorator = (req: RequestContext) => RequestContext | Promise<RequestContext>;
+
+export type ParamRequestDecorator<Params extends Array<unknown> = []> = (...args: Params) => RequestDecorator;
diff --git a/src/backend/core.ts b/src/backend/core.ts
index 55771bb..053c25c 100644
--- a/src/backend/core.ts
+++ b/src/backend/core.ts
@@ -23,8 +23,8 @@ export interface BackendBuilder<T extends BaseDataSource = BaseDataSource> {
 	showTotalItemCountOnGetCollection(b?: boolean): this;
 	showTotalItemCountOnCreateItem(b?: boolean): this;
 	checksSerializersOnDelete(b?: boolean): this;
-	throws404OnDeletingNotFound(b?: boolean): this;
-	createServer(serverParams?: CreateServerParams): http.Server | https.Server;
+	throwsErrorOnDeletingNotFound(b?: boolean): this;
+	createHttpServer(serverParams?: CreateServerParams): http.Server | https.Server;
 	dataSource?: (resource: Resource) => T;
 }
 
@@ -57,7 +57,7 @@ export const createBackend = (params: CreateBackendParams) => {
 			backendState.showTotalItemCountOnCreateItem = b;
 			return this;
 		},
-		throws404OnDeletingNotFound(b = true) {
+		throwsErrorOnDeletingNotFound(b = true) {
 			backendState.throws404OnDeletingNotFound = b;
 			return this;
 		},
@@ -65,8 +65,8 @@ export const createBackend = (params: CreateBackendParams) => {
 			backendState.checksSerializersOnDelete = b;
 			return this;
 		},
-		createServer(serverParams = {} as CreateServerParams) {
+		createHttpServer(serverParams = {} as CreateServerParams) {
 			return createServer(backendState, serverParams);
-		}
+		},
 	} satisfies BackendBuilder;
 };
diff --git a/src/backend/decorators/backend/content-negotiation.ts b/src/backend/decorators/backend/content-negotiation.ts
new file mode 100644
index 0000000..7ba8f42
--- /dev/null
+++ b/src/backend/decorators/backend/content-negotiation.ts
@@ -0,0 +1,29 @@
+import {ContentNegotiation} from '../../../common';
+import {RequestDecorator} from '../../common';
+import Negotiator from 'negotiator';
+
+declare module '../../common' {
+	interface RequestContext {
+		cn: ContentNegotiation;
+	}
+}
+
+export const decorateRequestWithContentNegotiation: RequestDecorator = (req) => {
+	const negotiator = new Negotiator(req);
+
+	const availableLanguages = Array.from(req.backend.app.languages.values() ?? []);
+	const availableCharsets = Array.from(req.backend.app.charsets.values() ?? []);
+	const availableMediaTypes = Array.from(req.backend.app.mediaTypes.values() ?? []);
+
+	const languageCandidate = negotiator.language(availableLanguages.map((l) => l.name)) ?? req.backend.cn.language.name;
+	const charsetCandidate = negotiator.charset(availableCharsets.map((l) => l.name)) ?? req.backend.cn.charset.name;
+	const mediaTypeCandidate = negotiator.mediaType(availableMediaTypes.map((l) => l.name)) ?? req.backend.cn.mediaType.name;
+
+	req.cn = {
+		language: req.backend.app.languages.get(languageCandidate) ?? req.backend.cn.language,
+		mediaType: req.backend.app.mediaTypes.get(mediaTypeCandidate) ?? req.backend.cn.mediaType,
+		charset: req.backend.app.charsets.get(charsetCandidate) ?? req.backend.cn.charset,
+	};
+
+	return req;
+};
diff --git a/src/backend/decorators/backend/index.ts b/src/backend/decorators/backend/index.ts
new file mode 100644
index 0000000..b8d52ee
--- /dev/null
+++ b/src/backend/decorators/backend/index.ts
@@ -0,0 +1,18 @@
+import {BackendState, ParamRequestDecorator} from '../../common';
+import {decorateRequestWithContentNegotiation} from './content-negotiation';
+import {decorateRequestWithResource} from './resource';
+
+declare module '../../common' {
+	interface RequestContext {
+		backend: BackendState;
+	}
+}
+
+export const decorateRequestWithBackend: ParamRequestDecorator<[BackendState]> = (backend) => (req) => {
+	req.backend = backend;
+
+	decorateRequestWithContentNegotiation(req);
+	decorateRequestWithResource(req);
+
+	return req;
+};
diff --git a/src/backend/decorators/backend/resource.ts b/src/backend/decorators/backend/resource.ts
new file mode 100644
index 0000000..673bb3d
--- /dev/null
+++ b/src/backend/decorators/backend/resource.ts
@@ -0,0 +1,25 @@
+import {RequestDecorator} from '../../common';
+import {DataSource} from '../../data-source';
+import {Resource} from '../../../common';
+import {BackendResource} from '../../core';
+
+declare module '../../common' {
+	interface RequestContext {
+		resource?: Resource;
+		resourceId?: string;
+	}
+}
+
+export const decorateRequestWithResource: RequestDecorator = (req) => {
+	const [, resourceRouteName, resourceId = ''] = req.url?.split('/') ?? [];
+	const resource = Array.from(req.backend.app.resources)
+		.find((r) => r.state.routeName === resourceRouteName) as BackendResource | undefined;
+
+	if (typeof resource !== 'undefined') {
+		req.resource = resource;
+		req.resource.dataSource = req.backend.dataSource(req.resource) as DataSource;
+		req.resourceId = resourceId;
+	}
+
+	return req;
+};
diff --git a/src/backend/decorators/method/index.ts b/src/backend/decorators/method/index.ts
new file mode 100644
index 0000000..412feca
--- /dev/null
+++ b/src/backend/decorators/method/index.ts
@@ -0,0 +1,7 @@
+import {RequestDecorator} from '../../common';
+
+export const decorateRequestWithMethod: RequestDecorator = (req) => {
+	req.method = req.method?.trim().toUpperCase() ?? '';
+
+	return req;
+};
diff --git a/src/backend/decorators/url/base-path.ts b/src/backend/decorators/url/base-path.ts
new file mode 100644
index 0000000..17e230c
--- /dev/null
+++ b/src/backend/decorators/url/base-path.ts
@@ -0,0 +1,13 @@
+import {ParamRequestDecorator} from '../../common';
+
+declare module '../../common' {
+	interface RequestContext {
+		basePath: string;
+	}
+}
+
+export const decorateRequestWithBasePath: ParamRequestDecorator<[string]> = (basePath) => (req) => {
+	req.basePath = basePath;
+
+	return req;
+}
diff --git a/src/backend/decorators/url/host.ts b/src/backend/decorators/url/host.ts
new file mode 100644
index 0000000..2cf8143
--- /dev/null
+++ b/src/backend/decorators/url/host.ts
@@ -0,0 +1,13 @@
+import {ParamRequestDecorator} from '../../common';
+
+declare module '../../common' {
+	interface RequestContext {
+		host: string;
+	}
+}
+
+export const decorateRequestWithHost: ParamRequestDecorator<[string]> = (host) => (req) => {
+	req.host = host;
+
+	return req;
+};
diff --git a/src/backend/decorators/url/index.ts b/src/backend/decorators/url/index.ts
new file mode 100644
index 0000000..1bfa385
--- /dev/null
+++ b/src/backend/decorators/url/index.ts
@@ -0,0 +1,26 @@
+import {ParamRequestDecorator} from '../../common';
+import {CreateServerParams} from '../../server';
+import {decorateRequestWithScheme} from './scheme';
+import {decorateRequestWithHost} from './host';
+import {decorateRequestWithBasePath} from './base-path';
+
+declare module '../../common' {
+	interface RequestContext {
+		rawUrl?: string;
+		query: URLSearchParams;
+	}
+}
+
+export const decorateRequestWithUrl: ParamRequestDecorator<[CreateServerParams]> = (serverParams) => (req) => {
+	const isHttps = 'key' in serverParams && 'cert' in serverParams;
+	decorateRequestWithScheme(isHttps ? 'https' : 'http')(req);
+	decorateRequestWithHost(serverParams.host ?? '127.0.0.1')(req);
+	decorateRequestWithBasePath(serverParams.basePath ?? '')(req);
+	const basePath = new URL(req.basePath, `${req.scheme}://${req.host}`);
+	const parsedUrl = new URL(`${basePath.pathname}/${req.url ?? ''}`, basePath.origin);
+	req.rawUrl = req.url;
+	req.url = req.url?.slice(basePath.pathname.length) ?? '';
+	req.query = parsedUrl.searchParams;
+
+	return req;
+};
diff --git a/src/backend/decorators/url/scheme.ts b/src/backend/decorators/url/scheme.ts
new file mode 100644
index 0000000..e877e2d
--- /dev/null
+++ b/src/backend/decorators/url/scheme.ts
@@ -0,0 +1,13 @@
+import {ParamRequestDecorator} from '../../common';
+
+declare module '../../common' {
+	interface RequestContext {
+		scheme: string;
+	}
+}
+
+export const decorateRequestWithScheme: ParamRequestDecorator<[string]> = (scheme) => (req) => {
+	req.scheme = scheme;
+
+	return req;
+};
diff --git a/src/backend/handlers.ts b/src/backend/handlers.ts
index 149e087..184f844 100644
--- a/src/backend/handlers.ts
+++ b/src/backend/handlers.ts
@@ -1,15 +1,17 @@
 import { constants } from 'http2';
 import * as v from 'valibot';
 import {HttpMiddlewareError, PlainResponse, Middleware} from './server';
+import {LinkMap} from './utils';
+import {BackendResource} from './core';
 
 export const handleGetRoot: Middleware = (req) => {
 	const { backend, basePath } = req;
 
 	const data = {
-		name: backend!.app.name
+		name: backend.app.name
 	};
 
-	const registeredResources = Array.from(backend!.app.resources);
+	const registeredResources = Array.from(backend.app.resources);
 	const availableResources = registeredResources.filter((r) => (
 		r.state.canFetchCollection
 		|| r.state.canCreate
@@ -18,13 +20,16 @@ export const handleGetRoot: Middleware = (req) => {
 	const headers: Record<string, string> = {};
 	if (availableResources.length > 0) {
 		// https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Link
-		headers['Link'] = availableResources
-			.map((r) => [
-				`<${basePath}/${r.state.routeName}>`,
-				'rel="related"',
-				`name="${encodeURIComponent(r.state.routeName)}"`
-			].join('; '))
-			.join(', ');
+		headers['Link'] = new LinkMap(
+			availableResources.map((r) => ({
+				url: `${basePath}/${r.state.routeName}`,
+				params: {
+					rel: 'related',
+					name: r.state.routeName,
+				},
+			}))
+		)
+			.toString();
 	}
 
 	return new PlainResponse({
@@ -36,7 +41,12 @@ export const handleGetRoot: Middleware = (req) => {
 };
 
 export const handleGetCollection: Middleware = async (req) => {
-	const { query, resource, backend } = req;
+	const { query, resource: resourceRaw, backend } = req;
+
+	if (typeof resourceRaw === 'undefined') {
+		throw new Error('No resource');
+	}
+	const resource = resourceRaw as BackendResource;
 
 	let data: v.Output<typeof resource.schema>[];
 	let totalItemCount: number | undefined;
@@ -57,7 +67,6 @@ export const handleGetCollection: Middleware = async (req) => {
 	}
 
 	const headers: Record<string, string> = {};
-
 	if (typeof totalItemCount !== 'undefined') {
 		headers['X-Resource-Total-Item-Count'] = totalItemCount.toString();
 	}
@@ -71,7 +80,12 @@ export const handleGetCollection: Middleware = async (req) => {
 };
 
 export const handleGetItem: Middleware = async (req) => {
-	const { resource, resourceId } = req;
+	const { resource: resourceRaw, resourceId } = req;
+
+	if (typeof resourceRaw === 'undefined') {
+		throw new Error('No resource');
+	}
+	const resource = resourceRaw as BackendResource;
 
 	if (typeof resourceId === 'undefined') {
 		throw new HttpMiddlewareError(
@@ -82,6 +96,15 @@ export const handleGetItem: Middleware = async (req) => {
 		);
 	}
 
+	if ((resourceId.trim().length ?? 0) < 1) {
+		throw new HttpMiddlewareError(
+			'resourceIdNotGiven',
+			{
+				statusCode: constants.HTTP_STATUS_INTERNAL_SERVER_ERROR,
+			}
+		);
+	}
+
 	let data: v.Output<typeof resource.schema> | null = null;
 	try {
 		data = await resource.dataSource.getById(resourceId);
@@ -112,7 +135,12 @@ export const handleGetItem: Middleware = async (req) => {
 };
 
 export const handleDeleteItem: Middleware = async (req) => {
-	const { resource, resourceId, backend } = req;
+	const { resource: resourceRaw, resourceId, backend } = req;
+
+	if (typeof resourceRaw === 'undefined') {
+		throw new Error('No resource');
+	}
+	const resource = resourceRaw as BackendResource;
 
 	if (typeof resourceId === 'undefined') {
 		throw new HttpMiddlewareError(
@@ -157,7 +185,21 @@ export const handleDeleteItem: Middleware = async (req) => {
 };
 
 export const handlePatchItem: Middleware = async (req) => {
-	const { resource, resourceId, body } = req;
+	const { resource: resourceRaw, resourceId, body } = req;
+
+	if (typeof resourceRaw === 'undefined') {
+		throw new Error('No resource');
+	}
+	const resource = resourceRaw as BackendResource;
+
+	if (typeof resourceId === 'undefined') {
+		throw new HttpMiddlewareError(
+			'resourceIdNotGiven',
+			{
+				statusCode: constants.HTTP_STATUS_INTERNAL_SERVER_ERROR,
+			}
+		);
+	}
 
 	let existing: unknown | null;
 	try {
@@ -195,7 +237,12 @@ export const handlePatchItem: Middleware = async (req) => {
 };
 
 export const handleCreateItem: Middleware = async (req) => {
-	const { resource, body, backend, basePath } = req;
+	const { resource: resourceRaw, body, backend, basePath } = req;
+
+	if (typeof resourceRaw === 'undefined') {
+		throw new Error('No resource');
+	}
+	const resource = resourceRaw as BackendResource;
 
 	let newId;
 	let params: v.Output<typeof resource.schema>;
@@ -249,7 +296,12 @@ export const handleCreateItem: Middleware = async (req) => {
 }
 
 export const handleEmplaceItem: Middleware =  async (req) => {
-	const { resource, resourceId, basePath, body, backend } = req;
+	const { resource: resourceRaw, resourceId, basePath, body, backend } = req;
+
+	if (typeof resourceRaw === 'undefined') {
+		throw new Error('No resource');
+	}
+	const resource = resourceRaw as BackendResource;
 
 	let newObject: v.Output<typeof resource.schema>;
 	let isCreated: boolean;
diff --git a/src/backend/server.ts b/src/backend/server.ts
index e7df9b4..24d83eb 100644
--- a/src/backend/server.ts
+++ b/src/backend/server.ts
@@ -1,8 +1,7 @@
 import http from 'http';
-import {BackendState} from './common';
-import {Language, Resource, Charset, MediaType, LanguageStatusMessageMap} from '../common';
+import {BackendState, RequestContext} from './common';
+import {Language, Resource, LanguageStatusMessageMap} from '../common';
 import https from 'https';
-import Negotiator from 'negotiator';
 import {constants} from 'http2';
 import {
 	handleCreateItem,
@@ -18,7 +17,9 @@ import {
 } from './core';
 import * as v from 'valibot';
 import {getBody} from './utils';
-import {DataSource} from './data-source';
+import {decorateRequestWithBackend} from './decorators/backend';
+import {decorateRequestWithMethod} from './decorators/method';
+import {decorateRequestWithUrl} from './decorators/url';
 
 export interface Response {
 	statusCode: number;
@@ -83,36 +84,6 @@ export interface CreateServerParams {
 	streamResponses?: boolean;
 }
 
-export interface RequestContext extends http.IncomingMessage {
-	backend?: BackendState;
-
-	host?: string;
-
-	scheme?: string;
-
-	basePath?: string;
-
-	method?: string;
-
-	url?: string;
-
-	rawUrl?: string;
-
-	cn: {
-		language: Language;
-		mediaType: MediaType;
-		charset: Charset;
-	};
-
-	query: URLSearchParams;
-
-	resource: BackendResource;
-
-	resourceId?: string;
-
-	body?: unknown;
-}
-
 export interface Middleware<Req extends RequestContext = RequestContext> {
 	(req: Req): undefined | Response | Promise<undefined | Response>;
 }
@@ -175,73 +146,6 @@ const getAllowedMiddlewares = <T extends v.BaseSchema>(resource?: Resource<T>, m
 	return middlewares;
 };
 
-const adjustRequestForContentNegotiation = (req: RequestContext, res: http.ServerResponse<RequestContext>) => {
-	const negotiator = new Negotiator(req);
-	const availableLanguages = Array.from(req.backend!.app.languages);
-	const availableCharsets = Array.from(req.backend!.app.charsets);
-	const availableMediaTypes = Array.from(req.backend!.app.mediaTypes);
-
-	const languageCandidate = negotiator.language(availableLanguages.map((l) => l.name)) ?? req.backend!.cn.language.name;
-	const charsetCandidate = negotiator.charset(availableCharsets.map((l) => l.name)) ?? req.backend!.cn.charset.name;
-	const mediaTypeCandidate = negotiator.mediaType(availableMediaTypes.map((l) => l.name)) ?? req.backend!.cn.mediaType.name;
-
-	// TODO refactor
-	const currentLanguage = availableLanguages.find((l) => l.name === languageCandidate);
-	if (typeof currentLanguage === 'undefined') {
-		const data = req.backend?.cn.language.bodies.languageNotAcceptable;
-		const responseRaw = req.backend?.cn.mediaType.serialize(data);
-		const response = typeof responseRaw !== 'undefined' ? req.backend?.cn.charset.encode(responseRaw) : undefined;
-		res.writeHead(constants.HTTP_STATUS_NOT_ACCEPTABLE, {
-			'Content-Language': req.backend?.cn.language.name,
-			'Content-Type': [
-				req.backend?.cn.mediaType.name,
-				`charset="${req.backend?.cn.charset.name}"`
-			].join('; '),
-		});
-		res.statusMessage = req.backend?.cn.language.statusMessages.languageNotAcceptable ?? '';
-		res.end(response);
-		return;
-	}
-
-	const currentMediaType = availableMediaTypes.find((l) => l.name === mediaTypeCandidate);
-	if (typeof currentMediaType === 'undefined') {
-		const data = req.backend?.cn.language.bodies.mediaTypeNotAcceptable;
-		const responseRaw = req.backend?.cn.mediaType.serialize(data);
-		const response = typeof responseRaw !== 'undefined' ? req.backend?.cn.charset.encode(responseRaw) : undefined;
-		res.writeHead(constants.HTTP_STATUS_NOT_ACCEPTABLE, {
-			'Content-Language': req.backend?.cn.language.name,
-			'Content-Type': [
-				req.backend?.cn.mediaType.name,
-				`charset="${req.backend?.cn.charset.name}"`
-			].join('; '),
-		});
-		res.statusMessage = req.backend?.cn.language.statusMessages.mediaTypeNotAcceptable ?? '';
-		res.end(response);
-		return;
-	}
-
-	const responseBodyCharset = availableCharsets.find((l) => l.name === charsetCandidate);
-	if (typeof responseBodyCharset === 'undefined') {
-		const data = req.backend!.cn.language.bodies.encodingNotAcceptable;
-		const responseRaw = req.backend!.cn.mediaType.serialize(data);
-		const response = typeof responseRaw !== 'undefined' ? req.backend!.cn.charset.encode(responseRaw) : undefined;
-		res.writeHead(constants.HTTP_STATUS_NOT_ACCEPTABLE, {
-			'Content-Language': req.backend?.cn.language.name,
-			'Content-Type': [
-				req.backend?.cn.mediaType.name,
-				`charset="${req.backend?.cn.charset.name}"`
-			].join('; '),
-		});
-		res.statusMessage = req.backend?.cn.language.statusMessages.encodingNotAcceptable ?? '';
-		res.end(response);
-		return;
-	}
-
-	req.cn.language = currentLanguage;
-	req.cn.mediaType = currentMediaType;
-	req.cn.charset = responseBodyCharset;
-};
-
 export const createServer = (backendState: BackendState, serverParams = {} as CreateServerParams) => {
 	const isHttps = 'key' in serverParams && 'cert' in serverParams;
 
@@ -255,31 +159,32 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 			requestTimeout: serverParams.requestTimeout,
 		});
 
-	server.on('request', async (req: RequestContext, res: http.ServerResponse<RequestContext>) => {
-		req.backend = backendState;
-		req.basePath = serverParams.basePath ?? '';
-		req.host = serverParams.host ?? 'localhost';
-		req.scheme = isHttps ? 'https' : 'http';
-		req.cn = req.backend.cn;
-		req.method = req.method?.trim().toUpperCase() ?? '';
-
-		const theBasePathUrl = req.basePath ?? '';
-		const basePath = new URL(theBasePathUrl, 'http://localhost');
-		const parsedUrl = new URL(`${theBasePathUrl}/${req.url ?? ''}`, 'http://localhost');
-		req.rawUrl = req.url;
-		req.url = req.url?.slice(basePath.pathname.length) ?? '';
-		req.query = parsedUrl.searchParams;
-
-		adjustRequestForContentNegotiation(req, res);
+	const requestDecorators = [
+		decorateRequestWithMethod,
+		decorateRequestWithUrl(serverParams),
+		decorateRequestWithBackend(backendState),
+	];
+
+	const handleRequest = async (reqRaw: RequestContext, res: http.ServerResponse<RequestContext>) => {
+		let req: RequestContext;
+		// TODO custom decorators
+		const effectiveRequestDecorators = requestDecorators;
+		req = await effectiveRequestDecorators.reduce(
+			async (resultRequestPromise, decorator) => {
+				const resultRequest = await resultRequestPromise;
+
+				return await decorator(resultRequest);
+			},
+			Promise.resolve(reqRaw)
+		);
 
 		let middlewareState;
 		if (req.url === '/' || req.url === '') {
 			middlewareState = await handleGetRoot(req);
 		}
 
+		let resource = req.resource as BackendResource | undefined;
 		if (typeof middlewareState === 'undefined') {
-			const [, resourceRouteName, resourceId = ''] = req.url?.split('/') ?? [];
-			const resource = Array.from(req.backend.app.resources).find((r) => r.state!.routeName === resourceRouteName);
 			if (typeof resource === 'undefined') {
 				res.statusCode = constants.HTTP_STATUS_NOT_FOUND;
 				res.statusMessage = req.backend.cn.language.statusMessages.urlNotFound;
@@ -287,12 +192,8 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 				return;
 			}
 
-			req.resource = resource as BackendResource;
-			req.resource.dataSource = req.backend.dataSource(req.resource) as DataSource;
-			req.resourceId = resourceId;
-
 			try {
-				await req.resource.dataSource.initialize();
+				await resource.dataSource.initialize();
 			} catch (cause) {
 				throw new HttpMiddlewareError(
 					'unableToInitializeResourceDataSource',
@@ -321,8 +222,8 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 					}
 
 					if (schema) {
-						const availableSerializers = Array.from(req.backend!.app.mediaTypes);
-						const availableCharsets = Array.from(req.backend!.app.charsets);
+						const availableSerializers = Array.from(req.backend!.app.mediaTypes.values());
+						const availableCharsets = Array.from(req.backend!.app.charsets.values());
 						const contentTypeHeader = req.headers['content-type'] ?? 'application/octet-stream';
 						const fragments = contentTypeHeader.split(';');
 						const mediaType = fragments[0];
@@ -424,7 +325,7 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 					}
 
 					const statusMessageKey = middlewareState.statusMessage ? req.cn.language.statusMessages[middlewareState.statusMessage] : undefined;
-					res.statusMessage = statusMessageKey?.replace(/\$RESOURCE/g, req.resource.state.itemName) ?? '';
+					res.statusMessage = statusMessageKey?.replace(/\$RESOURCE/g, resource!.state.itemName) ?? '';
 					res.writeHead(middlewareState.statusCode, headers);
 					if (typeof encoded !== 'undefined') {
 						res.end(encoded);
@@ -459,7 +360,7 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 				].join('; ');
 
 				const statusMessageKey = finalErr.response.statusMessage ? req.backend.cn.language.statusMessages[finalErr.response.statusMessage] : undefined;
-				res.statusMessage = statusMessageKey?.replace(/\$RESOURCE/g, req.resource.state.itemName) ?? '';
+				res.statusMessage = statusMessageKey?.replace(/\$RESOURCE/g, resource!.state.itemName) ?? '';
 				res.writeHead(finalErr.response.statusCode, headers);
 				if (typeof encoded !== 'undefined') {
 					res.end(encoded);
@@ -471,7 +372,7 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 		}
 
 		if (middlewares.length > 0) {
-			res.statusMessage = req.backend.cn.language.statusMessages.methodNotAllowed.replace(/\$RESOURCE/g, req.resource.state.itemName) ?? '';
+			res.statusMessage = req.backend.cn.language.statusMessages.methodNotAllowed.replace(/\$RESOURCE/g, resource!.state.itemName) ?? '';
 			res.writeHead(constants.HTTP_STATUS_METHOD_NOT_ALLOWED, {
 				Allow: middlewares.map((m) => m[0]).join(', '),
 				'Content-Language': req.backend.cn.language.name,
@@ -481,13 +382,15 @@ export const createServer = (backendState: BackendState, serverParams = {} as Cr
 		}
 
 		// TODO error handler in line with authentication
-		res.statusMessage = req.backend.cn.language.statusMessages.urlNotFound.replace(/\$RESOURCE/g, req.resource.state.itemName) ?? '';
+		res.statusMessage = req.backend.cn.language.statusMessages.urlNotFound.replace(/\$RESOURCE/g, resource!.state.itemName) ?? '';
 		res.writeHead(constants.HTTP_STATUS_NOT_FOUND, {
 			'Content-Language': req.backend.cn.language.name,
 		});
 		res.end();
 		return;
-	});
+	};
+
+	server.on('request', handleRequest);
 
 	return server;
 }
diff --git a/src/backend/utils.ts b/src/backend/utils.ts
index c8036a2..e9e733b 100644
--- a/src/backend/utils.ts
+++ b/src/backend/utils.ts
@@ -3,26 +3,46 @@ import {MediaType, Charset} from '../common';
 import {BaseSchema, parseAsync} from 'valibot';
 
 export const getBody = (
-    req: IncomingMessage,
-    schema: BaseSchema,
-    encodingPair?: Charset,
-    deserializer?: MediaType,
+	req: IncomingMessage,
+	schema: BaseSchema,
+	encodingPair?: Charset,
+	deserializer?: MediaType,
 ) => new Promise((resolve, reject) => {
-    let body = Buffer.from('');
-    req.on('data', (chunk) => {
-        body = Buffer.concat([body, chunk]);
-    });
-    req.on('end', async () => {
-        const bodyStr = encodingPair?.decode(body) ?? body.toString();
-        try {
-            const bodyDeserialized = await parseAsync(
-                schema,
-                deserializer?.deserialize(bodyStr) ?? body,
-                {abortEarly: false},
-            );
-            resolve(bodyDeserialized);
-        } catch (err) {
-            reject(err);
-        }
-    });
+	let body = Buffer.from('');
+	req.on('data', (chunk) => {
+		body = Buffer.concat([body, chunk]);
+	});
+	req.on('end', async () => {
+		const bodyStr = encodingPair?.decode(body) ?? body.toString();
+		try {
+			const bodyDeserialized = await parseAsync(
+				schema,
+				deserializer?.deserialize(bodyStr) ?? body,
+				{abortEarly: false},
+			);
+			resolve(bodyDeserialized);
+		} catch (err) {
+			reject(err);
+		}
+	});
 });
+
+interface LinkMapEntry {
+	url: string;
+	params: Record<string, string>;
+}
+
+export class LinkMap extends Set<LinkMapEntry> {
+	toString() {
+		const entries = Array.from(this.values());
+
+		return entries.map((e) => {
+			const params = Object.entries(e.params);
+
+			return [
+				`<${encodeURIComponent(e.url)}>`,
+				...params.map(([key, value]) => `${encodeURIComponent(key)}="${encodeURIComponent(value)}"`)
+			].join(';')
+		}).join(',');
+	}
+}
diff --git a/src/client/index.ts b/src/client/index.ts
index 5aa8842..73cdd1e 100644
--- a/src/client/index.ts
+++ b/src/client/index.ts
@@ -16,9 +16,9 @@ export interface ClientState {
 }
 
 export interface ClientBuilder {
-	setLanguage(languageCode: ClientState['language']['name']): this;
-	setCharset(charset: ClientState['charset']['name']): this;
-	setMediaType(mediaType: ClientState['mediaType']['name']): this;
+	language(languageCode: ClientState['language']['name']): this;
+	charset(charset: ClientState['charset']['name']): this;
+	mediaTyoe(mediaType: ClientState['mediaType']['name']): this;
 }
 
 export interface CreateClientParams {
@@ -34,18 +34,18 @@ export const createClient = (params: CreateClientParams) => {
 	};
 
 	return {
-		setMediaType(mediaTypeName) {
-			const mediaType = Array.from(clientState.app.mediaTypes).find((l) => l.name === mediaTypeName);
+		mediaTyoe(mediaTypeName) {
+			const mediaType = clientState.app.mediaTypes.get(mediaTypeName);
 			clientState.mediaType = mediaType ?? FALLBACK_MEDIA_TYPE;
 			return this;
 		},
-		setCharset(charsetName) {
-			const charset = Array.from(clientState.app.charsets).find((l) => l.name === charsetName);
+		charset(charsetName) {
+			const charset = clientState.app.charsets.get(charsetName);
 			clientState.charset = charset ?? FALLBACK_CHARSET;
 			return this;
 		},
-		setLanguage(languageCode) {
-			const language = Array.from(clientState.app.languages).find((l) => l.name === languageCode);
+		language(languageCode) {
+			const language = clientState.app.languages.get(languageCode);
 			clientState.language = language ?? FALLBACK_LANGUAGE;
 			return this;
 		}
diff --git a/src/common/app.ts b/src/common/app.ts
index e60ec9d..262b863 100644
--- a/src/common/app.ts
+++ b/src/common/app.ts
@@ -2,15 +2,77 @@ import {Resource} from './resource';
 import {Language} from './language';
 import {MediaType} from './media-type';
 import {Charset} from './charset';
+import * as v from 'valibot';
+import {BackendBuilder, createBackend, CreateBackendParams} from '../backend';
+import {ClientBuilder, createClient, CreateClientParams} from '../client';
+import {FALLBACK_CHARSET, FALLBACK_LANGUAGE, FALLBACK_MEDIA_TYPE} from './index';
+
+type ApplicationMap<T extends { name: string }> = Map<T['name'], T>;
 
 export interface ApplicationState {
 	name: string;
 	resources: Set<Resource<any>>;
-	languages: Set<Language>;
-	mediaTypes: Set<MediaType>;
-	charsets: Set<Charset>;
+	languages: ApplicationMap<Language>;
+	mediaTypes: ApplicationMap<MediaType>;
+	charsets: ApplicationMap<Charset>;
 }
 
 export interface ApplicationParams {
 	name: string;
 }
+
+export interface ApplicationBuilder {
+	mediaType(mediaType: MediaType): this;
+	language(language: Language): this;
+	charset(charset: Charset): this;
+	resource<T extends v.BaseSchema>(resRaw: Resource<T>): this;
+	createBackend(params: Omit<CreateBackendParams, 'app'>): BackendBuilder;
+	createClient(params: Omit<CreateClientParams, 'app'>): ClientBuilder;
+}
+
+export const application = (appParams: ApplicationParams): ApplicationBuilder => {
+	const appState: ApplicationState = {
+		name: appParams.name,
+		resources: new Set<Resource<any>>(),
+		languages: new Map<Language["name"], Language>([
+			[FALLBACK_LANGUAGE.name, FALLBACK_LANGUAGE],
+		]),
+		mediaTypes: new Map<MediaType["name"], MediaType>([
+			[FALLBACK_MEDIA_TYPE.name, FALLBACK_MEDIA_TYPE],
+		]),
+		charsets: new Map<Charset["name"], Charset>([
+			[FALLBACK_CHARSET.name, FALLBACK_CHARSET],
+		]),
+	};
+
+	return {
+		mediaType(mediaType: MediaType) {
+			appState.mediaTypes.set(mediaType.name, mediaType);
+			return this;
+		},
+		charset(charset: Charset) {
+			appState.charsets.set(charset.name, charset);
+			return this;
+		},
+		language(language: Language) {
+			appState.languages.set(language.name, language);
+			return this;
+		},
+		resource<T extends v.BaseSchema>(resRaw: Resource<T>) {
+			appState.resources.add(resRaw);
+			return this;
+		},
+		createBackend(params: Omit<CreateBackendParams, 'app'>) {
+			return createBackend({
+				...params,
+				app: appState
+			});
+		},
+		createClient(params: Omit<CreateClientParams, 'app'>) {
+			return createClient({
+				...params,
+				app: appState
+			});
+		},
+	};
+};
diff --git a/src/common/charset.ts b/src/common/charset.ts
index 32c4cd8..7af75b2 100644
--- a/src/common/charset.ts
+++ b/src/common/charset.ts
@@ -3,3 +3,9 @@ export interface Charset {
 	encode: (str: string) => Buffer;
 	decode: (buf: Buffer) => string;
 }
+
+export const FALLBACK_CHARSET = {
+	encode: (str: string) => Buffer.from(str, 'utf-8'),
+	decode: (buf: Buffer) => buf.toString('utf-8'),
+	name: 'utf-8' as const,
+} satisfies Charset;
diff --git a/src/common/index.ts b/src/common/index.ts
index 53c271f..24ad819 100644
--- a/src/common/index.ts
+++ b/src/common/index.ts
@@ -8,55 +8,8 @@ export * from './media-type';
 export * from './resource';
 export * from './language';
 
-export const FALLBACK_LANGUAGE = {
-	name: 'en' as const,
-	statusMessages: {
-		unableToSerializeResponse: 'Unable To Serialize Response',
-		unableToEncodeResponse: 'Unable To Encode Response',
-		unableToInitializeResourceDataSource: 'Unable To Initialize $RESOURCE Data Source',
-		unableToFetchResourceCollection: 'Unable To Fetch $RESOURCE Collection',
-		unableToFetchResource: 'Unable To Fetch $RESOURCE',
-		unableToDeleteResource: 'Unable To Delete $RESOURCE',
-		languageNotAcceptable: 'Language Not Acceptable',
-		encodingNotAcceptable: 'Encoding Not Acceptable',
-		mediaTypeNotAcceptable: 'Media Type Not Acceptable',
-		methodNotAllowed: 'Method Not Allowed',
-		urlNotFound: 'URL Not Found',
-		badRequest: 'Bad Request',
-		ok: 'OK',
-		resourceCollectionFetched: '$RESOURCE Collection Fetched',
-		resourceFetched: '$RESOURCE Fetched',
-		resourceNotFound: '$RESOURCE Not Found',
-		deleteNonExistingResource: 'Delete Non-Existing $RESOURCE',
-		resourceDeleted: '$RESOURCE Deleted',
-		unableToDeserializeRequest: 'Unable To Deserialize Request',
-		patchNonExistingResource: 'Patch Non-Existing $RESOURCE',
-		unableToPatchResource: 'Unable To Patch $RESOURCE',
-		invalidResourcePatch: 'Invalid $RESOURCE Patch',
-		invalidResource: 'Invalid $RESOURCE',
-		resourcePatched: '$RESOURCE Patched',
-		resourceCreated: '$RESOURCE Created',
-		resourceReplaced: '$RESOURCE Replaced',
-		unableToGenerateIdFromResourceDataSource: 'Unable To Generate ID From $RESOURCE Data Source',
-		unableToEmplaceResource: 'Unable To Emplace $RESOURCE',
-		resourceIdNotGiven: '$RESOURCE ID Not Given',
-		unableToCreateResource: 'Unable To Create $RESOURCE',
-	},
-	bodies: {
-		languageNotAcceptable: [],
-		encodingNotAcceptable: [],
-		mediaTypeNotAcceptable: []
-	},
-} satisfies Language;
-
-export const FALLBACK_CHARSET = {
-	encode: (str: string) => Buffer.from(str, 'utf-8'),
-	decode: (buf: Buffer) => buf.toString('utf-8'),
-	name: 'utf-8' as const,
-} satisfies Charset;
-
-export const FALLBACK_MEDIA_TYPE = {
-	serialize: (obj: unknown) => JSON.stringify(obj),
-	deserialize: (str: string) => JSON.parse(str),
-	name: 'application/json' as const,
-} satisfies MediaType;
+export interface ContentNegotiation {
+	language: Language;
+	mediaType: MediaType;
+	charset: Charset;
+}
diff --git a/src/common/language.ts b/src/common/language.ts
index 8848030..d1c1a1b 100644
--- a/src/common/language.ts
+++ b/src/common/language.ts
@@ -52,3 +52,44 @@ export interface Language {
 	statusMessages: LanguageStatusMessageMap,
 	bodies: LanguageBodyMap
 }
+
+export const FALLBACK_LANGUAGE = {
+	name: 'en' as const,
+	statusMessages: {
+		unableToSerializeResponse: 'Unable To Serialize Response',
+		unableToEncodeResponse: 'Unable To Encode Response',
+		unableToInitializeResourceDataSource: 'Unable To Initialize $RESOURCE Data Source',
+		unableToFetchResourceCollection: 'Unable To Fetch $RESOURCE Collection',
+		unableToFetchResource: 'Unable To Fetch $RESOURCE',
+		unableToDeleteResource: 'Unable To Delete $RESOURCE',
+		languageNotAcceptable: 'Language Not Acceptable',
+		encodingNotAcceptable: 'Encoding Not Acceptable',
+		mediaTypeNotAcceptable: 'Media Type Not Acceptable',
+		methodNotAllowed: 'Method Not Allowed',
+		urlNotFound: 'URL Not Found',
+		badRequest: 'Bad Request',
+		ok: 'OK',
+		resourceCollectionFetched: '$RESOURCE Collection Fetched',
+		resourceFetched: '$RESOURCE Fetched',
+		resourceNotFound: '$RESOURCE Not Found',
+		deleteNonExistingResource: 'Delete Non-Existing $RESOURCE',
+		resourceDeleted: '$RESOURCE Deleted',
+		unableToDeserializeRequest: 'Unable To Deserialize Request',
+		patchNonExistingResource: 'Patch Non-Existing $RESOURCE',
+		unableToPatchResource: 'Unable To Patch $RESOURCE',
+		invalidResourcePatch: 'Invalid $RESOURCE Patch',
+		invalidResource: 'Invalid $RESOURCE',
+		resourcePatched: '$RESOURCE Patched',
+		resourceCreated: '$RESOURCE Created',
+		resourceReplaced: '$RESOURCE Replaced',
+		unableToGenerateIdFromResourceDataSource: 'Unable To Generate ID From $RESOURCE Data Source',
+		unableToEmplaceResource: 'Unable To Emplace $RESOURCE',
+		resourceIdNotGiven: '$RESOURCE ID Not Given',
+		unableToCreateResource: 'Unable To Create $RESOURCE',
+	},
+	bodies: {
+		languageNotAcceptable: [],
+		encodingNotAcceptable: [],
+		mediaTypeNotAcceptable: []
+	},
+} satisfies Language;
diff --git a/src/common/media-type.ts b/src/common/media-type.ts
index a5733ca..b73302a 100644
--- a/src/common/media-type.ts
+++ b/src/common/media-type.ts
@@ -3,3 +3,9 @@ export interface MediaType {
 	serialize: <T>(object: T) => string;
 	deserialize: <T>(s: string) => T;
 }
+
+export const FALLBACK_MEDIA_TYPE = {
+	serialize: (obj: unknown) => JSON.stringify(obj),
+	deserialize: (str: string) => JSON.parse(str),
+	name: 'application/json' as const,
+} satisfies MediaType;
diff --git a/src/common/resource.ts b/src/common/resource.ts
index e45d61b..2ab6a34 100644
--- a/src/common/resource.ts
+++ b/src/common/resource.ts
@@ -147,3 +147,7 @@ export const resource = <
 		},
 	} as Resource<Schema, CurrentName, CurrentRouteName, CurrentIdAttr, IdSchema>;
 };
+
+export type ResourceType<R extends Resource> = v.Output<R['schema']>;
+
+export type ResourceTypeWithId<R extends Resource> = ResourceType<R> & Record<R['state']['idAttr'], v.Output<R['state']['idConfig']['schema']>>;
diff --git a/src/common/validation.ts b/src/common/validation.ts
index abecf2c..1120a62 100644
--- a/src/common/validation.ts
+++ b/src/common/validation.ts
@@ -1,6 +1,5 @@
 import * as v from 'valibot';
 export * from 'valibot';
-import { Resource } from './resource';
 
 export const datelike = () => v.transform(
 	v.union([
@@ -12,7 +11,3 @@ export const datelike = () => v.transform(
 	(value) => new Date(value).toISOString(),
 	v.string([v.isoTimestamp()])
 );
-
-export type ResourceType<R extends Resource> = v.Output<R['schema']>;
-
-export type ResourceTypeWithId<R extends Resource> = ResourceType<R> & Record<R['state']['idAttr'], v.Output<R['state']['idConfig']['schema']>>;
diff --git a/src/index.ts b/src/index.ts
index 4536052..a2c399a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -2,5 +2,3 @@ export * from './common';
 export * as validation from './common/validation';
 
 export * as dataSources from './backend/data-sources';
-
-export * from './app';
diff --git a/test/e2e/default.test.ts b/test/e2e/default.test.ts
index 8955994..1bee371 100644
--- a/test/e2e/default.test.ts
+++ b/test/e2e/default.test.ts
@@ -6,7 +6,6 @@ import {
 	describe,
 	expect,
 	it,
-	test,
 } from 'vitest';
 import {
 	tmpdir
@@ -93,9 +92,9 @@ describe('yasumi', () => {
 			.createBackend({
 				dataSource: (resource) => new dataSources.jsonlFile.DataSource(resource, baseDir),
 			})
-			.throws404OnDeletingNotFound();
+			.throwsErrorOnDeletingNotFound();
 
-		server = backend.createServer({
+		server = backend.createHttpServer({
 			basePath: '/api'
 		});
 
@@ -750,13 +749,4 @@ describe('yasumi', () => {
 			});
 		});
 	});
-
-	// https://github.com/mayajs/maya/blob/main/test/index.test.ts
-	//
-	// peak unit test
-	describe("Contribute to see a unit test", () => {
-		test("should have a unit test", () => {
-			expect("Is this a unit test?").not.toEqual("Yes this is a unit test.");
-		});
-	});
 });