db-vendo-client/docs

db-vendo-client documentation

JS API documentation

REST API OpenAPI schema (open in Swagger Editor)

Migrating from an old (v5) hafas-client version

db-vendo-client tries to be as compatible as possible with hafas-client v6. If you were still on v5 or earlier, see the 5 → 6 migration guide of hafas-client.

Throttling requests

There's opt-in support for throttling requests to the endpoint.

import {createClient} from 'db-vendo-client'
import {withThrottling} from 'db-vendo-client/throttle.js'
import {profile as dbProfile} from 'db-vendo-client/p/db/index.js'

const userAgent = 'link-to-your-project-or-email' // adapt this to your project!

// create a throttled HAFAS client with Deutsche Bahn profile
const client = createClient(withThrottling(dbProfile), userAgent)

// Berlin Jungfernheide to München Hbf
await client.journeys('8011167', '8000261', {results: 1})

You can also pass custom values for the nr of requests (limit) per interval into withThrottling:

// 2 requests per second
const throttledDbProfile = withThrottling(dbProfile, 2, 1000)
const client = createClient(throttledDbProfile, userAgent)

Retrying failed requests

There's opt-in support for retrying failed requests to the endpoint.

import {createClient} from 'db-vendo-client'
import {withRetrying} from 'db-vendo-client/retry.js'
import {profile as dbProfile} from 'db-vendo-client/p/db/index.js'

const userAgent = 'link-to-your-project-or-email' // adapt this to your project!

// create a client with Deutsche Bahn profile that will retry on HAFAS errors
const client = createClient(withRetrying(dbProfile), userAgent)

You can pass custom options into withRetrying. They will be passed into retry.

// retry 2 times, after 10 seconds & 30 seconds
const retryingDbProfile = withRetrying(dbProfile, {
	retries: 2,
	minTimeout: 10 * 1000,
	factor: 3
})
const client = createClient(retryingDbProfile, userAgent)

User agent randomization

By default, db-vendo-client does not randomize the client name that you pass into createClient, and sends it as User-Agent as it is. At least DB Navigator always sends the same user agent as well (cf. dbnav profile). You can turn on randomization by setting profile.randomizeUserAgent to false:

const client = createClient({
	...someProfile,
	randomizeUserAgent: true,
}, userAgent)

Logging requests

You can use profile.logRequest and profile.logResponse to process the raw Fetch Request and Response, respectively.

As an example, we can implement a custom logger:

import {createClient} from 'db-vendo-client'
import {profile as dbProfile} from 'db-vendo-client/p/db/index.js'

const userAgent = 'link-to-your-project-or-email' // adapt this to your project!

const logRequest = (ctx, fetchRequest, requestId) => {
	// ctx looks just like with the other profile.* hooks:
	const {dbProfile, opt} = ctx

	console.debug(requestId, fetchRequest.headers, fetchRequest.body + '')
}

const logResponse = (ctx, fetchResponse, body, requestId) => {
	console.debug(requestId, fetchResponse.headers, body + '')
}

// create a client with Deutsche Bahn profile that debug-logs
const client = createClient({
	...dbProfile,
	logRequest,
	logResponse,
}, userAgent)

// logRequest output:
'29d0e3' {
	accept: 'application/json',
	'accept-encoding': 'gzip, br, deflate',
	'content-type': 'application/json',
	connection: 'keep-alive',
	'user-agent': 'hafas842c51-clie842c51nt debug C842c51LI'
} {"lang":"de","svcReqL":[{"cfg":{"polyEnc":"GPA"},"meth":"LocMatch",…
// logResponse output:
'29d0e3' {
	'content-encoding': 'gzip',
	'content-length': '1010',
	'content-type': 'application/json; charset=utf-8',
	date: 'Thu, 06 Oct 2022 12:31:09 GMT',
	server: 'Apache',
	vary: 'User-Agent'
} {"ver":"1.45","lang":"deu","id":"sb42zgck4mxtxm4s","err":"OK","graph"…

The default profile.logRequest console.errors the request body, if you have set $DEBUG to hafas-client. Likewise, profile.logResponse console.errors the response body.

Error handling

Unexpected errors – e.g. due to bugs in db-vendo-client itself – aside, its methods may reject with the following errors:

• Error – A generic error, e.g. if the DB backend returned a HTTP error.
• HafasError – A generic error to signal that something HAFAS-related went wrong, either in the client, or in the HAFAS endpoint.

Each HafasError error has the following properties:

• isHafasError – Always true. Allows you to differente HAFAS-related errors from e.g. network errors.
• code – A string representing the error type for all other error classes, e.g. INVALID_REQUEST for HafasInvalidRequestError. null for plain HafasErrors.
• isCausedByServer – Boolean, telling you if the HAFAS endpoint says that it couldn't process your request because it is unavailable/broken.
• hafasCode – A HAFAS-specific error code, if the HAFAS endpoint returned one; e.g. H890 when no journeys could be found. null otherwise.
• request – The Fetch API Request of the request.
• url – The URL of the request.
• response – The Fetch API Response.

Using db-vendo-client from another language

If you want to use db-vendo-client to access DB APIs but work with non-Node.js environments, you can use it together with hafas-rest-api to create a REST API (see the root readme and the Docker image). Or use hafas-client-rpc to create a JSON-RPC interface that you can send commands to.

General documentation and notes for DB APIs

db-apis.md