diff --git a/docs/readme.md b/docs/readme.md new file mode 100644 index 00000000..ea55aa82 --- /dev/null +++ b/docs/readme.md @@ -0,0 +1,13 @@ +# API documentation + +- [`journeys(from, to, [opt])`](journeys.md) – get journeys between locations +- [`journeyLeg(ref, lineName, [opt])`](journey-leg.md) – get details for a leg of a journey +- [`departures(station, [opt])`](departures.md) – query the next departures at a station +- [`locations(query, [opt])`](locations.md) – find stations, POIs and addresses +- [`location(id)`](location.md) – get details about a location +- [`nearby(location, [opt])`](nearby.md) – show stations & POIs around +- [`radar(north, west, south, east, [opt])`](radar.md) – find all vehicles currently in a certain area + +## Writing a profile + +Check [the guide](writing-a-profile.md). diff --git a/docs/writing-a-profile.md b/docs/writing-a-profile.md new file mode 100644 index 00000000..1aca3f2e --- /dev/null +++ b/docs/writing-a-profile.md @@ -0,0 +1,166 @@ +# Writing a profile + +**Per endpoint, `hafas-client` has an endpoint-specific customisation called *profile*** which may for example do the following: + +- handle the additional requirements of the endpoint (e.g. authentication), +- extract additional information from the data provided by the endpoint, +- guard against triggering bugs of certain endpoints (e.g. time limits). + +This guide is about writing such a profile. If you just want to use an already supported endpoint, refer to the [API documentation](readme.md) instead. + +*Note*: **If you get stuck, ask for help by [creating an issue](https://github.com/derhuerst/hafas-client/issues/new)!** We want to help people expand the scope of this library. + +## 0. How do the profiles work? + +A profile contains of three things: + +- **mandatory details about the HAFAS endpoint** + - `endpoint`: The protocol, host and path of the endpoint. + - `locale`: The [BCP 47](https://en.wikipedia.org/wiki/IETF_language_tag) [locale](https://en.wikipedia.org/wiki/Locale_(computer_software)) of your endpoint (or the area that your endpoint covers). + - `timezone`: An [IANA-time-zone](https://www.iana.org/time-zones)-compatible [timezone](https://en.wikipedia.org/wiki/Time_zone) of your endpoint. +- **flags indicating that features are supported by the endpoint** – e.g. `journeyRef` +- **methods overriding the [default profile](../lib/default-profile.js)** + +As an example, let's say we have an [Austrian](https://en.wikipedia.org/wiki/Austria) endpoint: + +```js +const myProfile = { + endpoint: 'https://example.org/bin/mgate.exe', + locale: 'de-AT', + timezone: 'Europe/Vienna' +} +``` + +Assuming the endpoint returns all lines names prefixed with `foo `, We can strip them like this: + +```js +// get the default line parser +const createParseLine = require('hafas-client/parse/line') + +const createParseLineWithoutFoo = (profile, operators) => { + const parseLine = createParseLine(profile, operators) + + // wrapper function with additional logic + const parseLineWithoutFoo = (l) => { + const line = parseLine(l) + line.name = line.name.replace(/foo /g, '') + return line + } + return parseLineWithoutFoo +} + +profile.parseLine = createParseLineWithoutFoo +``` + +If you pass this profile into `hafas-client`, the `parseLine` method will override [the default one](../parse/line.js). + +## 1. Setup + +*Note*: There are many ways to find the required values. This way is rather easy and has worked for most of the apps that we've looked at so far. + +1. **Get an iOS or Android device and download the "official" app** for the public transport provider that you want to build a profile for. +2. **Configure a [man-in-the-middle HTTP proxy](https://docs.mitmproxy.org/stable/concepts-howmitmproxyworks/)** like [mitmproxy](https://mitmproxy.org). + - Configure your device to trust the self-signed SSL certificate, [as outlined in the mitmproxy docs](https://docs.mitmproxy.org/stable/concepts-certificates/). + - *Note*: This method does not work if the app uses [public key pinning](https://en.wikipedia.org/wiki/HTTP_Public_Key_Pinning). In this case (the app won't be able to query data), please [create an issue](https://github.com/derhuerst/hafas-client/issues/new), so we can discuss other techniques. +3. **Record requests of the app.** + - [There's a video showing this step](https://stuff.jannisr.de/how-to-record-hafas-requests.mp4). + - Make sure to cover all relevant sections of the app, e.g. "journeys", "departures", "live map". Better record more than less; You will regret not having enough information later on. + - To help others in the future, post the requests (in their entirety!) on GitHub, e.g. in as format like [this](https://gist.github.com/derhuerst/5fa86ed5aec63645e5ae37e23e555886). This will also let us help you if you have any questions. + +## 2. Basic profile + +- **Identify the `endpoint`.** The protocol, host and path of the endpoint, *but not* the query string. + - *Note*: **`hafas-client` for now only supports the interface providing JSON** (generated from XML), which is being used by the corresponding iOS/Android apps. It supports neither the JSONP, nor the XML, nor the HTML interface. If the endpoint does not end in `mgate.exe`, it mostly likely won't work. +- **Identify the `locale`.** Basically guess work; Use the date & time formats as an indicator. +- **Identify the `timezone`.** This may be tricky, a for example [Deutsche Bahn](https://en.wikipedia.org/wiki/Deutsche_Bahn) returns departures for Moscow as `+01:00` instead of `+03:00`. +- **Copy the authentication** and other meta fields, namely `ver`, `ext`, `client` and `lang`. + - You can find these fields in the root of each request JSON. Check [a VBB request](https://gist.github.com/derhuerst/5fa86ed5aec63645e5ae37e23e555886#file-1-http-L13-L22) and [the corresponding VBB profile](https://github.com/derhuerst/hafas-client/blob/6e61097687a37b60d53e767f2711466b80c5142c/p/vbb/index.js#L22-L29) for an example. + - Add a function `transformReqBody(body)` to your profile, which assigns them to `body`. + - Some profiles have a `checksum` parameter (like [here](https://gist.github.com/derhuerst/2a735268bd82a0a6779633f15dceba33#file-journey-details-1-http-L1)) or two `mic` & `mac` parameters (like [here](https://gist.github.com/derhuerst/5fa86ed5aec63645e5ae37e23e555886#file-1-http-L1)). If you see one of them in your requests, jump to [*Appendix A: checksum, mic, mac*](#appendix-a-checksum-mic-mac). Unfortunately, this is necessary to get the profile working. + +## 3. Products + +In `hafas-client`, there's a difference between the `mode` and the `product` field: + +- The `mode` field describes the mode of transport in general. [Standardised by the *Friendly Public Transport Format* `1.0.1`](https://github.com/public-transport/friendly-public-transport-format/blob/1.0.1/spec/readme.md#modes), it is on purpose limited to a very small number of possible values, e.g. `train` or `bus`. +- The value for `product` relates to how a means of transport "works" *in local context*. Example: Even though [*S-Bahn*](https://en.wikipedia.org/wiki/Berlin_S-Bahn) and [*U-Bahn*](https://en.wikipedia.org/wiki/Berlin_U-Bahn) in Berlin are both `train`s, they have different operators, service patterns, stations and look different. Therefore, they are two distinct `product`s `subway` and `suburban`. + +**Specify `product`s that appear in the app** you recorded requests of. For a fictional transit network, this may look like this: + +```js +const products = { + commuterTrain: { + product: 'commuterTrain', + mode: 'train', + bitmask: 1, + name: 'ACME Commuter Rail', + short: 'CR' + }, + metro: { + product: 'metro', + mode: 'train', + bitmask: 2, + name: 'Foo Bar Metro', + short: 'M' + } +} +``` + +Let's break this down: + +- `product`: A sensible, [camelCased](https://en.wikipedia.org/wiki/Camel_case#Variations_and_synonyms), alphanumeric identifier. Use it for the key in the `products` object as well. +- `mode`: A [valid *Friendly Public Transport Format* `1.0.1` mode](https://github.com/public-transport/friendly-public-transport-format/blob/1.0.1/spec/readme.md#modes). +- `bitmask`: HAFAS endpoints work with a [bitmask](https://en.wikipedia.org/wiki/Mask_(computing)#Arguments_to_functions) that toggles the individual products. the value should toggle the appropriate bit(s) in the bitmask (see below). +- `name`: A short, but distinct name for the means of transport, *just precise enough in local context*, and in the local language. In Berlin, `S-Bahn-Schnellzug` would be too much, because everyone knows what `S-Bahn` means. +- `short`: The shortest possible symbol that identifies the product. + +todo: `defaultProducts`, `allProducts`, `bitmasks`, add to profile + +If you want, you can now **verify that the profile works**; We've prepared [a script](https://runkit.com/derhuerst/hafas-client-profile-example) for that. Alternatively, [submit a Pull Request](https://help.github.com/articles/creating-a-pull-request-from-a-fork/) and we will help you out with testing and improvements. + +### Finding the right values for the `bitmask` field + +As shown in [the video](https://stuff.jannisr.de/how-to-record-hafas-requests.mp4), search for a journey and toggle off one product at a time, recording the requests. After extracting the products bitmask ([example](https://gist.github.com/derhuerst/193ef489f8aa50c2343f8bf1f2a22069#file-via-http-L34)) you will end up with values looking like these: + +``` +toggles value binary subtraction bit(s) +all products 31 11111 31 - 0 +all but ACME Commuter Rail 15 01111 31 - 2^4 2^4 +all but Foo Bar Metro 23 10111 31 - 2^3 2^3 +all but product E 30 11001 31 - 2^2 - 2^1 2^2, 2^1 +all but product F 253 11110 31 - 2^1 2^0 +``` + +## 4. Additional info + +We consider these improvements to be *optional*: + +- **Check if the endpoint supports the journey legs call.** + - In the app, check if you can query details for the status of a single journey leg. It should load realtime delays and the current progress. + - If this feature is supported, add `journeyLeg: true` to the profile. +- **Check if the endpoint supports the live map call.** Does the app have a "live map" showing all vehicles within an area? If so, add `radar: true` to the profile. +- **Consider transforming station & line names** into the formats that's most suitable for *local users*. Some examples: + - `M13 (Tram)` -> `M13`. With Berlin context, it is obvious that `M13` is a tram. + - `Berlin Jungfernheide Bhf` -> `Berlin Jungfernheide`. With local context, it's obvious that *Jungfernheide* is a train station. +- **Check if the endpoint has non-obvious limitations** and let use know about these. Examples: + - Some endpoints have a time limit, after which they won't return more departures, but silently discard them. + +--- + +## Appendix A: `checksum`, `mic`, `mac` + +As far as we know, there are three different types of authentication used among HAFAS deployments. + +### unprotected endpoints + +You can just query these, as long as you send a formally correct request. + +### endpoints using the `checksum` query parameter + +`checksum` is a [message authentication code](https://en.wikipedia.org/wiki/Message_authentication_code): `hafas-client` will compute it by [hashing](https://en.wikipedia.org/wiki/Hash_function) the request body and a secret *salt*. **This secret can be read from the config file inside the app bundle.** There is no guide for this yet, so please [open an issue](https://github.com/derhuerst/hafas-client/issues/new) instead. + +### endpoints using the `mic` & `mac` query parameters + +`mic` is a [message integrity code](https://en.wikipedia.org/wiki/Message_authentication_code), the [hash](https://en.wikipedia.org/wiki/Hash_function) of the request body. + +`mac` is a [message authentication code](https://en.wikipedia.org/wiki/Message_authentication_code), the hash of `mic` and a secret *salt*. **This secret can be read from the config file inside the app bundle.** There is no guide for this yet, so please [open an issue](https://github.com/derhuerst/hafas-client/issues/new) instead. diff --git a/lib/default-profile.js b/lib/default-profile.js index cf8493d8..340de25f 100644 --- a/lib/default-profile.js +++ b/lib/default-profile.js @@ -59,7 +59,7 @@ const defaultProfile = { formatRectangle, filters, - journeysNumF: true, // `journeys()` method: support for `numF` field + journeysNumF: true, // `journeys()` method: support for `numF` field? journeyLeg: false, radar: false } diff --git a/readme.md b/readme.md index d627004a..f2f620e8 100644 --- a/readme.md +++ b/readme.md @@ -32,13 +32,7 @@ npm install hafas-client ## API -- [`journeys(from, to, [opt])`](docs/journeys.md) – get journeys between locations -- [`journeyLeg(ref, lineName, [opt])`](docs/journey-leg.md) – get details for a leg of a journey -- [`departures(station, [opt])`](docs/departures.md) – query the next departures at a station -- [`locations(query, [opt])`](docs/locations.md) – find stations, POIs and addresses -- [`location(id)`](docs/location.md) – get details about a location -- [`nearby(location, [opt])`](docs/nearby.md) – show stations & POIs around -- [`radar(north, west, south, east, [opt])`](docs/radar.md) – find all vehicles currently in a certain area +[API documentation](docs/readme.md) ## Usage