Blockchain – Big Topic broken down to pieces

bccloud2

Blockchain is certainly not the latest buzzword any longer, it moved well forward on the Gartner Hype Cycle, passed the peak of inflated expectations and I am sure we will find it in the trough of disillusionment in the soon to be updated 2018 version. It is picked up by various industries looking for use-cases and applications. Unfortunately we are looking at Blockchain fatigue already, as there is much hype but little visible implementations outside the cryptocurrency space. I prefer projects that implement blockchain as the right tool for a particular problem over the “let’s see which business case we can throw blockchain at” approach.

In the aviation (airport) space I believe Blockchain has its appliance, but as previously stated I wont attempt to build an AODB with Blockchain as “database” for milestones just for the sake of integrating this technology. For some scenarios you certainly need immutability of data, but we can implement this with the means of other immutable data storage. It is also no point implementing a blockchain into a corporate network infrastructure with few nodes under the control of one entity, this does not fulfill the promise of distributed ledger and trust. A few use-cases that I see, usually involving multiple business parties:

  • Baggage tracking from end-to-end (goes well with IATA 753 effective since June 1st)
  • Service and contract management, billing (eg. groundhandler-airline)
  • Aircraft spare parts management (here the track of provenance have a huge impact)

Trying to understand blockchain can be overwhelming, ranging from Satoshi Nakamoto’s original whitepaper to a endless number of books, talks, websites.
One approach to understand the technology is to break it down into smaller pieces that are implementing proven existing technology or algorithms and understand how they come together eventually forming the much more complex blockchain.

I wont attempt to explain blockchain here, this is redundant, plenty of knowledgeable people have written books and articles you can refer to, but split it into some basic easy digestible portions, some coding included. Before attempting to code against real blockchain implementations, like Ethereum or Hyperledger, I will implement the most basic and simple blockchain first.

1. Hash

The most essential element of blockchain is a hash, a digital signature. A hash is a one way encryption,  once something is hashed there is no way to reverse the process and reveal the original text (decrypt it). Using the SHA (Secure Hash Algorithm), the most popular algorithm with its variants of 256, 384 and 512 bit, defined by NIST, we can convert a text (data) of any length to a 256 bit representation (for SHA256) which is represented by a 64 byte hex string. There is a number of libraries implementing the algorithm, below is the Apache DigestUtils version.

	private void testSHA(){

		String sha256hex = DigestUtils.sha256Hex("Jim Smith");
		System.out.println("\n1 SHA256: " + sha256hex);

		String sha256hex2 = DigestUtils.sha256Hex("jim smith");
		System.out.println("\n2 SHA256: " + sha256hex2);

		String sha256hex3 = DigestUtils.sha256Hex("jim smith and the lazy brown fox");
		System.out.println("\n3 SHA256: " + sha256hex3);

		String sha384hex = DigestUtils.sha384Hex("Jim Smith");
		System.out.println("\n4 SHA384: " + sha384hex);

		String sha512hex = DigestUtils.sha512Hex("Jim Smith");
		System.out.println("\n5 SHA512: " + sha512hex);
	}

resulting in

1 SHA256: 65742910cc03889474f1ee2c8f321a105603d0ae2f91070ffd95b35f8da88261
2 SHA256: bfae13266154ec3c4de5c09cf14358305e44f48d2156953723ebbb184a724499
3 SHA256: e5a4a1b8bd88eb7cf8bff9ee5dd235f87ef996262d4d0213c1387f6141ab9574
4 SHA384: c6e76ad773905c1eedb6a0bd9c0b1602a56928d1ce95d70190cd908797466b948dd342aa69dd0343251afece2e48bfc2
5 SHA512: f813c3d9deb66d4999f6839acc60eb6e2fff6a84266c02e0d4b183f5e56d9674c70b0b136f9e1388673cefbc9278f583e3a4c9803ef0c49f9af28aca60dae5ac

Important to notice:
– Change of one character in the original text produces a complete new hash.
– Independent from the length of the original text the hash has the same length.

2. Chained blocks

As the wording implies, there are blocks of information that are linked together. Sounds like a linked list, where every list entry is pointing to the next information. The chained blocks are linked differently, every block points to the hashed previous block.

For illustration I choose a typical baggage journey (simplified).

blockchain

A bag passes different key touchpoints and changes its custody a few times between the various parties during the handling. Every time there is a new milestone event we record it, eg. bag scanned by groundhandler at the chute at what time, and include the hash of the previous milestone. This way the lifecycle from bag drop at departure to bag delivery at destination is recorded in an immutable way and cannot be changed afterwards.

Pitfall: The bag journey is recorded in an immutable way, but the blockchain cannot verify or confirm the milestone actually happened. This falls into the responsibility of the overall design and service orchestration.

Let’s build a very simple application implementing the above blockchain for baggage handling.

A java class BagTransaction representing the bag attributes inclusive timestamp and the custody transfer.

package blockchaindemo;

import java.time.Instant;

import org.apache.commons.codec.digest.DigestUtils;

public class BagTransaction {

	private String bagTag;
	private String timeStamp;
	private String pnr;
	private String transferFrom;
	private String transferTo;

	private long blockID;
	private String blockHash;
	private String previousBlockHash;

	public BagTransaction(String bagTag, String pnr, String transferFrom, String transferTo, long blockID,
			String previousBlockHash) {
		super();
		this.bagTag = bagTag;
		this.timeStamp = Instant.now().toString();
		this.pnr = pnr;
		this.transferFrom = transferFrom;
		this.transferTo = transferTo;
		this.blockID = blockID;
		this.previousBlockHash = previousBlockHash;

		this.blockHash = createCurrentHash();
	}

	public String getHash() {
		return this.blockHash;
	}

	@Override
	public String toString() {
		return "BagTransaction [bagTag=" + bagTag + ", timeStamp=" + timeStamp + ", pnr=" + pnr + ", transferFrom="
				+ transferFrom + ", transferTo=" + transferTo + ", blockID=" + blockID + ", blockHash=" + blockHash
				+ ", previousBlockHash=" + previousBlockHash + "]";
	}

	private String createCurrentHash() {
		String returnHash = "";

		returnHash = DigestUtils.sha256Hex(
				this.bagTag + this.timeStamp + this.pnr + this.transferFrom + this.transferTo + this.previousBlockHash);

		return returnHash;
	}

}

Take note of the hashing method that includes all fields inclusive of the previous hash.

A java class BagDemoApp using the transaction class.

package blockchaindemo;

import java.util.Random;

public class BagDemoApp {

	public static void main(String[] args) {

		BagDemoApp demoApp = new BagDemoApp();
		demoApp.demo1();

	}

	public void demo1() {

		String myBagTag = randomBagTagID();
		String myPNR = randomPNR();

		String currentBagBlockHash = "";

		// Print Bag Tag (Genesis Block)
		BagTransaction bagTransaction1 = new BagTransaction(myBagTag, myPNR, Entity.NIL.name(), Entity.PAX.name(), 1,
				"0");
		currentBagBlockHash = bagTransaction1.getHash();

		// Bag Drop
		BagTransaction bagTransaction2 = new BagTransaction(myBagTag, myPNR, Entity.PAX.name(), Entity.AIRP.name(), 2,
				currentBagBlockHash);
		currentBagBlockHash = bagTransaction2.getHash();

		// Bag SEC Scan
		BagTransaction bagTransaction3 = new BagTransaction(myBagTag, myPNR, Entity.AIRP.name(), Entity.SEC.name(), 3,
				currentBagBlockHash);
		currentBagBlockHash = bagTransaction3.getHash();

		// Display Transactions
		System.out.println(bagTransaction1);
		System.out.println(bagTransaction2);
		System.out.println(bagTransaction3);

	}

	// HELPER METHODS --------------------------------------------

	public String randomPNR() {
		final String alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
		final int N = alphabet.length();

		Random r = new Random();
		StringBuffer tempPNR = new StringBuffer();

		for (int i = 0; i < 6; i++) {
			char nxtChar = alphabet.charAt(r.nextInt(N));
			while ((i == 0) && (Character.isDigit(nxtChar)))
				nxtChar = alphabet.charAt(r.nextInt(N));
			tempPNR.append(nxtChar);
		}
		return tempPNR.toString();
	}

	public String randomBagTagID() {
		String tempBagTag = "";

		long range = 9999999999L;
		Random r = new Random();
		long number = (long) (r.nextDouble() * range);

		tempBagTag = String.format("%010d", number);
		return tempBagTag;
	}

	public enum Entity {

		PAX {
			@Override
			public String toString() {
				return "Passenger";
			}
		},
		GH {
			@Override
			public String toString() {
				return "Groundhandler";
			}
		},
		AIRL {
			@Override
			public String toString() {
				return "Airline";
			}
		},
		AIRP {
			@Override
			public String toString() {
				return "Airport";
			}
		},
		SEC {
			@Override
			public String toString() {
				return "Security";
			}
		},
		NIL {
			@Override
			public String toString() {
				return "nil";
			}
		}

	}

}

Executing the application

BagTransaction [bagTag=1691462171, timeStamp=2018-08-12T08:02:25.745Z, pnr=ICSEAH, transferFrom=NIL, transferTo=PAX, blockID=1, blockHash=3ff736f7158d224db6e2e8ba25f3d50321903cd911646576f442a60f8c5872ed, previousBlockHash=0]
BagTransaction [bagTag=1691462171, timeStamp=2018-08-12T08:02:25.808Z, pnr=ICSEAH, transferFrom=PAX, transferTo=AIRP, blockID=2, blockHash=88dd4a2be3bc90ebce71635bedd6bcb63b326044e4bd49634a859a86458de243, previousBlockHash=3ff736f7158d224db6e2e8ba25f3d50321903cd911646576f442a60f8c5872ed]
BagTransaction [bagTag=1691462171, timeStamp=2018-08-12T08:02:25.808Z, pnr=ICSEAH, transferFrom=AIRP, transferTo=SEC, blockID=3, blockHash=ea7767ddb2dd7c2bfed4d3a038b9249e43df15a0396ff71da717783db9fee3c4, previousBlockHash=88dd4a2be3bc90ebce71635bedd6bcb63b326044e4bd49634a859a86458de243]

Please note, this is the most simple implementation of a blockchain for illustration purpose, it still misses a lot of features to pass to production, eg. mining, proof-of-work, etc.

In a second part might spin this a bit further. Stay tuned.

 

Disclaimer: This discussion, datamodel and sourcecode or application is for study purpose solely. It does not reflect or replicate any existing commercial product.

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Design an AODB for a mobile server platform ?

5997469039_0736c09bd7_b

Mobile clients for AODB (Airport Operational Database) products running on tablets and mobile phones are a standard offering today. These clients allow convenient access to operational data while being on the floor, at the tarmac etc. I remember my first mobile AODB project more than 10 years back operating on a proprietary Nokia platform. Today it is not a major technology challenge any longer with current mobile hardware, platforms and libraries available at hand.
The remaining questions are often: How to design the app for a small screen landscape available, but facing a big amount of operational data ? What features does a mobile user really need, what info is key to be displayed, what updates need to be entered while being mobile ? How to simplify user interaction ? How to handle the data synchronization when being offline, aka in areas without wireless or mobile coverage ? Build a hybrid app or go native ?

I believe we at an interim stage of mobile computing at this moment, while current mobile apps replicate desktop applications (screen, mouse, keyboard) with the means of mobile interaction (touch, swipe, pinch,..), we still sorting out the next evolutionary step. Mobile computing on mobile phones, handhelds, wearable computing, smart watches, AR glasses etc. etc. Ruggedized devices became standard while smart watches are still not taking off.
The next (or this !) generation of mobile apps should make use of the mobile characteristics and sensors built-into most mobile hardware. A few ideas: Location awareness, the app should know where the user is at the apron and already open the relevant flight and information or support manual milestone recording. Depending on the users role, tasks should be highlighted to him/her, eg. a service manager that is closest to a problem location should be notified. NFC reader, barcode scanner and AR glasses should assist the user to identify cargo, baggage, vehicles, etc.

Putting aside this considerations, I like to engage in a little thought-experiment:
Can we run an AODB, aka the server, on a mobile phone (Android) ? (without using any external core service, eg. data storage or rule engine etc. Standalone only, allowing other clients to connect, simple interfaces only)
Lets play with pro and con argument and check on the feasibility.

Hardware

This topic triggered the discussion when comparing current hardware in mobile phones with server hardware 20+ years ago when the first generation of AODB products appeared. A standard server of that time was something like a Sun Ultra II with dual 200 MHz processors, 256 to 512 MB of RAM and maybe a SCSI rack with 3x 10GB diskspace, running Solaris, 32bit. Easily priced at 20.000 to 50.000U$ depending on configuration plus various commercial licenses.
Lets look at a current mobile phone like the Huawei P20, Octa-core (4×2.4 GHz Cortex-A73 & 4×1.8 GHz Cortex-A53) with 4GB of memory and 128GB of SD card space, coming at 600U$.

Operating System

Android is obviously not a server OS, it does not give us control over settings that we can rely on under Linux. We cant assign memory and priority, it is actually the OS that controls apps and services, going to the extend of terminating unused apps and similar. The only way of having a persistent app running is as service. Apps are living in sealed sandboxes, only a rooted device would give us more control.

Solution architecture

We cant build a multi-tier solution with the classical database, business logic and frontend layers. Android enforces monolithic applications, the only way to escape this is by building services and relying on ICP (AIDL, Intents, Binder). Anonymous shared memory is only available in Android 8+.

Database and Application/Web-Server

App-server ? Easy to answer, it does not exist. Maybe simple http server is possible.
Database ? Only a few solutions at hand, either the built-in SQLite, not really a DB known for performance, or some alternatives, mostly key-pair and relational DB’s and some NoSQL DB (Comparison chart here).

Scalability

We cant scale vertical, no adding of CPU’s or memory possible. Horizontal scaling would not be easy, unless we deploy more mobile phones to outsource certain services, but implementing a load-balancer would not be possible.

Availability

In terms of network connection we are limited to 1 wireless or (!) 1 mobile connection at a time, no redundancy. Power-failure is less of a problem, we have built-in battery that could last at least 1 hour under heavy usage. Android as OS is quite stable, it can run for prolonged periods, though it is uncertain if services running permanently with load create a problem.

Integration

Integration of interfaces with other systems is a bit more challenging. Though it is no problem to consume webservices, download from ftp server or receive emails as part of interface client, we will have a hard time to provide an interface, eg. to offer a webservice. There is no ESB running on Android.

Conclusion

It is definitely possible to run a very lightweight AODB solution without lots of fancy bells and whistles on a mobile phone, ideally to act both as server and client integrated into one solution (app). All under the premise to limit our requirements to a basic set of features like managing schedule, daily operations, milestone handling, simple resource management.
The longer I review this idea the more arguments I collect against this use-case, the platform is too limited to allow scaling, does not provide real server features and will not be able to run heavy services like rule engines, ESB, etc.
Maybe feasible for small scale operations at an airport with few commercial flights a day, some GA, few users and utilizing third party services in the cloud for billing, ESB, etc.

I suggest we rather invest our thinktank energy in building a serverless AODB by using orchestrated microservices and use the mobile platform solely as client.

Image: Creative Commons, National Library of Ireland on The Commons, “St. Albert at Dublin Airport, circa 1950”

Aviation API – Airline and Airport Webservices

The term API (Application programming interface) is not new, basically a defined access to a set of methods, subroutines and data-types made available by one component/service to be used/consumed by another component or application. You can think of API as the car manual and the library being the engine under the hood.

Since the early days of tinkering with the Windows DLL hell more than 20 years have passed, we have better tools and standards by now. In the space of native apps for Windows, Android and iOS we still work with libraries and SDK’s (still can be challenging when resolving dependencies and deployment).
In the world of web applications today we look mostly at RESTful Webservices responding in JSON or XML, a rather straight forward implementation, the only complexity depends on the authorization mode or the mapping of attributes. A lot of websites, portals, services or products expose their WS for usage by third parties, from Salesforce, Ebay, Amazon to Twitter and infinite more. While these mentioned samples operate independently or work as standalone services there is not much need for standardization of the payload, aka the structure of attributes, naming conventions etc. For others business domain there is a need of standardization of such, despite the availability of AIDX, AIDM and a few more data exchange models, there is no standard widely used in the (public) WS space in aviation.
I have to highlight in ACI ACRIS a Semantic Model is being actively developed and the Open API Shop exists as project as well.

I researched what webservices are currently offered to the public by airports and airlines, excluding the API’s of system vendors and travel platforms.
So far I found these webservices (last update 2018-07-06):

Airline

International Airline Group
British Airways, Iberia, Avios
https://developer.iairgroup.com/
Lufthansa https://developer.lufthansa.com/
Airfrance, KLM https://developer.airfranceklm.com/
Alaska Air
https://developer.alaskaair.com/
Transavia https://developer.transavia.com/
FlyDubai https://developer.flydubai.com/
Virgin Australia
https://developer.virginaustralia.com/
Ryanair https://developer.ryanair.com/
Turkish Airlines
https://developer.turkishairlines.com

Airports

Schiphol Airport
https://developer.schiphol.nl/
San Francisco Airport
https://www.flysfo.com/api
Frankfurt Airport
https://developer.fraport.de/
Svedavia Airports
https://apideveloper.swedavia.se/

Others

FAA US
https://app.swaggerhub.com/apis/FAA/ASWS/1.1.0
Flightaware
http://flightaware.com/commercial/flightxml

The usage terms and price models vary but basically all give some kind of developer access to evaluate the services and data at no cost.

To compare a few of the services using a flight status related call, omitting the authentication. The lack of standard, putting aside JSON response format and date format, is quite obvious. It might not be relevant in the space of individual apps to have the same response format, but if you want to combine data from various sources you have to handle the formats separately. Even the request format with the query parameter differs.

British Airways

https://api.ba.com/rest-v1/v1/flights;departureLocation=FRA;startTime=06:00;endTime=11:00

ba

Swedavia Airports

https://api.swedavia.se/flightinfo/v2/query?filter=airport eq ‘ARN’ and scheduled eq ‘180713’ and flightType eq ‘A’ and flightId eq ‘DY4572’

IMG122

Lufthansa

https://api.lufthansa.com/v1/operations/flightstatus/LH778/2018-07-13

IMG123

I also tried with RyanAir (still waiting for approval to get api key), Turkish Airlines (no flight status API), Schiphol (no webservice test available on the website).

Image: Creative Commons, Robert Yarnall Richie Photograph Collection, “Models with Oldsmobile Automobile, Lockheed 10B Electra, Delta Air Lines, 1940”

Airport Simulator on Android

Dont rise your expectation to high on this topic for now. Before jumping into the serious use cases for airport process and environment simulations, as well the gamification of enterprise environments, I will review some simulator apps available on Android and PC in a rather humorous way.

I just love simulators, it is amazing to see how current 3D and physic engines running on today’s powerful and affordable hardware can execute real-time simulations that were only possible in well equipped research labs 2 decades ago. I am experimenting with various 3D engines like Unity and CryEngine, both freely available as personal or educational version or for indie games.

OK, lets have a look at simulators available for the Android mobile platform. If you search for the term simulator you will get thousands of apps, and there is a simulator for almost everything and anything you never heard of before, though the majority is plain crap and only exists because Unity makes it so easy to create a game by clicking-together some assets and adjusting some properties, almost without the need to code. Most of them are just badly made and often only serve the purpose to bombard you with ads once installed or running.

We find 100’s of car, truck, train simulation apps, plus dozens of somewhat strange apps to simulate dogs, cats, dinosaurs, Fishing, Fork Lifts, shark attacks, Miami Crime, swimming trains, flying boats and tuk tuk’s and endless more objects.

Finetuning our search towards the term airport (vehicle) simulator we still reveal dozens of results. Here we have a selection of flying, airport construction and all kind of driving around the airport tasks. The majority is made with Unity engine and the free assets, one reason why most of these apps display the same assets like cars, trucks and planes.

AirportSimulator_13

Selection of simulator apps

Most of them have in common: Well rendered icons and preview images in the play store to catch your interest, generous with requested permissions and truckloads of ads.
Surprisingly all of them have downloads of well beyond 100.000 ! Guess we don’t know the uninstall-rate though, but if you look at the user comments you know.

AirportSimulator_30

Permissions galore inclusive to run as service during startup, snooping accounts and location, downloading files.

Here some actual screenshots of the often weird gameplay or scenery I found.

AirportSimulator_9

Factory Airport ? Not much room to maneuver. Where are taxiways, positions, gates ? But 3 Towers !

AirportSimulator_28

If your are short of pushbacks, go for a regular truck as fallback !

AirportSimulator_29

Personal pickup service for MIB passengers in Area 51 ?

AirportSimulator_3

Taking off from a construction site with speed limits and stop signs. Here the tower also a bit too close to the runway maybe.

AirportSimulator_19

Disembarking Zombie passengers walking down from the service staircase to the waiting Cobus(?)

AirportSimulator_11

Driving a heavy duty tow truck between the planes parked on the grass. Nothing else to do. Maybe one of these defunc airline desert airplane parking grounds ?

AirportSimulator_25

This time we drive an airport security car in a totally static airport. Someone forgot to add tarmac lines here ?

AirportSimulator_7

This plane looks like the airport fire brigade drill setup. But in this app all planes look like this model (front part is mocking a war train from the 1930’s). Not so standard cargo handling either.

AirportSimulator_32

Interesting, floating mobile stairs supported by a RC wreck. Walls at the tarmac ?

AirportSimulator_33

Winter wonderland. Random assets like palms, lamp posts and others stuff thrown at the scene. Big Christmas trees at the end of the runway… Walls again.

AirportSimulator_34

Gives the term Greenfield Airport a more genuine meaning ! Randomly appearing zombie passengers again. Leave the boarding gate through the window ?

AirportSimulator_35

Oh yes, that is a smart way to avoid a potential IP conflict with a famous airline ! Bonus: Floating bridge and you fly with a 1:5 scale plane ?

AirportSimulator_36

Smart parking, what to say ? Smart as in stacking cars on the back of a truck or smart as in placing this thing at the end of the runway ?

Conclusion: Dont expect anything when downloading these simulators, other than uninstalling it again and potentially being spied or bombarded with ads. None of the app I tried even remotely comes close to any real operations. These are games – confirmed – nothing else.

In the next blog entry we will look at Simulator Software available for Windows PC’s.

Stay tuned.

 

Build an Async Restful Webservice Client in Android in 5min and read BA flight data

In an earlier blog post we build a Restful WS running on Wildfly, now lets build the client part for Android. Thanks to the okHttp, an Apache 2.0 licensed java and Android library, this becomes a very easy challenge. In a mobile application we definitely want to implement a async call as we cannot rely on the response time being fast and a blocked application is not a pleasant user experience.

To make it a bit more interesting for the aviation context of my blog, we will take a real airline webservice and show operational flight data  in the second step.

Step 1: The Basic Webservice Client

Lets get started, I skip the project creation steps, you can create any basic empty Android application.

Add the dependency

..
dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:24.1.1'
    testCompile 'junit:junit:4.12'
compile 'com.squareup.okhttp3:okhttp:3.9.0'
}

Implement the WS call with a call back

(we use the serverside we implemented previously with 2 parameters)

    private void testOKHttp() {

        OkHttpClient httpClient = new OkHttpClient();
        String callURL = "http://www.yourservername.com/DemoRandomizer/randomservice/random/numberrange";

        HttpUrl.Builder urlBuilder = HttpUrl.parse(callURL).newBuilder();
        urlBuilder.addQueryParameter("min", "10");
        urlBuilder.addQueryParameter("max", "100");
        callURL = urlBuilder.build().toString();

        Request request = new Request.Builder().url(callURL).build();
        httpClient.newCall(request).enqueue(new Callback() {

            @Override
            public void onFailure(Call call, IOException e) {
                System.out.println(e.getMessage());
            }
            @Override
            public void onResponse(Call call, Response response) throws IOException {
                ResponseBody responseBody = response.body();
                if (!response.isSuccessful()) {
                    throw new IOException("Error response " + response);
                } else {
                    String str = new String(responseBody.bytes());
                    System.out.println(str);
                }
            }
        });

    }

It is good practice to block UI features (buttons, etc) that rely on the WS response or use a progress dialogm which is in some way blocking but the user is aware of the ongoing request.

 

// Set progress dialog befor the call
        prgDialog = new ProgressDialog(this);
        prgDialog.setMessage("Please wait...");
        prgDialog.setCancelable(false);
        prgDialog.show();

// remove the call after successful response or error
        prgDialog.dismiss();

Step 2: Client to read British Airways data

device-2017-10-14-092750

Lets gets our hand on some real data and tap into one of the open API’s offered by some airlines and airports, though I have to say that only very few players offer their data for public consumption. I will list some API’s in another blog post. Today we will make use of the British Airways API running on the Tibco Mashery platform. BA offers a variety of flight related data and we look at the flight status webservice. We can use the service for evaluation purpose up to 1 call a second and 500 calls a day, good enough to play with their data. We will collect the status of outbound flights from LHR (London Heathrow) for +/- 2hours. Before jumping into sourcode I recommend using a tool to test the webservice manually, eg. the Chrome Browser Rest Web Service Client extension.

2017-10-14 09_24_58-Rest Web Service Client

Using Chrome extension to get data from BA Webservice

One of the challenges, every API offering might support JSON and XML as WS GET, but the attributes and response format is different, we have to implement for every airline or airport we want to use the data, or add some kind of mapping layer.

For the BA service we have to change to call from step 1 above because we need to add the API key that you apply for under your account, also the parameter are not handled as query parameters but as parameter matrix.

The first code block only lists the relevant parts and the complete code block below adds some extras to handle GUI access, exception handling and the parameter creation.

 private void testWSCall() {

        OkHttpClient httpClient = new OkHttpClient();
        String callURL = "https://api.ba.com/rest-v1/v1/flights;departureLocation=LHR;startTime=12:00;endTime=18:00;";

        Request request = new Request.Builder().url(callURL)
                .addHeader("Content-Type", "application/json")
                .addHeader("client-key", "YOUR_KEY_HERE")
                .build();

        httpClient.newCall(request).enqueue(new Callback() {

            @Override
            public void onFailure(Call call, IOException e) {
                System.out.println("WS Call failed (1):" + e.getMessage());
            }

            @Override
            public void onResponse(Call call, Response response) {
                ResponseBody responseBody = response.body();
                if (!response.isSuccessful()) {
                    final String errRep = "WS Call failed (2):" + response.toString();
		    System.out.println(errRep);
                } else {
                    String str = new String(responseBody.bytes());
		    System.out.println(str);
                }
            }
        });

}
 private void testOKHttp() {

        OkHttpClient httpClient = new OkHttpClient();

        DateFormat dateFormatShort = new SimpleDateFormat("HH:mm");
        Date date = new Date();
        long timeNow = date.getTime();
        long timePlus = timeNow + 120 * 60 * 1000;
        long timeMinus = timeNow - 120 * 60 * 1000;
        Date datePlus = new Date(timePlus);
        Date dateMinus = new Date(timeMinus);

        String callURL = "https://api.ba.com/rest-v1/v1/flights;departureLocation=LHR;startTime=" + dateFormatShort.format(dateMinus) +";endTime=" + dateFormatShort.format(datePlus) +";";
        System.out.println(callURL);

        Request request = new Request.Builder().url(callURL)
                .addHeader("Content-Type", "application/json")
                .addHeader("client-key", "YOUR_KEY_HERE<span 				data-mce-type="bookmark" 				id="mce_SELREST_start" 				data-mce-style="overflow:hidden;line-height:0" 				style="overflow:hidden;line-height:0" 			></span>")
                .build();

        httpClient.newCall(request).enqueue(new Callback() {

            @Override
            public void onFailure(Call call, IOException e) {
                System.out.println("WS Call failed (1):" + e.getMessage());
                prgDialog.dismiss();
            }

            @Override
            public void onResponse(Call call, Response response) {
                ResponseBody responseBody = response.body();
                if (!response.isSuccessful()) {
                    final String errRep = "WS Call failed (2):" + response.toString();
                    mHandler.post(new Runnable() {
                        @Override
                        public void run() {
                            editTextResult.setText(errRep);
                        }
                    });
                    prgDialog.dismiss();
                } else {
                    try {
                        System.out.println("Response " + response.toString());
                        String str = new String(responseBody.bytes());
                        prgDialog.dismiss();

                        final JSONObject svcresponse = new JSONObject(str);
                        int spacesToIndentEachLevel = 2;
                        final String prettyPrintString = svcresponse.toString(spacesToIndentEachLevel);
                        mHandler.post(new Runnable() {
                            @Override
                            public void run() {
                                editTextResult.setText(prettyPrintString);
                            }
                        });

                    } catch (Exception e) {
                        e.printStackTrace();
                        final String errStr = e.getMessage();
                        mHandler.post(new Runnable() {
                            @Override
                            public void run() {
                                editTextResult.setText(errStr);
                            }
                        });
                        prgDialog.dismiss();
                    }
                }
            }
        });

    }

Read My Boarding Pass App

In the previous blog post I discussed the underlying standards of the BCBP (Bar Coded Boarding Pass) following IATA Reso 792. Today I will built an Android mobile app that scans the PDF417 barcode and shows the raw content as well the decoded fields.

The are 3 main challenges for building the app, scanning/reading the barcode and decoding the text to individual attributes and as last, not to use any internet connection (to assure the user the users privacy and avoid any potential identity theft discussions)

As we build a native Android app we can rely on third party libraries to scan and decode barcodes. There is a number of commercial libraries in the market, but as I build a free app I will use the zxing-android-embedded library, which is a port of the ZXing (“Zebra Crossing”) barcode scanning library for Android with added embedding features, ZXing only provides the decoding logic. Both are licensed under Apache 2.0, ZXing can decode all the common types, such as EAN-8, EAN-13, UPC, ITF, PDF417, QRCode, Aztec, Data Matrix and a few more.

Integration Barcode Library ZXing

With the library the integration becomes as simple as adding a few lines of code only.

Add the dependency to the build gradle file

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.3.1'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'

    compile 'com.journeyapps:zxing-android-embedded:3.5.0'
}

Trigger the scan and read the result

public void scanCode(View view){
        new IntentIntegrator(this).initiateScan();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        if(result != null) {
            if(result.getContents() == null) {
                System.out.println("Scan failed or cancelled.");
            } else {
                System.out.println(result.getContents());
            }
        } else {
            super.onActivityResult(requestCode, resultCode, data);
        }
    }

For now, the app (“ReadMyBoP – Read My Boarding Pass”) does nothing but scan the barcode, identify if it is a valid boarding pass barcode, display the raw content and makes the content more human-readable. You can download from Google Playstore. It works with Android 4.1 and above.
There is one extra feature for now, it decodes the IATA fare codes (First, business, economy classes and the various discounted codes, it follows IATA Reso 728 if you want to look for the complete codeset.

Decoding the Raw Text

Given the fact, this is a fixed-length field text, it is no big deal to split the relevant info by substring’ing it using the decoding table that we started in the previous post. As basic validation we can use the mandatory “M” on position 1 and a length of not less than 59 characters (mandatory fields).

# Element Mandatory Size Sample Remark
1 Format Code M 1 M Always “M”
2 Number of legs encoded M 1
3 Passenger Name M 20
4 Electronic Ticket Indicator M 2 E
5 Operating carrier PNR Code M 7
6 Origin IATA Code M 3 FRA Airport Code
7 Destination IATA Code M 3 SIN Airport Code
8 Operating carrier IATA Code M 3 LH Airline
9 Flight Number M 5 3456
10 Date of Flight M 3 280 Julian Date
11 Compartment Code M 1 B First, Business, Economy
12 Seat Number M 4 25A
13 Check-in Sequence Number M 5 0012
14 Passenger Status M 1 00
15 Size of optional Block M 2 5D hexadecimal
16 Start Version Number 1 > Always “>”
17 Version Number 1 5
18 Field Size of follow ing structured message 2
19 Passenger Description 1
20 Source of check-in 1
21 Source of Boarding Pass Issuance 1
22 Date of Issue of Boarding Pass (Julian Date) 4
23 Document Type 1
24 Airline Designator of boarding pass issuer 3
25 Baggage Tag Licence Plate Number 1 13
26 Baggage Tag Licence Plate Number 2 13
27 Baggage Tag Licence Plate Number 3 13
28 Field Size of follow ing structured message 2
29 Airline Numeric Code 3
30 Document Form/Serial Number 10

Is there a roadmap ? For sure, if I find the time I will add the optional fields, an airline and airport code dictionary (must check the size of a local sqllite db if we want to stay offline). Maybe add baggage tag reader feature and local barcode image storage for boarding. Stay tuned !

readmybop1.2

Application Disclaimer: The application is for educational and research purpose. It is provided as-is, no warranty included. It does not transmit data over the internet and does not store any data upon exiting the app.

What’s in my boarding pass barcode ?

Since more than 10 years passengers are used to the barcode imprinted on the traditional ticket boarding pass slip, the home printed boarding pass or the boarding pass displayed in the mobile app provided by the airline. To be more precise the 2004 IATA Passenger Service Conference approved Resolution 792 setting the BCBP (Bar Coded Boarding Pass) standard as part of the STB (Simplify The Business) program.

The barcode simplifies passenger handling as the barcode can be read automatically by barcode readers along the passenger journey for bag-drop, security check area access and boarding. It significantly reduces the error rate to the time before barcode and eventually saved millions of Euros/Dollars due to mishandling and delays. Today we see self-boarding gates that remove the need for an agent, though business and first class passenger are still welcomed by a human gate agent. Btw, the magnetic stripe on the back of the old tickets expired in 2010.

Old Passenger Ticket without barcode (Image Public Domain)

The BCBP standard defines PDF417 (public domain standard, no fees or licenses) as the barcode symbol format as well defines the encoded content. The content in the barcode contains the same information as printed on the standard boarding pass, though some airlines omit information on the self-printed version in favor of simplicity, some extra info is optionally encoded.

2017-10-07 06_47_41-Boarding-Pass Barcode Aztec QR Generator

Sample PDF 417 barcode

M1SMITH/JOHN          EHJK345 FRASINLH 3456 280C015A0001 100

The standard covers 3 additional barcodes that are not used for printing, but used for mobile apps, these are Aztec and QR Code.

The encoding is straight foward using fix-length fields and the code can carry up to 4 legs of a journey.

Element Size Sample Remark
Format Code 1 M Always “M”
Number of legs encoded 1 1
Passenger Name 20
Electronic Ticket Indicator 2 E
Operating carrier PNR Code 7
Origin IATA Code 3 FRA Airport Code
Destination IATA Code 3 SIN Airport Code
Operating carrier IATA Code 3 LH Airline
Flight Number 5 3456
Date of Flight 3 280 Julian Date
Compartment Code 1 B First, Business, Economy
Seat Number 4 25A
Check-in Sequence Number 5 0012
Passenger Status 1 00

These are the mandatory fields, there are additional optional fields and blocks for baggage info, document info, frequent flyer number or security data.

To be noted, the IATA PADIS XML message standard shall be used for the exchange of BCBP data between systems, defined in Resolution 783 – Passenger and Airport Data Interchange Standards.

I like to add also, the printed barcode is the current common nominator for international travel, but there are initiatives on the way to simplify the passenger journey even further with newer technology such as biometric ID’s and identity management, eg. IATA OneIdentity Initiative.

In the next post we will assemble a simple Android application to read the boarding pass barcode. Stay tuned.

Disclaimer: The information provided here might not be correct or complete. It is for educational purpose only. For reliable information please refer to the IATA manuals.