{"id":2633,"date":"2017-08-28T01:20:27","date_gmt":"2017-08-27T23:20:27","guid":{"rendered":"https:\/\/blog.mi.hdm-stuttgart.de\/?p=2633"},"modified":"2023-06-08T15:41:30","modified_gmt":"2023-06-08T13:41:30","slug":"how-to-build-an-alexa-skill-to-get-information-about-your-timetable","status":"publish","type":"post","link":"https:\/\/blog.mi.hdm-stuttgart.de\/index.php\/2017\/08\/28\/how-to-build-an-alexa-skill-to-get-information-about-your-timetable\/","title":{"rendered":"How to build an Alexa Skill to get information about your timetable"},"content":{"rendered":"

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Introduction<\/span><\/h1>\n

With information technology today we can easily get any kind of information someone is interested in. Whether you want to know how the weather will be tomorrow or how to cook your favorite cake, you can find out almost anything today. But as a user it\u2019s getting more important to gain information quickly, and in a comfortable way. Google for example did just that. If you are using Google\u2019s search engine, then you either type in what you are searching for or you can just say it. With spoken language this feature can be used easier and the response you get is quicker.
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\nWe as a team decided, that there is a lot of potential in applications, that can be used by spoken language. That\u2019s why we have built an Alexa Skill for HdM Students, where they get information of their personal timetable. Every HdM student, owning an Amazon Alexa device, can ask Alexa something about his personal timetable.<\/p>\n

Well, the benefits of this skill are clear. Students will have a more comfortable way to gain such information. A big advantage of such a skill is, that it will not be necessary anymore to use a computer, smartphone or tablet then to visit the web page and then to enter the personal credentials for gaining such information. This way includes many steps that have to be taken, considering the fact, that you want to gain only a few information sometimes. With this skill, students can just ask Alexa almost anything about their timetable, without taking the previous described steps.<\/p>\n

General Information<\/span><\/h1>\n

Alexa is Amazon\u2019s voice service. To use this voice service Amazon has released two devices, the Amazon Echo and the Amazon Echo Dot. With these devices you can interact with the Alexa Voice Service (AVS). With spoken language you can play music for example or you could ask about the latest sport results.
\nAmazon also enables you, as a developer, to use AVS, to add Alexa to your own devices. Which means, that you are not strictly bound to Amazon\u2019s devices.
\nAt the beginning, your device provides standard applications like playing music or retrieving weather information for example. As a developer you can add more applications, so that they can be used as well. This can be achieved by developing an Amazon Alexa Skill (AAS). An AAS is an extension to the default skill set.<\/p>\n

To build an Alexa Skill you need to sign up for an Amazon Developer Account. The Alexa Skill consists of three main parts: the logical part, intents with slots and Alexa App to provide configuration possibilities to the user.<\/p>\n

The logical part is the typical piece of software that contains all links between the Alexa API and (in this example) the HdM API.<\/p>\n

Authentication in Alexa Skills<\/span><\/h1>\n

For many skills the user needs to authenticate to use it. To provide the login credentials the user needs the Alexa App installed on his smartphone where he can configure anything possible.<\/p>\n

We, as developers have to build a website with input fields for dealing with the user credentials. During the process of authentication a authentication token is generated by the request processing service.<\/p>\n

The user has to activate the skill in the Alexa App Skill Store. After the activation the app will show a tab for the skill configuration. If the user activates the skill on the echo device it will call the website with the configured credentials to get the token. This token is now used in every request, sent by the Alexa Skill.<\/p>\n

Create an Alexa Skill on Amazon Backend<\/span><\/h1>\n

When you have signed up, you need to create a new skill in the Amazon backend. After that you need to configure it to get the skill working. The configuration starts with the display and activation name of the skill.<\/p>\n

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Amazon Echo works with so called intents and slots. An intent is something like a function where slots are parameters. Echo will recognize which intent a user is asking for and automatically fills the slots. All the information to perform this action have been configured by us with intents and the corresponding slots. On the bottom of the same site you write the speech commands mapped to the intents.<\/p>\n

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To test the skill it\u2019s sufficient to configure the host where the skill is hosted. In our case the skill was hosted on AWS Lambda.<\/p>\n

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Implementation<\/span><\/h1>\n

Development with Alexa Skills Kit for Java<\/span><\/h2>\n

Amazon provides a library for skill development with java. It manages the parsing of the in- and output JSON strings.<\/p>\n

So we can focus on the skills logic. The library provides an interface named Speechlet. There are four predefined methods which are called by the skill.<\/p>\n

@Override\npublic SpeechletResponse onIntent(IntentRequest request, Session session) throws SpeechletException {\n    \/\/ TODO Auto-generated method stub\n    return null;\n}\n\n@Override\npublic SpeechletResponse onLaunch(LaunchRequest arg0, Session session) throws SpeechletException {\n    \/\/ TODO Auto-generated method stub\n    return null;\n}\n\n@Override\npublic void onSessionEnded(SessionEndedRequest arg0, Session session) throws SpeechletException {\n    \/\/ TODO Auto-generated method stub  \n}\n\n@Override\npublic void onSessionStarted(SessionStartedRequest arg0, Session session) throws SpeechletException {\n    \/\/ TODO Auto-generated method stub\n}<\/pre>\n
The methods onIntent<\/em> and onLaunch<\/em> are most important for our skill..<\/p>\n
Like the name says, the onLaunch method is called when a user starts the skill. Here we simply generate a greeting for the user and ask him how the skill (in \u2018person\u2019 of Alexa) can help.<\/p>\n
@Override\npublic SpeechletResponse onLaunch(LaunchRequest arg0, Session arg1) throws SpeechletException {\n    PlainTextOutputSpeech speech = new PlainTextOutputSpeech();\n    speech.setText(\"Willkommen im Stundenplan der Hochschule der Medien. Wie kann ich helfen?\");\n\n    return SpeechletResponse.newAskResponse(speech, createRepromptSpeech());\n}\n<\/pre>\n
The method onIntent<\/em> is called when a user calls an intent of the skill. Information about the intent is passed in the request parameter. So we can simply read an intent name to determine which function of our code should be called.<\/p>\n
private static final String INTENT_LECTUREOFDAY = \"lectureOfDay\";\n\n@Override\npublic SpeechletResponse onIntent(IntentRequest request, Session session) throws SpeechletException {\n    String intentName = request.getIntent().getName();\n\n    if (intentName != null) {\n\n        switch (intentName) {\n        case INTENT_LECTUREOFDAY:\n            return handleLectureOfDay(request.getIntent(), session);\n        case INTENT_STOP:\n            return this.handleStopIntent();\n        }\n    }\n    throw new SpeechletException(\"Invalid intent\");\n}<\/pre>\n
The method shown above lets us read the slot values from the intent. Therefore the skill libraries class Intent<\/em> provides the method getSlot(string slotName)<\/em>. The slot itself has a method getValue<\/em>.<\/p>\n
intent.getSlot(\u201cMySlot\u201d).getValue()<\/pre>\n
HdM Timetable API<\/span><\/h2>\n
In general the HdM Timetable API gives an overview of the current week. So it\u2019s not possible to gain information about the upcoming or previous week(s).<\/p>\n
When calling the API link (http:\/\/www.hdm-stuttgart.de\/studenten\/stundenplan\/pers_stundenplan\/stundenplanfunktionen\/all_in_one_sql\/timetable) by using the basic authentication method, a JSON like this will be responded:<\/p>\n
{\n\"lectures\":[\n    {\n        \"vorlesung_id\":\"5214854\",\n        \"sgblock_vorlesung_semester_id\":\"5170336\",\n        \"name\":\"Software Development for Cloud Computing\",\n        \"type\":\"regular\",\n        \"tag_id\":4,\n        \"zeit_id\":5,\n        \"edvnr\":\"113479a\",\n        \"raum\":\"136\",\n        \"findet_statt\":1\n    },\n    {\n        \"vorlesung_id\":\"5214854\",\n        \"sgblock_vorlesung_semester_id\":\"5170336\",\n        \"name\":\"Software Development for Cloud Computing\",\n        \"type\":\"regular\",\n        \"tag_id\":4,\n        \"zeit_id\":6,\n        \"edvnr\":\"113479a\",\n        \"raum\":\"135\",\n        \"findet_statt\":1\n    }\n    ]\n}\n<\/pre>\n
The example shows the lecture Software Development for Cloud Computing<\/em> which takes place in the 5th<\/sup> and 6th<\/sup> lecture block on a Thursday. That means from 2:15 PM to 3:45 PM and from 4 PM to 5:30 PM. First part of the lecture is in room 136, and second in room 135. As you can see, both of them took place (if you make the same request e.g. during the time of holidays you will get a \u20180\u2019 for \u2018findet_statt\u2019 instead). At least \u2018edvnr\u2019 which is the university\u2019s internal unique id for a lecture.<\/p>\n
There is a few more information provided but due missing documentation we unfortunately can\u2019t give a clear explanation for it.<\/p>\n
For our skill we used this fields:<\/p>\n