HANA Cloud Platform IoT Services API (hcp-iot-api)

This is a lightweight Node.js based wrapper for the SAP HANA Cloud Platform IoT Services API.
Instead of wrangling with authentication and request configuration, you can use the libraries methods to communicate with the API.
Both services (Remote Device Management Servcie and Message Management Service) have been implemented in their own class (see documentation below).

There is also a utility class available to request OAuth tokens for configured HCP clients.

Installation (when available)

You can install the module through the public npm registry by running the
following command in CLI:

``
npm install --save hcp-iot-api
`

Promises

The library is using promises for a cleaner syntax and to avoid nested callbacks.
So when there is the need to have things be in sequence, you would normally have to write nested callbacks in JavaScript:

`js
// This is how the API would look without promises
rdms.createDeviceType({...} , function (deviceType) {
rdms.createMessageType({...}, function(messageType) {
rdms.registerDevice({...}, function(device) {
...
}, function(error) { console.log(error); });
}, function(error) { console.log(error); });
}, function(error) { console.log(error); });
`
Because the libraries methods return Promises, it is much easer to deal with sychronous requests, avoid handling errors multiple times and keep everything more readable. So the API actually looks like this:

`js
rdms.createDeviceType({...})
.then(function(deviceType){
return rdms.createMessageType({...});
})
.then(function(messageType){
return rdms.registerDevice({...});
}).
.then(function(device){
...
}).
catch(function(error) { console.log(error) });
`
Every time you want something to run in sync, just put the code in the then function and return the promise.
More on promises can be found here.

Remote Device Management Service (RDMS)

The IoT Services Cockit inside HCP contains a user interface to manage devices, device types, message types, etc. The Remote Device Management Service can be used to programatically do the administration without the need to access the cockpit.
Especially in big projects it may be a good solution to store the definition of message types, etc. as code fragements in one central place with versioning support (e.g. git).

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The RDMS always needs the users HCP username and password for authentication. This information needs to be given when initializing a new object.

`js
var API = require("hcp-iot-api");
var rdms = new API.RemoteDeviceManagementService({
"account": "",
"password": ""
});
`


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The API allows to completly configure the HCP IoT services without the need to access a GUI. Instead there are fuctions available to read, create and delete all kinds of entity types.
A simple example showing how to fetch all message types:
`js
rdms.getMessageTypes()
.then(function(messageTypes) {
// Do something meaningful with the returned array of objects
})
.catch(function(error) { console.log(error.message) });
`
And another one showing how to create a device type and after that, create a corresponding message type. The available fields can be read in the official documentation.

`js
rdms.createDeviceType({ "name": "Device Type 1" })
.then(function (deviceType) {
return rdms.createMessageType({'device_type': deviceType.id, ...}); // Create the message type
.then(function (messageType) {
... // Maybe do something else
.catch(function(error) { console.log(error.message) });
`

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It is possible to dynamically register devices via API. A key requirement is the former definition of a device type, because its id and token need to be applied. A possible call could look like:

`js
rdms.registerDevice({
"name": "Device 1",
"device_type": deviceType.id,
"attributes": [
{ "key": "customKey", "value": "custom value" }
]
}, deviceType.token);
})
.then(function(device) {
var deviceToken = device.token; // Needs to be stored!
var deviceId = device.id;
...
});
`

When registering a device, the API returns the devices JSON object containing a token. This is only returned once directly after creation, so it is important to store it for later usage. When using the MMS to send sensor data from a device, this token needs to be passed in as the OAuth token.
If you do not store the token programatically, it can be reset in the IoT Cockpit.

Message Management Service (MMS)

The Message Management Service is the actual service to send data from an IoT device into the Hana Cloud Platform and/or back to the device.

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The MMS is a bit more complex in terms of authorization. There are several methods, which are bound to a specific device. For exampe, if you want to send sensor data from a device into the HCP (mms.sendData(...)), you need the deviceId and deviceToken information. Other methods (e.g. mms.pushToDevice(...)) require a user authentication via HTTP Basic Auth (account/password) or OAuth (oauthToken).
The authentication information could be assigned in the constructor or when calling a method (see full API below). Passing all parameters in upfront would look like this:
`js
var API = require("hcp-iot-api");
var mms = new API.MessageManagementService({
"account": "", // This one is mandatory!
"password": "",
"deviceToken": "",
"deviceId": "",
"oauthToken": ""
});
`

Send sensor data via HTTP(S)

The main purpose of the MMS is to send sensor data from the device into the HCP. The API is straight forward when using HTTP(S) as the message protocol:

`js
mms.sendData({
"messageType": "",
"messages": [{
"sensor1": "Value 1",
"sensor2": "Value 2"
}]
})
.catch(function(error) { console.log(error.message) });
`

If the deviceId and deviceToken have not been included in the constructor, they can be passed to the sendData method as the second and third parameter:

`js
var mms = new API.MessageManagementService({ "account": "" });
mms.sendData({
"messageType": "",
"messages": [{
"sensor1": "Value 1",
"sensor2": "Value 2"
}]
}, "", "")
.catch(function(error) { console.log(error.message) });
`

Sending information back to a device

Using MMS it is also possible, to send information to a device. When sending the information, it ca be specified if the message should be delivered via HTTP or a Websocket connection. It is also required to register a message type with direction ToDevice and use this one, when sending the information.
Authentication for using the pushToDevice function is either via password or via oauthToken.

`js
var mms = new API.MessageManagementService({
"account": "",
"password": ""
});

mms.pushToDevice("", {
"method": "http", // or "ws"
"sender": "My IoT application",
"messageType": "",
"messages":[
{
"abc": "switch on",
}
]
});
`

If HTTP as the transport protocol, the message is being stored inside the HCP in table T_IOT_HTTP_PUSH and can be retrieved by polling via the mms.getData() method. Again, if specificed in the constructor, the method parameters can be omitted.

`js
var mms = new API.MessageManagementService({
"account": "",
"password": ""
});

mms.getData("", "")
.then(function(messages) {
// Fetch the existing messages for this device
});
`

Using websockets

The MMS also allows a persistent connection to the API via websocket protocol. This should be used if a bidirectional communication is required. When using websockets, messages send to a device do not need to be pulled, but are pushed through the websocket connection.

The following example shows how to establish a websocket connection and once this is established, send data into the HCP. The sendData method detects the open connection and will send the data over the connection instead of over HTTP(S). The onWebsocketMessage function registers a callback, which is being called whenever a message for the device arrives. Please note, that we are not using promises here, because this method may be called multiple times.
`js
var mms = new API.MessageManagementService({
"account": "",
"deviceId": "",
"deviceToken": ""
});

mms.openWebsocketConnection()
.then(function() {

// Register callback for when data is being pushed to the device
mms.onWebsocketMessage(function(message) {
// Do something the message
});

// Send data through the websocket
mms.sendData({
"messageType": "",
"messages": [{
"sensor1": "Value 1",
"sensor2": "Value 2"
}]
});
});


// Close, when not required anymore
mms.closeWebsocketConnection()
.then(function() {
// Maybe do something when closed
});;
`

MMS configuration via API

Since version 2.15.0 of the MMS, it is possible to set a wide range of options for configuration. This can be done either via GUI in the MMS Cockpit or via API. The following example shows, how you can tell the API to create all tables using the column instead of the row store. Authentication must be done either with password or oauthToken.

`js
var mms = new API.MessageManagementService({
"account": "",
"password": ""
});

mms.updateConfig({
"config": [
{ "key": "mms.processing.sql.hana.table_type", "value": "column" }
]
}).catch(function(error) { console.log(error.message) });
`

Be aware, that in the official API documentation the configuration format is currently incorrect. So if you want to set settings programmatically, you have to explicitly use key and value like in the example shown above.
For a list of all existing options, there is a mms.getConfig() method available, wich returns the whole configuration.

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Full documentation (will be updated soon)

The following section describes the full API.

Class: RemoteDeviceManagementService

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* options Object
* account String
* password String

Construct a new rdms object. account and password need to be set for HTTP authentication.

Example:
`js
var API = require("hcp-iot-api");
var rdms = new API.RemoteDeviceManagementService({
"account": "",
"password": ""
});
`

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* options Object – For a list of options check out the official docs.

Creates a new device type.

Example:
`js
rdms.createDeviceType({ "name": "Device Type 1" })
.then(function (deviceType) {
...
})
.catch(function(error) { console.log(error.message) });
`

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Returns all existing device types.

Example:
`js
rdms.getDeviceTypes()
.then(function (deviceTypes) {
...
})
.catch(function(error) { console.log(error.message) });
`

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* id String

Returns one specific device type.

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* id String

Deletes the device type.

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* options Object – For a list of options check out the official docs.

Creates a new message type. A message type is always bound to a specific device type and needs the direction set to either fromDevice or toDevice.

Example:
`js
rdms.createMessageType({
"device_type": deviceType.id,
"name": "Message Type 1",
"direction": "fromDevice",
"fields": [
{
"position": 1,
"name": "sensor1",
"type": "string"
},
{
"position": 2,
"name": "sensor2",
"type": "string"
}
]
});
.catch(function(error) { console.log(error.message) });
`

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Returns all existing message types.

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* id String

Returns one specific message type.

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* id String

Deletes the message type.

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* options Object – For a list of options check out the official docs.
* deviceTypeToken String – The token from the device type

Registers a new device. A device is always bound to a specific device type. A device can be created using the registerDevice or createDevice method. The latter one does not return the OAuth-token required to send data to the API via MMS.
The token itself can be read and recreated via the IoT Cockpit.

Example:
`js
rdms.registerDevice({
"name": "Device 1",
"device_type": device_type.id,
"attributes": [
{ "key": "customKey1", "value": "custom value" },
{ "key": "customKey2", "value": "custom value" }
]}, deviceTypeToken);
.catch(function(error) { console.log(error.message) });
`

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* options Object – For a list of options check out the official docs.

Creates a new device. To use the device for sending data, you have to read the token from the IoT Cockpit.

Example:
`js
rdms.createDevice({
"name": "Device 1",
"device_type": device_type.id,
"attributes": [
{ "key": "customKey1", "value": "custom value" },
{ "key": "customKey2", "value": "custom value" }
]
});
.catch(function(error) { console.log(error.message) });
`

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Returns all existing deviced.

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* id String

Returns one specific device.

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* id String

Deletes the device.

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* id String

Returns all attributes for a device.

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* id String – The id of the device
* options Object – For all options please check out the official docs

Creates a specific attribute for a device.

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* id String
* key String

Deletes a specific attribute of a device.

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Returns the RDMS settings. For more information please check out the official docs

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Class: MessageManagementService

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* options Object
* account String (mandatory)
* password String (optional)
* deviceId String (optional)
* deviceToken String (optional)

Construct a new mms object. account and password need to be set for HTTP authentication.

Example:
`js
var API = require("hcp-iot-api");
var rdms = new API.MessageManagementService({
"account": "",
"deviceId": "",
"deviceToken": ""
});
`

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* options Object – For a list of options check out the official docs.
* deviceId String (optional) – Has to be given if not set on global level
* deviceToken String (optional) – Has to be given if not set on global level

Send sensor data to the IoT Cockpit from a specific device.

Example:
`js
mms.sendData({
"mode": "async",
"messageType": "",
"messages": [
{
"sensor1": "Value 1",
"sensor2": "Value 2"
}
]
})
.catch(function(error) { console.log(error.message) });
``