The library provides a mechanism for the periodic reporting of stats related to the library's work. In order to activate the use of the periodic stats, it must be configured in the config file, as described in the Configuration section.
The Stats Registry holds two dictionaries, with the same set of stats. For each stat, one of the dictionaries holds the historical global value and the other one stores the value since the last value reporting (or current value).
The stats library currently stores only the following values:
- deviceCreationRequests: number of Device Creation Requests that arrived to the API (no matter the result).
- deviceRemovalRequests: number of Removal Device Requests that arrived to the API (no matter the result).
- measureRequests: number of times the ngsiService.update() function has been invoked (no matter the result).
More values will be added in the future to the library. The applications using the library can add values to the Stats Registry just by using the following function:
iotagentLib.statsRegistry.add("statName", statIncrementalValue, callback);The first time this function is invoked, it will add the new stat to the registry. Subsequent calls will add the value to the specified stat both to the current and global measures. The stat will be cleared in each interval as usual.
The library provide an alarm module that can be used to track through the logs alarms raised in the IoTAgent. This module provides:
-
Two functions to raise and release and alarm (
raise()andrelease()): every alarm is identified by a name and a description. When the alarm is raised, an error with the textRaising [%s]is logged. When the alarm is released, the corresponding text,Releasing [%s]is logged. If an alarm is raised multiple times, it is only logged once. If its released multiple times it is only released once. Releasing a non-existing alarm has no effect. -
Functions to list all the raised alarms and clean all the alarms (
list()andclean()). -
A function to instrument other functions, so when one of that functions return an error, an alarm is raised, and when it returns a success an alarm is ceased (
intercept()).
All this functions can be accessed through the .alarms attribute of the library.
The library implements a concept of transactions, in order to follow the execution flow the library follows when treating requests entering both from the North and the South ports of the IoT Agent.
To follow the transactions, a new Domain is created for each incoming request; in the case of requests received on the
North Port of the IoT Agent, this domain is automatically created by a Express middleware, and no further action is
needed from the user. For the case of requests received on the South Port of the IoT Agent, the user is responsible of
creating an stopping the transaction, using the ensureSouthboundDomain and finishSouthBoundTransaction. In this
case, the transaction will last from the invocation to the former to the invocation of the latter.
The Transaction Correlator is used along all the IoT Platform to follow the trace of a transaction between multiple
components. To do so, in all the HTTP requests sent to other components of the platform, a custom header named
Fiware-Correlator is sent with the correlator of the transaction that generated the request. If a component of the
platform receives a request containing this header that starts a transaction, the component will create the transaction
with the received correlator, instead of creating a new one. If the header is not present or the transaction originates
in the component, the transaction ID in this component will be used as the correlator.
During the duration of a transaction, all the log entries created by the code will write the current Transaction ID and correlator for the operation being executed.
In order to use the library, add the following dependency to your package.json file:
"iotagent-node-lib": "*"In order to use this library, first you must require it:
var iotagentLib = require("iotagent-node-lib");The library supports four groups of features, one for each direction of the communication: client-to-server and server-to-client (and each flow both for the client and the server). Each feature set is defined in the following sections.
function activate(newConfig, callback)Activates the IoT Agent to start listening for NGSI Calls (acting as a Context Provider). It also creates the device registry for the IoT Agent (based on the deviceRegistry.type configuration option).
- newConfig: Configuration of the Context Server (described in the Configuration section).
function deactivate(callback)Stops the HTTP server.
function registerDevice(deviceObj, callback)Register a new device in the IoT Agent. This registration will also trigger a Context Provider registration in the Context Broker for all its lazy attributes.
The device Object can have the following attributes:
id: Device ID of the device.type: type to be assigned to the device.name: name that will be used for the Entity representing the device in the Context Broker.service: name of the service associated with the device.subservice: name of the subservice associated with th device.lazy: list of lazy attributes with their types.active: list of active attributes with their types.staticAttributes: list of NGSI attributes to add to the device entity 'as is' in updates, queries and registrations.internalAttributes: optional section with free format, to allow specific IoT Agents to store information along with the devices in the Device Registry.
The device id and type are required fields for any registration. The rest of the attributes are optional, but, if
they are not present in the function call arguments, the type must be registered in the configuration, so the service
can infer their default values from the configured type. If an optional attribute is not given in the parameter list and
there isn't a default configuration for the given type, a TypeNotFound error is raised.
If the device has been previously preprovisioned, the missing data will be completed with the values from the registered device.
- deviceObj: object containing all the information about the device to be registered (mandatory).
function unregisterDevice(id, service, subservice, callback)Unregister a device from the Context broker and the internal registry.
- id: Device ID of the device to register.
- service: Service of the device to unregister.
- subservice: Subservice inside the service for the unregistered device.
function update(entityName, attributes, typeInformation, token, callback)Makes an update in the Device's entity in the context broker, with the values given in the 'attributes' array. This array should comply to the NGSI's attribute format.
- entityName: Name of the entity to register.
- attributes: Attribute array containing the values to update.
- typeInformation: Configuration information for the device.
- token: User token to identify against the PEP Proxies (optional).
function setCommandResult(entityName, resource, apikey, commandName, commandResult, status, deviceInformation, callback)Update the result of a command in the Context Broker. The result of the command has two components: the result of the
command itself will be represented with the suffix _result in the entity while the status is updated in the attribute
with the _info suffix.
- entityName: Name of the entity holding the command.
- resource: Resource name of the endpoint the device is calling.
- apikey: Apikey the device is using to send the values (can be the empty string if none is needed).
- commandName: Name of the command whose result is being updated.
- commandResult: Result of the command in string format.
- deviceInformation: Device information, including security and service information. (optional).
function listDevices(callback)
function listDevices(limit, offset, callback)
function listDevices(service, subservice, limit, offset, callback)Return a list of all the devices registered in the specified service and subservice. This function can be invoked in three different ways:
- with just one parameter (the callback)
- with three parameters (service, subservice and callback)
- or with five parameters (including limit and offset).
- service: service from where the devices will be retrieved.
- subservice: subservice from where the devices will be retrieved.
- limit: maximum number of results to retrieve (optional).
- offset: number of results to skip from the listing (optional).
function setDataUpdateHandler(newHandler)Sets the new user handler for Entity update requests. This handler will be called whenever an update request arrives with the following parameters: (id, type, service, subservice, attributes, callback). The handler is in charge of updating the corresponding values in the devices with the appropriate protocol.
Once all the updates have taken place, the callback must be invoked with the updated Context Element. E.g.:
callback(null, {
type: "TheType",
isPattern: false,
id: "EntityID",
attributes: [
{
name: "lumniscence",
type: "Lumens",
value: "432",
},
],
});In the case of NGSI requests affecting multiple entities, this handler will be called multiple times, one for each entity, and all the results will be combined into a single response.
- newHandler: User handler for update requests
function setDataQueryHandler(newHandler)Sets the new user handler for Entity query requests. This handler will be called whenever a query request arrives, with the following parameters: (id, type, service, subservice, attributes, callback). The handler must retrieve all the corresponding information from the devices and return a NGSI entity with the requested values.
The callback must be invoked with the updated Context Element, using the information retrieved from the devices. E.g.:
callback(null, {
type: "TheType",
isPattern: false,
id: "EntityID",
attributes: [
{
name: "lumniscence",
type: "Lumens",
value: "432",
},
],
});In the case of NGSI requests affecting multiple entities, this handler will be called multiple times, one for each entity, and all the results will be combined into a single response.
- newHandler: User handler for query requests.
function setNotificationHandler(newHandler)Sets the new handler for incoming notifications. The notifications are sent by the Context Broker based on the IoT Agent
subscriptions created with the subscribe() function.
The handler must adhere to the following signature:
function mockedHandler(device, data, callback)The device parameter contains the device object corresponding to the entity whose changes were notified with the
incoming notification. Take into account that multiple entities may be modified with each single notification. The
handler will be called once for each one of those entities.
The data parameter is an array with all the attributes that were requested in the subscription and its respective
values.
The handler is expected to call its callback once with no parameters (failing to do so may cause unexpected behaviors in the IoT Agent).
function setProvisioningHandler (newHandler)Sets the new user handler for the provisioning of devices. This handler will be called every time a new device is created.
The handler must adhere to the following signature:
function(newDevice, callback)The newDevice parameter will contain the newly created device. The handler is expected to call its callback with no
parameters (this handler should only be used for reconfiguration purposes of the IoT Agent).
function setRemoveDeviceHandler(newHandler)Sets the new user handler for the removal of a device. This handler will be called every time a device is removed.
The handler must adhere to the following signature:
function(deviceToDelete, callback)The deviceToDelete parameter will contain the device to be deleted. The handler is expected to call its callback with
no parameters (this handler should only be used for reconfiguration purposes of the IoT Agent).
function setConfigurationHandler(newHandler)Sets the new user handler for the configuration updates. This handler will be called every time a new configuration is created or an old configuration is updated.
The handler must adhere to the following signature:
function(newConfiguration, callback)The newConfiguration parameter will contain the newly created configuration. The handler is expected to call its
callback with no parameters (this handler should only be used for reconfiguration purposes of the IoT Agent).
For the cases of multiple updates (a single Device Configuration POST that will create several device groups), the handler will be called once for each of the configurations (both in the case of the creations and the updates).
The handler will be also called in the case of updates related to configurations. In that situation, the
newConfiguration parameter contains also the fields needed to identify the configuration to be updated, i.e.,
service, subservice, resource and apikey.
function setRemoveConfigurationHandler(newHandler)Sets the new user handler for the removal of configuratios. This handler will be called every time a configuration is removed.
The handler must adhere to the following signature:
function(configurationToDelete, callback)The configurationToDelete parameter will contain the configuration to be deleted. The handler is expected to call its
callback with no parameters (this handler should only be used for reconfiguration purposes of the IoT Agent).
function getDevice(deviceId, service, subservice, callback)Retrieve all the information about a device from the device registry.
- deviceId: ID of the device to be found.
- service: Service for which the requested device.
- subservice: Subservice inside the service for which the device is requested.
function getDeviceByName(deviceName, service, subservice, callback)Retrieve a device from the registry based on its entity name.
- deviceName: Name of the entity associated to a device.
- service: Service the device belongs to.
- subservice: Division inside the service.
function getDevicesByAttribute(attributeName, attributeValue, service, subservice, callback)Retrieve all the devices having an attribute named name with value value.
- name: name of the attribute to match.
- value: value to match in the attribute.
- service: Service the device belongs to.
- subservice: Division inside the service.
function retrieveDevice(deviceId, apiKey, callback)Retrieve a device from the device repository based on the given APIKey and DeviceID, creating one if none is found for the given data.
- deviceId: Device ID of the device that wants to be retrieved or created.
- apiKey: APIKey of the Device Group (or default APIKey).
function mergeDeviceWithConfiguration(fields, defaults, deviceData, configuration, callback)Complete the information of the device with the information in the configuration group (with precedence of the device). The first argument indicates what fields would be merged.
- fields: Fields that will be merged.
- defaults: Default values fot each of the fields.
- deviceData: Device data.
- configuration: Configuration data.
function getConfiguration(resource, apikey, callback)Gets the device group identified by the given (resource, apikey) pair.
- resource: representation of the configuration in the IoT Agent (dependent on the protocol) .
- apikey: special key the devices will present to prove they belong to a particular configuration.
function findConfiguration(service, subservice, callback)Find a device group based on its service and subservice.
- service: name of the service of the configuration.
- subservice: name of the subservice of the configuration.
function getEffectiveApiKey(service, subservice, type, callback)Get the API Key for the selected service if there is any, or the default API Key if a specific one does not exist.
- service: Name of the service whose API Key we are retrieving.
- subservice: Name of the subservice whose API Key we are retrieving.
- type: Type of the device.
function subscribe(device, triggers, content, callback)Creates a subscription for the IoTA to the entity representing the selected device.
- device: Object containing all the information about a particular device.
- triggers: Array with the names of the attributes that would trigger the subscription
- content: Array with the names of the attributes to retrieve in the notification.
function unsubscribe(device, id, callback)Removes a single subscription from the selected device, identified by its ID.
device: Object containing all the information about a particular device.id: ID of the subscription to remove.
function ensureSouthboundTransaction(context, callback)Ensures that the current operation is executed inside a transaction with all the information needed for the appropriate platform logging: start date, transaction ID and correlator in case one is needed. If the function is executed in the context of a previous transaction, just the context is changed (and the Transaction ID and start time are kept).
- context: New context data for the transaction.
function finishSouthboundTransaction(callback)Terminates the current transaction, if there is any, cleaning its context.
function startServer(newConfig, iotAgent, callback)Start the HTTP server either in single-thread or multi-thread (multi-core) based on the value of multiCore variable
(described in the Configuration section). If the value is False (either was
directly specified False in the config.js or it was not specified and by default is assigned False), it is a
normal (single-thread) behaviour. Nevertheless, if multiCore is True, the IoTAgent is executed in multi-thread
environment.
The number of parallel processes is calculated based on the number of available CPUs. In case of some of the process unexpectedly dead, a new process is created automatically to keep always the maximum of them working in parallel.
Note:
startServer()initializes the server but it does not activate the library. The function in the Node Lib will call theiotAgent.start()in order to complete the activation of the library. Therefore, it is expected that the IoT Agent implement theiotAgent.start()function with the proper invocation to theiotAgentLib.activate().
- newConfig: Configuration of the Context Server (described in the Configuration section).
- iotAgent: The IoT Agent Objects, used to start the agent.
- callback: The callback function.
This collection of utility middlewares is aimed to be used to north of the IoT Agent Library, as well as in other
HTTP-based APIs of the IoT Agents. All the middlewares follow the Express convention of (req, res, next) objects, so
this information will not be repeated in the descriptions for the middleware functions. All the middlewares can be added
to the servers using the standard Express mechanisms.
function handleError(error, req, res, next)Express middleware for handling errors in the IoTAs. It extracts the code information to return from the error itself returning 500 when no error code has been found.
function traceRequest(req, res, next)Express middleware for tracing the complete request arriving to the IoTA in debug mode.
function changeLogLevel(req, res, next)Changes the log level to the one specified in the request.
function ensureType(req, res, next)Ensures the request type is one of the supported ones.
function validateJson(template)Generates a Middleware that validates incoming requests based on the JSON Schema template passed as a parameter.
Returns an Express middleware used in request validation with the given template.
- template: JSON Schema template to validate the request.
function retrieveVersion(req, res, next)Middleware that returns all the IoTA information stored in the module.
function setIotaInformation(newIoTAInfo)Stores the information about the IoTAgent for further use in the retrieveVersion() middleware.
- newIoTAInfo: Object containing all the IoTA Information.