@sorrir/framework
v0.29.0
Published
This project contains the execution framework developed in the [SORRIR](https://sorrir.io) project. SORRIR aims at supporting the development of resilient IoT systems.
Downloads
44
Keywords
Readme
SORRIR Framework
This project contains the execution framework developed in the SORRIR project. SORRIR aims at supporting the development of resilient IoT systems.
[[TOC]]
Installation
If this is your first TypeScript project, you may need to [install nodejs](https://nodejs. org/en/download/package-manager/) and an IDE of your choice, e.g., WebStorm, VSCode, or VSCodium (same as VSCode but without all the Microsoft tracking).
To add the SORRIR framework to your application, run npm install @sorrir/framework
from the root of your
Typescript application.
SORRIR Framework Overview
In the following section, we will give an overview about the inner workings of the Framework, disregarding implementation details.
Components
From the top level view, our application consists of interconnected components. Components are the building blocks that make it possible to implement the application's logic.
The internal behavior of a component is defined by a state machine. Each component has a set of states, ports and transitions. Incoming events through specific ports can raise a transition from one state to another.
Ports & Connections
To communicate - or to be more precise, send events from one component to another - ports of components can be connected with connections. Connections logically describe to which target port a source port's events are send to.
graph TD
subgraph Component A
PA1(Port A1)
end
subgraph Component B
PB1(Port B1)
PB2(Port B2)
end
subgraph Component C
PC1(Port C1)
end
PA1 -->|Connection 1| PB1
PB2 -->|Connection 2| PC1
Ports are either in our out ports, but can be part of multiple connections. Connections are unidirectional and have exactly one source and one target port.
Events & Transitions
Events are instruction to other components to transition from on state to another. Events can be raised for multiple reasons, for instance as a result of transitions following events from other components, or from an external source like a sensor. Events have certain types, tied to the ports they have been sent through.
Transitions define how a component is to behave after receving certain events. For an event to trigger a certain transition, for requirements have to be met:
- Event needs to be the correct type
- Event needs to be the correct eventClass
- Event was received on the correct port
- Receiving component is in the correct state
If all requirements are fulfilled, the component executes the behaviour defined in the transition and consequently, for instance, transitions from one state to another or raises follow-up events.
Depending on the purpose of the event, there are four different event classes. oneway
events are 'fire-and-forget', while request
events indicate that the components awaits an answer, eiher in form of a resolve
event (on success) or an error
event (on error).
Example implementation: Smart Parking Garage
In the following section, we will explain the basics on how to implement your first testbed according to a example, the Smart Parking Garage.
Here you can see the structure of the example including components, ports and connections between ports:
graph TD
subgraph barrier
TO_PARKING_MANAGEMENT(TO_PARKING_MANAGEMENT)
FROM_BUTTON_MCU(FROM_BUTTON_MCU)
end
subgraph signalMCU
FROM_PARKING_MANAGEMENT(FROM_PARKING_MANAGEMENT)
end
subgraph buttonMCU
TO_BARRIER(TO_BARRIER)
end
subgraph parkingManagement
FROM_BARRIER(FROM_BARRIER)
TO_SIGNAL_MCU(TO_SIGNAL_MCU)
end
TO_SIGNAL_MCU --> FROM_PARKING_MANAGEMENT
TO_BARRIER --> FROM_BUTTON_MCU
TO_PARKING_MANAGEMENT --> FROM_BARRIER
These are the components that need to be implemented. We start building our testbed by specifying the barrier
component step-by-step followed by specifying a parkingManagement
component. Furthermore, we explain how to integrate MQTT I/O components.
Components
To create a new component, we have to describe its states, the external events it can handle, the ports through which it can be connected to other components, its internal state, and a state machine to describe its behavior.
States
barrier
has two states IDLE
and CAR_ENTRY
. Define the state of a component within its *.ts
file – in this case Barrier.ts
.
enum BarrierStates {
IDLE = "IDLE",
CAR_ENTRY = "CAR_ENTRY"
}
Ports
Since ports are used to connect a component to another component, it is a good naming pattern to start the name of port with its direction followed by the target or target group. Events can be sent and received only to components that are connected to a component.
In the current version of the SORRIR framework prototype a port's direction is just a naming convention. It is possible to send an event through port
FROM_MY_COMPONENT
whereas its name would indicate the other way round. In a future version, we will ensure a correct behavior within the framework.
barrier
is connected to barrierController
via port FROM_BARRIER_CONTROLLER
and to parkingManagement
via port TO_PARKING_MANAGEMENT
. You have to define the ports of a controller as an enum:
export enum BarrierPorts {
TO_PARKING_MANAGEMENT = "TO_PARKING_MANAGEMENT",
FROM_BARRIER_CONTROLLER = "FROM_BARRIER_CONTROLLER"
}
Events
Since events are sent across various components of your application, their types should be defined in a central file events.ts
. Event types must be defined as an enum:
export enum EventTypesIntern {
CAR_IN = "CAR_IN",
CAR_OUT = "CAR_OUT",
}
export enum EventTypesExtern {
BUTTON_UP_PRESSED = "BUTTON_UP_PRESSED",
BUTTON_DOWN_PRESSED = "BUTTON_DOWN_PRESSED",
LED_RED = "LED_RED",
LED_GREEN = "LED_GREEN",
DISPLAY = "DISPLAY",
}
In this example, we use a two enums for the whole application, one for incoming events, one for outgoing ones. If your application grows, you can think of splitting it into several more specific event enums.
The events that are passed from component to component or within a component are typed by the EventTypes you specified in your enum. This way a component can react depending on the type of the event it has received. In general, an Event looks like this:
export interface Event<EVENT_TYPE, PORT_TYPE> {
// all event classes
readonly eventClass: EventClass;
readonly type: EVENT_TYPE;
readonly port?: PORT_TYPE | typeof Internal;
readonly timestamp?: number;
readonly id: UUID;
// only oneway, request, resolve
readonly param?: any;
// only resolve, error
readonly rc: number;
readonly answerToRequestID: UUID;
// only error
readonly error: string;
readonly layer: EventSourceApplicationLayer | EventSourceFrameworkLayer;
}
type
is the aforementioned event type, for instanceEventTypesIntern.CAR_IN
eventClass
specifies the class of event that is being sent, so eitheroneway
,request
,resolve
orerror
.port
is the port the event is being sent through, e.g.BarrierPorts.TO_PARKING_MANAGEMENT
. If you do not specify aport
, the event is an internal event of your component and is not being forwarded to other components by the engine.timestamp
(set by the engine) is a number representing an incrementing logical clock. A higher number means a newer event.id
(set by the engine) is a unique identifier of the event in UUID v4 format.param
contains a user-defined payload for the event.rc
is a user-defined return code of the event.answerToRequestID
is the UUID of the precedingrequest
event.error
is an error message.layer
is the layer an error occured on.
In the following, for simplification purposes, all events that we use are oneway
events.
Internal State
A component can also have an internal state or data state that is passed from step to step. It can include any entry required for a component, however all of them should be readonly. After every transition, the internal state is rebuilt, external changes in between transition are not desired.
Define your internal state as a type alias containing all the attributes you need for your component:
type BarrierState = {
lastAction : number;
}
The internal state of barrier
holds a single attribute lastAction: number
. We use this attribute to save the last timestamp a car passed the barrier (or a button was pressed) to ensure that this can happen only once per second.
Behavior
We describe the behavior of a component as a state machine. All the states, ports, event types, and the internal state defined before have to be passed as type parameters to the state machine:
const sm : StateMachine<BarrierStates, BarrierState, EventTypesIntern | EventTypesExtern, BarrierPorts> = {
transitions: [...]
};
How, when, and under what conditions the state machine can switch from a state to another state is expressed by a transition. The interface of a transition looks as follows:
export interface Transition<
DISCRETE_STATE,
ABSTRACT_STATE,
EVENT_TYPE,
PORT_TYPE,
EVENT extends Event<EVENT_TYPE, PORT_TYPE>
> {
readonly sourceState: DISCRETE_STATE;
readonly event?: [EventClass, EVENT_TYPE, PORT_TYPE?];
readonly condition?: (myState: ABSTRACT_STATE, event?: EVENT) => boolean;
readonly action?: Action<ABSTRACT_STATE, EVENT_TYPE, PORT_TYPE, EVENT>;
readonly targetState: DISCRETE_STATE;
}
As we can see, we at least have to define a source and a target state. We can react to a specific event (otherwise the transition is activated automatically). We also can define a guard (condition) which ensures that the transition is activated only if a user defined condition is satisfied. Furthermore, we can define an action function that is executed if the transition is activated. Within this action function, we can update the internal state of the state machine or raise new events.
As you can see in the overview image of barrier
above, if it is in state IDLE
and receives one of the events BUTTON_UP_PRESSED
or BUTTON_DOWN_PRESSED
via port FROM_BARRIER_CONTROLLER
it should send CAR_IN
or CAR_OUT
correspondingly to parkingManagement
via port TO_PARKING_MANAGEMENT
and switch to state CAR_ENTRY
. Let's see how this works by creating a new transition inside the state machine:
...
transitions: [
{
sourceState: BarrierStates.IDLE,
targetState: BarrierStates.CAR_ENTRY
}
]
...
This is the most basic transition. To activate it only on event BUTTON_DOWN_PRESSED
you have to add:
{
sourceState: BarrierStates.IDLE,
targetState: BarrierStates.CAR_ENTRY,
event: ["oneway", EventTypesExtern.BUTTON_UP_PRESSED, BarrierPorts.FROM_BUTTON_MCU]
}
Besides specifying the event that can activate that transition, we also have to define the port through which the event will be received. As you may noticed, you only can choose from events that were specified and passed as parameter to the state machine before.
To raise a new event, you can specify an action function:
{
...
action: (myState, raiseEvent, event) => {
raiseEvent({ eventClass: "oneway", type: EventTypesIntern.CAR_OUT, port: BarrierPorts.TO_PARKING_MANAGEMENT});
return { lastAction: Date.now() };
}
...
}
Our action function gets the internal state, raiseEvent
, and the occurring event. raiseEvent
is a callback function to raise a new event. It expects an Event
as parameter. The interface of Event
requires the attribute type
and optional port
and payload
(see above). You can call raiseEvent
as many times you need to.
The last line { lastAction: Date.now() }
updates the internal state by setting the current timestamp. We need this timestamp to simulate the time a car takes to pass the barrier. barrier
should only switch back from CAR_ENTRY
to IDLE
after 1s. The corresponding transition looks as follows:
{
sourceState: BarrierStates.CAR_ENTRY,
targetState: BarrierStates.IDLE,
condition: myState => myState.lastAction + 1000 <= Date.now(),
action: myState => {
// action is actually not required
return myState;
}
}
The condition ensures that this transition can be activated only if the last action happened at least 1000 ms back in time.
During the time barrier
is in CAR_ENTRY
, all incoming button events will not be processed but stored and processed when barrier
is switched back to IDLE
.
To complete the definition of barrier
you have to define a transition for event BUTTON_UP_PRESSED
correspondingly to BUTTON_DOWN_PRESSED
.
AtomicComponent
Next, all things are grouped into a AtomicComponent. Unfortunately, the current version of the framework requires all elements of the ports enum to be listed manually and passed as argument to createStatemachineComponent(...)
. The first array given is a list of ports and their specific event types. sm
is the state machine you created before and "barrier"
is the name of that component:
export const barrier: AtomicComponent<
EventTypesIntern | EventTypesExtern,
BarrierPorts
> = createStatemachineComponent(
[
{
name: BarrierPorts.TO_PARKING_MANAGEMENT,
eventTypes: Object.values(EventTypesIntern),
},
{
name: BarrierPorts.FROM_BUTTON_MCU,
eventTypes: Object.values(EventTypesExtern),
},
],
sm,
"barrier"
);
Initial State
Finally, we have to describe the initial state of the component. In our case the start state is set to IDLE
, the internal state to lastAction: 0
and we did not put any prepared event in the event queue.
export const barrierStartState: StateMachineState<BarrierStates, BarrierState, EventTypes, BarrierPorts> = {
state: {
fsm: BarrierStates.IDLE,
my: {
lastAction: 0
}
},
events: [],
tsType: "State"
};
If we want to dynamically set a start state without recompilation, e.g. with a configurable lastAction
value, we can instead define a StateGenerator
to create our state on runtime instead:
export const barrierStartStateGenerator: StateMachineStateGenerator<BarrierStates, BarrierState, EventTypes, BarrierPorts> = {
tsType: "StateGenerator",
argTypes: { lastAction: number } // allowed types are number, boolean or string
generate: ({ lastAction }) => {
return {
state: {
fsm: BarrierStates.IDLE,
my: {
lastAction: <number>lastAction
}
},
events: [],
tsType: "State"
}
}
};
Component parkingManagement
You can find parkingManagement
inside ParkingManagement.ts
of our examples repository. parkingManagement
consist of the states AVAILABLE
(there are free parking spaces in the parking garage) and FULL
(no free parking spaces left). It is connected via port FROM_BARRIER
to barrier
and via port TO_SIGNAL_CONTROLLER
to signalController
I/O component.
On every transition this component sends three events to the signalController
: LED RED on or off, LED GREEN on or off, and the remaining free parking spaces. Depending on the received car event from barrier
the number of free parking spaces (stored in the internal state of parkingManagement
) is in- or decreased. While there are free parking spaces left, parkingManagement
stays in AVAILABLE
. If there are no spaces left, it switches to FULL
.
Regarding to the way MQTT works, we raise three single events for each of the hardware components we want to control:
...
{
sourceState: ParkingManagementStates.AVAILABLE,
targetState: ParkingManagementStates.FULL,
event: ["oneway", EventTypesIntern.CAR_IN, ParkingManagementPorts.FROM_BARRIER],
condition: (myState) => myState.freeParkingSpaces - 1 === 0,
action: (myState, raiseEvent) => {
const updatedFreeParkingSpaces = myState.freeParkingSpaces - 1;
const pubPayloadRed: MQTTPubPayloadEventsEncoded = {
type: EventTypesExtern.LED_RED,
payload: { stringPayload: testbedStatusEncoder(true) },
};
const pubPayloadGreen: MQTTPubPayloadEventsEncoded = {
type: EventTypesExtern.LED_GREEN,
payload: { stringPayload: testbedStatusEncoder(false) },
};
const pubPayloadDisplay: MQTTPubPayloadEventsEncoded = {
type: EventTypesExtern.DISPLAY,
payload: {
stringPayload: testbedSpacesEncoder(updatedFreeParkingSpaces),
},
};
raiseEvent({
eventClass: "oneway",
type: pubPayloadRed,
port: ParkingManagementPorts.TO_SIGNAL_MCU,
});
raiseEvent({
eventClass: "oneway",
type: pubPayloadGreen,
port: ParkingManagementPorts.TO_SIGNAL_MCU,
});
raiseEvent({
eventClass: "oneway",
type: pubPayloadDisplay,
port: ParkingManagementPorts.TO_SIGNAL_MCU,
});
return {
freeParkingSpaces: updatedFreeParkingSpaces,
totalParkingSpaces: myState.totalParkingSpaces,
};
},
},
There is a small but important difference to the events we raised from barrier
. This time, the raised events have a payload.
raiseEvent({
eventClass: "oneway",
type: pubPayloadGreen,
port: ParkingManagementPorts.TO_SIGNAL_MCU,
});
To enable a state machine to handle events with a payload, we have to specify an additional payload type at the state machine definition MQTTPubPayloadEventsEncoded
:
const sm: StateMachine<
ParkingManagementStates,
ParkingManagementState,
MQTTPubPayloadEventsEncoded | EventTypesIntern | EventTypesExtern,
ParkingManagementPorts
> =
{ ... }
We can specify any arbitrary data type or interface as payload. In our case, the payload looks like this:
export interface MQTTPubPayloadEventsEncoded {
type: EventTypesExtern;
payload: {
stringPayload?: string;
};
}
The remaining things to do are similar to barrier
.
In the next section, we describe how MQTT I/O components can be specified.
MQTT Components
We use the MQTT protocol to communicate with the sensor nodes. MQTT follows the publish/subscribe pattern and is a lightweight machine-to-machine protocol for the Internet of Things.
Be aware that using MQTT requires a MQTT broker. You can run a broker at your own, for example Mosquitto, or use one that is public available, e.g., mqtt://test.mosquitto.org
. Whatever you decide to do, you must add your MQTT credentials to your configuration.
Something to keep in mind: During the start of your application each MQTT component connects to the MQTT broker, which could take some time.
We have two MQTT components: signalMCU
and buttonMCU
, which are defined in ext-components.ts
. Similarly to regular components, they require the an enum
to contain their ports:
export enum signalMCUPort {
FROM_PARKING_MANAGEMENT = "FROM_PARKING_MANAGEMENT",
}
export enum buttonMCUPort {
TO_BARRIER = "TO_BARRIER",
}
However, while MQTT components appear as regular components to others, the differ in their inner workings. They have no explicitly specified behavior, instead they mask the real, physical component (e.g. a micro controller) and act as a proxy messages sent by the device. On every MQTT message the component receives, it calls a decode function. If your function returns an event, the component will send it through the specified port.
Since in other regards the MQTT components are stateless, we define a function to create an empty component:
function createEmptyComponent(
name: string,
port: buttonMCUPort | signalMCUPort
): AtomicComponent<EventTypesExtern, buttonMCUPort | signalMCUPort> {
return {
name: name,
step: (state) => undefined,
allSteps: (state) => [state],
ports: [createPort(port, Object.values(EventTypesExtern))],
tsType: "Component",
};
}
and the create the components by calling
export const signalMCU = createEmptyComponent(
"signalMCU",
signalMCUPort.FROM_PARKING_MANAGEMENT
);
export const buttonMCU = createEmptyComponent(
"buttonMCU",
buttonMCUPort.TO_BARRIER
);
As mentioned, the MQTT-components are stateless, so their state is just a dummy:
export const compState: AbstractState<string, unknown, unknown> = {
state: "dummy_state",
events: [],
tsType: "State",
};
Setup configuration
At this point, we have declared the components and defined their logic, but they, as building blocks, are yet to be connected to each other. To achieve that, we have to do two things:
- we need to expose them to the framework logic
- we need to specify instances of our components, as well as connections between their ports.
Registering components
First, we need to make components and their states visible. We start by creating an index.ts
in the root of the folder the components are stored (in our case ./components
):
export * from "./barrier";
export * from "./ext-components";
export * from "./parking-management";
export * from "./event-types";
Then we add it to the index.ts
of the root folder of the project:
export * from "./components";
If we have done everything correctly, our components will show up if we call getSetupInfo()
from reflect.ts
, e.g. from the command line with node -e 'console.log(JSON.stringify(require(\"@sorrir/framework\").getSetupInfo(),undefined,2))'
:
{
"components": {
"barrier": {
"name": "barrier",
"ports": [
{
"name": "TO_PARKING_MANAGEMENT",
"eventTypes": [
"CAR_IN",
"CAR_OUT"
]
},
{
"name": "FROM_BUTTON_MCU",
"eventTypes": [
"BUTTON_UP_PRESSED",
"BUTTON_DOWN_PRESSED",
"LED_RED",
"LED_GREEN",
"DISPLAY"
]
}
],
"tsType": "Component"
},
...
},
"startStates": {
"barrierStartState": {
"state": {
"fsm": "IDLE",
"my": {
"lastAction": 0
}
},
"events": [],
"tsType": "State"
},
...
}
}
Component instances and connections
After we have registered the components, we can now declare instances of each component and connect their ports with each other. This is done via setup.json
in ./config
:
{
"componentInstances": {
"barrier": [
{
"name": "barrier",
"startState": "barrierStartState"
}
],
"signalMCU": [
{
"name": "signalMCU",
"startState": "compState"
}
],
"buttonMCU": [
{
"name": "buttonMCU",
"startState": "compState"
}
],
"parkingManagement": [
{
"name": "parkingManagement",
"startState": "parkingManagementStartState"
}
]
},
"connections": [
{
"sourceComponent": "barrier",
"sourcePort": "TO_PARKING_MANAGEMENT",
"targetComponent": "parkingManagement",
"targetPort": "FROM_BARRIER"
},
{
"sourceComponent": "buttonMCU",
"sourcePort": "TO_BARRIER",
"targetComponent": "barrier",
"targetPort": "FROM_BUTTON_MCU"
},
{
"sourceComponent": "parkingManagement",
"sourcePort": "TO_SIGNAL_MCU",
"targetComponent": "signalMCU",
"targetPort": "FROM_PARKING_MANAGEMENT"
}
]
}
In our case, we have one instance of every component. For example, one instance of type barrier
, called barrier
itself:
"barrier": [
{
"name": "barrier",
"startState": "barrierStartState"
}
],
Our barrier
instance has the start state barrierStartState
. If we were to use a dynamic state instantiation instead via the previously defined `barrierStartStateGenerator, we could instead also do this:
/* alternative with dynamic start state */
"barrier": [
{
"name": "barrier",
"startStateGenerator": "barrierStartStateGenerator",
"startStateArgs": {
"lastAction": 0
}
}
],
Application Configuration
Now that we have connected components to each other logically, we need to configure our application before being able to run it. This includes defining where components are to be executed, as well as how they shall communicate with each other.
Multiple components can be grouped into units, which can be run in seperate threads on the same machine or on separate devices. If we again look at our example, both barrier
and parkingManagement
will have their own unit (a
and b
), while external components are grouped into a unit called ext
:
graph TD
subgraph a [unit a]
subgraph barrier
TO_PARKING_MANAGEMENT(TO_PARKING_MANAGEMENT)
FROM_BUTTON_MCU(FROM_BUTTON_MCU)
end
end
subgraph ext [unit ext]
subgraph signalMCU
FROM_PARKING_MANAGEMENT(FROM_PARKING_MANAGEMENT)
end
subgraph buttonMCU
TO_BARRIER(TO_BARRIER)
end
end
subgraph b [unit b]
subgraph parkingManagement
FROM_BARRIER(FROM_BARRIER)
TO_SIGNAL_MCU(TO_SIGNAL_MCU)
end
end
style a fill:transparent,stroke-dasharray: 5 5;
style b fill:transparent,stroke-dasharray: 5 5;
style ext fill:transparent,stroke-dasharray: 5 5;
TO_SIGNAL_MCU --> FROM_PARKING_MANAGEMENT
TO_BARRIER --> FROM_BUTTON_MCU
TO_PARKING_MANAGEMENT --> FROM_BARRIER
Grouping and configuring components to work in units can be done with the deployment configuration, which is situation in three files within the ./config
folder: units.json
, development.json
and production.json
. The contents of the configuration files are loaded by convict
, a library that allows to overwrite parameters via command line parameters or environment variables. The schemas of each configuration are defined in config.ts
of the framework.
First, we define our units in units.json
:
{
"units": ["a", "b", "ext"]
}
Afterwards, we can go about define the parameters of each unit in development.json
and production.json
. During development and as long as NODE_ENV
is set to development
, development.json
is loaded, if set to production
, production.json
is loaded instead.
DeploymentConfiguration
In the DeploymentConfiguration
, we can set which components are part of which unit:
"DeploymentConfiguration": {
"a": {
"components": ["barrier"]
},
"b": {
"components": ["parking-management"]
},
"ext": {
"components": ["signalMCU", "buttonMCU"]
}
}
Configuring connection technologies
As mentioned earlier, three connection technologies are currently available (MQTT
, REST
and BLE
). Eachs configuration is done in a separate parameter.
HostConfiguration
HostConfiguration
holds the config for the REST
technology. Each host requires a hostname and a port.
"HostConfiguration": {
"a": {
"host": "localhost",
"port": 1234
},
"b": {
"host": "localhost",
"port": 1235
},
"ext": {
"host": "ext"
}
}
MQTTConfiguration
MQTTConfiguration
configures MQTT
. It does not require host specific parameters, just a global host address, as well as login credentials. Because of security concerns, it is better to not include the username
and password
keys into the configuration itself if possible, rather they should be set as environment variables.
"MQTTConfiguration": {
"host": "test.mosquitto.org"
}
BLEConfiguration
BLEConfiguration
configures communication via Bluetooth Low Energy. In contrast to REST
and MQTT
, it is not IP-based, meaning it requires an additional Bluetooth adapter to function. The control of the Bluetooth adapter is implemented in a separate repository (ble-ms-service
). This Bluetooth service needs to run in parallel to the framework on every device that is supposed to include Bluetooth functionality. Internal communication between framework and the service is done via REST
. Each unit sends its messages to the service listening on sendHost
at the specific sendPort
and receives accordingly for answers.
"BLEConfiguration": {
"a": {
"sendHost": "localhost",
"sendPort": 8080,
"listenHost": "localhost",
"listenPort": 8081
},
"b": {
"sendHost": "localhost",
"sendPort": 8080,
"listenHost": "localhost",
"listenPort": 8081
},
"ext": {
"sendHost": "ext",
"sendPort": 8080,
"listenHost": "ext",
"listenPort": 8081
}
}
REST
is configured in HostConfiguration
, MQTT
and BLE
in their parameter accordingly.
CommunicationConfiguration
In CommunicationConfiguration
, we can set the technologies that are to be used for each specific connection. Currently, the three aforementioned options are available: MQTT
, REST
and BLE
. Connections that are defined in setup.json
, but not in here, default to REST
.
"CommunicationConfiguration": {
"connectionTechs": [
{
"sourceContainer": "ext",
"sourceComponent": "buttonMCU",
"sourcePort": "TO_BARRIER",
"targetContainer": "a",
"targetComponent": "barrier",
"targetPort": "FROM_BUTTON_MCU",
"commOption": "MQTT"
},
{
"sourceContainer": "b",
"sourceComponent": "parking-management",
"sourcePort": "TO_SIGNAL_MCU",
"targetContainer": "ext",
"targetComponent": "signalMCU",
"targetPort": "FROM_PARKING_MANAGEMENT",
"commOption": "MQTT"
},
{
"sourceContainer": "a",
"sourceComponent": "barrier",
"sourcePort": "TO_PARKING_MANAGEMENT",
"targetContainer": "b",
"targetComponent": "parking-management",
"targetPort": "FROM_BARRIER",
"commOption": "REST"
}
]
}
In our case, the communication between barrier
and parkingManagement
is done with REST
, while communication with external components is done with MQTT
.
ResilienceConfiguration
In the ResilienceConfiguration
, you can configure resilience mechanisms to be applied to a list of components. Currently supported mechanisms are activeReplication
and checkpointRecovery
.
The mechanism activeReplication
allows you to run n
independent replicas of a component to tolerate up to f
faults. SORRIR currently provides two different fault models (faultModel
) to choose from: BFT
(Byzantine fault tolerance) and CFT
(Crash fault tolerance). After choosing a faultModel
and the assumed upper bound of expected faults f
, you need to keep in mind to provide sufficiently enough replicas n
. The number of n
depends on both fault model and f: n=3f+1 (BFT) or 2f+1 (CFT)
.
The mechanism checkpointRecovery
allows you to persist the state of your component on non-volatile storage in the form of a checkpoint file for each component (in JSON format). The checkpoints are located in the checkpoints
folder. Upon restart of a crashed component, SORRIR then recovers the application state of a component from its checkpoint.
At the moment, you may not select both activeReplication
and checkpointRecovery
for the same component.
An example for a ResilienceConfiguration
may look like this:
"ResilienceConfiguration": {
"components": [
{
"id": "user",
"mechanisms": {
"activeReplication": {
"enabled": true,
"faultModel": "BFT",
"n": "4",
"f": 1,
"executionSites": [ "a", "c", "d", "e" ]
}
}
},
{
"id": "barrier",
"mechanisms": {
"checkpointRecovery": {
"recovery": {
"enabled": true
},
"checkpoint": {
"enabled": true
}
}
}
}
]
}
Run the application
To execute the application, we must define a small start up script, for example in a file called app.ts
.
import { executeRunConfiguration } from "@sorrir/framework";
import { INIT_SEQUENCER_CLOCK_STATE } from "@sorrir/framework";
import { computeLocallyDeployedConfiguration } from "@sorrir/framework";
import { setup } from "@sorrir/framework";
const runConfig = setup();
async function main() {
if (
runConfig.toExecute &&
runConfig.toExecute !== "" &&
runConfig.hostConfiguration.hasOwnProperty(runConfig.toExecute)
) {
await executeRunConfiguration(runConfig);
} else if (
runConfig.toExecute !== "" &&
!runConfig.hostConfiguration.hasOwnProperty(runConfig.toExecute)
) {
console.log(`unknown host "${runConfig.toExecute}`);
} else {
console.log("no container defined to execute");
}
}
main().catch((e) => console.log(e));
If this script is executed with npm run start
, you can start each unit separately with
npm run start -- --to-execute=<unit name>
Communicate with the running application
To test functionality, for instance by sending mock-events to specific components/ports, the sendEvent
script can be utilized. To do this, make sure your package.json
includes
"scripts": {
"sendEvent": "node node_modules/@sorrir/framework/dist/scripts/sendEvent.js"
...
},
Then you can send an event via
npm run sendEvent -- --source barrier --target parking-management --type CAR_OUT --class oneway --port TO_PARKING_MANAGEMENT
For full documentation of sendEvent.js
types, enter npm run sendEvent -- --help
.
Agent-Configuration
Shadow-Agent
The shadow-agent needs to be configured to allow automatic degradation. To configure it, use the parameter ShadowModeConfiguration
in the deployment-configuration.
"ShadowModeConfiguration": {
"<unit-name>": {
"shadowAgent": {
"enabled": true, // Specifies if the shadow agent is enabled for this unit.
"commOptions": ["REST","MQTT"], // Communication technologies that shadow-agent uses.
"autoUpdate": {
"intervalSeconds": 2, // Interval in which the shadow map is automatically updated. A value of '-1' disables auto-updating.
"strategy": "gossip", // Strategy for auto-updates of shadow map. Allowed is "push" or "gossip"
"limit": -1, // Specifies the maximum number of entries to be shared in an auto-update message. '-1' disables the limit.
"content": "local-only", // Specifies if only local components are shared or if entries of the whole shadow-map can be shared.
}
},
"inMessageSharing": {
"enabled": true, // Specifies if shadow modes are shared as part of regular messages.
"limit": -1, // Specifies the maximum number of entries to be shared in a message. '-1' disables the limit.
"content": "local-only", // Specifies if only local components are shared or if entries of the whole shadow-map can be shared.
}
},
...
}
Debugging-Agent
The debugging agent can be configured to allow observing a distributed execution of the framwork. To configure it, use the parameter DebuggingConfiguration
in the deployment-configuration.
"DebuggingConfiguration": {
"<unit-name>": {
"debuggingAgent": {
"enabled": true, // Specifies if the debugging agent is enabled for this unit.
"isServer": false, // Specifies if the debugging agent shall receive data from and be able to control other debugging agents.
"checkForChangesIntervalMs": 1000, // The interval in which changes are being checked, potentially triggering an update to servers.
"commOptions": ["REST","MQTT"], // Communication technologies that debugging-agent uses.
}
},
...
}
There are two different kinds of debugging agents. Non-server agents send their data to server-agents. In return, server-agents can control non-server agents.
Temporary Store
The following part was moved from the examples repo and needs to be integrated in this readme file.
Howto: Implementation of external communication capability with a sorrir component
Create an empty component representing the external actor and associated connections to the sorrir component. E.g.:
...
export enum EventTypesExtern {
EXT_EVENT = "EXT_EVENT",
}
...
export enum externalActorPort {
TO_BARRIER = "TO_BARRIER",
}
function createEmptyComponent(
name: string,
port: externalActorPort
): AtomicComponent<EventTypesExtern, externalActorPort> {
return {
name: name,
step: (state) => undefined,
allSteps: (state) => [state],
ports: [createPort(port, Object.values(EventTypesExtern))],
};
}
export const compState = { state: "dummy_state" };
export const externalActor = createEmptyComponent(
"externalActor,
externalActorPort.TO_BARRIER
);
In units.json, add an entry for gthe external component:
{
"units": ["a", "b", "ext"]
}
In development.json or production.json, set the connection approprietly:
{
"HostConfiguration": {
...
"ext": {
"host": "ext"
}
},
"DeploymentConfiguration": {
...
"ext": {
"components": ["externalActor"]
}
},
"CommunicationConfiguration": {
"connectionTechs": [
{
"sourceContainer": "ext",
"sourceComponent": "externalActor",
"sourcePort": "TO_BARRIER",
"targetContainer": "a",
"targetComponent": "barrier",
"targetPort": "FROM_EXTERNAL_ACTOR",
"commOption": "MQTT"
},
...
In setup.json:
{
"components": {
...
"externalActor": {
"resources": {
"component": "externalActor",
"ports": "externalActorPort",
"startState": "compState",
"eventTypes": "EventTypesExtern"
},
"inPorts": [],
"outPorts": [ "TO_BARRIER" ]
},
...