Table of Contents

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Introduction to Subscriptions

Subscriptions allow two picos to communicate with each other on a secure channel. Subscriptions have several advantages and uses:

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Subscriptions are formed from two channels from two different Picos. Each channel has a corresponding Eci stored for the other Picos channel.

From each pico's perspective there is an incoming channel and an outgoing channel. The pico receives events and queries from the other pico in the subscriptions over the incoming channel and makes queries and sends events to the other pico using the outgoing channel.

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Pico A receives a wrangler:subscription event that includes the following attributes:
1. name - name of subscription (if none is supplied, a random subscription name will be generated)
2. name_space - name space for subscription (if none is supplied shared will be used as the name space)
3. my_role - Pico A's role in the subscription (if none is supplied, peer will be used for the role)
4. subscriber_role - Pico B's role in the subscription (also defaults to peer).
5. subscriber_eci - Pico B's well known ECI. Pico A must receive an ECI to contact Pico B. (This eci will be stored after the subscription has been accepted. Events should be sent to the outbound eci, not the original subscriber eci.)
6. channel_type - the channel type for Pico A's yet to be created inbound ECI (if none is supplied, subs will be used).
7. attrs - the attributes for this subscription. These are used for Pico A's incoming channel's attributes. If none are supplied, the default is "status".
Pico A creates a channel for the subscription which stores subscription information in the new channel and provides a new inbound eci for this particular subscription.
Pico A sends a wrangler:pending_subscription event to Pico B, using the channel given by the subscriber_eci in step one with the following attributes:
1. name - name of subscription.
2. name_space - name space for subscription.
3. my_role - Pico B's role in the subscription.
4. subscriber_role - Pico A's role in the subscription.
5. outbound_eci - Pico A's newly created inbound ECI.
6. channel_type - the channel type for Pico B's yet to be created inbound ECI (the same as Pico A's).
7. attributes - the attributes for this subscription. These are used for Pico B's incoming channel's attributes.
Pico B creates a channel for the subscription which stores subscription information in the new channel and provides a new inbound eci for this particular subscription.
Pico A also raises an internal wrangler:pending_subscription event with the corresponding attributes above.
Upon receiving the wrangler:pending_subscription event, Pico B, creates a pending subscription (channel mentioned above) and raises the wrangler:inbound_pending_subscription_added event. Pico A raises the wrangler:outbound_pending_subscription_added event.
The state of each Picos subscription is static at this point. Pico A has an outgoing pending subscription and Pico B has an incoming pending subscription.
If Pico B wants to approve the subscription request, it raises the wrangler:pending_subscription_approval event with an attribute named channelsubscription_name giving the name of the channel/subscription to approve. Upon successfully creating the subscription. Pico B:
1. sends the wrangler:pending_subscription_approved event to Pico A on Pico B's outbound_eci value stored in its subscription.
2. raises the wrangler:subscription_added event
Upon receiving the wrangler:pending_subscription_approved event, Pico A adds an outbound_eci to the subscription on its side and raises the wrangler:subscription_added event.
1. Pico A then raises the wrangler:sending_key event to faclitate a key exchange with the pico it is subscribing to.
If Pico B wants to reject the subscription, it raises the wrangler:inbound_subscription_rejectioncancellation event (internally) with an attribute named channelsubscription_name - the name of the channel/subscription to reject. Pico B:
1. sends the wrangler:subscription_removal event to Pico A on Picos B outbound_eci, which then raises the wrangler:subscription_removed event to itself.
2. raises the wrangler:subscription_removal event, which raises the wrangler:subscription_removed event.

Upon receiving a wrangler:subscription_removal event, the pico deletes the named subscription from the inbound or outbound subscriptions list as appropriate.

Initial Subscription Flow

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Subscription Approval Flow

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Subscription Rejection Flow

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Subscription Events

Info
This section mentions getSubscriptions(), which is provided by the Subscriptions ruleset and returns a map from all subscription names to subscription objects.documented in the last section, Subscription Functions.

Overview

Event Domain	Event Type	Actions	Use
wrangler	subscription	creates outbound pending subscription and sends pending_subscription event to external pico	Creates a new outbound pending subscription
wrangler	pending_subscription	creates inbound pending subscription	Creates a new inbound pending subscription
wrangler	pending_subscription_approval	sends pending_subscription_approved event with inbound_eci and outbound status to external pico and raises pending_subscription_approved with inbound status	Aprove inbound pending subscription
wrangler	pending_subscription_approved	updates subscription status and outbound_eci if needed	Internally for adding aproved subscriptions
wrangler	subscription_cancellation \| inbound_subscription_rejection \| outbound_subscription_cancellation	sends subscription_removal event with eci and status and raise the same event to self	alert external pico to remove subscriptions and alert self to remove subscription
wrangler	subscription_removal	deletes channel used for subscription	internally for removing channel used for subscription

Events Users Might Raise

wrangler:subscription
wrangler:outbound_subscription_cancellation
wrangler:inbound_subscription_rejection
wrangler:subscription_cancellation
wrangler:pending_subscription_approval

Events Users Might React To

wrangler:outbound_pending_subscription_added
wrangler:inbound_pending_subscription_added
wrangler:subscription_removed
wrangler:subscription_added

Event Attributes

wrangler:subscription (pico A)

Name	Default	Use
attrs	"status"	additional data to store for the new subscription - can be any type
channel_type	"subs"	describes each pico's new channel created for the subscription
my_role	"peer"	describes pico A (self) in the context of the subscription
name	string including a random English word	If a subscription with the same combination of name and namespace exists in the engine hosting pico A, the subscription won't be created. Otherwise, pico A will receive wrangler:outbound_pending_subscription_added and pico B will receive wrangler:inbound_pending_subscription_added. If pico B is hosted on a different engine and a subscription with this full name already exists there (e.g. "namespace:name"), the new subscription will be cancelled and both picos will receive wrangler:subscription_removed after the '_added' events.
name_space	"shared" (doesn't work in 0.11.x)
subscriber_eci	the subscription won't be created	the subscription process needs one of pico B's existing eci's
subscriber_host	none	the public DNS name of the engine hosting pico B (only needed if different from pico A's) - e.g. "https://localhost:8080"
subscriber_role	"peer"	describes pico B in the context of the subscription

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Code Block

   { "eci": "cj3n6fe0w0003v8id271a0rlz", // pico B's new eci
     "name": "namespace:name",
     "type": "subssubscription",
    
     "attributes": 
      { "subscription_name": "name",
        "name_space": "namespace",
        "relationship": "peer 2<->peer 1",
        "my_role": "peer 2",
        "subscriber_role": "peer 1",
        "outbound_eci": "cj3lyamf30003pi0n6u39rsqs",
        "status": "inbound",
        "attributes": "status",
        "subscriber_host": "http://localhost:8080",
        "sid": "namespace:name" } }

wrangler:subscription_removed

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Name	Value
channel_name	full subscription name(e.g. "namespace:name")

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verify_key	public cryptographic key used to verify digital signatures
other_verify_key	the public crytpographic key from the pico that this pico is subscribed to. Used to verify digitally signed messages
encryption_public_key	the public key that can can be used by another channel to create a shared secret, in conjuction with that channl's private key, to allow encryption and decryption.
other_encryption_public_key	the public cryptographic key form the pico that this pico is subscribed to. It is used to allow encryption of channel messages.

example value of getSubscriptions(){channel_name}: (pico A)

Code Block

   { "eci": "cj3lyamf30003pi0n6u39rsqs", // pico A's new eci
     "name": "namespace:name",
     "name_spacetype": "namespacesubscription",
     "verify_key": "F9S4uC6bZ9pDBZMPeKUHCHrhdMkrTq9GExj8HHtGDTKq",
	 "relationshipother_verify_key": "peer 1<->peer 2GjmSgqkBpAcCkt9H179pqgrQ27zPn336aaNHHHtFspAz",
  
     "myencryption_public_rolekey": "peer 13cyFiAMRpq1Q4ciEzSoQNzAQHr9voTCu9P46Kyx6qCUz",
        "subscriber_role"other_encryption_public_key": "peer 27y9dqgw7KucvYToAguuBP4Shf1cqtnhUF93waBR799e3",
  
     "subscriber_eciattributes": "cj3ly7c9m0002pl0nk2zklk4g", 
      { "statussubscription_name": "subscribedname", // changed
        "attributesname_space": "statusnamespace",
        "subscriber_hostrelationship": "http://localhost:8081peer 1<->peer 2",
        "sidmy_role": "namespace:namepeer 1",
        "outboundsubscriber_ecirole": "cj3n6fe0w0003v8id271a0rlzpeer 2",
} } // now available to pico A

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Code Block

   { "subscriber_eci": "cj3n6fe0w0003v8id271a0rlzcj3ly7c9m0002pl0nk2zklk4g",
// pico B's new eci
     "namestatus": "namespace:namesubscribed", //   changed
 "type": "subs",      "attributes": "status",
       { "subscriptionsubscriber_namehost": "namehttp://localhost:8081",
        "nameoutbound_spaceeci": "namespacecj3n6fe0w0003v8id271a0rlz", } } // now available to   "relationship": "peer 2<->peer 1",
  pico A

example value of getSubscriptions(){channel_name}: (pico B)

Code Block

   { "eci": "cj3n6fe0w0003v8id271a0rlz", // pico B's new eci
     "my_rolename": "peer 2namespace:name",
  
     "subscriber_roletype": "peer 1subscription",
     "verify_key": "GjmSgqkBpAcCkt9H179pqgrQ27zPn336aaNHHHtFspAz",
	 "outboundother_verify_ecikey": "cj3lyamf30003pi0n6u39rsqsF9S4uC6bZ9pDBZMPeKUHCHrhdMkrTq9GExj8HHtGDTKq",
     "encryption_public_key": "7y9dqgw7KucvYToAguuBP4Shf1cqtnhUF93waBR799e3",
   "status  "other_encryption_public_key": "subscribed3cyFiAMRpq1Q4ciEzSoQNzAQHr9voTCu9P46Kyx6qCUz",
   // changed  "attributes": 
      { "attributessubscription_name": "statusname",
        "subscribername_hostspace": "namespace",
        "relationship"http://localhost:8080: "peer 2<->peer 1",
        "sidmy_role": "namespace:name" } }

Subscription Functions

Info
The following subscription functions are not yet implemented.

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Function

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Use

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All subscription functions return an object with a status and a return object except for checkSubscriptionName. Documentation will reference the return object only.

subscriptions

returns an array of subscription collections keyed to subscriptions. Each subscription object is owned by the pico that calls this function.

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Parameter

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Datatype

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Required

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<id> = <subscription channel_name> | <subscriptions channel_eci> | <subscriptions_name>
<collection> = <name_space> | <relationship> | <status> | <channel_name> | <inbound_eci> | <outbound_eci> | <subscriber_role> | <my_role> | <subscriber_eci>(might break things) |<attributes>
<filtered> = <desired value of collection>

On success

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key

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value

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subscriptions

<name_space:channel_name>:

      {"name_space":<string>,

       "relationship":<string>,

       "status":<string>,

       "channel_name":<string>,

       "inbound_eci":<string>,

       "subscriber_role":<string>,

peer 2",
        "subscriber_role": "peer 1",
        "outbound_eci": "cj3lyamf30003pi0n6u39rsqs",
        "status": "subscribed", // changed
        "attributes: "status",
        "subscriber_host": "http://localhost:8080" } }

Subscription Functions

getSubscriptions

Returns a map from subscription names to subscription objects, or various forms of this map.

Parameter	Datatype	Required
<collectBy>	<hash path>	no
<filterValue>	<string>	no, and don't use if <collectBy> is omitted

getSubscriptions() with no arguments returns the entire map, e.g.

Code Block

{
  "namespace:name1": {
    "name": "namespace:name1",
    "attributes": {
      "status": "subscribed",
      ...
    },
    ...
  },
  "namespace:name2": {
    "name": "namespace:name2",
    "attributes": {
      "status": "inbound",
      ...
    },
    ...
  }
}

getSubscriptions(["attributes", "status"]) collects by the value at that hash path, returning a map from subscription statuses (in this example) to arrays of subscription objects with those values, e.g.

Code Block
{ "inbound": [ { "namespace:name2": { "name": "namespace:name2", "attributes": { "status": "inbound", ... }, ... } } ], "subscribed": [ { "namespace:name1": { "name": "namespace:name1", "

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attributes":

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status":

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 "subscribed",

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}

uses example

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language	javascript
theme	Confluence

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   },
        ...
      }
    }
  ]
}

getSubscriptions(["attributes", "status"], "inbound") uses "inbound" as the filter value, returning only the first array above.

Versions Compared

Old Version 29

New Version Current

Key

Introduction to Subscriptions

Initial Subscription Flow

Subscription Approval Flow

Subscription Rejection Flow

Subscription Events

Overview

Events Users Might Raise

Events Users Might React To

Event Attributes

Subscription Functions

subscriptions

Subscription Functions

getSubscriptions

Page Comparison

Versions Compared

Old Version 29

New Version Current

Key

Introduction to Subscriptions

Initial Subscription Flow

Subscription Approval Flow

Subscription Rejection Flow

Subscription Events

Overview

Events Users Might Raise

Events Users Might React To

Event Attributes

Subscription Functions

subscriptions

Subscription Functions

getSubscriptions