Internet DRAFT - draft-wendt-modern-drip
draft-wendt-modern-drip
modern C. Wendt
Internet-Draft H. Bellur
Intended status: Standards Track Comcast
Expires: January 4, 2018 July 03, 2017
Distributed Registry Protocol (DRiP)
draft-wendt-modern-drip-02
Abstract
This document describes a protocol for allowing a distributed set of
nodes to synchronize a set of information in real-time with minimal
amount of delay. This is useful for registry types of information
like identity and telephone numbers with associated routing and
ownership information and could be extended to support other
distributed real-time information updates as well.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 4, 2018.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. DRiP Overview . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Distributed MESH Architecture . . . . . . . . . . . . . . . . 3
5. DRiP procedures . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Distributed Registry Rules . . . . . . . . . . . . . . . 4
5.2. Node State . . . . . . . . . . . . . . . . . . . . . . . 5
5.2.1. API - POST /node/:nodeid/active . . . . . . . . . . . 5
5.2.2. API - POST /node/:nodeid/inactive . . . . . . . . . . 5
5.2.3. API - GET /state . . . . . . . . . . . . . . . . . . 5
5.3. Custom HTTP header fields . . . . . . . . . . . . . . . . 6
5.4. Key-Value Data Propagation Rules . . . . . . . . . . . . 8
5.5. Key-Value Data Update . . . . . . . . . . . . . . . . . . 9
5.5.1. Voting Phase . . . . . . . . . . . . . . . . . . . . 10
5.5.2. Commit Phase . . . . . . . . . . . . . . . . . . . . 12
5.6. Node Sync Operation . . . . . . . . . . . . . . . . . . . 14
5.6.1. API - PUT /sync/node/:nodeid . . . . . . . . . . . . 14
5.7. Heartbeat . . . . . . . . . . . . . . . . . . . . . . . . 15
5.7.1. API - POST /heartbeat/node/:nodeid . . . . . . . . . 16
5.8. Key-Value Data Update Entitlement Verification . . . . . 16
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
6.1. HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 16
6.3. Payload Validation . . . . . . . . . . . . . . . . . . . 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
9.1. Normative References . . . . . . . . . . . . . . . . . . 17
9.2. Informative References . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
This document describes the Distributed Registry Protocol (DRiP).
DRiP defines a set of peer protocols for how an arbitrary number of
nodes arranged in a distributed mesh architecture can be used to
synchronize data in real-time across a network.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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Initiator Node - A node that initiates data propagation.
Receiver Node - A node that forwards the propagated key-value data.
3. DRiP Overview
DRiP uses a mix of a gossip protocol with update counters for
distribution of key-value data with the addition of a voting system
to avoid race conditions on writing of key-value data.
4. Distributed MESH Architecture
The DRiP architecture is based on a peer-to-peer communication model
where a given node associated with a data store is not necessarily
aware of the total number of nodes in the entire network. Minimally,
every node should reachable by at least one multi-node path from
every other node. Each node in the DRiP network maintains a list of
peer nodes from which it receives and transmits updates. Information
is propagated by forwarding to it's peer nodes until the information
received by a node has already been received.
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___ ___ ___ ___
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
| Data | | Data |
| Store | | Store |
_|_ Cluster _|_ _|_ Cluster _|_
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
\ /
\ /
_\___ DRIP _ /__
|Node |------------|Node |
| A | HTTPS | C |
|_____| |_____|
\H H/
D\T T/D
R\T P/R
I\P P/I
P\S S/P
__\__ / DRIP _____
|Node |------------|Node |
| B | HTTPS | D |
|_____| |_____|
/ /
___ ___ / __/_ ___
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
| Data | | Data |
| Store | | Store |
_|_ Cluster _|_ _|_ Cluster _|_
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
Distributed Mesh Architecture
5. DRiP procedures
5.1. Distributed Registry Rules
All nodes in the distributed mesh MUST agree upon a specific key-
value data model. The choice of data store is implementation
specific.
All nodes MUST be configured with at least one peer node before
propagation.
A node MUST ignore any updates or commands it receives from other
nodes that are not configured as peer nodes.
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All nodes MUST send a periodic heartbeat or keep-alive message via
HTTPS to the respective peer nodes. If a heartbeat is not received
the peer node is removed from the list of active peer nodes.
5.2. Node State
The peer node should maintain a state that defines whether it is
active, inactive, or synchronizing key-value data with a peer node.
The node should proactively tell it's peer nodes its state by sending
the following POST messages. The GET query is available for nodes to
query the state of peer nodes.
5.2.1. API - POST /node/:nodeid/active
Example (using cURL)
Request
$ curl -i -H "DRiP-Node-ID: nodeA" -H "Authorization: eyJ0e..."
-X POST https://nodearegistry.com/node/nodeA/active
Response
HTTP/1.1 200 OK
5.2.2. API - POST /node/:nodeid/inactive
Example (using cURL)
Request
$ curl -i -H "DRiP-Node-ID: nodeA" -H "Authorization: eyJ0e..."
-X POST https://nodearegistry.com/node/nodeA/inactive
Response
HTTP/1.1 200 OK
5.2.3. API - GET /state
Description:
A node should query the state of its peer node before it initiates a
sync operation. This request responds with either "active" or "sync"
or no response, if in "inactive" state.
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Example (using cURL)
Request
$ curl -i -H "DRiP-Node-ID: nodeA" -H "Authorization: eyJ0e..."
-X GET https://nodearegistry.com/state
Response
HTTP/1.1 200 OK with the following JSON object.
+----------+----------------------------------+
| Property | Description |
+----------+----------------------------------+
| state | "active" or "inactive" or "sync" |
+----------+----------------------------------+
5.3. Custom HTTP header fields
Custom HTTP header fields will be used to carry node specific
information.
+----------------+--------------------------------------------------+
| Field Name | Description |
+----------------+--------------------------------------------------+
| DRiP-Node-ID | Each node in the mesh MUST have a unique |
| | identifier. An Initiator node MUST set its own |
| | node ID as the field value. A Receiver Node MUST |
| | NOT change the DRiP-Node-ID field value as it |
| | forward the HTTPS request to its peer nodes. |
+----------------+--------------------------------------------------+
Example:
DRiP-Node-ID: xyz
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+---------------------+---------------------------------------------+
| Field Name | Description |
+---------------------+---------------------------------------------+
| DRiP-Node-Counter | Every node maintains a count of the number |
| | of times it initiates key-value data |
| | propagation. This counter MUST be an |
| | unsigned type, typically, a 64 bit integer. |
| | The Initiator node MUST set this count as |
| | the field value. A Receiver Node MUST NOT |
| | change the DRiP-Node-Counter field value as |
| | it forward the HTTPS request to its peer |
| | nodes. |
+---------------------+---------------------------------------------+
Example:
DRiP-Node-Counter: 123
+-------------------------+-----------------------------------------+
| Field Name | Description |
+-------------------------+-----------------------------------------+
| DRiP-Node-Counter-reset | A node can reset the count (to zero) of |
| | the number of times it initiates key- |
| | value data propagation. If the counter |
| | value is reset, prior to initiating |
| | data propagation, then this field value |
| | MUST be set to true. Otherwise, it MUST |
| | be set to false, at all times. A |
| | typical use case to reset the counter |
| | value is when the counter (of unsigned |
| | type) value wraps around. The Initiator |
| | node MUST set this field value to |
| | either true or false. A Receiver Node |
| | MUST NOT change the DRiP-Node-Counter- |
| | reset field value as it forward the |
| | HTTPS request to its peer nodes. |
+-------------------------+-----------------------------------------+
Example:
DRiP-Node-Counter-reset: false
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+-------------------------+-----------------------------------------+
| Field Name | Description |
+-------------------------+-----------------------------------------+
| DRiP-Transaction-Type | The Initiator node MUST set this field |
| | value to be either "update" or "sync". |
| | A Receiver Node MUST NOT change the |
| | DRiP-Transaction-Type field value as it |
| | forward the HTTPS request to its peer |
| | nodes. |
+-------------------------+-----------------------------------------+
Example:
DRiP-Transaction-Type: update
+-----------------------+-------------------------------------------+
| Field Name | Description |
+-----------------------+-------------------------------------------+
| DRiP-Sync-Complete | For sync transaction type, the Initiator |
| | node MUST set this field value to be |
| | true, if synchronization is complete. |
| | Otherwise, this field value MUST be set |
| | to false. |
+-----------------------+-------------------------------------------+
Example:
DRiP-Sync-Complete: false
5.4. Key-Value Data Propagation Rules
A node propagates key-value data to all its peer nodes except the the
node from which it received data. For example, in Figure 1, when
node B receives key-value data from node A, it will propagate the
data received to nodes C and D but not back to node A.
For each transaction type (Update or Sync), the following set of
actions MUST take place when a node receives a HTTPS request with
propagated key-value data:
o If DRiP-Node-ID field value (in the HTTP header) contains
Initiator node ID that has never been seen, both DRiP-Node-ID and
DRiP-Node-Counter field values MUST be stored for future reference
and the key-value data is propagated to all peer nodes.
o If DRiP-Node-ID field value (in the HTTP header) matches with a
stored node ID and DRiP-Node-Counter-reset field value is false.
* The received key-value data MUST be propagated to the peer
nodes if DRiP-Node-Counter field value is greater than the
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saved counter value. The DRiP-Node-Counter field value MUST be
saved as the new counter for the stored node ID.
* If DRiP-Node-Counter field value is less than or equal to saved
counter value, then the key-value data has already been
received and MUST NOT be propagated to peer nodes. This
ensures that propagation stops when all nodes have received the
key-value data from the Initiator node.
o If DRiP-Node-ID field value matches with a stored node ID and
DRiP-Node-Counter-reset field value is true:
* The received key-value data MUST be propagated to the peer
nodes. The DRiP-Node-Counter field value MUST be saved as the
new counter for the stored node ID.
5.5. Key-Value Data Update
When an Initiator node has new data it wants to propagate to the
distributed mesh, it initiates an Update. The Update consists of a
two-phase commit (2PC) procedure in order to guarantee there are no
race conditions for updating the same key's data, as well as for any
error conditions in the distributed mesh that would cause the update
to not complete for all nodes in the network.
The two phases are called the "voting" phase and the "commit" phase.
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_________
----------------------->| |
| | Waiting |
| | For |
| ---------------------| Events |
| | (Update, |_________|
| | Start Timer)
| | --------------------------------
| | | Received Update From Peer Node |
| | | |
| | ______________|_ If key matches an |
| | | | in-progress update |
| ----------->| | vote "no". |
| | Waiting For | Otherwise, vote "yes". |
| | Response From | |
| | Peer Nodes |<-----------------------------
| | |
| ----| |----
| Timer | |________________| |
| Expired | | Received Votes
| | | From All Peer
| | | Nodes
| | _______________ |
| | | | |
| | | | |
| --->| |<---
| | Validating |
| (If all Votes | Votes |
| are "YES", | |
| propagate | |
| commit) | |
---------------|________________|
Update State Diagram
5.5.1. Voting Phase
The voting phase is the phase where all nodes are queried to "vote"
whether they are aware of any potential conflict that would cause the
transaction not to complete.
The Initiator node MUST set a timeout period to get response from its
peer nodes.
The peer nodes known to the initiator node will continue propagate
the information to their peer nodes and so on. However, these peer
nodes beyond the initiator node will no longer need to keep track of
the time interval for responses. A node will stop continuing to
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propagate information when it determines it has received the same
information again. This can be determined by keeping track of the
counter and originating node id.
If all peer nodes vote "yes", then the second phase or commit phase
in the local node is initiated. If any node in the distributed mesh
votes "no" or if the timeout period expires and all peer nodes have
not responded, then the commit of the information MUST NOT be
completed. No action is taken for responses received after the
timeout period.
Note: The voting procedure is intentionally split into two separate
full HTTP transactions for reliability.
___ ___ ___ ___ ___ ___
|DB |_________|DB | |DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___| |___| |___|
| Data | | Data | | Data |
| Store | | Store | | Store |
_|_ Cluster _|_ _|_ Cluster _|_ _|_ Cluster _|_
|DB |_________|DB | |DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___| |___| |___|
\ \ |
\ \ |
_\___ Vote(HTTPS) _\___ Vote(HTTPS) |____
|Node | <---------- |Node | ----------> |Node |
| B |---------------| A |---------------| C |
|_____| ----------> |_____| <---------- |_____|
Yes/No Yes/No
Voting Phase
5.5.1.1. API - POST /voting
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Request:
POST /voting
Description:
A post from either Initiator node or subsequent peer nodes to request
a vote of "yes" or "no" whether the key-value data could be committed
without error or conflict.
Example (using cURL)
Request
$ curl -i -H "Content-Type: application/json" -H "DRiP-Node-ID:
nodeA" -H "DRiP-Node-Counter: 1234" -H
"DRiP-Node-Counter-reset: false" -X POST -d '{<key-value
data>}' https://nodebregistry.com/voting
Response
HTTP/1.1 200 OK
5.5.1.2. POST /votingphase/node/:nodeid/response/:response
Request:
POST /voting/peernode/:nodeid/response/:response
Description:
A POST from peer node back to node with response of vote.
Example (using cURL)
Request
$ curl -i -X POST http://nodearegistry.com/node/nodeA/response/yes
Response
HTTP/1.1 200 OK
5.5.2. Commit Phase
The Initiator node, that originated the gossip, upon receiving a
successful aggregated "yes" vote from all the peer nodes should start
the commit phase. This node MUST commit the data to its data store.
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Subsequently, this information is propagated to all the nodes so that
each node in the mesh will commit the same information in their
respective data stores.
___ ___ ___ ___
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
| Data | | Data |
| Store | | Store |
_|_ Cluster _|_ _|_ Cluster _|_
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
\ /
\COMMIT /COMMIT
_\___ COMMIT _ /__
|Node |------------|Node |
| A | HTTPS | C |
|_____| |_____|
\H H/
\T T/
COMMIT\T P/COMMIT
\P P/
\S S/
__\__ / COMMIT _____
|Node |------------|Node |
| B | HTTPS | D |
|_____| |_____|
/ /
/COMMIT /COMMIT
___ ___/ _/__ ___
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
| Data | | Data |
| Store | | Store |
_|_ Cluster _|_ _|_ Cluster _|_
|DB |_________|DB | |DB |_________|DB |
|___| |___| |___| |___|
Commit Phase
5.5.2.1. API - POST /commit
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Request:
POST /commit
Description:
A commit message is sent from Initiator or subsequent peer nodes to
signal the Receiver node to commit the data to its data store.
Example (using cURL)
Request
$ curl -i -H "Content-Type: application/json" -H "DRiP-Node-ID:
nodeA" -H "DRiP-Node-Counter: 1234" -H
"DRiP-Node-Counter-reset: false" -X POST -d
'<key-value data>' https://nodebregistry.com/commit
Response
HTTP/1.1 200 OK
5.6. Node Sync Operation
A node, either newly added to the distributed mesh or put back into
service after being inactive, will get the state of a peer node to
determine if it is in "active" state. If so, the node can
immediately initiate a Sync transaction. The peer node MUST start
propagating a comprehensive and complete set of key-value data from
its data store.
The two phase commit does NOT apply here as the contents of the
initiating node's data store is either outdated or empty. During
this phase (HTTPS requests received will have DRiP-Sync-Complete
field value set to false), this node SHOULD NOT become an Initiator
node to provision data. While this transaction is going on, this
node MUST vote "yes" to all real-time updates. The commits
corresponding to the Updates should also be completed and reflected
in the data store.
5.6.1. API - PUT /sync/node/:nodeid
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Request:
PUT /sync/node/:nodeid
Description:
API call for initiating a full registry synchronization from node to
peer-node.
Example (using cURL)
Request
$ curl -i -H "DRiP-Node-ID: nodeA" -H "Authorization: eyJ0e..."
-X POST https://peernode.com/sync/node/nodeA
Response
HTTP/1.1 200 OK
5.7. Heartbeat
Periodic heartbeats are required for a node to determine it's
visibility to the rest of it's peer nodes and whether it should put
itself in "inactive" mode. The procedure for heartbeats is as
follows.
A node sends periodic heartbeat requests to its peer nodes with an
indication of its state. These heartbeat requests are not to be
propagated beyond the peer nodes.
If all of its peer nodes cannot be reached or do not respond with
200OK, then the node that sent the heartbeat request will set its own
state to "inactive". This is based on the reasonable assumption that
none of the peer nodes are able to communicate with this node until a
new heartbeat request is successful. Once in the inactive state, the
node will
o not propagate any incoming key-value data
o not update any incoming key-value data
o continue to send the periodic heartbeat requests to its peer
nodes. If any one responds with 200 OK, then the node will move
its state to "synchronizing" and will re-synchronize its data with
any active peer node as detailed in section 4.6
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In addition, any one or more peer nodes that cannot be reached or did
not respond with 200 OK should not be used to propagate key-value
data until it responds (with 200 OK) to the heartbeat request.
5.7.1. API - POST /heartbeat/node/:nodeid
Example (using cURL)
Request
$ curl -i -H "DRiP-Node-ID: nodeA" -H "Authorization: eyJ0e..."
-X POST -d '<state>' https://peernode.com/heartbeat/node/nodeA
Response
HTTP/1.1 200 OK
5.8. Key-Value Data Update Entitlement Verification
When a node owner would like to create or modify particular key-value
data, generally in the context of a registry, there MAY be a
verification procedure that key-value data write or modification can
be performed. This could include validating whether key-value data
is entitled to be written, modified or subsequently propagated based
on application policy. For example, identity or telephone number
ownership or porting. The exact mechanics of this are out of scope
of this document and are generally application specific.
6. Security Considerations
6.1. HTTPS
All nodes MUST perform HTTP transactions using TLS as defined in
[RFC7230].
6.2. Authorization
All nodes MUST validate their authority to consume the HTTP APIs of a
peer node by adding a JSON Web Token (JWT) value [RFC7519] in the
Authorization request-header field.
The creation and verification of the JWT should be based on a digital
signature. For most distributed registry scenarios where the owner
of a node may not have a direct relationship with another node owner,
a PKI based certificate approach is highly suggested. For protection
against replay attacks, the claim set SHOULD contain an "iat" claim
and the signature should be verified to be signed by the expected
owner of the peer node. The "iat" claim identifies the time at which
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the JWT was issued and can be used to validate when the time of the
transaction occurred.
6.3. Payload Validation
In addition to the DRiP level protocol protection, it is highly
suggested to sign and validate part or all of the JSON update
payloads to the originator of the update. DRiP does not define
anything regarding the contents of the payload, so this document does
not address this in any way.
7. IANA Considerations
None
8. Acknowledgements
We would like to thank you for your interest in this work.
9. References
9.1. Normative References
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<http://www.rfc-editor.org/info/rfc7519>.
9.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
Authors' Addresses
Chris Wendt
Comcast
One Comcast Center
Philadelphia, PA 19103
USA
Email: chris-ietf@chriswendt.net
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Harsha Bellur
Comcast
One Comcast Center
Philadelphia, PA 19103
USA
Email: Harsha_Bellur@cable.comcast.com
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