Internet Engineering Task Force H. Bellur Internet-Draft C. Wendt, Ed. Intended status: Standards Track Comcast Expires: January 9, 2017 July 8, 2016 Distributed Registry Protocol draft-wendt-modern-drip-01 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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on January 9, 2017. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of Bellur & Wendt Expires January 9, 2017 [Page 1] Internet-Draft DRiP July 2016 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 2. DRiP Overview . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Distributed MESH Architecture . . . . . . . . . . . . . . . . 3 4. DRiP procedures . . . . . . . . . . . . . . . . . . . . . . . 4 4.1. Distributed Registry Rules . . . . . . . . . . . . . . . 4 4.2. Node State . . . . . . . . . . . . . . . . . . . . . . . 5 4.2.1. API - POST /node/:nodeid/active . . . . . . . . . . . 5 4.2.2. API - POST /node/:nodeid/inactive . . . . . . . . . . 5 4.2.3. API - GET /state . . . . . . . . . . . . . . . . . . 5 4.3. Custom HTTP header fields . . . . . . . . . . . . . . . . 6 4.4. Key-Value Data Propagation Rules . . . . . . . . . . . . 8 4.5. Key-Value Data Update . . . . . . . . . . . . . . . . . . 8 4.5.1. Voting Phase . . . . . . . . . . . . . . . . . . . . 9 4.5.1.1. API - POST /voting . . . . . . . . . . . . . . . 10 4.5.1.2. POST /votingphase/node/:nodeid/response/:response 11 4.5.2. Commit Phase . . . . . . . . . . . . . . . . . . . . 11 4.5.2.1. API - POST /commit . . . . . . . . . . . . . . . 12 4.6. Node Sync Operation . . . . . . . . . . . . . . . . . . . 13 4.6.1. API - PUT /sync/node/:nodeid . . . . . . . . . . . . 13 4.7. Heartbeat . . . . . . . . . . . . . . . . . . . . . . . . 14 4.7.1. API - POST /heartbeat/node/:nodeid . . . . . . . . . 14 4.8. Key-Value Data Update Entitlement Verification . . . . . 15 5. Security Considerations . . . . . . . . . . . . . . . . . . . 15 5.1. HTTPS . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 15 5.3. Payload Validation . . . . . . . . . . . . . . . . . . . 15 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 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. 1.1. 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 RFC 2119 [RFC2119]. Bellur & Wendt Expires January 9, 2017 [Page 2] Internet-Draft DRiP July 2016 Initiator Node: A node that initiates data propagation. Receiver Node: A node that forwards the propagated key-value data. 2. 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. 3. 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. Bellur & Wendt Expires January 9, 2017 [Page 3] Internet-Draft DRiP July 2016 ___ ___ ___ ___ |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 4. DRiP procedures 4.1. 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. Bellur & Wendt Expires January 9, 2017 [Page 4] Internet-Draft DRiP July 2016 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. 4.2. 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. 4.2.1. 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 4.2.2. 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 4.2.3. 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. Example (using cURL) Bellur & Wendt Expires January 9, 2017 [Page 5] Internet-Draft DRiP July 2016 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" | +---------------+----------------------------------+ 4.3. 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 +-------------------+-----------------------------------------------+ | 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 Bellur & Wendt Expires January 9, 2017 [Page 6] Internet-Draft DRiP July 2016 +-------------------------+-----------------------------------------+ | 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 +-----------------------+-------------------------------------------+ | 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 Bellur & Wendt Expires January 9, 2017 [Page 7] Internet-Draft DRiP July 2016 4.4. 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 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. 4.5. 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. Bellur & Wendt Expires January 9, 2017 [Page 8] Internet-Draft DRiP July 2016 _________ ----------------------->| | | | 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 4.5.1. 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 Bellur & Wendt Expires January 9, 2017 [Page 9] Internet-Draft DRiP July 2016 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 4.5.1.1. API - POST /voting 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 Bellur & Wendt Expires January 9, 2017 [Page 10] Internet-Draft DRiP July 2016 $ 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 '{}' https://nodebregistry.com/voting Response HTTP/1.1 200 OK 4.5.1.2. 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 4.5.2. 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. 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. Bellur & Wendt Expires January 9, 2017 [Page 11] Internet-Draft DRiP July 2016 ___ ___ ___ ___ |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 4.5.2.1. API - POST /commit 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. Bellur & Wendt Expires January 9, 2017 [Page 12] Internet-Draft DRiP July 2016 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 '' https://nodebregistry.com/commit Response HTTP/1.1 200 OK 4.6. 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. 4.6.1. API - PUT /sync/node/:nodeid 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 Bellur & Wendt Expires January 9, 2017 [Page 13] Internet-Draft DRiP July 2016 Response HTTP/1.1 200 OK 4.7. 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 proceedure 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 200 OK, 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 sucessful. 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 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. 4.7.1. API - POST /heartbeat/node/:nodeid Example (using cURL) Request $ curl -i -H "DRiP-Node-ID: nodeA" -H "Authorization: eyJ0e..." -X POST -d '' https://peernode.com/heartbeat/node/nodeA Response HTTP/1.1 200 OK Bellur & Wendt Expires January 9, 2017 [Page 14] Internet-Draft DRiP July 2016 4.8. 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. 5. Security Considerations 5.1. HTTPS All nodes MUST perform HTTP transactions using TLS as defined in [RFC7230]. 5.2. 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 scenerios 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 the JWT was issued and can be used to validate when the time of the transaction occurred. 5.3. 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. 6. References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Bellur & Wendt Expires January 9, 2017 [Page 15] Internet-Draft DRiP July 2016 [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, . [RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015, . Authors' Addresses Harsha Bellur Comcast One Comcast Center Philadelphia, PA 19103 USA Email: Harsha_Bellur@cable.comcast.com Chris Wendt (editor) Comcast One Comcast Center Philadelphia, PA 19103 USA Email: chris-ietf@chriswendt.net Bellur & Wendt Expires January 9, 2017 [Page 16]