Introduce api/send

Added events and requests for support. Reworked delivery_monitor into a featured devlivery_service, that - supports relay publish and lightpush depending on configuration but with fallback options - if available and configured it utilizes store api to confirm message delivery - emits message delivery events accordingly Notice: There are parts still in WIP and needs review and follow ups. prepare for use in api_example
2026-01-03 22:43:09 +00:00 · 2025-11-21 16:11:58 +01:00 · 2025-11-21 16:11:58 +01:00 · 70c3afb4a7
commit 70c3afb4a7
parent ae74b9018a
54 changed files with 1152 additions and 515 deletions
--- a/6
+++ b/6
@ -147,7 +147,7 @@ NIM_PARAMS := $(NIM_PARAMS) -d:disable_libbacktrace
 endif

 # enable experimental exit is dest feature in libp2p mix
-NIM_PARAMS := $(NIM_PARAMS) -d:libp2p_mix_experimental_exit_is_dest 
+NIM_PARAMS := $(NIM_PARAMS) -d:libp2p_mix_experimental_exit_is_dest

 libbacktrace:
 	+ $(MAKE) -C vendor/nim-libbacktrace --no-print-directory BUILD_CXX_LIB=0
@ -266,6 +266,10 @@ lightpushwithmix: | build deps librln
 	echo -e $(BUILD_MSG) "build/$@" && \
 		$(ENV_SCRIPT) nim lightpushwithmix $(NIM_PARAMS) waku.nims

+api_example: | build deps librln
+	echo -e $(BUILD_MSG) "build/$@" && \
+		$(ENV_SCRIPT) nim api_example $(NIM_PARAMS) waku.nims
+
 build/%: | build deps librln
 	echo -e $(BUILD_MSG) "build/$*" && \
 		$(ENV_SCRIPT) nim buildone $(NIM_PARAMS) waku.nims $*
--- a/examples/api_example/api_example.nim
+++ b/examples/api_example/api_example.nim
@ -7,6 +7,22 @@ type CliArgs = object
    defaultValue: "", desc: "ETH RPC Endpoint, if passed, RLN is enabled"
  .}: string

+proc periodicSender(w: Waku): Future[void] {.async.} =
+  ## Periodically sends a Waku message every 30 seconds
+  var counter = 0
+  while true:
+    let envelope = MessageEnvelope.init(
+      contentTopic = "example/content/topic",
+      payload = "Hello Waku! Message number: " & $counter,
+    )
+
+    let sendRequestId = (await w.send(envelope)).valueOr:
+      echo "Failed to send message: ", error
+      quit(QuitFailure)
+
+    counter += 1
+    await sleepAsync(30.seconds)
+
 when isMainModule:
  let args = CliArgs.load()

@ -21,7 +37,7 @@ when isMainModule:
      )
    else:
      # Connect to TWN, use ETH RPC Endpoint for RLN
-      NodeConfig.init(ethRpcEndpoints = @[args.ethRpcEndpoint])
+      NodeConfig.init(mode = WakuMode.Core, ethRpcEndpoints = @[args.ethRpcEndpoint])

  # Create the node using the library API's createNode function
  let node = (waitFor createNode(config)).valueOr:
@ -37,4 +53,6 @@ when isMainModule:

  echo "Node started successfully!"

+  asyncSpawn periodicSender(node)
+
  runForever()
--- a/library/waku_context.nim
+++ b/library/waku_context.nim
@ -8,7 +8,8 @@ import
  waku/common/logging,
  waku/factory/waku,
  waku/node/peer_manager,
-  waku/waku_relay/[protocol, topic_health],
+  waku/waku_relay/protocol,
+  waku/node/health_monitor/topic_health,
  waku/waku_core/[topics/pubsub_topic, message],
  ./waku_thread_requests/[waku_thread_request, requests/debug_node_request],
  ./ffi_types,
--- a/vendor/nim-libp2p
+++ b/vendor/nim-libp2p
@ -1 +1 @@
-Subproject commit e82080f7b1aa61c6d35fa5311b873f41eff4bb52
+Subproject commit 0309685cd27d4bf763c8b3be86a76c33bcfe67ea
--- a/waku.nim
+++ b/waku.nim
@ -1,10 +1,10 @@
 ## Main module for using nwaku as a Nimble library
-## 
+##
 ## This module re-exports the public API for creating and managing Waku nodes
 ## when using nwaku as a library dependency.

-import waku/api/[api, api_conf]
-export api, api_conf
+import waku/api/[api, api_conf, types]
+export api, api_conf, types

 import waku/factory/waku
 export waku
--- a/waku.nimble
+++ b/waku.nimble
@ -177,6 +177,10 @@ task lightpushwithmix, "Build lightpushwithmix":
  let name = "lightpush_publisher_mix"
  buildBinary name, "examples/lightpush_mix/"

+task api_example, "Build api_example":
+  let name = "api_example"
+  buildBinary name, "examples/api_example/"
+
 task buildone, "Build custom target":
  let filepath = paramStr(paramCount())
  discard buildModule filepath
--- a/waku/api/api.nim
+++ b/waku/api/api.nim
@ -1,8 +1,12 @@
 import chronicles, chronos, results

 import waku/factory/waku
+import waku/[requests/health_request, waku_core, waku_node]
+import waku/node/delivery_service/send_service
+import ./[api_conf, types], ./subscribe/subscribe

-import ./api_conf
+logScope:
+  topics = "api"

 # TODO: Specs says it should return a `WakuNode`. As `send` and other APIs are defined, we can align.
 proc createNode*(config: NodeConfig): Future[Result[Waku, string]] {.async.} =
@ -15,3 +19,45 @@ proc createNode*(config: NodeConfig): Future[Result[Waku, string]] {.async.} =
    return err("Failed setting up Waku: " & $error)

  return ok(wakuRes)
+
+proc checkApiAvailability(w: Waku): Result[void, string] =
+  if w.isNil():
+    return err("Waku node is not initialized")
+
+  # check if health is satisfactory
+  # If Node is not healthy, return err("Waku node is not healthy")
+  let healthStatus = waitFor RequestNodeHealth.request()
+
+  if healthStatus.isErr():
+    warn "Failed to get Waku node health status: ", error = healthStatus.error
+    # Let's suppose the node is hesalthy enough, go ahead
+  else:
+    if healthStatus.get().healthStatus != NodeHealth.Unhealthy:
+      return err("Waku node is not healthy, has got no connections.")
+
+  return ok()
+
+proc subscribe*(
+    w: Waku, contentTopic: ContentTopic
+): Future[Result[RequestId, string]] {.async.} =
+  ?checkApiAvailability(w)
+
+  let requestId = newRequestId(w.rng)
+
+  asyncSpawn w.subscribeImpl(requestId, contentTopic)
+
+  return ok(requestId)
+
+proc send*(
+    w: Waku, envelope: MessageEnvelope
+): Future[Result[RequestId, string]] {.async.} =
+  ?checkApiAvailability(w)
+
+  let requestId = newRequestId(w.rng)
+
+  let deliveryTask = DeliveryTask.create(requestId, envelope).valueOr:
+    return err("Failed to create delivery task: " & error)
+
+  asyncSpawn w.deliveryService.sendService.send(deliveryTask)
+
+  return ok(requestId)
--- a/waku/api/api_conf.nim
+++ b/waku/api/api_conf.nim
@ -131,8 +131,9 @@ proc toWakuConf*(nodeConfig: NodeConfig): Result[WakuConf, string] =

    b.rateLimitConf.withRateLimits(@["filter:100/1s", "lightpush:5/1s", "px:5/1s"])
  of Edge:
-    return err("Edge mode is not implemented")
-
+    # All client side protocols are mounted by default
+    # Peer exchange client is always enabled and start_node will start the px loop
+    discard
  ## Network Conf
  let protocolsConfig = nodeConfig.protocolsConfig

--- a/waku/api/request_id.nim
+++ b/waku/api/request_id.nim
@ -0,0 +1,13 @@
+{.push raises: [].}
+
+import bearssl/rand
+
+import waku/utils/requests as request_utils
+
+import ./types
+
+proc newRequestId*(rng: ref HmacDrbgContext): RequestId =
+	## Generate a new RequestId using the provided RNG.
+	RequestId(request_utils.generateRequestId(rng))
+
+{.pop.}
--- a/waku/api/send_api.md
+++ b/waku/api/send_api.md
@ -0,0 +1,46 @@
+# SEND API
+
+**THIS IS TO BE REMOVED BEFORE PR MERGE**
+
+This document collects logic and todo's around the Send API.
+
+## Overview
+
+Send api hides the complex logic of using raw protocols for reliable message delivery.
+The delivery method is chosen based on the node configuration and actual availabilites of peers.
+
+## Delivery task
+
+Each message send request is boundled into a task that not just holds the composed message but also the state of the delivery.
+
+## Delivery methods
+
+Depending on the configuration and the availability of store client protocol + actual configured and/or discovered store nodes:
+- P2PReliability validation - checking network store node wheather the message is reached at least a store node.
+- Simple retry until message is propagated to the network
+  - Relay says >0 peers as publish result
+  - LightushClient returns with success
+
+Depending on node config:
+- Relay
+- Lightpush
+
+These methods are used in combination to achieve the best reliability.
+Fallback mechanism is used to switch between methods if the current one fails.
+
+Relay+StoreCheck -> Relay+simeple retry -> Lightpush+StoreCheck -> Lightpush simple retry -> Error
+
+Combination is dynamicly chosen on node configuration. Levels can be skipped depending on actual connectivity.
+Actual connectivity is checked:
+- Relay's topic health check - at least dLow peers in the mesh for the topic
+- Store nodes availability - at least one store service node is available in peer manager
+- Lightpush client availability - at least one lightpush service node is available in peer manager
+
+## Delivery processing
+
+At every send request, each task is tried to be delivered right away.
+Any further retries and store check is done as a background task in a loop with predefined intervals.
+Each task is set for a maximum number of retries and/or maximum time to live.
+
+In each round of store check and retry send tasks are selected based on their state.
+The state is updated based on the result of the delivery method.
--- a/waku/api/subscribe/subscribe.nim
+++ b/waku/api/subscribe/subscribe.nim
@ -0,0 +1,12 @@
+# import chronicles, chronos, results
+import chronos
+import waku/waku_core
+import waku/api/types
+import waku/factory/waku
+
+proc subscribeImpl*(
+    w: Waku, requestId: RequestId, contentTopic: ContentTopic
+): Future[void] {.async.} =
+  ## Implementation of the subscribe API
+  ## This is a placeholder implementation
+  await sleepAsync(1000) # Simulate async work
--- a/waku/api/types.nim
+++ b/waku/api/types.nim
@ -0,0 +1,64 @@
+{.push raises: [].}
+
+import bearssl/rand, std/times, chronos, chronicles
+import stew/byteutils
+import waku/utils/requests as request_utils
+import waku/waku_core/[topics/content_topic, message/message, time]
+import waku/requests/requests
+
+logScope:
+  topics = "message envelope"
+
+type
+  MessageEnvelope* = object
+    contentTopic*: ContentTopic
+    payload*: seq[byte]
+    ephemeral*: bool
+
+  RequestId* = distinct string
+
+  NodeHealth* {.pure.} = enum
+    Healthy
+    MinimallyHealthy
+    Unhealthy
+
+proc newRequestId*(rng: ref HmacDrbgContext): RequestId =
+  ## Generate a new RequestId using the provided RNG.
+  RequestId(request_utils.generateRequestId(rng))
+
+proc `$`*(r: RequestId): string {.inline.} =
+  string(r)
+
+proc init*(
+    T: type MessageEnvelope,
+    contentTopic: ContentTopic,
+    payload: seq[byte] | string,
+    ephemeral: bool = false,
+): MessageEnvelope =
+  when payload is seq[byte]:
+    MessageEnvelope(contentTopic: contentTopic, payload: payload, ephemeral: ephemeral)
+  else:
+    MessageEnvelope(
+      contentTopic: contentTopic, payload: payload.toBytes(), ephemeral: ephemeral
+    )
+
+proc toWakuMessage*(envelope: MessageEnvelope): WakuMessage =
+  ## Convert a MessageEnvelope to a WakuMessage.
+  var wm = WakuMessage(
+    contentTopic: envelope.contentTopic,
+    payload: envelope.payload,
+    ephemeral: envelope.ephemeral,
+    timestamp: getNanosecondTime(getTime().toUnixFloat()),
+  )
+
+  # TODO: First find out if proof is needed at all
+  let requestedProof = (
+    waitFor RequestGenerateRlnProof.request(wm, getTime().toUnixFloat())
+  ).valueOr:
+    warn "Failed to add RLN proof to WakuMessage: ", error = error
+    return wm
+
+  wm.proof = requestedProof.proof
+  return wm
+
+{.pop.}
--- a/waku/events/delivery_events.nim
+++ b/waku/events/delivery_events.nim
@ -0,0 +1,27 @@
+import waku/waku_core/[message/message, message/digest], waku/common/broker/event_broker
+
+type DeliveryDirection* {.pure.} = enum
+  PUBLISHING
+  RECEIVING
+
+type DeliverySuccess* {.pure.} = enum
+  SUCCESSFUL
+  UNSUCCESSFUL
+
+EventBroker:
+  type DeliveryFeedbackEvent* = ref object
+    success*: DeliverySuccess
+    dir*: DeliveryDirection
+    comment*: string
+    msgHash*: WakuMessageHash
+    msg*: WakuMessage
+
+EventBroker:
+  type OnFilterSubscribeEvent* = object
+    pubsubTopic*: string
+    contentTopics*: seq[string]
+
+EventBroker:
+  type OnFilterUnSubscribeEvent* = object
+    pubsubTopic*: string
+    contentTopics*: seq[string]
--- a/waku/events/events.nim
+++ b/waku/events/events.nim
@ -0,0 +1,3 @@
+import ./[message_events, delivery_events]
+
+export message_events, delivery_events
--- a/waku/events/message_events.nim
+++ b/waku/events/message_events.nim
@ -0,0 +1,23 @@
+import waku/common/broker/event_broker
+import waku/api/types
+
+export types
+
+EventBroker:
+  # Event emitted when a message is sent to the network
+  type MessageSentEvent* = object
+    requestId*: RequestId
+    messageHash*: string
+
+EventBroker:
+  # Event emitted when a message send operation fails
+  type MessageErrorEvent* = object
+    requestId*: RequestId
+    messageHash*: string
+    error*: string
+
+EventBroker:
+  # Confirmation that a message has been correctly delivered to some neighbouring nodes.
+  type MessagePropagatedEvent* = object
+    requestId*: RequestId
+    messageHash*: string
--- a/waku/factory/waku.nim
+++ b/waku/factory/waku.nim
@ -27,7 +27,7 @@ import
  ../node/peer_manager,
  ../node/health_monitor,
  ../node/waku_metrics,
-  ../node/delivery_monitor/delivery_monitor,
+  ../node/delivery_service/delivery_service,
  ../rest_api/message_cache,
  ../rest_api/endpoint/server,
  ../rest_api/endpoint/builder as rest_server_builder,
@ -69,7 +69,7 @@ type Waku* = ref object

  healthMonitor*: NodeHealthMonitor

-  deliveryMonitor: DeliveryMonitor
+  deliveryService*: DeliveryService

  restServer*: WakuRestServerRef
  metricsServer*: MetricsHttpServerRef
@ -200,16 +200,10 @@ proc new*(
    return err("Failed setting up app callbacks: " & $error)

  ## Delivery Monitor
-  var deliveryMonitor: DeliveryMonitor
-  if wakuConf.p2pReliability:
-    if wakuConf.remoteStoreNode.isNone():
-      return err("A storenode should be set when reliability mode is on")
-
-    let deliveryMonitor = DeliveryMonitor.new(
-      node.wakuStoreClient, node.wakuRelay, node.wakuLightpushClient,
-      node.wakuFilterClient,
-    ).valueOr:
-      return err("could not create delivery monitor: " & $error)
+  let deliveryService = DeliveryService.new(
+    wakuConf.p2pReliability, node,
+  ).valueOr:
+    return err("could not create delivery service: " & $error)

  var waku = Waku(
    version: git_version,
@ -218,7 +212,7 @@ proc new*(
    key: wakuConf.nodeKey,
    node: node,
    healthMonitor: healthMonitor,
-    deliveryMonitor: deliveryMonitor,
+    deliveryService: deliveryService,
    appCallbacks: appCallbacks,
    restServer: restServer,
  )
@ -403,8 +397,8 @@ proc startWaku*(waku: ptr Waku): Future[Result[void, string]] {.async.} =
      return err("failed to start waku discovery v5: " & $error)

  ## Reliability
-  if not waku[].deliveryMonitor.isNil():
-    waku[].deliveryMonitor.startDeliveryMonitor()
+  if not waku[].deliveryService.isNil():
+    waku[].deliveryService.startDeliveryService()

  ## Health Monitor
  waku[].healthMonitor.startHealthMonitor().isOkOr:
@ -463,3 +457,16 @@ proc stop*(waku: Waku): Future[void] {.async: (raises: [Exception]).} =

  if not waku.restServer.isNil():
    await waku.restServer.stop()
+
+proc isModeCoreAvailable*(waku: Waku): bool =
+  return not waku.node.wakuRelay.isNil()
+
+proc isModeEdgeAvailable*(waku: Waku): bool =
+  return
+    waku.node.wakuRelay.isNil() and not waku.node.wakuStoreClient.isNil() and
+    not waku.node.wakuFilterClient.isNil() and not waku.node.wakuLightPushClient.isNil()
+
+proc isP2PReliabilityEnabled*(waku: Waku): bool =
+  return not waku.deliveryService.isNil()
+
+{.pop.}
--- a/waku/node/delivery_monitor/delivery_callback.nim
+++ b/waku/node/delivery_monitor/delivery_callback.nim
@ -1,17 +0,0 @@
-import ../../waku_core
-
-type DeliveryDirection* {.pure.} = enum
-  PUBLISHING
-  RECEIVING
-
-type DeliverySuccess* {.pure.} = enum
-  SUCCESSFUL
-  UNSUCCESSFUL
-
-type DeliveryFeedbackCallback* = proc(
-  success: DeliverySuccess,
-  dir: DeliveryDirection,
-  comment: string,
-  msgHash: WakuMessageHash,
-  msg: WakuMessage,
-) {.gcsafe, raises: [].}
--- a/waku/node/delivery_monitor/delivery_monitor.nim
+++ b/waku/node/delivery_monitor/delivery_monitor.nim
@ -1,43 +0,0 @@
-## This module helps to ensure the correct transmission and reception of messages
-
-import results
-import chronos
-import
-  ./recv_monitor,
-  ./send_monitor,
-  ./delivery_callback,
-  ../../waku_core,
-  ../../waku_store/client,
-  ../../waku_relay/protocol,
-  ../../waku_lightpush/client,
-  ../../waku_filter_v2/client
-
-type DeliveryMonitor* = ref object
-  sendMonitor: SendMonitor
-  recvMonitor: RecvMonitor
-
-proc new*(
-    T: type DeliveryMonitor,
-    storeClient: WakuStoreClient,
-    wakuRelay: protocol.WakuRelay,
-    wakuLightpushClient: WakuLightpushClient,
-    wakuFilterClient: WakuFilterClient,
-): Result[T, string] =
-  ## storeClient is needed to give store visitility to DeliveryMonitor
-  ## wakuRelay and wakuLightpushClient are needed to give a mechanism to SendMonitor to re-publish
-  let sendMonitor = ?SendMonitor.new(storeClient, wakuRelay, wakuLightpushClient)
-  let recvMonitor = RecvMonitor.new(storeClient, wakuFilterClient)
-  return ok(DeliveryMonitor(sendMonitor: sendMonitor, recvMonitor: recvMonitor))
-
-proc startDeliveryMonitor*(self: DeliveryMonitor) =
-  self.sendMonitor.startSendMonitor()
-  self.recvMonitor.startRecvMonitor()
-
-proc stopDeliveryMonitor*(self: DeliveryMonitor) {.async.} =
-  self.sendMonitor.stopSendMonitor()
-  await self.recvMonitor.stopRecvMonitor()
-
-proc setDeliveryCallback*(self: DeliveryMonitor, deliveryCb: DeliveryFeedbackCallback) =
-  ## The deliveryCb is a proc defined by the api client so that it can get delivery feedback
-  self.sendMonitor.setDeliveryCallback(deliveryCb)
-  self.recvMonitor.setDeliveryCallback(deliveryCb)
--- a/waku/node/delivery_monitor/publish_observer.nim
+++ b/waku/node/delivery_monitor/publish_observer.nim
@ -1,9 +0,0 @@
-import chronicles
-import ../../waku_core/message/message
-
-type PublishObserver* = ref object of RootObj
-
-method onMessagePublished*(
-    self: PublishObserver, pubsubTopic: string, message: WakuMessage
-) {.base, gcsafe, raises: [].} =
-  error "onMessagePublished not implemented"
--- a/waku/node/delivery_monitor/send_monitor.nim
+++ b/waku/node/delivery_monitor/send_monitor.nim
@ -1,212 +0,0 @@
-## This module reinforces the publish operation with regular store-v3 requests.
-##
-
-import std/[sequtils, tables]
-import chronos, chronicles, libp2p/utility
-import
-  ./delivery_callback,
-  ./publish_observer,
-  ../../waku_core,
-  ./not_delivered_storage/not_delivered_storage,
-  ../../waku_store/[client, common],
-  ../../waku_archive/archive,
-  ../../waku_relay/protocol,
-  ../../waku_lightpush/client
-
-const MaxTimeInCache* = chronos.minutes(1)
-  ## Messages older than this time will get completely forgotten on publication and a
-  ## feedback will be given when that happens
-
-const SendCheckInterval* = chronos.seconds(3)
-  ## Interval at which we check that messages have been properly received by a store node
-
-const MaxMessagesToCheckAtOnce = 100
-  ## Max number of messages to check if they were properly archived by a store node
-
-const ArchiveTime = chronos.seconds(3)
-  ## Estimation of the time we wait until we start confirming that a message has been properly
-  ## received and archived by a store node
-
-type DeliveryInfo = object
-  pubsubTopic: string
-  msg: WakuMessage
-
-type SendMonitor* = ref object of PublishObserver
-  publishedMessages: Table[WakuMessageHash, DeliveryInfo]
-    ## Cache that contains the delivery info per message hash.
-    ## This is needed to make sure the published messages are properly published
-
-  msgStoredCheckerHandle: Future[void] ## handle that allows to stop the async task
-
-  notDeliveredStorage: NotDeliveredStorage
-    ## NOTE: this is not fully used because that might be tackled by higher abstraction layers
-
-  storeClient: WakuStoreClient
-  deliveryCb: DeliveryFeedbackCallback
-
-  wakuRelay: protocol.WakuRelay
-  wakuLightpushClient: WakuLightPushClient
-
-proc new*(
-    T: type SendMonitor,
-    storeClient: WakuStoreClient,
-    wakuRelay: protocol.WakuRelay,
-    wakuLightpushClient: WakuLightPushClient,
-): Result[T, string] =
-  if wakuRelay.isNil() and wakuLightpushClient.isNil():
-    return err(
-      "Could not create SendMonitor. wakuRelay or wakuLightpushClient should be set"
-    )
-
-  let notDeliveredStorage = ?NotDeliveredStorage.new()
-
-  let sendMonitor = SendMonitor(
-    notDeliveredStorage: notDeliveredStorage,
-    storeClient: storeClient,
-    wakuRelay: wakuRelay,
-    wakuLightpushClient: wakuLightPushClient,
-  )
-
-  if not wakuRelay.isNil():
-    wakuRelay.addPublishObserver(sendMonitor)
-
-  if not wakuLightpushClient.isNil():
-    wakuLightpushClient.addPublishObserver(sendMonitor)
-
-  return ok(sendMonitor)
-
-proc performFeedbackAndCleanup(
-    self: SendMonitor,
-    msgsToDiscard: Table[WakuMessageHash, DeliveryInfo],
-    success: DeliverySuccess,
-    dir: DeliveryDirection,
-    comment: string,
-) =
-  ## This procs allows to bring delivery feedback to the API client
-  ## It requires a 'deliveryCb' to be registered beforehand.
-  if self.deliveryCb.isNil():
-    error "deliveryCb is nil in performFeedbackAndCleanup",
-      success, dir, comment, hashes = toSeq(msgsToDiscard.keys).mapIt(shortLog(it))
-    return
-
-  for hash, deliveryInfo in msgsToDiscard:
-    info "send monitor performFeedbackAndCleanup",
-      success, dir, comment, msg_hash = shortLog(hash)
-
-    self.deliveryCb(success, dir, comment, hash, deliveryInfo.msg)
-    self.publishedMessages.del(hash)
-
-proc checkMsgsInStore(
-    self: SendMonitor, msgsToValidate: Table[WakuMessageHash, DeliveryInfo]
-): Future[
-    Result[
-      tuple[
-        publishedCorrectly: Table[WakuMessageHash, DeliveryInfo],
-        notYetPublished: Table[WakuMessageHash, DeliveryInfo],
-      ],
-      void,
-    ]
-] {.async.} =
-  let hashesToValidate = toSeq(msgsToValidate.keys)
-
-  let storeResp: StoreQueryResponse = (
-    await self.storeClient.queryToAny(
-      StoreQueryRequest(includeData: false, messageHashes: hashesToValidate)
-    )
-  ).valueOr:
-    error "checkMsgsInStore failed to get remote msgHashes",
-      hashes = hashesToValidate.mapIt(shortLog(it)), error = $error
-    return err()
-
-  let publishedHashes = storeResp.messages.mapIt(it.messageHash)
-
-  var notYetPublished: Table[WakuMessageHash, DeliveryInfo]
-  var publishedCorrectly: Table[WakuMessageHash, DeliveryInfo]
-
-  for msgHash, deliveryInfo in msgsToValidate.pairs:
-    if publishedHashes.contains(msgHash):
-      publishedCorrectly[msgHash] = deliveryInfo
-      self.publishedMessages.del(msgHash) ## we will no longer track that message
-    else:
-      notYetPublished[msgHash] = deliveryInfo
-
-  return ok((publishedCorrectly: publishedCorrectly, notYetPublished: notYetPublished))
-
-proc processMessages(self: SendMonitor) {.async.} =
-  var msgsToValidate: Table[WakuMessageHash, DeliveryInfo]
-  var msgsToDiscard: Table[WakuMessageHash, DeliveryInfo]
-
-  let now = getNowInNanosecondTime()
-  let timeToCheckThreshold = now - ArchiveTime.nanos
-  let maxLifeTime = now - MaxTimeInCache.nanos
-
-  for hash, deliveryInfo in self.publishedMessages.pairs:
-    if deliveryInfo.msg.timestamp < maxLifeTime:
-      ## message is too old
-      msgsToDiscard[hash] = deliveryInfo
-
-    if deliveryInfo.msg.timestamp < timeToCheckThreshold:
-      msgsToValidate[hash] = deliveryInfo
-
-  ## Discard the messages that are too old
-  self.performFeedbackAndCleanup(
-    msgsToDiscard, DeliverySuccess.UNSUCCESSFUL, DeliveryDirection.PUBLISHING,
-    "Could not publish messages. Please try again.",
-  )
-
-  let (publishedCorrectly, notYetPublished) = (
-    await self.checkMsgsInStore(msgsToValidate)
-  ).valueOr:
-    return ## the error log is printed in checkMsgsInStore
-
-  ## Give positive feedback for the correctly published messages
-  self.performFeedbackAndCleanup(
-    publishedCorrectly, DeliverySuccess.SUCCESSFUL, DeliveryDirection.PUBLISHING,
-    "messages published correctly",
-  )
-
-  ## Try to publish again
-  for msgHash, deliveryInfo in notYetPublished.pairs:
-    let pubsubTopic = deliveryInfo.pubsubTopic
-    let msg = deliveryInfo.msg
-    if not self.wakuRelay.isNil():
-      info "trying to publish again with wakuRelay", msgHash, pubsubTopic
-      (await self.wakuRelay.publish(pubsubTopic, msg)).isOkOr:
-        error "could not publish with wakuRelay.publish",
-          msgHash, pubsubTopic, error = $error
-      continue
-
-    if not self.wakuLightpushClient.isNil():
-      info "trying to publish again with wakuLightpushClient", msgHash, pubsubTopic
-      (await self.wakuLightpushClient.publishToAny(pubsubTopic, msg)).isOkOr:
-        error "could not publish with publishToAny", error = $error
-      continue
-
-proc checkIfMessagesStored(self: SendMonitor) {.async.} =
-  ## Continuously monitors that the sent messages have been received by a store node
-  while true:
-    await self.processMessages()
-    await sleepAsync(SendCheckInterval)
-
-method onMessagePublished(
-    self: SendMonitor, pubsubTopic: string, msg: WakuMessage
-) {.gcsafe, raises: [].} =
-  ## Implementation of the PublishObserver interface.
-  ##
-  ## When publishing a message either through relay or lightpush, we want to add some extra effort
-  ## to make sure it is received to one store node. Hence, keep track of those published messages.
-
-  info "onMessagePublished"
-  let msgHash = computeMessageHash(pubSubTopic, msg)
-
-  if not self.publishedMessages.hasKey(msgHash):
-    self.publishedMessages[msgHash] = DeliveryInfo(pubsubTopic: pubsubTopic, msg: msg)
-
-proc startSendMonitor*(self: SendMonitor) =
-  self.msgStoredCheckerHandle = self.checkIfMessagesStored()
-
-proc stopSendMonitor*(self: SendMonitor) =
-  discard self.msgStoredCheckerHandle.cancelAndWait()
-
-proc setDeliveryCallback*(self: SendMonitor, deliveryCb: DeliveryFeedbackCallback) =
-  self.deliveryCb = deliveryCb
--- a/waku/node/delivery_monitor/subscriptions_observer.nim
+++ b/waku/node/delivery_monitor/subscriptions_observer.nim
@ -1,13 +0,0 @@
-import chronicles
-
-type SubscriptionObserver* = ref object of RootObj
-
-method onSubscribe*(
-    self: SubscriptionObserver, pubsubTopic: string, contentTopics: seq[string]
-) {.base, gcsafe, raises: [].} =
-  error "onSubscribe not implemented"
-
-method onUnsubscribe*(
-    self: SubscriptionObserver, pubsubTopic: string, contentTopics: seq[string]
-) {.base, gcsafe, raises: [].} =
-  error "onUnsubscribe not implemented"
--- a/waku/node/delivery_service/delivery_service.nim
+++ b/waku/node/delivery_service/delivery_service.nim
@ -0,0 +1,36 @@
+## This module helps to ensure the correct transmission and reception of messages
+
+import results
+import chronos
+import
+  ./recv_service,
+  ./send_service,
+  waku/[
+    waku_core,
+    waku_node,
+    waku_store/client,
+    waku_relay/protocol,
+    waku_lightpush/client,
+    waku_filter_v2/client,
+  ]
+
+type DeliveryService* = ref object
+  sendService*: SendService
+  recvService: RecvService
+
+proc new*(
+    T: type DeliveryService, useP2PReliability: bool, w: WakuNode
+): Result[T, string] =
+  ## storeClient is needed to give store visitility to DeliveryService
+  ## wakuRelay and wakuLightpushClient are needed to give a mechanism to SendService to re-publish
+  let sendService = ?SendService.new(useP2PReliability, w)
+  let recvService = RecvService.new(w)
+  return ok(DeliveryService(sendService: sendService, recvService: recvService))
+
+proc startDeliveryService*(self: DeliveryService) =
+  self.sendService.startSendService()
+  self.recvService.startRecvService()
+
+proc stopDeliveryService*(self: DeliveryService) {.async.} =
+  self.sendService.stopSendService()
+  await self.recvService.stopRecvService()
--- a/waku/node/delivery_service/not_delivered_storage/migrations.nim
+++ b/waku/node/delivery_service/not_delivered_storage/migrations.nim
@ -4,7 +4,7 @@ import std/[tables, strutils, os], results, chronicles
 import ../../../common/databases/db_sqlite, ../../../common/databases/common

 logScope:
-  topics = "waku node delivery_monitor"
+  topics = "waku node delivery_service"

 const TargetSchemaVersion* = 1
  # increase this when there is an update in the database schema
--- a/waku/node/delivery_service/not_delivered_storage/not_delivered_storage.nim
+++ b/waku/node/delivery_service/not_delivered_storage/not_delivered_storage.nim
@ -1,17 +1,17 @@
 ## This module is aimed to keep track of the sent/published messages that are considered
 ## not being properly delivered.
-## 
+##
 ## The archiving of such messages will happen in a local sqlite database.
-## 
+##
 ## In the very first approach, we consider that a message is sent properly is it has been
 ## received by any store node.
-## 
+##

 import results
 import
  ../../../common/databases/db_sqlite,
  ../../../waku_core/message/message,
-  ../../../node/delivery_monitor/not_delivered_storage/migrations
+  ../../../node/delivery_service/not_delivered_storage/migrations

 const NotDeliveredMessagesDbUrl = "not-delivered-messages.db"

--- a/waku/node/delivery_service/recv_service.nim
+++ b/waku/node/delivery_service/recv_service.nim
@ -0,0 +1,3 @@
+import ./recv_service/recv_service
+
+export recv_service
--- a/waku/node/delivery_service/recv_service/recv_service.nim
+++ b/waku/node/delivery_service/recv_service/recv_service.nim
@ -5,12 +5,15 @@
 import std/[tables, sequtils, options]
 import chronos, chronicles, libp2p/utility
 import
-  ../../waku_core,
-  ./delivery_callback,
-  ./subscriptions_observer,
-  ../../waku_store/[client, common],
-  ../../waku_filter_v2/client,
-  ../../waku_core/topics
+  waku/[
+    waku_core,
+    waku_store/client,
+    waku_store/common,
+    waku_filter_v2/client,
+    waku_core/topics,
+    events/delivery_events,
+    waku_node,
+  ]

 const StoreCheckPeriod = chronos.minutes(5) ## How often to perform store queries

@ -28,14 +31,14 @@ type RecvMessage = object
  rxTime: Timestamp
    ## timestamp of the rx message. We will not keep the rx messages forever

-type RecvMonitor* = ref object of SubscriptionObserver
+type RecvService* = ref object of RootObj
  topicsInterest: Table[PubsubTopic, seq[ContentTopic]]
    ## Tracks message verification requests and when was the last time a
    ## pubsub topic was verified for missing messages
    ## The key contains pubsub-topics
-
-  storeClient: WakuStoreClient
-  deliveryCb: DeliveryFeedbackCallback
+  node: WakuNode
+  onSubscribeListener: OnFilterSubscribeEventListener
+  onUnsubscribeListener: OnFilterUnsubscribeEventListener

  recentReceivedMsgs: seq[RecvMessage]

@ -46,10 +49,10 @@ type RecvMonitor* = ref object of SubscriptionObserver
  endTimeToCheck: Timestamp

 proc getMissingMsgsFromStore(
-    self: RecvMonitor, msgHashes: seq[WakuMessageHash]
+    self: RecvService, msgHashes: seq[WakuMessageHash]
 ): Future[Result[seq[TupleHashAndMsg], string]] {.async.} =
  let storeResp: StoreQueryResponse = (
-    await self.storeClient.queryToAny(
+    await self.node.wakuStoreClient.queryToAny(
      StoreQueryRequest(includeData: true, messageHashes: msgHashes)
    )
  ).valueOr:
@ -62,25 +65,21 @@ proc getMissingMsgsFromStore(
  )

 proc performDeliveryFeedback(
-    self: RecvMonitor,
+    self: RecvService,
    success: DeliverySuccess,
    dir: DeliveryDirection,
    comment: string,
    msgHash: WakuMessageHash,
    msg: WakuMessage,
 ) {.gcsafe, raises: [].} =
-  ## This procs allows to bring delivery feedback to the API client
-  ## It requires a 'deliveryCb' to be registered beforehand.
-  if self.deliveryCb.isNil():
-    error "deliveryCb is nil in performDeliveryFeedback",
-      success, dir, comment, msg_hash
-    return
-
  info "recv monitor performDeliveryFeedback",
    success, dir, comment, msg_hash = shortLog(msgHash)
-  self.deliveryCb(success, dir, comment, msgHash, msg)

-proc msgChecker(self: RecvMonitor) {.async.} =
+  DeliveryFeedbackEvent.emit(
+    success = success, dir = dir, comment = comment, msgHash = msgHash, msg = msg
+  )
+
+proc msgChecker(self: RecvService) {.async.} =
  ## Continuously checks if a message has been received
  while true:
    await sleepAsync(StoreCheckPeriod)
@ -90,7 +89,7 @@ proc msgChecker(self: RecvMonitor) {.async.} =
    var msgHashesInStore = newSeq[WakuMessageHash](0)
    for pubsubTopic, cTopics in self.topicsInterest.pairs:
      let storeResp: StoreQueryResponse = (
-        await self.storeClient.queryToAny(
+        await self.node.wakuStoreClient.queryToAny(
          StoreQueryRequest(
            includeData: false,
            pubsubTopic: some(PubsubTopic(pubsubTopic)),
@ -126,8 +125,8 @@ proc msgChecker(self: RecvMonitor) {.async.} =
    ## update next check times
    self.startTimeToCheck = self.endTimeToCheck

-method onSubscribe(
-    self: RecvMonitor, pubsubTopic: string, contentTopics: seq[string]
+proc onSubscribe(
+    self: RecvService, pubsubTopic: string, contentTopics: seq[string]
 ) {.gcsafe, raises: [].} =
  info "onSubscribe", pubsubTopic, contentTopics
  self.topicsInterest.withValue(pubsubTopic, contentTopicsOfInterest):
@ -135,8 +134,8 @@ method onSubscribe(
  do:
    self.topicsInterest[pubsubTopic] = contentTopics

-method onUnsubscribe(
-    self: RecvMonitor, pubsubTopic: string, contentTopics: seq[string]
+proc onUnsubscribe(
+    self: RecvService, pubsubTopic: string, contentTopics: seq[string]
 ) {.gcsafe, raises: [].} =
  info "onUnsubscribe", pubsubTopic, contentTopics

@ -150,19 +149,13 @@ method onUnsubscribe(
  do:
    error "onUnsubscribe unsubscribing from wrong topic", pubsubTopic, contentTopics

-proc new*(
-    T: type RecvMonitor,
-    storeClient: WakuStoreClient,
-    wakuFilterClient: WakuFilterClient,
-): T =
+proc new*(T: type RecvService, node: WakuNode): T =
  ## The storeClient will help to acquire any possible missed messages

  let now = getNowInNanosecondTime()
-  var recvMonitor = RecvMonitor(storeClient: storeClient, startTimeToCheck: now)
-
-  if not wakuFilterClient.isNil():
-    wakuFilterClient.addSubscrObserver(recvMonitor)
+  var recvService = RecvService(node: node, startTimeToCheck: now)

+  if not node.wakuFilterClient.isNil():
    let filterPushHandler = proc(
        pubsubTopic: PubsubTopic, message: WakuMessage
    ) {.async, closure.} =
@ -170,27 +163,40 @@ proc new*(

      let msgHash = computeMessageHash(pubSubTopic, message)
      let rxMsg = RecvMessage(msgHash: msgHash, rxTime: message.timestamp)
-      recvMonitor.recentReceivedMsgs.add(rxMsg)
+      recvService.recentReceivedMsgs.add(rxMsg)

-    wakuFilterClient.registerPushHandler(filterPushHandler)
+    node.wakuFilterClient.registerPushHandler(filterPushHandler)

-  return recvMonitor
+  return recvService

-proc loopPruneOldMessages(self: RecvMonitor) {.async.} =
+proc loopPruneOldMessages(self: RecvService) {.async.} =
  while true:
    let oldestAllowedTime = getNowInNanosecondTime() - MaxMessageLife.nanos
    self.recentReceivedMsgs.keepItIf(it.rxTime > oldestAllowedTime)
    await sleepAsync(PruneOldMsgsPeriod)

-proc startRecvMonitor*(self: RecvMonitor) =
+proc startRecvService*(self: RecvService) =
  self.msgCheckerHandler = self.msgChecker()
  self.msgPrunerHandler = self.loopPruneOldMessages()

-proc stopRecvMonitor*(self: RecvMonitor) {.async.} =
+  self.onSubscribeListener = OnFilterSubscribeEvent.listen(
+    proc(subsEv: OnFilterSubscribeEvent): Future[void] {.async: (raises: []).} =
+      self.onSubscribe(subsEv.pubsubTopic, subsEv.contentTopics)
+  ).valueOr:
+    error "Failed to set OnFilterSubscribeEvent listener", error = error
+    quit(QuitFailure)
+
+  self.onUnsubscribeListener = OnFilterUnsubscribeEvent.listen(
+    proc(subsEv: OnFilterUnsubscribeEvent): Future[void] {.async: (raises: []).} =
+      self.onUnsubscribe(subsEv.pubsubTopic, subsEv.contentTopics)
+  ).valueOr:
+    error "Failed to set OnFilterUnsubscribeEvent listener", error = error
+    quit(QuitFailure)
+
+proc stopRecvService*(self: RecvService) {.async.} =
+  OnFilterSubscribeEvent.dropListener(self.onSubscribeListener)
+  OnFilterUnSubscribeEvent.dropListener(self.onUnsubscribeListener)
  if not self.msgCheckerHandler.isNil():
    await self.msgCheckerHandler.cancelAndWait()
  if not self.msgPrunerHandler.isNil():
    await self.msgPrunerHandler.cancelAndWait()
-
-proc setDeliveryCallback*(self: RecvMonitor, deliveryCb: DeliveryFeedbackCallback) =
-  self.deliveryCb = deliveryCb
--- a/waku/node/delivery_service/send_service.nim
+++ b/waku/node/delivery_service/send_service.nim
@ -0,0 +1,6 @@
+## This module reinforces the publish operation with regular store-v3 requests.
+##
+
+import ./send_service/[send_service, delivery_task]
+
+export send_service, delivery_task
--- a/waku/node/delivery_service/send_service/delivery_task.nim
+++ b/waku/node/delivery_service/send_service/delivery_task.nim
@ -0,0 +1,66 @@
+import std/[options, times], chronos
+import waku/waku_core, waku/api/types, waku/requests/node_requests
+
+type DeliveryState* {.pure.} = enum
+  Entry
+  SuccessfullyPropagated
+  SuccessfullyValidated
+  FallbackRetry
+  NextRoundRetry
+  FailedToDeliver
+
+type DeliveryTask* = ref object
+  requestId*: RequestId
+  pubsubTopic*: PubsubTopic
+  msg*: WakuMessage
+  msgHash*: WakuMessageHash
+  tryCount*: int
+  state*: DeliveryState
+  deliveryTime*: Moment
+  errorDesc*: string
+
+proc create*(
+    T: type DeliveryTask, requestId: RequestId, envelop: MessageEnvelope
+): Result[T, string] =
+  let msg = envelop.toWakuMessage()
+  # TODO: use sync request for such as soon as available
+  let relayShardRes = (
+    waitFor RequestRelayShard.request(none[PubsubTopic](), envelop.contentTopic)
+  ).valueOr:
+    return err($error)
+
+  let pubsubTopic = relayShardRes.relayShard.toPubsubTopic()
+  let msgHash = computeMessageHash(pubsubTopic, msg)
+
+  return ok(
+    T(
+      requestId: requestId,
+      pubsubTopic: pubsubTopic,
+      msg: msg,
+      msgHash: msgHash,
+      tryCount: 0,
+      state: DeliveryState.Entry,
+    )
+  )
+
+func `==`*(r, l: DeliveryTask): bool =
+  if r.isNil() == l.isNil():
+    r.isNil() or r.msgHash == l.msgHash
+  else:
+    false
+
+proc messageAge*(self: DeliveryTask): timer.Duration =
+  let actual = getNanosecondTime(getTime().toUnixFloat())
+  if self.msg.timestamp >= 0 and self.msg.timestamp < actual:
+    nanoseconds(actual - self.msg.timestamp)
+  else:
+    ZeroDuration
+
+proc deliveryAge*(self: DeliveryTask): timer.Duration =
+  if self.state == DeliveryState.SuccessfullyPropagated:
+    timer.Moment.now() - self.deliveryTime
+  else:
+    ZeroDuration
+
+proc isEphemeral*(self: DeliveryTask): bool =
+  return self.msg.ephemeral
--- a/waku/node/delivery_service/send_service/lightpush_processor.nim
+++ b/waku/node/delivery_service/send_service/lightpush_processor.nim
@ -0,0 +1,74 @@
+import chronicles, chronos, results
+import std/options
+
+import
+  waku/waku_node,
+  waku/waku_core,
+  waku/node/peer_manager,
+  waku/waku_lightpush/[callbacks, common, client, rpc]
+
+import ./[delivery_task, send_processor]
+
+logScope:
+  topics = "send service lightpush processor"
+
+type LightpushSendProcessor* = ref object of BaseSendProcessor
+  peerManager: PeerManager
+  lightpushClient: WakuLightPushClient
+
+proc new*(
+    T: type LightpushSendProcessor,
+    peerManager: PeerManager,
+    lightpushClient: WakuLightPushClient,
+): T =
+  return T(peerManager: peerManager, lightpushClient: lightpushClient)
+
+proc isLightpushPeerAvailable(
+    self: LightpushSendProcessor, pubsubTopic: PubsubTopic
+): bool =
+  return self.peerManager.selectPeer(WakuLightPushCodec, some(pubsubTopic)).isSome()
+
+method isValidProcessor*(
+    self: LightpushSendProcessor, task: DeliveryTask
+): Future[bool] {.async.} =
+  return self.isLightpushPeerAvailable(task.pubsubTopic)
+
+method sendImpl*(
+    self: LightpushSendProcessor, task: DeliveryTask
+): Future[void] {.async.} =
+  task.tryCount.inc()
+  info "Trying message delivery via Lightpush",
+    requestId = task.requestId, msgHash = task.msgHash, tryCount = task.tryCount
+
+  let peer = self.peerManager.selectPeer(WakuLightPushCodec, some(task.pubsubTopic)).valueOr:
+    task.state = DeliveryState.NextRoundRetry
+    return
+
+  let pushResult =
+    await self.lightpushClient.publish(some(task.pubsubTopic), task.msg, peer)
+  if pushResult.isErr:
+    error "LightpushSendProcessor sendImpl failed",
+      error = pushResult.error.desc.get($pushResult.error.code)
+    case pushResult.error.code
+    of LightPushErrorCode.NO_PEERS_TO_RELAY, LightPushErrorCode.TOO_MANY_REQUESTS,
+        LightPushErrorCode.OUT_OF_RLN_PROOF, LightPushErrorCode.SERVICE_NOT_AVAILABLE,
+        LightPushErrorCode.INTERNAL_SERVER_ERROR:
+      task.state = DeliveryState.NextRoundRetry
+    else:
+      # the message is malformed, send error
+      task.state = DeliveryState.FailedToDeliver
+      task.errorDesc = pushResult.error.desc.get($pushResult.error.code)
+      task.deliveryTime = Moment.now()
+    return
+
+  if pushResult.isOk and pushResult.get() > 0:
+    info "Message propagated via Relay",
+      requestId = task.requestId, msgHash = task.msgHash
+    task.state = DeliveryState.SuccessfullyPropagated
+    task.deliveryTime = Moment.now()
+    # TODO: with a simple retry processor it might be more accurate to say `Sent`
+  else:
+    # Controversial state, publish says ok but no peer. It should not happen.
+    task.state = DeliveryState.NextRoundRetry
+
+  return
--- a/waku/node/delivery_service/send_service/relay_processor.nim
+++ b/waku/node/delivery_service/send_service/relay_processor.nim
@ -0,0 +1,67 @@
+import chronos, chronicles
+import std/options
+import waku/[waku_node, waku_core], waku/waku_lightpush/[common, callbacks, rpc]
+import waku/requests/health_request
+import waku/api/types
+import ./[delivery_task, send_processor]
+
+logScope:
+  topics = "send service relay processor"
+
+type RelaySendProcessor* = ref object of BaseSendProcessor
+  publishProc: PushMessageHandler
+  fallbackStateToSet: DeliveryState
+
+proc new*(
+    T: type RelaySendProcessor,
+    lightpushAvailable: bool,
+    publishProc: PushMessageHandler,
+): RelaySendProcessor =
+  let fallbackStateToSet =
+    if lightpushAvailable:
+      DeliveryState.FallbackRetry
+    else:
+      DeliveryState.FailedToDeliver
+
+  return
+    RelaySendProcessor(publishProc: publishProc, fallbackStateToSet: fallbackStateToSet)
+
+proc isTopicHealthy(topic: PubsubTopic): Future[bool] {.async.} =
+  let healthReport = (await RequestRelayTopicsHealth.request(@[topic])).valueOr:
+    return false
+
+  if healthReport.topicHealth.len() < 1:
+    return false
+  let health = healthReport.topicHealth[0].health
+  return health == MINIMALLY_HEALTHY or health == SUFFICIENTLY_HEALTHY
+
+method isValidProcessor*(
+    self: RelaySendProcessor, task: DeliveryTask
+): Future[bool] {.async.} =
+  return await isTopicHealthy(task.pubsubTopic)
+
+method sendImpl*(self: RelaySendProcessor, task: DeliveryTask): Future[void] {.async.} =
+  task.tryCount.inc()
+  info "Trying message delivery via Relay",
+    requestId = task.requestId, msgHash = task.msgHash, tryCount = task.tryCount
+
+  let pushResult = await self.publishProc(task.pubsubTopic, task.msg)
+  if pushResult.isErr():
+    let errorMessage = pushResult.error.desc.get($pushResult.error.code)
+    error "Failed to publish message with relay",
+      request = task.requestId, msgHash = task.msgHash, error = errorMessage
+    if pushResult.error.code != LightPushErrorCode.NO_PEERS_TO_RELAY:
+      task.state = DeliveryState.FailedToDeliver
+      task.errorDesc = errorMessage
+    else:
+      task.state = self.fallbackStateToSet
+    return
+
+  if pushResult.isOk and pushResult.get() > 0:
+    info "Message propagated via Relay",
+      requestId = task.requestId, msgHash = task.msgHash
+    task.state = DeliveryState.SuccessfullyPropagated
+    task.deliveryTime = Moment.now()
+  else:
+    # It shall not happen, but still covering it
+    task.state = self.fallbackStateToSet
--- a/waku/node/delivery_service/send_service/send_processor.nim
+++ b/waku/node/delivery_service/send_service/send_processor.nim
@ -0,0 +1,32 @@
+import chronos
+import ./delivery_task
+
+type BaseSendProcessor* = ref object of RootObj
+  fallbackProcessor*: BaseSendProcessor
+
+proc chain*(self: BaseSendProcessor, next: BaseSendProcessor) =
+  self.fallbackProcessor = next
+
+method isValidProcessor*(
+    self: BaseSendProcessor, task: DeliveryTask
+): Future[bool] {.async, base.} =
+  return false
+
+method sendImpl*(
+    self: BaseSendProcessor, task: DeliveryTask
+): Future[void] {.async, base.} =
+  assert false, "Not implemented"
+
+method process*(
+    self: BaseSendProcessor, task: DeliveryTask
+): Future[void] {.async, base.} =
+  var currentProcessor: BaseSendProcessor = self
+  var keepTrying = true
+  while not currentProcessor.isNil() and keepTrying:
+    if await currentProcessor.isValidProcessor(task):
+      await currentProcessor.sendImpl(task)
+    currentProcessor = currentProcessor.fallbackProcessor
+    keepTrying = task.state == DeliveryState.FallbackRetry
+
+  if task.state == DeliveryState.FallbackRetry:
+    task.state = DeliveryState.NextRoundRetry
--- a/waku/node/delivery_service/send_service/send_service.nim
+++ b/waku/node/delivery_service/send_service/send_service.nim
@ -0,0 +1,238 @@
+## This module reinforces the publish operation with regular store-v3 requests.
+##
+
+import std/[sequtils, tables, options]
+import chronos, chronicles, libp2p/utility
+import
+  ./[send_processor, relay_processor, lightpush_processor, delivery_task],
+  waku/[
+    waku_core,
+    node/waku_node,
+    node/peer_manager,
+    waku_store/client,
+    waku_store/common,
+    waku_archive/archive,
+    waku_relay/protocol,
+    waku_rln_relay/rln_relay,
+    waku_lightpush/client,
+    waku_lightpush/callbacks,
+    events/delivery_events,
+    events/message_events,
+  ]
+
+logScope:
+  topics = "send service"
+
+# This useful util is missing from sequtils, this extends applyIt with predicate...
+template applyItIf*(varSeq, pred, op: untyped) =
+  for i in low(varSeq) .. high(varSeq):
+    let it {.inject.} = varSeq[i]
+    if pred:
+      op
+      varSeq[i] = it
+
+template forEach*(varSeq, op: untyped) =
+  for i in low(varSeq) .. high(varSeq):
+    let it {.inject.} = varSeq[i]
+    op
+
+const MaxTimeInCache* = chronos.minutes(1)
+  ## Messages older than this time will get completely forgotten on publication and a
+  ## feedback will be given when that happens
+
+const ServiceLoopInterval* = chronos.seconds(1)
+  ## Interval at which we check that messages have been properly received by a store node
+
+const ArchiveTime = chronos.seconds(3)
+  ## Estimation of the time we wait until we start confirming that a message has been properly
+  ## received and archived by a store node
+
+type SendService* = ref object of RootObj
+  taskCache: seq[DeliveryTask]
+    ## Cache that contains the delivery task per message hash.
+    ## This is needed to make sure the published messages are properly published
+
+  serviceLoopHandle: Future[void] ## handle that allows to stop the async task
+  sendProcessor: BaseSendProcessor
+
+  node: WakuNode
+  checkStoreForMessages: bool
+
+proc setupSendProcessorChain(
+    peerManager: PeerManager,
+    lightpushClient: WakuLightPushClient,
+    relay: WakuRelay,
+    rlnRelay: WakuRLNRelay,
+): Result[BaseSendProcessor, string] =
+  let isRelayAvail = not relay.isNil()
+  let isLightPushAvail = not lightpushClient.isNil()
+
+  if not isRelayAvail and not isLightPushAvail:
+    return err("No valid send processor found for the delivery task")
+
+  var processors = newSeq[BaseSendProcessor]()
+
+  if isRelayAvail:
+    let rln: Option[WakuRLNRelay] =
+      if rlnRelay.isNil():
+        none[WakuRLNRelay]()
+      else:
+        some(rlnRelay)
+    let publishProc = getRelayPushHandler(relay, rln)
+
+    processors.add(RelaySendProcessor.new(isLightPushAvail, publishProc))
+  if isLightPushAvail:
+    processors.add(LightpushSendProcessor.new(peerManager, lightpushClient))
+
+  var currentProcessor: BaseSendProcessor = processors[0]
+  for i in 1 ..< processors.len():
+    currentProcessor.chain(processors[i])
+    currentProcessor = processors[i]
+
+  return ok(processors[0])
+
+proc new*(
+    T: type SendService, preferP2PReliability: bool, w: WakuNode
+): Result[T, string] =
+  if w.wakuRelay.isNil() and w.wakuLightpushClient.isNil():
+    return err(
+      "Could not create SendService. wakuRelay or wakuLightpushClient should be set"
+    )
+
+  let checkStoreForMessages = preferP2PReliability and not w.wakuStoreClient.isNil()
+
+  let sendProcessorChain = setupSendProcessorChain(
+    w.peerManager, w.wakuLightPushClient, w.wakuRelay, w.wakuRlnRelay
+  ).valueOr:
+    return err(error)
+
+  let sendService = SendService(
+    taskCache: newSeq[DeliveryTask](),
+    serviceLoopHandle: nil,
+    sendProcessor: sendProcessorChain,
+    node: w,
+    checkStoreForMessages: checkStoreForMessages,
+  )
+
+  return ok(sendService)
+
+proc addTask(self: SendService, task: DeliveryTask) =
+  self.taskCache.addUnique(task)
+
+proc isStorePeerAvailable*(sendService: SendService): bool =
+  return sendService.node.peerManager.selectPeer(WakuStoreCodec).isSome()
+
+proc checkMsgsInStore(self: SendService, tasksToValidate: seq[DeliveryTask]) {.async.} =
+  if tasksToValidate.len() == 0:
+    return
+
+  if not isStorePeerAvailable(self):
+    warn "Skipping store validation for ",
+      messageCount = tasksToValidate.len(), error = "no store peer available"
+    return
+
+  var hashesToValidate = tasksToValidate.mapIt(it.msgHash)
+
+  let storeResp: StoreQueryResponse = (
+    await self.node.wakuStoreClient.queryToAny(
+      StoreQueryRequest(includeData: false, messageHashes: hashesToValidate)
+    )
+  ).valueOr:
+    error "Failed to get store validation for messages",
+      hashes = hashesToValidate.mapIt(shortLog(it)), error = $error
+    return
+
+  let storedItems = storeResp.messages.mapIt(it.messageHash)
+
+  # Set success state for messages found in store
+  self.taskCache.applyItIf(storedItems.contains(it.msgHash)):
+    it.state = DeliveryState.SuccessfullyValidated
+
+  # set retry state for messages not found in store
+  hashesToValidate.keepItIf(not storedItems.contains(it))
+  self.taskCache.applyItIf(hashesToValidate.contains(it.msgHash)):
+    it.state = DeliveryState.NextRoundRetry
+
+proc checkStoredMessages(self: SendService) {.async.} =
+  if not self.checkStoreForMessages:
+    return
+
+  let tasksToValidate = self.taskCache.filterIt(
+    it.state == DeliveryState.SuccessfullyPropagated and it.deliveryAge() > ArchiveTime and
+      not it.isEphemeral()
+  )
+
+  await self.checkMsgsInStore(tasksToValidate)
+
+proc reportTaskResult(self: SendService, task: DeliveryTask) =
+  case task.state
+  of DeliveryState.SuccessfullyPropagated:
+    # TODO: in case of of unable to strore check messages shall we report success instead?
+    info "Message successfully propagated",
+      requestId = task.requestId, msgHash = task.msgHash
+    MessagePropagatedEvent.emit(task.requestId, task.msgHash.toString())
+    return
+  of DeliveryState.SuccessfullyValidated:
+    info "Message successfully sent", requestId = task.requestId, msgHash = task.msgHash
+    MessageSentEvent.emit(task.requestId, task.msgHash.toString())
+    return
+  of DeliveryState.FailedToDeliver:
+    error "Failed to send message",
+      requestId = task.requestId, msgHash = task.msgHash, error = task.errorDesc
+    MessageErrorEvent.emit(task.requestId, task.msgHash.toString(), task.errorDesc)
+    return
+  else:
+    # rest of the states are intermediate and does not translate to event
+    discard
+
+  if task.messageAge() > MaxTimeInCache:
+    error "Failed to send message",
+      requestId = task.requestId, msgHash = task.msgHash, error = "Message too old"
+    task.state = DeliveryState.FailedToDeliver
+    MessageErrorEvent.emit(
+      task.requestId, task.msgHash.toString(), "Unable to send within retry time window"
+    )
+
+proc evaluateAndCleanUp(self: SendService) =
+  self.taskCache.forEach(self.reportTaskResult(it))
+  self.taskCache.keepItIf(
+    it.state != DeliveryState.SuccessfullyValidated or
+      it.state != DeliveryState.FailedToDeliver
+  )
+
+  # remove propagated ephemeral messages as no store check is possible
+  self.taskCache.keepItIf(
+    not (it.isEphemeral() and it.state == DeliveryState.SuccessfullyPropagated)
+  )
+
+proc trySendMessages(self: SendService) {.async.} =
+  let tasksToSend = self.taskCache.filterIt(it.state == DeliveryState.NextRoundRetry)
+
+  for task in tasksToSend:
+    # Todo, check if it has any perf gain to run them concurrent...
+    await self.sendProcessor.process(task)
+
+proc serviceLoop(self: SendService) {.async.} =
+  ## Continuously monitors that the sent messages have been received by a store node
+  while true:
+    await self.trySendMessages()
+    await self.checkStoredMessages()
+    self.evaluateAndCleanUp()
+    ## TODO: add circuit breaker to avoid infinite looping in case of persistent failures
+    ## Use OnlienStateChange observers to pause/resume the loop
+    await sleepAsync(ServiceLoopInterval)
+
+proc startSendService*(self: SendService) =
+  self.serviceLoopHandle = self.serviceLoop()
+
+proc stopSendService*(self: SendService) =
+  if not self.serviceLoopHandle.isNil():
+    discard self.serviceLoopHandle.cancelAndWait()
+
+proc send*(self: SendService, task: DeliveryTask): Future[void] {.async.} =
+  assert(not task.isNil(), "task for send must not be nil")
+
+  await self.sendProcessor.process(task)
+  reportTaskResult(self, task)
+  if task.state != DeliveryState.FailedToDeliver:
+    self.addTask(task)
--- a/waku/node/health_monitor/topic_health.nim
+++ b/waku/node/health_monitor/topic_health.nim
@ -1,11 +1,12 @@
 import chronos

-import ../waku_core
+import waku/waku_core

 type TopicHealth* = enum
  UNHEALTHY
  MINIMALLY_HEALTHY
  SUFFICIENTLY_HEALTHY
+  NOT_SUBSCRIBED

 proc `$`*(t: TopicHealth): string =
  result =
@ -13,6 +14,7 @@ proc `$`*(t: TopicHealth): string =
    of UNHEALTHY: "UnHealthy"
    of MINIMALLY_HEALTHY: "MinimallyHealthy"
    of SUFFICIENTLY_HEALTHY: "SufficientlyHealthy"
+    of NOT_SUBSCRIBED: "NotSubscribed"

 type TopicHealthChangeHandler* = proc(
  pubsubTopic: PubsubTopic, topicHealth: TopicHealth
--- a/waku/node/kernel_api/lightpush.nim
+++ b/waku/node/kernel_api/lightpush.nim
@ -188,7 +188,6 @@ proc lightpushPublishHandler(
    mixify: bool = false,
 ): Future[lightpush_protocol.WakuLightPushResult] {.async.} =
  let msgHash = pubsubTopic.computeMessageHash(message).to0xHex()
-
  if not node.wakuLightpushClient.isNil():
    notice "publishing message with lightpush",
      pubsubTopic = pubsubTopic,
@ -196,21 +195,23 @@ proc lightpushPublishHandler(
      target_peer_id = peer.peerId,
      msg_hash = msgHash,
      mixify = mixify
-    if mixify: #indicates we want to use mix to send the message
-      #TODO: How to handle multiple addresses?
-      let conn = node.wakuMix.toConnection(
-        MixDestination.exitNode(peer.peerId),
-        WakuLightPushCodec,
-        MixParameters(expectReply: Opt.some(true), numSurbs: Opt.some(byte(1))),
-          # indicating we only want a single path to be used for reply hence numSurbs = 1
-      ).valueOr:
-        error "could not create mix connection"
-        return lighpushErrorResult(
-          LightPushErrorCode.SERVICE_NOT_AVAILABLE,
-          "Waku lightpush with mix not available",
-        )
+    if defined(libp2p_mix_experimental_exit_is_dest) and mixify:
+      #indicates we want to use mix to send the message
+      when defined(libp2p_mix_experimental_exit_is_dest):
+        #TODO: How to handle multiple addresses?
+        let conn = node.wakuMix.toConnection(
+          MixDestination.exitNode(peer.peerId),
+          WakuLightPushCodec,
+          MixParameters(expectReply: Opt.some(true), numSurbs: Opt.some(byte(1))),
+            # indicating we only want a single path to be used for reply hence numSurbs = 1
+        ).valueOr:
+          error "could not create mix connection"
+          return lighpushErrorResult(
+            LightPushErrorCode.SERVICE_NOT_AVAILABLE,
+            "Waku lightpush with mix not available",
+          )

-      return await node.wakuLightpushClient.publish(some(pubsubTopic), message, conn)
+        return await node.wakuLightpushClient.publish(some(pubsubTopic), message, conn)
    else:
      return await node.wakuLightpushClient.publish(some(pubsubTopic), message, peer)

@ -259,7 +260,7 @@ proc lightpushPublish*(
        LightPushErrorCode.NO_PEERS_TO_RELAY, "no suitable remote peers"
      )

-  let pubsubForPublish = pubSubTopic.valueOr:
+  let pubsubForPublish = pubsubTopic.valueOr:
    if node.wakuAutoSharding.isNone():
      let msg = "Pubsub topic must be specified when static sharding is enabled"
      error "lightpush publish error", error = msg
--- a/waku/node/kernel_api/relay.nim
+++ b/waku/node/kernel_api/relay.nim
@ -165,7 +165,7 @@ proc unsubscribe*(

 proc publish*(
    node: WakuNode, pubsubTopicOp: Option[PubsubTopic], message: WakuMessage
-): Future[Result[void, string]] {.async, gcsafe.} =
+): Future[Result[int, string]] {.async, gcsafe.} =
  ## Publish a `WakuMessage`. Pubsub topic contains; none, a named or static shard.
  ## `WakuMessage` should contain a `contentTopic` field for light node functionality.
  ## It is also used to determine the shard.
@ -184,16 +184,20 @@ proc publish*(
      let msg = "Autosharding error: " & error
      return err(msg)

-  #TODO instead of discard return error when 0 peers received the message
-  discard await node.wakuRelay.publish(pubsubTopic, message)
+  let numPeers = (await node.wakuRelay.publish(pubsubTopic, message)).valueOr:
+    warn "waku.relay did not publish", error = error
+    # Todo: If NoPeersToPublish, we might want to return ok(0) instead!!!
+    return err($error)

  notice "waku.relay published",
    peerId = node.peerId,
    pubsubTopic = pubsubTopic,
    msg_hash = pubsubTopic.computeMessageHash(message).to0xHex(),
-    publishTime = getNowInNanosecondTime()
+    publishTime = getNowInNanosecondTime(),
+    numPeers = numPeers

-  return ok()
+  # TODO: investigate if we can return error in case numPeers is 0
+  ok(numPeers)

 proc mountRelay*(
    node: WakuNode,
--- a/waku/node/waku_node.nim
+++ b/waku/node/waku_node.nim
@ -27,38 +27,41 @@ import
  libp2p/protocols/mix/mix_protocol

 import
-  ../waku_core,
-  ../waku_core/topics/sharding,
-  ../waku_relay,
-  ../waku_archive,
-  ../waku_archive_legacy,
-  ../waku_store_legacy/protocol as legacy_store,
-  ../waku_store_legacy/client as legacy_store_client,
-  ../waku_store_legacy/common as legacy_store_common,
-  ../waku_store/protocol as store,
-  ../waku_store/client as store_client,
-  ../waku_store/common as store_common,
-  ../waku_store/resume,
-  ../waku_store_sync,
-  ../waku_filter_v2,
-  ../waku_filter_v2/client as filter_client,
-  ../waku_metadata,
-  ../waku_rendezvous/protocol,
-  ../waku_rendezvous/client as rendezvous_client,
-  ../waku_rendezvous/waku_peer_record,
-  ../waku_lightpush_legacy/client as legacy_ligntpuhs_client,
-  ../waku_lightpush_legacy as legacy_lightpush_protocol,
-  ../waku_lightpush/client as ligntpuhs_client,
-  ../waku_lightpush as lightpush_protocol,
-  ../waku_enr,
-  ../waku_peer_exchange,
-  ../waku_rln_relay,
+  waku/[
+    waku_core,
+    waku_core/topics/sharding,
+    waku_relay,
+    waku_archive,
+    waku_archive_legacy,
+    waku_store_legacy/protocol as legacy_store,
+    waku_store_legacy/client as legacy_store_client,
+    waku_store_legacy/common as legacy_store_common,
+    waku_store/protocol as store,
+    waku_store/client as store_client,
+    waku_store/common as store_common,
+    waku_store/resume,
+    waku_store_sync,
+    waku_filter_v2,
+    waku_filter_v2/client as filter_client,
+    waku_metadata,
+    waku_rendezvous/protocol,
+    waku_rendezvous/client as rendezvous_client,
+    waku_rendezvous/waku_peer_record,
+    waku_lightpush_legacy/client as legacy_ligntpuhs_client,
+    waku_lightpush_legacy as legacy_lightpush_protocol,
+    waku_lightpush/client as ligntpuhs_client,
+    waku_lightpush as lightpush_protocol,
+    waku_enr,
+    waku_peer_exchange,
+    waku_rln_relay,
+    common/rate_limit/setting,
+    common/callbacks,
+    common/nimchronos,
+    waku_mix,
+    requests/node_requests,
+  ],
  ./net_config,
-  ./peer_manager,
-  ../common/rate_limit/setting,
-  ../common/callbacks,
-  ../common/nimchronos,
-  ../waku_mix
+  ./peer_manager

 declarePublicCounter waku_node_messages, "number of messages received", ["type"]

@ -131,6 +134,18 @@ type
    rateLimitSettings*: ProtocolRateLimitSettings
    wakuMix*: WakuMix

+proc deduceRelayShard(
+    node: WakuNode,
+    contentTopic: ContentTopic,
+    pubsubTopicOp: Option[PubsubTopic] = none[PubsubTopic](),
+): Result[RelayShard, string] =
+  let pubsubTopic = pubsubTopicOp.valueOr:
+    if node.wakuAutoSharding.isNone():
+      return err("Pubsub topic must be specified when static sharding is enabled.")
+    node.wakuAutoSharding.get().getShard(contentTopic).valueOr:
+      let msg = "Deducing shard failed: " & error
+      return err(msg)
+
 proc getShardsGetter(node: WakuNode): GetShards =
  return proc(): seq[uint16] {.closure, gcsafe, raises: [].} =
    # fetch pubsubTopics subscribed to relay and convert them to shards
@ -252,6 +267,7 @@ proc mountAutoSharding*(
  info "mounting auto sharding", clusterId = clusterId, shardCount = shardCount
  node.wakuAutoSharding =
    some(Sharding(clusterId: clusterId, shardCountGenZero: shardCount))
+
  return ok()

 proc getMixNodePoolSize*(node: WakuNode): int =
@ -443,6 +459,20 @@ proc updateAnnouncedAddrWithPrimaryIpAddr*(node: WakuNode): Result[void, string]

  return ok()

+proc startProvidersAndListeners*(node: WakuNode) =
+  RequestRelayShard.setProvider(
+    proc(
+        pubsubTopic: Option[PubsubTopic], contentTopic: ContentTopic
+    ): Future[Result[RequestRelayShard, string]] {.async.} =
+      let shard = node.deduceRelayShard(contentTopic, pubsubTopic).valueOr:
+        return err($error)
+      return ok(RequestRelayShard(relayShard: shard))
+  ).isOkOr:
+    error "Can't set proveder for RequestRelayShard", error = error
+
+proc stopProvidersAndListeners*(node: WakuNode) =
+  RequestRelayShard.clearProvider()
+
 proc start*(node: WakuNode) {.async.} =
  ## Starts a created Waku Node and
  ## all its mounted protocols.
@ -491,6 +521,8 @@ proc start*(node: WakuNode) {.async.} =
  ## The switch will update addresses after start using the addressMapper
  await node.switch.start()

+  node.startProvidersAndListeners()
+
  node.started = true

  if not zeroPortPresent:
@ -503,6 +535,9 @@ proc start*(node: WakuNode) {.async.} =

 proc stop*(node: WakuNode) {.async.} =
  ## By stopping the switch we are stopping all the underlying mounted protocols
+
+  node.stopProvidersAndListeners()
+
  await node.switch.stop()

  node.peerManager.stop()
--- a/waku/requests/health_request.nim
+++ b/waku/requests/health_request.nim
@ -0,0 +1,23 @@
+import waku/common/broker/[request_broker, multi_request_broker]
+
+import waku/api/types
+import waku/node/health_monitor/[protocol_health, topic_health]
+import waku/waku_core/topics
+
+export protocol_health, topic_health
+
+RequestBroker:
+  type RequestNodeHealth* = object
+    healthStatus*: NodeHealth
+
+RequestBroker:
+  type RequestRelayTopicsHealth* = object
+    topicHealth*: seq[tuple[topic: PubsubTopic, health: TopicHealth]]
+
+  proc signature(
+    topics: seq[PubsubTopic]
+  ): Future[Result[RequestRelayTopicsHealth, string]] {.async.}
+
+MultiRequestBroker:
+  type RequestProtocolHealth* = object
+    healthStatus*: ProtocolHealth
--- a/waku/requests/node_requests.nim
+++ b/waku/requests/node_requests.nim
@ -0,0 +1,11 @@
+import std/options
+import waku/common/broker/[request_broker, multi_request_broker]
+import waku/waku_core/[topics]
+
+RequestBroker:
+  type RequestRelayShard* = object
+    relayShard*: RelayShard
+
+  proc signature(
+    pubsubTopic: Option[PubsubTopic], contentTopic: ContentTopic
+  ): Future[Result[RequestRelayShard, string]] {.async.}
--- a/waku/requests/requests.nim
+++ b/waku/requests/requests.nim
@ -0,0 +1,3 @@
+import ./[health_request, rln_requests, node_requests]
+
+export health_request, rln_requests, node_requests
--- a/waku/requests/rln_requests.nim
+++ b/waku/requests/rln_requests.nim
@ -0,0 +1,9 @@
+import waku/common/broker/request_broker, waku/waku_core/message/message
+
+RequestBroker:
+  type RequestGenerateRlnProof* = object
+    proof*: seq[byte]
+
+  proc signature(
+    message: WakuMessage, senderEpoch: float64
+  ): Future[Result[RequestGenerateRlnProof, string]] {.async.}
--- a/waku/waku_core/event/event_emitter.nim
+++ b/waku/waku_core/event/event_emitter.nim
@ -0,0 +1,20 @@
+
+
+type
+  EventEmitter* = object
+    # Placeholder for future event emitter implementation
+    observers*: seq[proc (data: EventData): void]
+
+
+proc initEventEmitter*(): EventEmitter =
+  EventEmitter(observers: @[])
+
+proc emitEvent*(emitter: var EventEmitter, data: EventData) =
+  for observer in emitter.observers:
+    asyncSpawn observer(data)
+
+proc subscribeToEvent*(emitter: var EventEmitter, observer: proc (data: EventData): void) =
+  emitter.observers.add(observer)
+
+proc unsubscribeFromEvent*(emitter: var EventEmitter, observer: proc (data: EventData): void) =
+  emitter.observers = emitter.observers.filterIt(it != observer)
--- a/waku/waku_core/message/digest.nim
+++ b/waku/waku_core/message/digest.nim
@ -19,6 +19,11 @@ func shortLog*(hash: WakuMessageHash): string =
 func `$`*(hash: WakuMessageHash): string =
  shortLog(hash)

+func toString*(hash: WakuMessageHash): string =
+  var hexhash = newStringOfCap(64)
+  hexhash &= hash.toOpenArray(hash.low, hash.high).to0xHex()
+  hexhash
+
 const EmptyWakuMessageHash*: WakuMessageHash = [
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0,
--- a/waku/waku_filter_v2/client.nim
+++ b/waku/waku_filter_v2/client.nim
@ -10,9 +10,7 @@ import
  bearssl/rand,
  stew/byteutils
 import
-  ../node/peer_manager,
-  ../node/delivery_monitor/subscriptions_observer,
-  ../waku_core,
+  waku/[node/peer_manager, waku_core, events/delivery_events],
  ./common,
  ./protocol_metrics,
  ./rpc_codec,
@ -25,16 +23,12 @@ type WakuFilterClient* = ref object of LPProtocol
  rng: ref HmacDrbgContext
  peerManager: PeerManager
  pushHandlers: seq[FilterPushHandler]
-  subscrObservers: seq[SubscriptionObserver]

 func generateRequestId(rng: ref HmacDrbgContext): string =
  var bytes: array[10, byte]
  hmacDrbgGenerate(rng[], bytes)
  return toHex(bytes)

-proc addSubscrObserver*(wfc: WakuFilterClient, obs: SubscriptionObserver) =
-  wfc.subscrObservers.add(obs)
-
 proc sendSubscribeRequest(
    wfc: WakuFilterClient,
    servicePeer: RemotePeerInfo,
@ -132,8 +126,7 @@ proc subscribe*(

  ?await wfc.sendSubscribeRequest(servicePeer, filterSubscribeRequest)

-  for obs in wfc.subscrObservers:
-    obs.onSubscribe(pubSubTopic, contentTopicSeq)
+  OnFilterSubscribeEvent.emit(pubSubTopic, contentTopicSeq)

  return ok()

@ -156,8 +149,7 @@ proc unsubscribe*(

  ?await wfc.sendSubscribeRequest(servicePeer, filterSubscribeRequest)

-  for obs in wfc.subscrObservers:
-    obs.onUnsubscribe(pubSubTopic, contentTopicSeq)
+  OnFilterUnSubscribeEvent.emit(pubSubTopic, contentTopicSeq)

  return ok()

--- a/waku/waku_lightpush/callbacks.nim
+++ b/waku/waku_lightpush/callbacks.nim
@ -31,7 +31,7 @@ proc checkAndGenerateRLNProof*(

 proc getNilPushHandler*(): PushMessageHandler =
  return proc(
-      peer: PeerId, pubsubTopic: string, message: WakuMessage
+      pubsubTopic: string, message: WakuMessage
  ): Future[WakuLightPushResult] {.async.} =
    return lightpushResultInternalError("no waku relay found")

@ -39,7 +39,7 @@ proc getRelayPushHandler*(
    wakuRelay: WakuRelay, rlnPeer: Option[WakuRLNRelay] = none[WakuRLNRelay]()
 ): PushMessageHandler =
  return proc(
-      peer: PeerId, pubsubTopic: string, message: WakuMessage
+      pubsubTopic: string, message: WakuMessage
  ): Future[WakuLightPushResult] {.async.} =
    # append RLN proof
    let msgWithProof = checkAndGenerateRLNProof(rlnPeer, message).valueOr:
--- a/waku/waku_lightpush/client.nim
+++ b/waku/waku_lightpush/client.nim
@ -5,7 +5,6 @@ import libp2p/peerid, libp2p/stream/connection
 import
  ../waku_core/peers,
  ../node/peer_manager,
-  ../node/delivery_monitor/publish_observer,
  ../utils/requests,
  ../waku_core,
  ./common,
@ -19,16 +18,12 @@ logScope:
 type WakuLightPushClient* = ref object
  rng*: ref rand.HmacDrbgContext
  peerManager*: PeerManager
-  publishObservers: seq[PublishObserver]

 proc new*(
    T: type WakuLightPushClient, peerManager: PeerManager, rng: ref rand.HmacDrbgContext
 ): T =
  WakuLightPushClient(peerManager: peerManager, rng: rng)

-proc addPublishObserver*(wl: WakuLightPushClient, obs: PublishObserver) =
-  wl.publishObservers.add(obs)
-
 proc ensureTimestampSet(message: var WakuMessage) =
  if message.timestamp == 0:
    message.timestamp = getNowInNanosecondTime()
@ -40,36 +35,43 @@ func shortPeerId(peer: PeerId): string =
 func shortPeerId(peer: RemotePeerInfo): string =
  shortLog(peer.peerId)

-proc sendPushRequestToConn(
-    wl: WakuLightPushClient, request: LightPushRequest, conn: Connection
+proc sendPushRequest(
+    wl: WakuLightPushClient,
+    req: LightPushRequest,
+    peer: PeerId | RemotePeerInfo,
+    conn: Option[Connection] = none(Connection),
 ): Future[WakuLightPushResult] {.async.} =
-  try:
-    await conn.writeLp(request.encode().buffer)
-  except LPStreamRemoteClosedError:
-    error "Failed to write request to peer", error = getCurrentExceptionMsg()
-    return lightpushResultInternalError(
-      "Failed to write request to peer: " & getCurrentExceptionMsg()
-    )
+  let connection = conn.valueOr:
+    (await wl.peerManager.dialPeer(peer, WakuLightPushCodec)).valueOr:
+      waku_lightpush_v3_errors.inc(labelValues = [dialFailure])
+      return lighpushErrorResult(
+        LightPushErrorCode.NO_PEERS_TO_RELAY,
+        dialFailure & ": " & $peer & " is not accessible",
+      )
+
+  defer:
+    await connection.closeWithEOF()
+
+  await connection.writeLP(req.encode().buffer)

  var buffer: seq[byte]
  try:
-    buffer = await conn.readLp(DefaultMaxRpcSize.int)
+    buffer = await connection.readLp(DefaultMaxRpcSize.int)
  except LPStreamRemoteClosedError:
    error "Failed to read response from peer", error = getCurrentExceptionMsg()
    return lightpushResultInternalError(
      "Failed to read response from peer: " & getCurrentExceptionMsg()
    )
+
  let response = LightpushResponse.decode(buffer).valueOr:
-    error "failed to decode response", error = $error
+    error "failed to decode response"
    waku_lightpush_v3_errors.inc(labelValues = [decodeRpcFailure])
    return lightpushResultInternalError(decodeRpcFailure)

-  let requestIdMismatch = response.requestId != request.requestId
-  let tooManyRequests = response.statusCode == LightPushErrorCode.TOO_MANY_REQUESTS
-  if requestIdMismatch and (not tooManyRequests):
-    # response with TOO_MANY_REQUESTS error code has no requestId by design
+  if response.requestId != req.requestId and
+      response.statusCode != LightPushErrorCode.TOO_MANY_REQUESTS:
    error "response failure, requestId mismatch",
-      requestId = request.requestId, responseRequestId = response.requestId
+      requestId = req.requestId, responseRequestId = response.requestId
    return lightpushResultInternalError("response failure, requestId mismatch")

  return toPushResult(response)
@ -80,37 +82,34 @@ proc publish*(
    wakuMessage: WakuMessage,
    dest: Connection | PeerId | RemotePeerInfo,
 ): Future[WakuLightPushResult] {.async, gcsafe.} =
-  let conn =
-    when dest is Connection:
-      dest
-    else:
-      (await wl.peerManager.dialPeer(dest, WakuLightPushCodec)).valueOr:
-        waku_lightpush_v3_errors.inc(labelValues = [dialFailure])
-        return lighpushErrorResult(
-          LightPushErrorCode.NO_PEERS_TO_RELAY,
-          "Peer is not accessible: " & dialFailure & " - " & $dest,
-        )
-
-  defer:
-    await conn.closeWithEOF()
-
  var message = wakuMessage
  ensureTimestampSet(message)

  let msgHash = computeMessageHash(pubSubTopic.get(""), message).to0xHex()
+
+  let peerIdStr =
+    when dest is Connection:
+      shortPeerId(dest.peerId)
+    else:
+      shortPeerId(dest)
+
  info "publish",
    myPeerId = wl.peerManager.switch.peerInfo.peerId,
-    peerId = shortPeerId(conn.peerId),
+    peerId = peerIdStr,
    msgHash = msgHash,
    sentTime = getNowInNanosecondTime()

  let request = LightpushRequest(
    requestId: generateRequestId(wl.rng), pubsubTopic: pubSubTopic, message: message
  )
-  let relayPeerCount = ?await wl.sendPushRequestToConn(request, conn)

-  for obs in wl.publishObservers:
-    obs.onMessagePublished(pubSubTopic.get(""), message)
+  let relayPeerCount =
+    when dest is Connection:
+      ?await wl.sendPushRequest(request, dest.peerId, some(dest))
+    elif dest is RemotePeerInfo:
+      ?await wl.sendPushRequest(request, dest)
+    else:
+      ?await wl.sendPushRequest(request, dest)

  return lightpushSuccessResult(relayPeerCount)

@ -124,3 +123,12 @@ proc publishToAny*(
      LightPushErrorCode.NO_PEERS_TO_RELAY, "no suitable remote peers"
    )
  return await wl.publish(some(pubsubTopic), wakuMessage, peer)
+
+proc publishWithConn*(
+    wl: WakuLightPushClient,
+    pubSubTopic: PubsubTopic,
+    message: WakuMessage,
+    conn: Connection,
+    destPeer: PeerId,
+): Future[WakuLightPushResult] {.async, gcsafe.} =
+  return await wl.publish(some(pubSubTopic), message, conn)
--- a/waku/waku_lightpush/common.nim
+++ b/waku/waku_lightpush/common.nim
@ -25,7 +25,7 @@ type ErrorStatus* = tuple[code: LightpushStatusCode, desc: Option[string]]
 type WakuLightPushResult* = Result[uint32, ErrorStatus]

 type PushMessageHandler* = proc(
-  peer: PeerId, pubsubTopic: PubsubTopic, message: WakuMessage
+  pubsubTopic: PubsubTopic, message: WakuMessage
 ): Future[WakuLightPushResult] {.async.}

 const TooManyRequestsMessage* = "Request rejected due to too many requests"
@ -39,7 +39,7 @@ func toPushResult*(response: LightPushResponse): WakuLightPushResult =
    return (
      if (relayPeerCount == 0):
        # Consider publishing to zero peers an error even if the service node
-        # sent us a "successful" response with zero peers 
+        # sent us a "successful" response with zero peers
        err((LightPushErrorCode.NO_PEERS_TO_RELAY, response.statusDesc))
      else:
        ok(relayPeerCount)
--- a/waku/waku_lightpush/protocol.nim
+++ b/waku/waku_lightpush/protocol.nim
@ -71,7 +71,7 @@ proc handleRequest(
    msg_hash = msg_hash,
    receivedTime = getNowInNanosecondTime()

-  let res = (await wl.pushHandler(peerId, pubsubTopic, pushRequest.message)).valueOr:
+  let res = (await wl.pushHandler(pubsubTopic, pushRequest.message)).valueOr:
    return err((code: error.code, desc: error.desc))
  return ok(res)

--- a/waku/waku_lightpush_legacy/callbacks.nim
+++ b/waku/waku_lightpush_legacy/callbacks.nim
@ -30,7 +30,7 @@ proc checkAndGenerateRLNProof*(

 proc getNilPushHandler*(): PushMessageHandler =
  return proc(
-      peer: PeerId, pubsubTopic: string, message: WakuMessage
+      pubsubTopic: string, message: WakuMessage
  ): Future[WakuLightPushResult[void]] {.async.} =
    return err("no waku relay found")

@ -38,7 +38,7 @@ proc getRelayPushHandler*(
    wakuRelay: WakuRelay, rlnPeer: Option[WakuRLNRelay] = none[WakuRLNRelay]()
 ): PushMessageHandler =
  return proc(
-      peer: PeerId, pubsubTopic: string, message: WakuMessage
+      pubsubTopic: string, message: WakuMessage
  ): Future[WakuLightPushResult[void]] {.async.} =
    # append RLN proof
    let msgWithProof = ?checkAndGenerateRLNProof(rlnPeer, message)
--- a/waku/waku_lightpush_legacy/client.nim
+++ b/waku/waku_lightpush_legacy/client.nim
@ -5,7 +5,6 @@ import libp2p/peerid
 import
  ../waku_core/peers,
  ../node/peer_manager,
-  ../node/delivery_monitor/publish_observer,
  ../utils/requests,
  ../waku_core,
  ./common,
@ -19,7 +18,6 @@ logScope:
 type WakuLegacyLightPushClient* = ref object
  peerManager*: PeerManager
  rng*: ref rand.HmacDrbgContext
-  publishObservers: seq[PublishObserver]

 proc new*(
    T: type WakuLegacyLightPushClient,
@ -28,9 +26,6 @@ proc new*(
 ): T =
  WakuLegacyLightPushClient(peerManager: peerManager, rng: rng)

-proc addPublishObserver*(wl: WakuLegacyLightPushClient, obs: PublishObserver) =
-  wl.publishObservers.add(obs)
-
 proc sendPushRequest(
    wl: WakuLegacyLightPushClient, req: PushRequest, peer: PeerId | RemotePeerInfo
 ): Future[WakuLightPushResult[void]] {.async, gcsafe.} =
@ -86,9 +81,6 @@ proc publish*(
  let pushRequest = PushRequest(pubSubTopic: pubSubTopic, message: message)
  ?await wl.sendPushRequest(pushRequest, peer)

-  for obs in wl.publishObservers:
-    obs.onMessagePublished(pubSubTopic, message)
-
  notice "publishing message with lightpush",
    pubsubTopic = pubsubTopic,
    contentTopic = message.contentTopic,
@ -111,7 +103,4 @@ proc publishToAny*(
  let pushRequest = PushRequest(pubSubTopic: pubSubTopic, message: message)
  ?await wl.sendPushRequest(pushRequest, peer)

-  for obs in wl.publishObservers:
-    obs.onMessagePublished(pubSubTopic, message)
-
  return ok()
--- a/waku/waku_lightpush_legacy/common.nim
+++ b/waku/waku_lightpush_legacy/common.nim
@ -9,7 +9,7 @@ export WakuLegacyLightPushCodec
 type WakuLightPushResult*[T] = Result[T, string]

 type PushMessageHandler* = proc(
-  peer: PeerId, pubsubTopic: PubsubTopic, message: WakuMessage
+  pubsubTopic: PubsubTopic, message: WakuMessage
 ): Future[WakuLightPushResult[void]] {.async.}

 const TooManyRequestsMessage* = "TOO_MANY_REQUESTS"
--- a/waku/waku_lightpush_legacy/protocol.nim
+++ b/waku/waku_lightpush_legacy/protocol.nim
@ -53,7 +53,7 @@ proc handleRequest*(
      msg_hash = msg_hash,
      receivedTime = getNowInNanosecondTime()

-    let handleRes = await wl.pushHandler(peerId, pubsubTopic, message)
+    let handleRes = await wl.pushHandler(pubsubTopic, message)
    isSuccess = handleRes.isOk()
    pushResponseInfo = (if isSuccess: "OK" else: handleRes.error)

--- a/waku/waku_relay.nim
+++ b/waku/waku_relay.nim
@ -1,3 +1,4 @@
-import ./waku_relay/[protocol, topic_health]
+import ./waku_relay/protocol
+import waku/node/health_monitor/topic_health

 export protocol, topic_health
--- a/waku/waku_relay/protocol.nim
+++ b/waku/waku_relay/protocol.nim
@ -17,8 +17,12 @@ import
  libp2p/protocols/pubsub/rpc/messages,
  libp2p/stream/connection,
  libp2p/switch
+
 import
-  ../waku_core, ./message_id, ./topic_health, ../node/delivery_monitor/publish_observer
+  waku/waku_core,
+  waku/node/health_monitor/topic_health,
+  waku/requests/health_request,
+  ./message_id

 from ../waku_core/codecs import WakuRelayCodec
 export WakuRelayCodec
@ -157,7 +161,6 @@ type
      # map topic with its assigned validator within pubsub
    topicHandlers: Table[PubsubTopic, TopicHandler]
      # map topic with the TopicHandler proc in charge of attending topic's incoming message events
-    publishObservers: seq[PublishObserver]
    topicsHealth*: Table[string, TopicHealth]
    onTopicHealthChange*: TopicHealthChangeHandler
    topicHealthLoopHandle*: Future[void]
@ -321,6 +324,19 @@ proc initRelayObservers(w: WakuRelay) =

  w.addObserver(administrativeObserver)

+proc initRequestProviders(w: WakuRelay) =
+  RequestRelayTopicsHealth.setProvider(
+    proc(
+        topics: seq[PubsubTopic]
+    ): Future[Result[RequestRelayTopicsHealth, string]] {.async.} =
+      var collectedRes: RequestRelayTopicsHealth
+      for topic in topics:
+        let health = w.topicsHealth.getOrDefault(topic, TopicHealth.NOT_SUBSCRIBED)
+        collectedRes.topicHealth.add((topic, health))
+      return ok(collectedRes)
+  ).isOkOr:
+    error "Cannot set Relay Topics Health request provider", error = error
+
 proc new*(
    T: type WakuRelay, switch: Switch, maxMessageSize = int(DefaultMaxWakuMessageSize)
 ): WakuRelayResult[T] =
@ -340,9 +356,10 @@ proc new*(
    )

    procCall GossipSub(w).initPubSub()
+    w.topicsHealth = initTable[string, TopicHealth]()
    w.initProtocolHandler()
    w.initRelayObservers()
-    w.topicsHealth = initTable[string, TopicHealth]()
+    w.initRequestProviders()
  except InitializationError:
    return err("initialization error: " & getCurrentExceptionMsg())

@ -353,12 +370,6 @@ proc addValidator*(
 ) {.gcsafe.} =
  w.wakuValidators.add((handler, errorMessage))

-proc addPublishObserver*(w: WakuRelay, obs: PublishObserver) =
-  ## Observer when the api client performed a publish operation. This
-  ## is initially aimed for bringing an additional layer of delivery reliability thanks
-  ## to store
-  w.publishObservers.add(obs)
-
 proc addObserver*(w: WakuRelay, observer: PubSubObserver) {.gcsafe.} =
  ## Observes when a message is sent/received from the GossipSub PoV
  procCall GossipSub(w).addObserver(observer)
@ -628,9 +639,6 @@ proc publish*(
  if relayedPeerCount <= 0:
    return err(NoPeersToPublish)

-  for obs in w.publishObservers:
-    obs.onMessagePublished(pubSubTopic, message)
-
  return ok(relayedPeerCount)

 proc getConnectedPubSubPeers*(
--- a/waku/waku_rln_relay/rln_relay.nim
+++ b/waku/waku_rln_relay/rln_relay.nim
@ -24,10 +24,13 @@ import
  ./nonce_manager

 import
-  ../common/error_handling,
-  ../waku_relay, # for WakuRelayHandler
-  ../waku_core,
-  ../waku_keystore
+  waku/[
+    common/error_handling,
+    waku_relay, # for WakuRelayHandler
+    waku_core,
+    requests/rln_requests,
+    waku_keystore,
+  ]

 logScope:
  topics = "waku rln_relay"
@ -91,6 +94,7 @@ proc stop*(rlnPeer: WakuRLNRelay) {.async: (raises: [Exception]).} =

  # stop the group sync, and flush data to tree db
  info "stopping rln-relay"
+  RequestGenerateRlnProof.clearProvider()
  await rlnPeer.groupManager.stop()

 proc hasDuplicate*(
@ -275,11 +279,11 @@ proc validateMessageAndUpdateLog*(

  return isValidMessage

-proc appendRLNProof*(
-    rlnPeer: WakuRLNRelay, msg: var WakuMessage, senderEpochTime: float64
-): RlnRelayResult[void] =
-  ## returns true if it can create and append a `RateLimitProof` to the supplied `msg`
-  ## returns false otherwise
+proc createRlnProof(
+    rlnPeer: WakuRLNRelay, msg: WakuMessage, senderEpochTime: float64
+): RlnRelayResult[seq[byte]] =
+  ## returns a new `RateLimitProof` for the supplied `msg`
+  ## returns an error if it cannot create the proof
  ## `senderEpochTime` indicates the number of seconds passed since Unix epoch. The fractional part holds sub-seconds.
  ## The `epoch` field of `RateLimitProof` is derived from the provided `senderEpochTime` (using `calcEpoch()`)

@ -291,7 +295,14 @@ proc appendRLNProof*(
  let proof = rlnPeer.groupManager.generateProof(input, epoch, nonce).valueOr:
    return err("could not generate rln-v2 proof: " & $error)

-  msg.proof = proof.encode().buffer
+  return ok(proof.encode().buffer)
+
+proc appendRLNProof*(
+    rlnPeer: WakuRLNRelay, msg: var WakuMessage, senderEpochTime: float64
+): RlnRelayResult[void] =
+  msg.proof = rlnPeer.createRlnProof(msg, senderEpochTime).valueOr:
+    return err($error)
+
  return ok()

 proc clearNullifierLog*(rlnPeer: WakuRlnRelay) =
@ -438,6 +449,18 @@ proc mount(

  # Start epoch monitoring in the background
  wakuRlnRelay.epochMonitorFuture = monitorEpochs(wakuRlnRelay)
+
+  RequestGenerateRlnProof.setProvider(
+    proc(
+        msg: WakuMessage, senderEpochTime: float64
+    ): Future[Result[RequestGenerateRlnProof, string]] {.async.} =
+      let proof = createRlnProof(wakuRlnRelay, msg, senderEpochTime).valueOr:
+        return err("Could not create RLN proof: " & $error)
+
+      return ok(RequestGenerateRlnProof(proof: proof))
+  ).isOkOr:
+    return err("Proof generator provider cannot be set")
+
  return ok(wakuRlnRelay)

 proc isReady*(rlnPeer: WakuRLNRelay): Future[bool] {.async: (raises: [Exception]).} =