diff --git a/ICCC/CacheTimerLogic.go b/ICCC/CacheTimerLogic.go
index 81be0cb..553c26d 100644
--- a/ICCC/CacheTimerLogic.go
+++ b/ICCC/CacheTimerLogic.go
@@ -7,43 +7,61 @@ import (
 	LM "github.com/SommerEngineering/Ocean/Log/Meta"
 	"github.com/SommerEngineering/Ocean/Shutdown"
 	"gopkg.in/mgo.v2/bson"
-	"time"
 )
 
-// Internal function for the timer logic thread.
-func cacheTimerLogic(waiting bool) {
+// Internal function for the timer-logic thread.
+func cacheTimerLogic() {
 
 	// Case: This server goes down now.
 	if Shutdown.IsDown() {
 		return
 	}
 
-	// Define the query and get the iterator:
-	lastCount := cacheListenerDatabase.Len()
-	selection := bson.D{{`IsActive`, true}}
-	entriesIterator := collectionListener.Find(selection).Iter()
+	// Get the current counts:
+	lastCountListener := cacheListenerDatabase.Len()
+	lastCountHosts := cacheHostDatabase.Len()
 
-	entry := Scheme.Listener{}
+	// Define the queries:
+	selectionListeners := bson.D{{`IsActive`, true}}
+	selectionHosts := bson.D{}
+
+	// Get the iterators:
+	entriesIteratorListeners := collectionListener.Find(selectionListeners).Iter()
+	entriesIteratorHosts := collectionHosts.Find(selectionHosts).Iter()
+
+	//
+	// Execute the listeners first:
+	//
+
+	entryListener := Scheme.Listener{}
 	cacheListenerDatabaseLock.Lock()
 
 	// Re-init the cache:
 	cacheListenerDatabase.Init()
 
 	// Loop over all entries
-	for entriesIterator.Next(&entry) {
-		cacheListenerDatabase.PushBack(entry)
+	for entriesIteratorListeners.Next(&entryListener) {
+		cacheListenerDatabase.PushBack(entryListener)
 	}
 
 	cacheListenerDatabaseLock.Unlock()
-	Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameEXECUTE, `The listener cache was refreshed with the values from the database.`, fmt.Sprintf(`last count=%d`, lastCount), fmt.Sprintf(`new count=%d`, cacheListenerDatabase.Len()))
+	Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameEXECUTE, `The listener cache was refreshed with the values from the database.`, fmt.Sprintf(`last count=%d`, lastCountListener), fmt.Sprintf(`new count=%d`, cacheListenerDatabase.Len()))
 
-	// In case, that this function runs at a thread, we want to wait:
-	if waiting {
-		nextDuration := time.Duration(5) * time.Minute
-		if cacheListenerDatabase.Len() == 0 {
-			nextDuration = time.Duration(10) * time.Second
-		}
+	//
+	// Execute now the hosts:
+	//
 
-		time.Sleep(nextDuration)
+	entryHost := Scheme.Host{}
+	cacheHostDatabaseLock.Lock()
+
+	// Re-init the cache:
+	cacheHostDatabase.Init()
+
+	// Loop over all entries
+	for entriesIteratorHosts.Next(&entryHost) {
+		cacheHostDatabase.PushBack(entryHost)
 	}
+
+	cacheHostDatabaseLock.Unlock()
+	Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameEXECUTE, `The host cache was refreshed with the values from the database.`, fmt.Sprintf(`last count=%d`, lastCountHosts), fmt.Sprintf(`new count=%d`, cacheHostDatabase.Len()))
 }
diff --git a/ICCC/ICCCDeleteHost.go b/ICCC/ICCCDeleteHost.go
new file mode 100644
index 0000000..ee2ebac
--- /dev/null
+++ b/ICCC/ICCCDeleteHost.go
@@ -0,0 +1,56 @@
+package ICCC
+
+import (
+	"fmt"
+	"github.com/SommerEngineering/Ocean/ICCC/SystemMessages"
+	"github.com/SommerEngineering/Ocean/Log"
+	LM "github.com/SommerEngineering/Ocean/Log/Meta"
+	"gopkg.in/mgo.v2/bson"
+)
+
+// The receiver function for the ICCC message, that deletes a host.
+func ICCCDeleteHostReceiver(data map[string][]string) (result map[string][]string) {
+
+	// Recover from errors:
+	defer func() {
+		if err := recover(); err != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC delete host message.")
+			result = make(map[string][]string, 0)
+			return
+		}
+	}()
+
+	// Converts the HTTP form data into an object:
+	_, _, obj := Data2Message(SystemMessages.ICCCDeleteHost{}, data)
+
+	// Was it possible to convert the data?
+	if obj != nil {
+
+		// Convert the object:
+		messageData := obj.(SystemMessages.ICCCDeleteHost)
+
+		// The database selection:
+		selectionDelete := bson.D{{`Hostname`, messageData.Hostname}, {`IPAddressPort`, messageData.IPAddressPort}}
+
+		// Delete the entry:
+		if errDelete := collectionHosts.Remove(selectionDelete); errDelete != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC delete host message.", errDelete.Error(), fmt.Sprintf("hostname='%s'", messageData.Hostname), fmt.Sprintf("ipAddressPort='%s'", messageData.IPAddressPort))
+			return Message2Data(``, ``, SystemMessages.AnswerNACK)
+		} else {
+			//
+			// Case: No error
+			//
+
+			// Update the cache as soon as possible:
+			InitCacheNow()
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelWARN, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNameSTATE, "An ICCC host was deleted.", fmt.Sprintf("hostname='%s'", messageData.Hostname), fmt.Sprintf("ipAddressPort='%s'", messageData.IPAddressPort))
+			return Message2Data(``, ``, SystemMessages.AnswerACK)
+		}
+	} else {
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to create the message.`)
+	}
+
+	// In any other error case:
+	result = make(map[string][]string, 0)
+	return
+}
diff --git a/ICCC/ICCCDeleteListenerReceiver.go b/ICCC/ICCCDeleteListenerReceiver.go
new file mode 100644
index 0000000..b8c8788
--- /dev/null
+++ b/ICCC/ICCCDeleteListenerReceiver.go
@@ -0,0 +1,56 @@
+package ICCC
+
+import (
+	"fmt"
+	"github.com/SommerEngineering/Ocean/ICCC/SystemMessages"
+	"github.com/SommerEngineering/Ocean/Log"
+	LM "github.com/SommerEngineering/Ocean/Log/Meta"
+	"gopkg.in/mgo.v2/bson"
+)
+
+// The receiver function for the ICCC message, that deletes an listener.
+func ICCCDeleteListenerReceiver(data map[string][]string) (result map[string][]string) {
+
+	// Recover from errors:
+	defer func() {
+		if err := recover(); err != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC delete listener message.")
+			result = make(map[string][]string, 0)
+			return
+		}
+	}()
+
+	// Converts the HTTP form data into an object:
+	_, _, obj := Data2Message(SystemMessages.ICCCDeleteListener{}, data)
+
+	// Was it possible to convert the data?
+	if obj != nil {
+
+		// Convert the object:
+		messageData := obj.(SystemMessages.ICCCDeleteListener)
+
+		// The database selection:
+		selectionDelete := bson.D{{`Channel`, messageData.Channel}, {`Command`, messageData.Command}, {`IPAddressPort`, messageData.IPAddressPort}}
+
+		// Delete the entry:
+		if errDelete := collectionListener.Remove(selectionDelete); errDelete != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC delete listener message.", errDelete.Error(), fmt.Sprintf("channel='%s'", messageData.Channel), fmt.Sprintf("command='%s'", messageData.Command), fmt.Sprintf("ipAddressPort='%s'", messageData.IPAddressPort))
+			return Message2Data(``, ``, SystemMessages.AnswerNACK)
+		} else {
+			//
+			// Case: No error
+			//
+
+			// Update the cache as soon as possible:
+			InitCacheNow()
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelWARN, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNameSTATE, "An ICCC listener was deleted.", fmt.Sprintf("channel='%s'", messageData.Channel), fmt.Sprintf("command='%s'", messageData.Command), fmt.Sprintf("ipAddressPort='%s'", messageData.IPAddressPort))
+			return Message2Data(``, ``, SystemMessages.AnswerACK)
+		}
+	} else {
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to create the message.`)
+	}
+
+	// In any other error case:
+	result = make(map[string][]string, 0)
+	return
+}
diff --git a/ICCC/ICCCGetHostsReceiver.go b/ICCC/ICCCGetHostsReceiver.go
new file mode 100644
index 0000000..cbaab11
--- /dev/null
+++ b/ICCC/ICCCGetHostsReceiver.go
@@ -0,0 +1,60 @@
+package ICCC
+
+import (
+	"github.com/SommerEngineering/Ocean/ICCC/Scheme"
+	"github.com/SommerEngineering/Ocean/ICCC/SystemMessages"
+	"github.com/SommerEngineering/Ocean/Log"
+	LM "github.com/SommerEngineering/Ocean/Log/Meta"
+)
+
+// The receiver function for the ICCC message, that yields the hosts.
+func ICCCGetHostsReceiver(data map[string][]string) (result map[string][]string) {
+
+	// Recover from errors:
+	defer func() {
+		if err := recover(); err != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC get hosts message.")
+			result = make(map[string][]string, 0)
+			return
+		}
+	}()
+
+	// Converts the HTTP form data into an object:
+	_, _, obj := Data2Message(SystemMessages.ICCCGetHosts{}, data)
+
+	// Was it possible to convert the data?
+	if obj != nil {
+
+		// We have to read from the cache:
+		cacheHostDatabaseLock.RLock()
+
+		// How many hosts we currently known?
+		countHosts := cacheHostDatabase.Len()
+
+		// Prepare the answer object:
+		answerMessage := SystemMessages.ICCCGetHostsAnswer{}
+		answerMessage.Hostnames = make([]string, countHosts, countHosts)
+		answerMessage.IPAddressesPorts = make([]string, countHosts, countHosts)
+
+		// Loop over all hosts which are currently available at the cache:
+		n := 0
+		for entry := cacheHostDatabase.Front(); entry != nil; entry = entry.Next() {
+			host := entry.Value.(Scheme.Host)
+			answerMessage.Hostnames[n] = host.Hostname
+			answerMessage.IPAddressesPorts[n] = host.IPAddressPort
+			n++
+		}
+
+		// Unlock the cache:
+		cacheHostDatabaseLock.RUnlock()
+
+		// Send the answer:
+		return Message2Data(``, ``, answerMessage)
+	} else {
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to create the message.`)
+	}
+
+	// In any other error case:
+	result = make(map[string][]string, 0)
+	return
+}
diff --git a/ICCC/ICCCGetListenersReceiver.go b/ICCC/ICCCGetListenersReceiver.go
new file mode 100644
index 0000000..c93e618
--- /dev/null
+++ b/ICCC/ICCCGetListenersReceiver.go
@@ -0,0 +1,62 @@
+package ICCC
+
+import (
+	"github.com/SommerEngineering/Ocean/ICCC/Scheme"
+	"github.com/SommerEngineering/Ocean/ICCC/SystemMessages"
+	"github.com/SommerEngineering/Ocean/Log"
+	LM "github.com/SommerEngineering/Ocean/Log/Meta"
+)
+
+// The receiver function for the ICCC message, that yields the listeners.
+func ICCCGetListenersReceiver(data map[string][]string) (result map[string][]string) {
+
+	// Recover from errors:
+	defer func() {
+		if err := recover(); err != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC get listeners message.")
+			result = make(map[string][]string, 0)
+			return
+		}
+	}()
+
+	// Converts the HTTP form data into an object:
+	_, _, obj := Data2Message(SystemMessages.ICCCGetListeners{}, data)
+
+	// Was it possible to convert the data?
+	if obj != nil {
+
+		// We have to read from the cache:
+		cacheListenerDatabaseLock.RLock()
+
+		// How many listeners we currently known?
+		countListeners := cacheListenerDatabase.Len()
+
+		// Prepare the answer object:
+		answerMessage := SystemMessages.ICCCGetListenersAnswer{}
+		answerMessage.Channels = make([]string, countListeners, countListeners)
+		answerMessage.Commands = make([]string, countListeners, countListeners)
+		answerMessage.IPAddressesPorts = make([]string, countListeners, countListeners)
+
+		// Loop over all hosts which are currently available at the cache:
+		n := 0
+		for entry := cacheListenerDatabase.Front(); entry != nil; entry = entry.Next() {
+			listener := entry.Value.(Scheme.Listener)
+			answerMessage.Channels[n] = listener.Channel
+			answerMessage.Commands[n] = listener.Command
+			answerMessage.IPAddressesPorts[n] = listener.IPAddressPort
+			n++
+		}
+
+		// Unlock the cache:
+		cacheListenerDatabaseLock.RUnlock()
+
+		// Send the answer:
+		return Message2Data(``, ``, answerMessage)
+	} else {
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to create the message.`)
+	}
+
+	// In any other error case:
+	result = make(map[string][]string, 0)
+	return
+}
diff --git a/ICCC/ICCCListenerUpdateReceiver.go b/ICCC/ICCCListenerUpdateReceiver.go
new file mode 100644
index 0000000..ce3fc89
--- /dev/null
+++ b/ICCC/ICCCListenerUpdateReceiver.go
@@ -0,0 +1,64 @@
+package ICCC
+
+import (
+	"fmt"
+	"github.com/SommerEngineering/Ocean/ICCC/Scheme"
+	"github.com/SommerEngineering/Ocean/ICCC/SystemMessages"
+	"github.com/SommerEngineering/Ocean/Log"
+	LM "github.com/SommerEngineering/Ocean/Log/Meta"
+	"gopkg.in/mgo.v2/bson"
+)
+
+// The receiver function for the ICCC message, that updates an listener.
+func ICCCListenerUpdateReceiver(data map[string][]string) (result map[string][]string) {
+
+	// Recover from errors:
+	defer func() {
+		if err := recover(); err != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC update listener message.")
+			result = make(map[string][]string, 0)
+			return
+		}
+	}()
+
+	// Converts the HTTP form data into an object:
+	_, _, obj := Data2Message(SystemMessages.ICCCListenerUpdate{}, data)
+
+	// Was it possible to convert the data?
+	if obj != nil {
+
+		// Convert the object:
+		messageData := obj.(SystemMessages.ICCCListenerUpdate)
+
+		// The database selection:
+		selectionUpdate := bson.D{{`Channel`, messageData.Channel}, {`Command`, messageData.Command}, {`IPAddressPort`, messageData.IPAddressPort}}
+
+		// The object with holds the new state:
+		updatedObject := Scheme.Listener{}
+		updatedObject.Channel = messageData.Channel
+		updatedObject.Command = messageData.Command
+		updatedObject.IPAddressPort = messageData.IPAddressPort
+		updatedObject.IsActive = messageData.IsActiveNew
+
+		// Update the entry:
+		if errUpdate := collectionListener.Update(selectionUpdate, updatedObject); errUpdate != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC update listener message.", errUpdate.Error(), fmt.Sprintf("channel='%s'", messageData.Channel), fmt.Sprintf("command='%s'", messageData.Command), fmt.Sprintf("ipAddressPort='%s'", messageData.IPAddressPort))
+			return Message2Data(``, ``, SystemMessages.AnswerNACK)
+		} else {
+			//
+			// Case: No error
+			//
+
+			// Update the cache as soon as possible:
+			InitCacheNow()
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelWARN, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNameSTATE, "An ICCC listener was updated.", fmt.Sprintf("channel='%s'", messageData.Channel), fmt.Sprintf("command='%s'", messageData.Command), fmt.Sprintf("ipAddressPort='%s'", messageData.IPAddressPort), fmt.Sprintf("isActive=%v", messageData.IsActiveNew))
+			return Message2Data(``, ``, SystemMessages.AnswerACK)
+		}
+	} else {
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to create the message.`)
+	}
+
+	// In any other error case:
+	result = make(map[string][]string, 0)
+	return
+}
diff --git a/ICCC/ICCCPingReceiver.go b/ICCC/ICCCPingReceiver.go
new file mode 100644
index 0000000..25ff9ab
--- /dev/null
+++ b/ICCC/ICCCPingReceiver.go
@@ -0,0 +1,35 @@
+package ICCC
+
+import (
+	"github.com/SommerEngineering/Ocean/ICCC/SystemMessages"
+	"github.com/SommerEngineering/Ocean/Log"
+	LM "github.com/SommerEngineering/Ocean/Log/Meta"
+)
+
+// The receiver function for the ICCC ping message.
+func ICCCPingReceiver(data map[string][]string) (result map[string][]string) {
+
+	// Recover from errors:
+	defer func() {
+		if err := recover(); err != nil {
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC ping message.")
+			result = make(map[string][]string, 0)
+			return
+		}
+	}()
+
+	// Converts the HTTP form data into an object:
+	_, _, obj := Data2Message(SystemMessages.ICCCPing{}, data)
+
+	// Was it possible to convert the data?
+	if obj != nil {
+		// An answer is necessary:
+		return Message2Data("", "", SystemMessages.AnswerACK)
+	} else {
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to convert the ping message.`)
+	}
+
+	// In any other error case:
+	result = make(map[string][]string, 0)
+	return
+}
diff --git a/ICCC/ICCCRegisterHostReceiver.go b/ICCC/ICCCRegisterHostReceiver.go
index d4aeb1d..0a99c87 100644
--- a/ICCC/ICCCRegisterHostReceiver.go
+++ b/ICCC/ICCCRegisterHostReceiver.go
@@ -8,12 +8,12 @@ import (
 )
 
 // The receiver function for the ICCC message, that registers a host.
-func ICCCRegisterHost(data map[string][]string) (result map[string][]string) {
+func ICCCRegisterHostReceiver(data map[string][]string) (result map[string][]string) {
 
 	// Recover from errors:
 	defer func() {
 		if err := recover(); err != nil {
-			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, fmt.Sprintf("Was not able to execute the ICCC register host message. %s", err))
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC register host message.")
 			result = make(map[string][]string, 0)
 			return
 		}
@@ -28,11 +28,14 @@ func ICCCRegisterHost(data map[string][]string) (result map[string][]string) {
 		messageData := obj.(SystemMessages.ICCCRegisterHost)
 
 		// Provide a log entry:
-		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Should register another host.`, messageData.Hostname, messageData.IPAddressPort)
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Register another host.`, fmt.Sprintf("hostname=%s", messageData.Hostname), fmt.Sprintf("ipAddressPort=%s", messageData.IPAddressPort))
 
 		// Execute the command:
 		registerHost2Database(messageData.Hostname, messageData.IPAddressPort)
 
+		// Update the caches:
+		InitCacheNow()
+
 		// An answer is necessary:
 		return Message2Data(``, ``, SystemMessages.AnswerACK)
 	} else {
diff --git a/ICCC/ICCCRegisterCommandReceiver.go b/ICCC/ICCCRegisterListenerReceiver.go
similarity index 65%
rename from ICCC/ICCCRegisterCommandReceiver.go
rename to ICCC/ICCCRegisterListenerReceiver.go
index 65eedfa..fcc87ec 100644
--- a/ICCC/ICCCRegisterCommandReceiver.go
+++ b/ICCC/ICCCRegisterListenerReceiver.go
@@ -7,13 +7,13 @@ import (
 	LM "github.com/SommerEngineering/Ocean/Log/Meta"
 )
 
-// The receiver function for the ICCC message, that registers a command.
-func ICCCRegisterCommand(data map[string][]string) (result map[string][]string) {
+// The receiver function for the ICCC message, that registers a listener.
+func ICCCRegisterListenerReceiver(data map[string][]string) (result map[string][]string) {
 
 	// Recover from errors:
 	defer func() {
 		if err := recover(); err != nil {
-			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, fmt.Sprintf("Was not able to execute the ICCC register command message. %s", err))
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC register listener message.")
 			result = make(map[string][]string, 0)
 			return
 		}
@@ -28,10 +28,13 @@ func ICCCRegisterCommand(data map[string][]string) (result map[string][]string)
 		messageData := obj.(SystemMessages.ICCCRegisterListener)
 
 		// Provide a log entry:
-		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Should register another command.`, `channel=`+messageData.Channel, `command=`+messageData.Command, `IPAddressPort=`+messageData.IPAddressPort, fmt.Sprintf(`isActive=%v`, messageData.IsActive))
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Should register another listener.`, `channel=`+messageData.Channel, `command=`+messageData.Command, `IPAddressPort=`+messageData.IPAddressPort, fmt.Sprintf(`isActive=%v`, messageData.IsActive))
 
 		// Execute the command:
-		registerCommand2Database(messageData.Channel, messageData.Command, messageData.IPAddressPort, messageData.IsActive)
+		registerListener2Database(messageData.Channel, messageData.Command, messageData.IPAddressPort, messageData.IsActive)
+
+		// Update the caches:
+		InitCacheNow()
 
 		// An answer is necessary:
 		return Message2Data(``, ``, SystemMessages.AnswerACK)
diff --git a/ICCC/Init.go b/ICCC/Init.go
index 53578c4..2f7825d 100644
--- a/ICCC/Init.go
+++ b/ICCC/Init.go
@@ -12,8 +12,9 @@ func init() {
 	Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameINIT, `Start init of ICCC.`)
 	defer Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameINIT, `Done init ICCC.`)
 
-	// Create the list as cache for all global listener (not only listener from this server):
+	// Create the list as cache for all global listener and hosts (not only listener from this server):
 	cacheListenerDatabase = list.New()
+	cacheHostDatabase = list.New()
 
 	// Create a mapping as cache for all local listener end-points (functions):
 	listeners = make(map[string]func(data map[string][]string) map[string][]string)
diff --git a/ICCC/InitCacheNow.go b/ICCC/InitCacheNow.go
index d643475..df94706 100644
--- a/ICCC/InitCacheNow.go
+++ b/ICCC/InitCacheNow.go
@@ -1,13 +1,6 @@
 package ICCC
 
-// Starts the timer cache once and exit it after (no thread, no endless loop).
+// Starts the timer cache logic once and return after (no thread, no endless loop)
 func InitCacheNow() {
-	startCacheTimerLock.Lock()
-	defer startCacheTimerLock.Unlock()
-
-	if cacheTimerRunning {
-		return
-	}
-
-	cacheTimerLogic(false)
+	cacheTimerLogic()
 }
diff --git a/ICCC/InitCacheTimer.go b/ICCC/InitCacheTimer.go
index 1f3e9cc..6c9abe5 100644
--- a/ICCC/InitCacheTimer.go
+++ b/ICCC/InitCacheTimer.go
@@ -1,5 +1,9 @@
 package ICCC
 
+import (
+	"time"
+)
+
 // Setup and starts the cache timer.
 func initCacheTimer() {
 	startCacheTimerLock.Lock()
@@ -11,11 +15,15 @@ func initCacheTimer() {
 		cacheTimerRunning = true
 	}
 
-	// Start another thread with the timer logic:
+	// Start another thread with the timer-logic:
 	go func() {
 		// Endless loop:
 		for {
-			cacheTimerLogic(true)
+			// Execute the logic:
+			cacheTimerLogic()
+
+			// Wait five minutes:
+			time.Sleep(time.Duration(5) * time.Minute)
 		}
 	}()
 }
diff --git a/ICCC/InitDB.go b/ICCC/InitDB.go
index 98dd9f6..f6c716c 100644
--- a/ICCC/InitDB.go
+++ b/ICCC/InitDB.go
@@ -52,15 +52,11 @@ func initDB() {
 	//
 	// Index for hosts:
 	//
-	collectionHosts.EnsureIndexKey(`Hostname`, `IPAddressPort`)
+	collectionHosts.EnsureIndexKey(`Hostname`)
+	collectionHosts.EnsureIndexKey(`IPAddressPort`)
 
 	indexName2 := mgo.Index{}
-	indexName2.Key = []string{`Hostname`}
+	indexName2.Key = []string{`Hostname`, `IPAddressPort`}
 	indexName2.Unique = true
 	collectionHosts.EnsureIndex(indexName2)
-
-	indexName3 := mgo.Index{}
-	indexName3.Key = []string{`IPAddressPort`}
-	indexName3.Unique = true
-	collectionHosts.EnsureIndex(indexName3)
 }
diff --git a/ICCC/RegisterCommand2Database.go b/ICCC/RegisterListener2Database.go
similarity index 92%
rename from ICCC/RegisterCommand2Database.go
rename to ICCC/RegisterListener2Database.go
index 15f3ed6..07e170a 100644
--- a/ICCC/RegisterCommand2Database.go
+++ b/ICCC/RegisterListener2Database.go
@@ -8,8 +8,8 @@ import (
 	"gopkg.in/mgo.v2/bson"
 )
 
-// The internal function to register a command to ICCC.
-func registerCommand2Database(channel, command, ipAddressPort string, isActive bool) {
+// The internal function to register an listener to ICCC.
+func registerListener2Database(channel, command, ipAddressPort string, isActive bool) {
 	Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `Register this ICCC command in to the database.`, `channel=`+channel, `command=`+command, `IPAddressPort=`+ipAddressPort, fmt.Sprintf("isActive=%v", isActive))
 
 	entry := Scheme.Listener{}
diff --git a/ICCC/RegisterLocalCommand2Database.go b/ICCC/RegisterLocalCommand2Database.go
deleted file mode 100644
index ea4472c..0000000
--- a/ICCC/RegisterLocalCommand2Database.go
+++ /dev/null
@@ -1,12 +0,0 @@
-package ICCC
-
-// The internal function to register a local command to ICCC.
-func registerLocalCommand2Database(channel, command string) {
-	/*
-		Cannot use here the ICCC command to register this command.
-		Because, this host is maybe the first one. In that case,
-		there would be no server which can execute the ICCC command.
-		Therefore, every Ocean server registers the own commans directly.
-	*/
-	registerCommand2Database(channel, command, correctAddressWithPort, true)
-}
diff --git a/ICCC/RegisterLocalListener2Database.go b/ICCC/RegisterLocalListener2Database.go
new file mode 100644
index 0000000..b91aa7c
--- /dev/null
+++ b/ICCC/RegisterLocalListener2Database.go
@@ -0,0 +1,12 @@
+package ICCC
+
+// The internal function to register a local listener to ICCC.
+func registerLocalListener2Database(channel, command string) {
+	/*
+		Cannot use here the ICCC command to register this listener.
+		Because, this host is maybe the first one. In that case,
+		there would be no server which can execute the ICCC command.
+		Therefore, every Ocean server registers the own listeners directly.
+	*/
+	registerListener2Database(channel, command, correctAddressWithPort, true)
+}
diff --git a/ICCC/Registrar.go b/ICCC/Registrar.go
index c0b41cc..c1db7b5 100644
--- a/ICCC/Registrar.go
+++ b/ICCC/Registrar.go
@@ -12,7 +12,7 @@ func Registrar(channel, command string, callback func(data map[string][]string)
 	defer listenersLock.Unlock()
 
 	// Write the command to the database:
-	registerLocalCommand2Database(channel, command)
+	registerLocalListener2Database(channel, command)
 
 	// Register the command at the local cache:
 	listeners[fmt.Sprintf(`%s::%s`, channel, command)] = callback
diff --git a/ICCC/Shutdown.go b/ICCC/Shutdown.go
index 20b04d3..8696fab 100644
--- a/ICCC/Shutdown.go
+++ b/ICCC/Shutdown.go
@@ -35,5 +35,5 @@ func (a ShutdownFunction) Shutdown() {
 	// Disconnect the database:
 	db.Logout()
 	dbSession.Close()
-	Log.LogShort(senderName, LM.CategoryAPP, LM.LevelWARN, LM.MessageNameSHUTDOWN, `Done shutting down now all ICCC listener for this host.`)
+	Log.LogShort(senderName, LM.CategoryAPP, LM.LevelWARN, LM.MessageNameSHUTDOWN, `Done shutting down all ICCC listener for this host.`)
 }
diff --git a/ICCC/SystemMessages/ICCCDeleteHost.go b/ICCC/SystemMessages/ICCCDeleteHost.go
new file mode 100644
index 0000000..f6742d3
--- /dev/null
+++ b/ICCC/SystemMessages/ICCCDeleteHost.go
@@ -0,0 +1,7 @@
+package SystemMessages
+
+// The message to delete a host from ICCC.
+type ICCCDeleteHost struct {
+	Hostname      string
+	IPAddressPort string
+}
diff --git a/ICCC/SystemMessages/ICCCDeleteListener.go b/ICCC/SystemMessages/ICCCDeleteListener.go
new file mode 100644
index 0000000..e44f806
--- /dev/null
+++ b/ICCC/SystemMessages/ICCCDeleteListener.go
@@ -0,0 +1,8 @@
+package SystemMessages
+
+// The message to delete an listener from ICCC.
+type ICCCDeleteListener struct {
+	Channel       string
+	Command       string
+	IPAddressPort string
+}
diff --git a/ICCC/SystemMessages/ICCCGetHosts.go b/ICCC/SystemMessages/ICCCGetHosts.go
new file mode 100644
index 0000000..f3a696c
--- /dev/null
+++ b/ICCC/SystemMessages/ICCCGetHosts.go
@@ -0,0 +1,11 @@
+package SystemMessages
+
+// A message to request the known ICCC hosts.
+type ICCCGetHosts struct {
+}
+
+// The answer to the hosts request.
+type ICCCGetHostsAnswer struct {
+	Hostnames        []string
+	IPAddressesPorts []string
+}
diff --git a/ICCC/SystemMessages/ICCCGetListeners.go b/ICCC/SystemMessages/ICCCGetListeners.go
new file mode 100644
index 0000000..4a509e5
--- /dev/null
+++ b/ICCC/SystemMessages/ICCCGetListeners.go
@@ -0,0 +1,12 @@
+package SystemMessages
+
+// A message to request the known ICCC listeners.
+type ICCCGetListeners struct {
+}
+
+// The answer to the listeners request.
+type ICCCGetListenersAnswer struct {
+	Channels         []string
+	Commands         []string
+	IPAddressesPorts []string
+}
diff --git a/ICCC/SystemMessages/ICCCListenerUpdate.go b/ICCC/SystemMessages/ICCCListenerUpdate.go
new file mode 100644
index 0000000..df33b4f
--- /dev/null
+++ b/ICCC/SystemMessages/ICCCListenerUpdate.go
@@ -0,0 +1,9 @@
+package SystemMessages
+
+// The message to update an listener from ICCC.
+type ICCCListenerUpdate struct {
+	Channel       string
+	Command       string
+	IPAddressPort string
+	IsActiveNew   bool
+}
diff --git a/ICCC/SystemMessages/ICCCPing.go b/ICCC/SystemMessages/ICCCPing.go
new file mode 100644
index 0000000..b63d1fb
--- /dev/null
+++ b/ICCC/SystemMessages/ICCCPing.go
@@ -0,0 +1,5 @@
+package SystemMessages
+
+// The ping message to check status of other hosts.
+type ICCCPing struct {
+}
diff --git a/ICCC/SystemMessages/ICCCRegisterListener.go b/ICCC/SystemMessages/ICCCRegisterListener.go
index 4f0378e..0f9e36f 100644
--- a/ICCC/SystemMessages/ICCCRegisterListener.go
+++ b/ICCC/SystemMessages/ICCCRegisterListener.go
@@ -1,6 +1,6 @@
 package SystemMessages
 
-// The message to register a command/listener to ICCC.
+// The message to register an listener to ICCC.
 type ICCCRegisterListener struct {
 	Channel       string // The channel for the provided command
 	Command       string // The provided command
diff --git a/ICCC/Variables.go b/ICCC/Variables.go
index dc7a255..9a395fa 100644
--- a/ICCC/Variables.go
+++ b/ICCC/Variables.go
@@ -27,6 +27,8 @@ var (
 	listenersLock             sync.RWMutex                                                  = sync.RWMutex{}                                                                       // The mutex for the listener cache
 	cacheListenerDatabase     *list.List                                                    = nil                                                                                  // The globally cache for all listeners from all servers
 	cacheListenerDatabaseLock sync.RWMutex                                                  = sync.RWMutex{}                                                                       // The mutex for the globally cache
+	cacheHostDatabase         *list.List                                                    = nil                                                                                  // The cache for all hosts entries
+	cacheHostDatabaseLock     sync.RWMutex                                                  = sync.RWMutex{}                                                                       // The read-write mutex for the host cache
 	startCacheTimerLock       sync.Mutex                                                    = sync.Mutex{}                                                                         // Mutex for the start timer
 	cacheTimerRunning         bool                                                          = false                                                                                // Is the timer running?
 	correctAddressWithPort    string                                                        = ``                                                                                   // The IP address and port of the this local server
diff --git a/NumGen/ICCCNextNumber.go b/NumGen/ICCCNextNumberReceiver.go
similarity index 84%
rename from NumGen/ICCCNextNumber.go
rename to NumGen/ICCCNextNumberReceiver.go
index 32ad4ee..e39e216 100644
--- a/NumGen/ICCCNextNumber.go
+++ b/NumGen/ICCCNextNumberReceiver.go
@@ -1,7 +1,6 @@
 package NumGen
 
 import (
-	"fmt"
 	"github.com/SommerEngineering/Ocean/ICCC"
 	"github.com/SommerEngineering/Ocean/ICCC/SystemMessages"
 	"github.com/SommerEngineering/Ocean/Log"
@@ -9,12 +8,12 @@ import (
 )
 
 // The receiver function for the ICCC message, that registers a command.
-func ICCCNextNumber(data map[string][]string) (result map[string][]string) {
+func ICCCNextNumberReceiver(data map[string][]string) (result map[string][]string) {
 
 	// Recover from errors:
 	defer func() {
 		if err := recover(); err != nil {
-			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, fmt.Sprintf("Was not able to execute the ICCC next number command message. %s", err))
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC next number command message.")
 			result = make(map[string][]string, 0)
 			return
 		}
diff --git a/System/ICCCComponentStartUpMessageReceiver.go b/System/ICCCComponentStartUpMessageReceiver.go
index aae4ee3..0e7352b 100644
--- a/System/ICCCComponentStartUpMessageReceiver.go
+++ b/System/ICCCComponentStartUpMessageReceiver.go
@@ -9,12 +9,12 @@ import (
 )
 
 // The receiver function for the ICCC message, that a external component is up and running.
-func icccComponentStartUpMessage(data map[string][]string) (result map[string][]string) {
+func icccComponentStartUpMessageReceiver(data map[string][]string) (result map[string][]string) {
 
 	// Recover from errors:
 	defer func() {
 		if err := recover(); err != nil {
-			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, fmt.Sprintf("Was not able to execute the ICCC component startup message. %s", err))
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC component startup message.")
 			result = make(map[string][]string, 0)
 			return
 		}
@@ -29,13 +29,12 @@ func icccComponentStartUpMessage(data map[string][]string) (result map[string][]
 		messageData := obj.(SystemMessages.ICCCComponentStartUpMessage)
 
 		// Provide a log entry:
-		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: The external component is now up and ready.`, messageData.IPAddressPort)
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: The external component is now up and ready.`, fmt.Sprintf("ipAddressPort=%s", messageData.IPAddressPort))
 
 		// An answer is necessary:
 		return ICCC.Message2Data("", "", SystemMessages.AnswerACK)
 	} else {
 		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to create the message.`)
-		fmt.Println(`[Error] ICCC message: Was not able to create the message.`)
 	}
 
 	// In any other error case:
diff --git a/System/ICCCOceanStartUpMessageReceiver.go b/System/ICCCOceanStartUpMessageReceiver.go
index a7276a0..b95a95c 100644
--- a/System/ICCCOceanStartUpMessageReceiver.go
+++ b/System/ICCCOceanStartUpMessageReceiver.go
@@ -9,12 +9,12 @@ import (
 )
 
 // The receiver function for the ICCC message, that an Ocean server is up and running.
-func icccOceanStartUpMessage(data map[string][]string) (result map[string][]string) {
+func icccOceanStartUpMessageReceiver(data map[string][]string) (result map[string][]string) {
 
 	// Recover from errors:
 	defer func() {
 		if err := recover(); err != nil {
-			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, fmt.Sprintf("Was not able to execute the ICCC Ocean server startup message. %s", err))
+			Log.LogFull(senderName, LM.CategorySYSTEM, LM.LevelERROR, LM.SeverityUnknown, LM.ImpactUnknown, LM.MessageNamePARSE, "Was not able to execute the ICCC Ocean server startup message.")
 			result = make(map[string][]string, 0)
 			return
 		}
@@ -29,13 +29,12 @@ func icccOceanStartUpMessage(data map[string][]string) (result map[string][]stri
 		messageData := obj.(SystemMessages.ICCCOceanStartUpMessage)
 
 		// Provide a log entry:
-		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: The Ocean server is now up and ready.`, messageData.PublicIPAddressPort, messageData.AdminIPAddressPort)
+		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: The Ocean server is now up and ready.`, fmt.Sprintf("public server=%s", messageData.PublicIPAddressPort), fmt.Sprintf("admin server=%s", messageData.AdminIPAddressPort))
 
 		// An answer is necessary:
 		return ICCC.Message2Data("", "", SystemMessages.AnswerACK)
 	} else {
 		Log.LogShort(senderName, LM.CategorySYSTEM, LM.LevelINFO, LM.MessageNameSTARTUP, `ICCC message: Was not able to create the message.`)
-		fmt.Println(`[Error] ICCC message: Was not able to create the message.`)
 	}
 
 	// In any other error case:
diff --git a/System/InitSystem.go b/System/InitSystem.go
index 7970ea9..670160e 100644
--- a/System/InitSystem.go
+++ b/System/InitSystem.go
@@ -97,11 +97,17 @@ func initSystem() {
 	// The logging subsystem is not registered here, because it will be automated called at the end
 
 	// Register all system ICCC commands:
-	ICCC.Registrar(ICCC.ChannelSYSTEM, `System::OceanStart`, icccOceanStartUpMessage)
-	ICCC.Registrar(ICCC.ChannelSYSTEM, `System::ComponentStart`, icccComponentStartUpMessage)
-	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::RegisterHost`, ICCC.ICCCRegisterHost)
-	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::RegisterCommand`, ICCC.ICCCRegisterCommand)
-	ICCC.Registrar(ICCC.ChannelNUMGEN, `NumGen::Next`, NumGen.ICCCNextNumber)
+	ICCC.Registrar(ICCC.ChannelSTARTUP, `System::OceanStart`, icccOceanStartUpMessageReceiver)
+	ICCC.Registrar(ICCC.ChannelSTARTUP, `System::ComponentStart`, icccComponentStartUpMessageReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::RegisterHost`, ICCC.ICCCRegisterHostReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::RegisterListener`, ICCC.ICCCRegisterListenerReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::DeleteListener`, ICCC.ICCCDeleteListenerReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::DeleteHost`, ICCC.ICCCDeleteHostReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::ListenerUpdate`, ICCC.ICCCListenerUpdateReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::Ping`, ICCC.ICCCPingReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::GetHosts`, ICCC.ICCCGetHostsReceiver)
+	ICCC.Registrar(ICCC.ChannelICCC, `ICCC::GetListeners`, ICCC.ICCCGetListenersReceiver)
+	ICCC.Registrar(ICCC.ChannelNUMGEN, `NumGen::Next`, NumGen.ICCCNextNumberReceiver)
 
 	// Start the ICCC Listener Cache:
 	ICCC.InitCacheNow() // Blocking, until the job is done
diff --git a/WebServer/Start.go b/WebServer/Start.go
index c95737a..a09bf68 100644
--- a/WebServer/Start.go
+++ b/WebServer/Start.go
@@ -28,7 +28,7 @@ func Start() {
 	}
 
 	// Notify the whole cluster, that this server is now up and ready:
-	answers := ICCC.WriteMessage2All(ICCC.ChannelSYSTEM, `System::Start`, data, SystemMessages.ICCCDefaultAnswer{})
+	answers := ICCC.WriteMessage2All(ICCC.ChannelSTARTUP, `System::OceanStart`, data, SystemMessages.ICCCDefaultAnswer{})
 	for n, obj := range answers {
 		if obj != nil {
 			answer := obj.(SystemMessages.ICCCDefaultAnswer)