changed usage of sessions

since sessions should be considered as a container for a sequence of
transactions the usage of one single session for the whole database was
removed.
Now a session is created for each specific transaction (write/read) and
closed after the transaction is done.

database/database.go

@@ -7,8 +7,7 @@ import (
 
 //Database is a database
 type Database struct {
-	driver  neo4j.Driver
-	session neo4j.Session
+	driver neo4j.Driver
 }
 
 //PND is a principle network domain
@@ -21,11 +20,9 @@ type PND struct {
 //NewDatabaseClient creates a database client
 func NewDatabaseClient(uri, username, password string, encrypted bool) Database {
 	driver := createDriver(uri, username, password, encrypted)
-	session := createSession(driver)
 
 	return Database{
-		driver:  driver,
-		session: session,
+		driver: driver,
 	}
 
 }
@@ -41,15 +38,22 @@ func createDriver(uri, username, password string, encrypted bool) neo4j.Driver {
 	)
 
 	if err != nil {
-		log.Info("failed creating database Driver:", err)
+		log.Info("failed creating database driver:", err)
 	}
 
 	return driver
 }
 
 //createSession creates a neo4j.Session
-func createSession(driver neo4j.Driver) neo4j.Session {
-	sessionConfig := neo4j.SessionConfig{AccessMode: neo4j.AccessModeWrite}
+func createSession(driver neo4j.Driver, write bool) neo4j.Session {
+	var sessionConfig neo4j.SessionConfig
+
+	if write {
+		sessionConfig = neo4j.SessionConfig{AccessMode: neo4j.AccessModeWrite}
+	} else {
+		sessionConfig = neo4j.SessionConfig{AccessMode: neo4j.AccessModeRead}
+	}
+
 	session, err := driver.NewSession(sessionConfig)
 
 	if err != nil {
@@ -61,6 +65,9 @@ func createSession(driver neo4j.Driver) neo4j.Session {
 
 //StorePND stores the given principle network domain
 func (d Database) StorePND(pnd *PND) {
+	session := createSession(d.driver, true)
+	defer session.Close()
+
 	query :=
 		`
 		MERGE (pnd:PND {name: $name})
@@ -68,7 +75,7 @@ func (d Database) StorePND(pnd *PND) {
 			pnd.southboundInterfaces = $southboundInterfaces
 		`
 		//refactor map[string]interface... in own function
-	_, err := d.session.Run(
+	_, err := session.Run(
 		query, map[string]interface{}{
 			"name":                 pnd.name,
 			"description":          pnd.description,
@@ -85,6 +92,12 @@ func (d Database) StorePND(pnd *PND) {
 //RemovePND removes the given principle network domain by id.
 func (d Database) RemovePND(id string) {}
 
+func (d Database) GetPNDByID(id string) {}
+
+func (d Database) GetNodesByLabel(label string) {}
+
+func (d Database) GetDeviceByID(id string) {}
+
 //StoreNodes stores the given nodes to the database and adds them to a
 //principle networt domain (PND). It is required for a node to belong to a PND.
 func (d Database) StoreNodes(json string) {
@@ -92,6 +105,9 @@ func (d Database) StoreNodes(json string) {
 	testPND := PND{name: "test_PND", description: "very, interesting", southboundInterfaces: []string{"TAPI", "RESTCONF"}}
 	d.StorePND(&testPND)
 
+	session := createSession(d.driver, true)
+	defer session.Close()
+
 	query :=
 		`
 		WITH apoc.convert.fromJsonMap($stringToAdd)
@@ -109,7 +125,7 @@ func (d Database) StoreNodes(json string) {
 		MERGE (device)-[:BELONGS_TO]->(pnd)
 		`
 
-	_, err := d.session.Run(
+	_, err := session.Run(
 		query, map[string]interface{}{
 			"stringToAdd": json,
 			"pnd":         testPND.name,
@@ -130,9 +146,11 @@ func (d Database) RemoveSingleNode(id string) {}
 
 //StoreLinks stores the links between nodes
 func (d Database) StoreLinks(json string) {
+	session := createSession(d.driver, true)
+	defer session.Close()
+
 	query :=
-		`
-		WITH apoc.convert.fromJsonMap($stringToAdd)
+		` WITH apoc.convert.fromJsonMap($stringToAdd)
 		AS value
 		UNWIND value.data as l
 		MATCH (d:Device), (d2:Device)
@@ -143,7 +161,7 @@ func (d Database) StoreLinks(json string) {
 		RETURN rel
 		`
 
-	_, err := d.session.Run(
+	_, err := session.Run(
 		query, map[string]interface{}{
 			"stringToAdd": json,
 		})
@@ -157,6 +175,9 @@ func (d Database) StoreLinks(json string) {
 
 //StoreNodeEdgePoints stores the given node edge points (interfaces)
 func (d Database) StoreNodeEdgePoints(json string) {
+	session := createSession(d.driver, true)
+	defer session.Close()
+
 	query :=
 		`
 		WITH apoc.convert.fromJsonMap($stringToAdd)
@@ -168,7 +189,7 @@ func (d Database) StoreNodeEdgePoints(json string) {
 		interface.location = i.object_data.` + "`tapi-object-data`.name[1].value," + `
 		interface.` + "`containing-node` = i.object_data.`tapi-object-data`.`containing-node`"
 
-	_, err := d.session.Run(
+	_, err := session.Run(
 		query, map[string]interface{}{
 			"stringToAdd": json,
 		})
@@ -177,7 +198,7 @@ func (d Database) StoreNodeEdgePoints(json string) {
 		log.Info("failed storing NodeEdgePoints into database:", err)
 	}
 
-	setNodeNodeEdgePointsRelation(d.session)
+	setNodeNodeEdgePointsRelation(session)
 
 	log.Info("successfully added NodeEdgePoints into database")
 
@@ -205,12 +226,25 @@ func setNodeNodeEdgePointsRelation(session neo4j.Session) {
 	log.Info("successfully stored NodeNodeEdgePointsRelation into database")
 }
 
+//StoreTopology creates a new network topology node. Can also create a relation
+//the new node and a existing one if desired
+func StoreTopology() {}
+
+//RemoveTopology removes the given network topology. This includes the node itself
+//aswell as the containing links and relations
+func RemoveTopology() {}
+
+//CreateTopologyRelation creates a relation between two given topologies
+func CreateTopologyRelation() {}
+
+//CreateLink creates a link between two network elements
+func CreateLink() {}
+
+//RemoveLink removes a link between two network elements
+func RemoveLink() {}
+
 //Shutdown closes the connection to the database
 func (d Database) Shutdown() {
-	//TODO: add logger
-	if err := d.session.Close(); err != nil {
-	}
-
 	if err := d.driver.Close(); err != nil {
 	}
 }