diff --git a/source/dom_persist.d b/source/dom_persist.d
index 0ee9d64..428e911 100644
--- a/source/dom_persist.d
+++ b/source/dom_persist.d
@@ -10,11 +10,13 @@
 
 import d2sqlite3;	// https://d2sqlite3.dpldocs.info/v1.0.0/d2sqlite3.database.Database.this.html
 
+version(unittest){	
+	//stuff only compiled for unittests
+	string sqlite_filename = "dom_persist_test.db";
+}
 
 unittest {
-	
-	string sqlite_filename = "dom_persist_test.db";
-	
+		
 	db_drop( sqlite_filename );
 	assert( !db_exists( sqlite_filename ) );
 
@@ -23,23 +25,23 @@
 	assert( db_exists( sqlite_filename ) );	
 	assert(db.tableColumnMetadata("params", "ID") == TableColumnMetadata("INTEGER", "BINARY", false, true, true));
 
-	Tree_Db tdb = new Tree_Db( db );
+	Tree_Db_Base tdb = new Tree_Db_Base( db );
 	tdb.db_create_schema( );
 	
 	assert(db.tableColumnMetadata("doctree", "ID") == TableColumnMetadata("INTEGER", "BINARY", false, true, true));
 	
 	long tree_id = tdb.create_tree("mytree");
 	
-	long nid = tdb.appendChild( tree_id, TreeNodeType.docType, "html" );
-	long html_nid = tdb.appendChild( tree_id, TreeNodeType.element, "html" );
+	long nid = tdb.appendChild( tree_id, tree_id, TreeNodeType.docType, "html" );
+	long html_nid = tdb.appendChild( tree_id, tree_id, TreeNodeType.element, "html" );
 	
-	long head_id = tdb.appendChild( html_nid, TreeNodeType.element, "head" );
-	tdb.appendChild( head_id, TreeNodeType.comment, "This is my comment" );
+	long head_id = tdb.appendChild( tree_id, html_nid, TreeNodeType.element, "head" );
+	tdb.appendChild( tree_id, head_id, TreeNodeType.comment, "This is my comment" );
 	
-	long body_id = tdb.appendChild( html_nid, TreeNodeType.element, "body" );
-	tdb.appendChild( body_id, TreeNodeType.text, "This is some text" );
-	tdb.appendChild( body_id, TreeNodeType.text, " with more text" );
-	tdb.appendChildElement( body_id, "input" );
+	long body_id = tdb.appendChild( tree_id, html_nid, TreeNodeType.element, "body" );
+	tdb.appendChild( tree_id, body_id, TreeNodeType.text, "This is some text" );
+	tdb.appendChild( tree_id, body_id, TreeNodeType.text, " with more text" );
+	tdb.appendChildElement( tree_id, body_id, "input" );
 	
 	string html_out = tdb.getTreeAsText( tree_id );	
 	//writeln( html_out );
@@ -82,6 +84,7 @@
 
 
 struct NodeData {
+	
 	long ID;
 	string e_data;
 	long pid;
@@ -95,10 +98,15 @@
 	}
 }
 
-class Tree_Db {
+/**
+ * This class provides direct database access to all trees in the database table. You can also obtain from it
+ * an instance of class Tree_Dd for a specific tree given its root node id.
+ */
+class Tree_Db_Base {
 	
 	protected:
 		Database* db;
+		static long node_count = 0;
 		
 	public:
 	
@@ -113,9 +121,9 @@
 	 * The tree node is marked with '0' (zero) since it has no parent.
 	 */
 	long create_tree( string tree_name ){		
-		return appendChild( 0, TreeNodeType.tree, tree_name);
+		return appendChild( 0, 0, TreeNodeType.tree, tree_name);
 	}
-
+	
 	/**
 	 * Read the DOM from this database for the given tree ID (tid) and return as
 	 * an html (or xml) string.
@@ -187,27 +195,27 @@
 	/**
 	 * Append a new element to the given parent id (pid)
 	 */
-	long appendChildElement( long pid, string elem_name ){
+	long appendChildElement( long tree_id, long pid, string elem_name ){
 		enforce(elem_name!=null && elem_name.length>0 );
-		return appendChild( pid, TreeNodeType.element, elem_name );
+		return appendChild( tree_id, pid, TreeNodeType.element, elem_name );
 	}
 
 	/**
 	 * Append new text to the given parent id (pid).
 	 * Returns the ID of the text node if appended or -1 otherwise.
 	 */
-	long appendChildText( long pid, string text ){
+	long appendChildText( long tree_id, long pid, string text ){
 		if(text==null || text.length==0 ) return -1;
-		return appendChild( pid, TreeNodeType.text, text );
+		return appendChild( tree_id, pid, TreeNodeType.text, text );
 	}
 
 	/**
 	 * Append new text to the given parent id (pid).
 	 * Returns the ID of the text node if appended or -1 otherwise.
 	 */
-	long appendChildComment( long pid, string text ){
+	long appendChildComment( long tree_id, long pid, string text ){
 		if(text==null || text.length==0 ) return -1;
-		return appendChild( pid, TreeNodeType.comment, text );
+		return appendChild( tree_id, pid, TreeNodeType.comment, text );
 	}
 
 	/**
@@ -216,13 +224,14 @@
 	 * 
 	 * The ID of the new node is returned.
 	 */
-	long appendChild( long pid, TreeNodeType nt, string node_data = "" ){
+	long appendChild( long tree_id, long pid, TreeNodeType nt, string node_data = "" ){
 		
 		if( nt == TreeNodeType.docType ){
 			//we might store the extra data as an attribute but this will suffice for the moment
 			node_data = "DOCTYPE "~node_data;
 		}
-		db.run( format("Insert into doctree(e_data, p_id, t_id ) values( '%s', %d, %d )", node_data, pid, nt) );
+		db.run( format("Insert into doctree(e_data, p_id, t_id, tree_id, c_odr ) values( '%s', %d, %d, %d, %d )", node_data, pid, nt, tree_id, node_count ) );
+		node_count+=1;
 		return db.lastInsertRowid;		
 	}
 
@@ -235,7 +244,7 @@
 	}
 	
 	void db_create_schema( ){		
-		db.run("CREATE TABLE IF NOT EXISTS doctree (ID INTEGER, e_data	TEXT,p_id INTEGER,t_id INTEGER NOT NULL,	PRIMARY KEY( ID AUTOINCREMENT))");
+		db.run("CREATE TABLE IF NOT EXISTS doctree (ID INTEGER, e_data	TEXT,p_id INTEGER,t_id INTEGER NOT NULL,tree_id INTEGER NOT NULL,	c_odr INTEGER NOT NULL, PRIMARY KEY( ID AUTOINCREMENT))");
 	}
 	
 	long getRootId(){
@@ -303,3 +312,138 @@
 	}
 	
 }
+
+
+struct TreeNameID {
+	long tree_id;
+	string name;
+}
+
+struct TreeNode {
+	NodeData node_data;
+	TreeNode*[] child_nodes;
+}
+
+/**
+ * An instance of this class contains access to a single tree. Tree operations are cached in RAM and only written to
+ * disk during a save operation. This can be done safely because of the single user access to Sqlite.
+ * 
+ * Multiple database connections should work on the same thread provided each is using a different tree.
+ * 
+ * Instantiation of the tree involves only one database select.
+ */
+class Tree_Db {
+
+	protected:
+	
+		long tree_id;
+		Database* db;		
+		
+		TreeNode[long]	all_nodes;
+		
+		
+	this( Database db, long tid ){
+
+		this.db = &db;
+		tree_id = tid;
+
+		//load the tree in one hit using the tree_id
+		//also order by the parent_id so that we know all siblings are grouped together
+		//and also by child order
+
+		auto results = db.execute( format("select ID, e_data, p_id, t_id from doctree where tree_id=%d or id=%d order by p_id,c_odr", tree_id, tree_id) );
+		foreach (row; results){
+			
+			long id = row.peek!long(0);
+			long p_id = row.peek!long(2);
+			TreeNode tn;
+			tn.node_data = NodeData(
+				id,
+				row.peek!string(1),
+				p_id,
+				getTreeNodeType( row.peek!int(3) )
+			);
+			all_nodes[id] = tn;
+			if(p_id==0) continue;
+			all_nodes[p_id].child_nodes ~= &all_nodes[id];
+		}
+
+	}
+	
+	public:
+	
+	/**
+	 * Return a list of all trees in the database with their ID's and names.
+	 */
+	static TreeNameID[] getTreeList( ref Database db ){
+
+		TreeNameID[] tree_list;
+		auto results = db.execute( format("select ID, e_data from doctree where p_id=0") );
+		foreach (row; results){
+			
+			tree_list ~= TreeNameID (
+				row.peek!long(0),
+				row.peek!string(1)
+			);			
+		}
+		return tree_list;		
+	}
+	
+	static Tree_Db loadTree( ref Database db, long tid ){
+		return new Tree_Db( db, tid );
+	}
+	
+	TreeNode getTreeNode(){
+		return all_nodes[tree_id];
+	}
+	
+}
+
+unittest{
+
+	auto db = Database( sqlite_filename );
+		
+	TreeNameID[] tree_list = Tree_Db.getTreeList( db );
+	assert( tree_list.length==1 );
+	
+	Tree_Db tree = Tree_Db.loadTree( db, tree_list[0].tree_id );
+	
+	TreeNode tree_node = tree.getTreeNode();
+	NodeData nd_t = tree_node.node_data;
+	assert( nd_t.ID == tree_list[0].tree_id );
+	assert( nd_t.e_data == tree_list[0].name );
+	assert( nd_t.pid == 0 );
+	assert( nd_t.type == TreeNodeType.tree );
+	
+	//writeln( tree_node.child_nodes );
+	
+	int i=0;
+	foreach( node_ptr; tree_node.child_nodes ){		
+
+		NodeData c_node = (*node_ptr).node_data;
+		
+		switch(i){
+		case 0:
+			assert( c_node.ID == 2 );
+			assert( c_node.e_data == "DOCTYPE html" );
+			assert( c_node.pid == tree_list[0].tree_id );
+			assert( c_node.type == TreeNodeType.docType );
+			break;
+
+		case 1:
+			assert( c_node.ID == 3 );
+			assert( c_node.e_data == "html" );
+			assert( c_node.pid == tree_list[0].tree_id );
+			assert( c_node.type == TreeNodeType.element );
+			break;
+		
+		default:
+		}
+	
+		//writeln( c_node );
+		i+=1;
+	}
+	
+	
+	
+}