Added subscriptions module to handle DB operations related to subscri…

…ptions.

include/yams_db.hrl

@@ -8,11 +8,11 @@
 
 %% subcription table will map Client ID with the topics 
 %% subscribed/unsubscribed by the client.
--record(subscription, {cid, %%Client ID
-		       timestamp, %% Date and Time when the record was inserted.
-		       topic, %%Topic
-		       qos, %%QoS
-		       status, %% Status (subscribed/unsubscribed)
-		       msgID %% Message ID
-		      }).
+-record(subscription, 
+	{
+	  cid, %%Client ID
+	  topic, %%Topic
+	  qos, %%QoS
+	  msgID %% Message ID
+	}).
 

src/subscriptions.erl

@@ -0,0 +1,38 @@
+%% Copyright 2013 KuldeepSinh Chauhan
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+
+%%%-------------------------------------------------------------------
+%%% @author  KuldeepSinh Chauhan
+%%% @copyright (C) 2013, 
+%%% @doc
+%%%     This module opens the acceptor-socket for incomming client messages.
+%%% @end
+%%% Created :  11 Sep 2013 by  KuldeepSinh Chauhan
+%%%-------------------------------------------------------------------
+
+-module(subscriptions).
+-export([insert/1, %% Insert topic.
+	 lookup/1 %% Lookup topic.
+	]).
+
+-include("../include/yams_db.hrl").
+
+%% "subscription" is a disc based table, which stores 
+%% the mapping between Client ID and associated Topics, their QoS and Message ID.
+insert(Subscriptions) ->
+    [mnesia:dirty_write(#subscription{cid = Cid, topic = Topic, qos = QoS, msgID = MsgID}) || {Cid, Topic, QoS, MsgID} <- Subscriptions].
+
+%% This fucntion will search the "subscription" table based on the given Client ID.
+lookup(Cid) ->
+    mnesia:dirty_read(subscription, Cid).