Skip to main content

Clean and Simple Email Sender Design

Recently review design for an email sender with following requirements:

  1. Build a service to send email
  2. Service must have failover recovery, in youcase if system goes down and comes back up it should still send out pending email reminders
  3. You are not expecting any acknowledgements for the messages sent.
The design proposal in place was to use a funky framework with persistence store etc etc. 

After going through the simple requirements stated above, used following clean and simple design and I am happy to say we made right decision:

  1. Use Java Mail API to send email reminders
  2. Create a table which stores reminders to be sent and update a flag after email reminder is sent
  3. In case system goes down, you can resend all reminders for which flag was not set.
It was so simple and easy to implement and we have all control in our hand and there was no RAMP up time to learn new frameworks.

So, if you are confused with n number of ideas available out there using x number of frameworks, you can use the simple design explained above.


Popular posts from this blog

Drools - An overview

For Java based applications the most challenging part has always been the business logic maintenance, and pick any applications which you find complex and if we ask ourself how complex it would be moving forward, the answer will always be nX times.

What do we do ? Drools comes for Rescue as a Rule Engine.

Drools provides mechanism:

a. To write business logic in simple english language
b. Easy to maintain and very simple to extend
c. Reusability of logic by defining keywords in a DSL file and using them in DSLR file.

But be careful nothing comes free, everything takes cost in terms of memory and time space.

Use Drools if you really have :

a. Business logic which you think is getting cluttered with multiple if conditions because of variety of scenarios
b. You will have growing demand of increase in the complexity
c. The business logic changes would be frequent (1 - 2 times a year would also be frequent)
d. Your server's have enough of memory as it is a memory hungary tool, it provi…

Java 8 streams performance on mathematical calculations

Java 8 Streams API supports many parallel operations to process the data, it abstracts low level multithreading logic. To test performance did following simple test to calculate factorial of first X number starting with N.

Following program calculates factorial of first 1000 numbers.

package; import java.math.BigInteger; import java.time.Duration; import java.time.Instant; import java.util.ArrayList; import java.util.List; publicclassMathCalculation { publicstaticvoid main(String[] args) { List<Runnable> runnables = generateRunnables(1, 1000); Instant start=; // Comment one of the lines below to test parallel or sequential streams runnables.parallelStream().forEach(r ->; // ->; Instant end =; System.out.println("Calculated in "+ Duration.between(start, end)); } privatestaticvoid factorial(int number) { int i; BigInteger fact = BigInteger.valueOf(1); for (i =1; i <= numb…

MQTT : Android step by step guide using Eclipse Paho

For MQTT integration, recently explored Paho Android project, very simple to use, here are the steps:

Intialize a client, set required options and connect.

    MqttAndroidClient mqttClient = new MqttAndroidClient(BaseApplication.getAppContext(), broker, MQTT_CLIENT_ID);
    //Set call back class
    mqttClient.setCallback(new MqttCallbackHandler(BaseApplication.getAppContext()));
    MqttConnectOptions connOpts = new MqttConnectOptions();
    IMqttToken token = mqttClient.connect(connOpts);

Subscribe to a topic.

    token.setActionCallback(new IMqttActionListener() {
      public void onSuccess(IMqttToken arg0) {
           mqttClient.subscribe("TOPIC_NAME" + userId, 2, null, new IMqttActionListener() {
                public void onSuccess(IMqttToken asyncActionToken) {
                    Log.d(LOG_TAG, "Successfully subscribed to topic.");

                public void onFailure…