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Chris 0:00
Okay, so today we're going to do a deep dive on Amazon. SNS, you're probably already pretty familiar with it as cloud engineer, yeah, you encounter this service a lot, both in real world projects and on AWS certification exams. Absolutely,
Kelly 0:16
it's a fundamental service, and understanding the nuances can be really valuable. Yeah,
Chris 0:20
totally. And we're talking about a fully managed PubSub messaging service, which is really crucial for things like decoupling microservices, sending notifications and just distributing messages across a lot of different subscribers, yeah.
Kelly 0:33
Think of it like a communication backbone for all your different applications, allows different parts of your system to talk to each other without being directly connected. Okay?
Chris 0:41
So let's, uh, let's make this a little bit more concrete. Yeah, let's imagine you have a system and you need to, like, alert multiple teams about a critical event, like a server outage or something like that, right?
Kelly 0:51
SNS can instantly fan out those notifications via email or SMS. It could even trigger automated actions to start recovery processes,
Chris 0:59
okay? Or think about like an E commerce application. SNS can handle things like order confirmations, shipping updates, inventory alerts, all without putting a strain on your core systems Exactly.
Kelly 1:10
And you know, what's really interesting is it's how it handles those different messaging models, the push and the pull. So with push messaging, SNS will deliver messages to subscribers as they come in, ideal for real time updates,
Chris 1:22
so like getting an instant notification on your phone
Kelly 1:24
exactly with pool messaging, subscribers can fetch messages when they're ready, kind of like checking your email inbox. It gives you that flexibility in how those messages are processed. Okay, so
Chris 1:34
let's unpack some of the core features and benefits of SNS. Okay, one of
Kelly 1:39
the key strengths of SNS is its simplicity and its scalability. You work with topics which are like channels for your messages and subscribers. They choose which topics they want to receive messages from, and it integrates seamlessly with other AWS services.
Chris 1:52
So you could trigger a Lambda function based on an SNS notification absolutely
Kelly 1:55
or send a notification from S3 when a new file is uploaded, use it with CloudWatch alarms for automated responses to system events. It sounds
Chris 2:04
like a really versatile tool for building those event driven architectures.
Kelly 2:08
It really is, and because it's fully managed, you don't have to worry about provisioning any servers or maintenance or scaling. It just works, and it's incredibly cost effective, especially compared to setting up your own messaging infrastructure sounds
Chris 2:21
almost too good to be true, but every service has its limitations, right? What are some things to watch out for? Of
Kelly 2:28
course, one key limitation is message size. SNS is designed for those smaller messages, up to 256 kbd, if you're dealing with larger payloads, you might want to consider SQS. It can handle larger messages and provides more complex queuing mechanisms that
Chris 2:42
makes sense. It's all about choosing the right tool for the job, exactly.
Kelly 2:45
And while SNS is highly reliable, it's not designed to guarantee message ordering for all the subscriber types. If message order is critical for you, SQS, FIFO queues would be a better fit. Okay,
Chris 2:56
now let's kind of shift gears a little bit and think about how SNS might pop up on those AWS exams. What kind of questions should we be prepared for? Oh, they'll
Kelly 3:05
definitely test your understanding of those core concepts. For example, they might ask, what are the different types of subscribers in SNS? That's
Chris 3:12
a good one, and it's important to remember that subscribers can be anything from individual email addresses to other AWS services like Lambda functions or SQS queues, right?
Kelly 3:22
They might also ask, when would you choose SNS over SQS? It's about knowing the strengths and limitations of each service. So
Chris 3:30
SNS is great for fan out and push based messaging, while SQS is better for queuing and pull based messaging, exactly.
Kelly 3:36
Let's dig into some more specific example questions. How about this one? How can you secure SNF topics using IAM?
Chris 3:44
That's a crucial aspect. We need to make sure the right people and services have access to publish and subscribe to those topics. Exactly
Kelly 3:51
the answer revolves around using IAM policies, you know, to control access at that granular level,
Chris 3:57
so you could have a policy that only allows certain users to publish messages about like critical system events, while others can only subscribe to receive those notifications Exactly. It's
Kelly 4:07
all about aligning permissions with responsibilities. And a really good answer would also mention some of the specific actions that can be controlled with IAM policies like us and s publish us and subscribe and sys receive,
Chris 4:20
to show the examiners that you really know your stuff. Okay, so that's a good lead into our next section, where we're going to unpack some more specific example questions and really dive deep into those answers. Are you ready? Absolutely.
Kelly 4:30
Let's get into the details and make sure you feel prepared to tackle any SNS question that comes your way. Okay, so
Chris 4:37
let's jump right into some of those more detailed exam questions about SNS. I think this is where a lot of people prepping for those certifications really want to focus. Yeah, absolutely. So let's start with that question that we kind of touched on earlier. How can you secure SNS topics using IAM,
Kelly 4:51
right? And this is about more than just knowing that I am is involved. It's really about showing that you have a deeper understanding of how. To apply those IAM policies effectively in the context of SNS, a good strong answer would explain that you can use IAM policies to control access to SNS topics at a very granular level, you could have a policy that allows only certain users or roles to publish messages to a topic, while others can only subscribe to receive those notifications. So
Chris 5:22
for example, you might have a policy that allows developers to publish messages about code deployments, but only the operations team can actually subscribe to those notifications Exactly.
Kelly 5:30
It's all about aligning those permissions with responsibilities. And a really good answer would also mention some of the specific actions that can be controlled with IAM policies like SNS, publish, sn subscribe and sets S, receive, to
Chris 5:44
show the examiner you know what you're talking about. Okay. Let's move on to another common question you might see, how does message filtering work in SNS? Okay, so
Kelly 5:53
this is where message attributes come in. You can think of message attributes as key value pairs that you attach to your messages to provide additional context. So
Chris 6:00
instead of just sending a generic notification, you can actually add more information about the event that triggered the notification, right. And
Kelly 6:08
subscribers can actually set up filtering policies. They use these attributes to decide which messages they want to receive. Okay,
Chris 6:15
so if we go back to like our E commerce example, a message attribute could be something like event type with a value of order placed, order shipped or order canceled exactly,
Kelly 6:26
and the customer service team to set up a filter to only receive messages where event type equals order canceled.
Chris 6:34
That's great for preventing notification overload, yeah, and making sure the teams are only getting the information they really need exactly. What are some common pitfalls people might fall into when answering this question. One mistake
Kelly 6:45
is thinking that filtering happens based on the message content itself. It's crucial to remember that filtering works only on message attributes, not the message body, so
Chris 6:54
you can't just search for keywords within the message, right? Okay, let's tackle a question about SNS integration. How can you trigger a Lambda function using an SNS notification?
Kelly 7:04
This gets to the heart of how SNS can be used to build those event driven architectures. You can configure an SNS topic to have a Lambda function as a subscriber. Then whenever a message is published to that topic, SNS will automatically invoke that Lambda function.
Chris 7:19
So an event in one part of your system triggers a notification, and that kicks off a process in another part of the system, all without you having to write a lot of glue code.
Kelly 7:28
Exactly. It's a very powerful way to connect different parts of your application and build these responsive, scalable systems. A strong answer to this question would also highlight the importance of IAM permissions. The Lambda function needs appropriate IAM permissions to be invoked by SNS, another
Chris 7:44
good reminder about the importance of IAM. Okay, let's try a question that tests a little bit of a deeper understanding of SNS architecture. What is the maximum size of a message that can be sent via SNS?
Kelly 7:56
Okay, this is one where you need to know the service limits. The maximum message size for SNS is 256 kBz, straightforward
Chris 8:02
enough, but why is it important for a cloud engineer to know that limit? It
Kelly 8:06
highlights the types of use cases. SNS is best suited for if you need to send larger messages, you'd have to look into other services like SQS, which can handle messages up to 256
Chris 8:17
KB, or you might need to break down larger messages into smaller chunks before sending them via SNS exactly. Okay, let's shift gears a little bit and talk about pricing. What kind of questions might come up regarding SNS pricing,
Kelly 8:29
they might ask about the free tier or how costs are calculated. It's important to understand that SNS pricing is primarily based on the number of messages you publish and the number of deliveries to subscribers. So
Chris 8:40
if you send one message to 10 subscribers, that counts as 10 deliveries Correct.
Kelly 8:45
A potential pitfall is forgetting about data transfer costs, especially when sending messages outside of AWS, like SMS messages. Okay, all right, let's
Chris 8:54
tackle one more question before we move on. Can you explain the concept of fan out in SNS and provide an example. Fan
Kelly 9:00
out is one of SNS core strengths, it's the ability to deliver a single message to multiple subscribers concurrently. So
Chris 9:07
one message many destinations. What's a good real world example? Imagine
Kelly 9:11
a news organization sending out breaking news alerts. They could publish a single message to an SNS topic, and that message would be instantly delivered to potentially millions of subscribers via email, SMS or even mobile push notifications. That's
Chris 9:27
a great visual. Now, what's a common mistake people make when answering this type of question?
Kelly 9:31
Sometimes people think that SNS guarantees message ordering for all subscriber types, and while it does guarantee ordering for FIFO queues, that's not the case for all subscriber types. So
Chris 9:41
if order is critical, you need to be careful about the type of subscriber you choose. Okay, so I think that was a good set of questions covering some fundamental SNS concepts. What else might they ask about? Well, they
Kelly 9:51
might get even more specific and ask about SNS integration with other AWS services, like how S3 can trigger SNS notification. Integrations, or how CloudWatch alarms can be used with SNS for automated responses.
Chris 10:04
Those are great examples. Let's dive into some of those integration scenarios and really break down how SNS works with other AWS services. Ready to explore those integrations Absolutely.
Kelly 10:13
Let's unpack how SNS fits into that broader AWS ecosystem. All right, so
Chris 10:18
we've covered a lot of ground with SNS just on its own. But now let's look at how it kind of plays with other AWS services. That's where its real power comes through, right? Absolutely,
Kelly 10:28
SNS becomes even more versatile when you start to consider its in aggression. So for example, let's talk about Amazon S3 a
Chris 10:36
classic pairing. I use this all the time. So S3 can actually trigger SNS notifications based on a bunch of different events, like when a new object is uploaded or when an object's deleted
Kelly 10:46
exactly. You could configure an S3 bucket to send an SNS notification every time, like a new log file is uploaded, and then a Lambda function subscribed to that topic could process that log file, maybe extract some data, or even trigger an alert if it detects something unusual.
Chris 11:01
It's like setting up this automated workflow without having to write a bunch of custom code
Kelly 11:06
exactly. And speaking of workflows, how about AWS Lambda itself? Another
Chris 11:10
great fit. We touched on this a little bit earlier, but it's worth going into a little bit more detail. SNS can actually directly invoke those Lambda functions, which is super powerful for serverless architectures? Yeah, imagine you've
Kelly 11:21
got an application that needs to process incoming data in real time. Instead of having servers constantly running waiting for that data, you can use SNS as that trigger. Data arrives, SNS sends out the notification, and a Lambda function spins up, processes that data and then shuts down all without you having to manage any servers. That's amazing. Talk
Chris 11:41
about efficiency and cost. Efficiency and cost effective too. Yeah. Okay. What about CloudWatch? That is evident. So
Kelly 11:47
CloudWatch can send notifications to SNS topics based on alarm thresholds. This is really useful for responding to changes in your environment.
Chris 11:54
Okay. So if a CloudWatch alarm, let's say monitoring CPU utilization, goes off, it could trigger an SNS notification, and then that notification could do a whole bunch of different things exactly.
Kelly 12:06
It could trigger an auto scaling event to add more EC2 instances, or just send, like a simple email alert to your team. It's about automating those responses to keep your systems running smoothly.
Chris 12:16
Okay, last integration for today, AWS, IAM. How important is that, when we're talking about
Kelly 12:21
SNS, it's essential for security and controlling access. You use IAM policies to define you know, who can publish messages, who can subscribe to topics, who can manage those topics,
Chris 12:30
no accidental message blasts or unauthorized access, exactly.
Kelly 12:33
And it's not just about users. You can use IAM roles to give permissions to other AWS services, like allowing S3 to publish to an SNS topic.
Chris 12:43
So to wrap things up, you've got this incredibly flexible messaging service in SNS, and it becomes even more powerful when you combine it with all these other AWS
Kelly 12:51
services. It's like having this toolkit for building event driven systems, decoupling applications, automating workflows and for
Chris 12:58
our listeners, prepping for those AWS exams, remember, these integrations are often the basis for a lot of those scenario based questions, so really understanding how all these different services work together is really key, absolutely
Kelly 13:09
and beyond the exam, this knowledge is so valuable for actually designing and building real world cloud solutions.
Speaker 1 13:16
That's a great point. It's not just about passing a test, it's about developing that deeper understanding of how to actually build robust and scalable systems in the cloud, so that all of our listeners out there keep experimenting, keep learning and keep pushing the boundaries of what's possible in the cloud. Thanks for joining us for this deep dive into Amazon. SNS, until next time.