codepalousa 2012

7/31/2019 CodepaLOUsa 2012

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Introduction to Windows Azure

Service Bus

Joe Feser

Logical Advantage@joefeser on twitter and github


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What is a Service Bus

An enterprise service bus (ESB)

is a software architecture model

used for designing and

implementing the interactionand communication between

mutually interacting software

applications in Service Oriented

Architecture.

Source: Wikipedia


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What is AppFabric Service Bus

Message Relay

Brokered Message

Queues

Topics (Pub/Sub)

Do not confuse it with Azure Queues (Queues, Tables and Blobs)

The Service Bus provides both relayed and brokered messagingcapabilities. In the relayed messaging pattern, the relay servicesupports direct one-way messaging, request/response messaging,and peer-to-peer messaging. Brokered messaging provides durable,asynchronous messaging components such as Queues, Topics,

and Subscriptions, with features that support publish-subscribe andtemporal decoupling: senders and receivers do not have to be onlineat the same time; the messaging infrastructure reliably storesmessages until the receiving party is ready to receive them. (FromMicrosoft)


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What makes it cool?

It does not take weeks to integrate

You dont have the change your entire

architecture to use it

It does not depend on the Azure SDK

It does not need to run on Azure but it can

Allows for easy integration with partnerswithout the need for a service to be up 24/7

Allows for massive scale out


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What makes it different than a web

service?

You can not discover the service

There is no WSDL

The message contract must be known up frontby both parties

A web server is not required. It can run from

any standard computer or server as a serviceor process.


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SB does not Require the Azure SDK

The library built by Microsoft does not depend

on the Azure SDK.

The service is also exposed via REST and you

may build your own if you wish.


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How does it authenticate

Azure Service Bus requires the AppFabric ACS

(Access control Service)

It is a very powerful namespace based

provider


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How does it communicate?

All communications are outbound

TCP is used by default and will fall back to

HTTP if TCP cant be used

No changes are required to your firewall

although you may need to configure your

proxy server


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Queues Introduction

A Queue is exactly what you would expect

Many sources places messages into a known

common endpoint

All messages are processed FIFO

One or many

receivers pull from

the queue


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Topics Introduction

Topics use the Pub/Sub model

Many sources publish messages onto a topic endpoint

Subscribers create subscriptions to the messagesand receivea copy when the filterevaluates to true

Subscribers then pullmessages from thetopic when they areavailable


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Difference between Queues and Topics

Queues cant be filtered. If you need to supporttwo different rules, you need to create twodifferent queues For example, if you have a system interested in new

orders and shipment notifications, you will need tocreate two queues

Topics may contain filters, allowing for manytypes of messages to be sent to the same

endpoint A topic may be created to receive an order object and

a different topic may be created for a shippingnotification object


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How are AppFabric Queues

different from Azure Queues?Comparison Criteria Windows Azure Queues Service Bus Queues

Ordering guarantee No Yes - First-In-First-Out (FIFO)

(through the use of messaging sessions)

Delivery guarantee At-Least-Once At-Least-Once

At-Most-Once

Transaction support No Yes

(through the use of local transactions)

Receive behavior Non-blocking

(completes immediately if no new message is

found)

Blocking with/without timeout

(offers long polling, or the Comet technique)

Non-blocking(through the use of .NET managed API only)

Receive mode Peek & Lease Peek & Lock

Receive & Delete

Exclusive access mode Lease-based Lock-based

Lease/Lock duration 30 seconds (default)

7 days (maximum)

60 seconds (default)

5 minutes (maximum)

Lease/Lock granularity Message level

(each message can have a different timeoutvalue)

Queue level

(each queue has a lock granularity applied to allof its messages, fixed for the lifetime of the

queue)

Batched receive Yes

(explicitly specifying message count when

retrieving messages, up to a maximum of 32

messages)

Yes

(implicitly enabling a pre-fetch property or

explicitly through the use of transactions)

Batched send No Yes

(through the use of transactions or client-side

batching)
http://en.wikipedia.org/wiki/Comet_(programming)http://en.wikipedia.org/wiki/Comet_(programming)


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Advanced Capabilities

Comparison Criteria Windows Azure Queues Service Bus Queues

Scheduled delivery Yes Yes

Automatic dead lettering No Yes

Message deferral Yes

(via in-place update of visibility timeout)

Yes

(provided via a dedicated API function)

Poison message support Yes Yes

In-place update Yes No

Server-side transaction log Yes No

Storage metrics Yes No

Purge queue function Yes No

Message groups No Yes

(through the use of messaging sessions)

Duplicate detection No Yes

(configurable on the sender side)

WCF integration No Yes

(offers out-of-the-box WCF bindings)

WF integration Custom

(requires building a custom WF activity)

Native

(offers out-of-the-box WF activities)


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Capacity and Quotas

Comparison Criteria Windows Azure Queues Service Bus Queues

Maximum message size 64 KB (Was 8k in SDK < 1.6)

(48 KB when

using Base64encoding)

256 KB

(including both header and body,

maximum header size: 64 KB)

Maximum queue size 100 TB

(limited to a single storage account

capacity)

1, 2, 3, 4 or 5 GB

(defined upon creation of a queue)

Maximum message TTL 7 days Unlimited

Maximum number of queues Unlimited 10,000

(per service namespace, can be

increased)

Maximum number of concurrent

clients

Unlimited Unlimited

(100 concurrent connection limit

only applies to TCP protocol-based

communication)


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Message Limits

Brokered messages have a 256k limit,

including the message overhead

The Header may be up to 64k

Messages over 64k are sent in chunks of 64k

and this will affect your performance and cost.


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What can the message be?

Any object that can be serialized with a

DataContractSerializer

Any Stream of data that you will manage

yourself

Any base CLR type (string, int, boolean)


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Metadata on your message

Every message supports up to a 64k Name

Object pair of values that may be used by your

handler or by the by your Topic Subscription

filters

An example key could be Department and

the value may be Payroll

For a topic, you could create a subscription that

only looks for messages with a Department of

Payroll


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Read once vs read at least once

ReceiveAndDelete You will only receive the message once

Great for logging non critical items

Very high performance vs PeekLock because a roundtrip is not required

PeekLock You will receive at least once

Until you call Complete, it will stay in the queue

You can read the DeliveryCount count property todetermine how many times you have received themessage.


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Default Time to Live

Be VERY careful with this setting. Keep at the

default unless you want the service to cleanup

old messages for you.

More geared toward priority based logging.

You will pull your hair out if you do not read

the last to bullet points 10 times. Trust me I

did.


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Duplicate Detection

The MessageId property of the BrokeredMessageis the Primary key of the message

If duplicate detection is set up and the timeframe is three minutes, only one message withthe same id will be accepted by the Topic orQueue

The second message will just be ignored

No error will be returned to the sender

Make sure you really are sending the samemessage


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Queues

A Queue in Azure Service busis nothing more than a Topicwith one subscription withno rules

Many senders can send amessage to the queue

To scale the read throughputall you need to do is addadditional receivers. Theservice bus will automaticallyload balance the requestsbetween the clients


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Load leveling

The biggest advantage to a queue is load

leveling. Your back end system can process the

messages at a constant rate with a consistent

response time on message acceptance


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Load balancing

You can query the queue for the message

count and determine if more instances of your

message processor need to be spun up


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Topics

Just like Queues, Topics allowfor multiple publishers to sendmessages to a pre definedendpoint

Messages can be sent in a fire

and forget manner No need to care if anyone is

subscribed to your message, ifno filters qualify the message isthrown out

Any mix and match of receivers

can process a givensubscription and just likequeues, they will automaticallyscale out


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How I used Service Bus to extend a web service?


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Sending a state change to the topic


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How it can be used for a Workflow?


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Service Bus Demo

Demo sample code from Project Extensions

If time show the emulator


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Limits to consider

DTC is not supported

Transactions work with a group of messages

but not in a Transaction scope containing any

SQL server, either Sql Azure or Sql Server.


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Resources used in the slides

An Introduction to Service Bus Topics

http://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspx

An Introduction to Service Bus Queues

http://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspx

How to Use Service Bus Queues

https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/

How to Use Service Bus Topics/Subscriptions

https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/

Windows Azure Queues and Windows Azure Service Bus Queues - Compared and Contrasted

http://msdn.microsoft.com/en-us/library/hh767287(VS.103).aspx

Service Bus Home Page

http://msdn.microsoft.com/en-us/library/windowsazure/ee732537.aspx

Wikipedia Enterprise Service Bus http://en.wikipedia.org/wiki/Enterprise_service_bus
http://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttps://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/http://msdn.microsoft.com/en-us/library/hh767287(VS.103).aspxhttp://msdn.microsoft.com/en-us/library/windowsazure/ee732537.aspxhttp://en.wikipedia.org/wiki/Enterprise_service_bushttp://en.wikipedia.org/wiki/Enterprise_service_bushttp://msdn.microsoft.com/en-us/library/windowsazure/ee732537.aspxhttp://msdn.microsoft.com/en-us/library/windowsazure/ee732537.aspxhttp://msdn.microsoft.com/en-us/library/windowsazure/ee732537.aspxhttp://msdn.microsoft.com/en-us/library/windowsazure/ee732537.aspxhttp://msdn.microsoft.com/en-us/library/hh767287(VS.103).aspxhttp://msdn.microsoft.com/en-us/library/hh767287(VS.103).aspxhttp://msdn.microsoft.com/en-us/library/hh767287(VS.103).aspxhttp://msdn.microsoft.com/en-us/library/hh767287(VS.103).aspxhttp://msdn.microsoft.com/en-us/library/hh767287(VS.103).aspxhttps://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-topics/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/https://www.windowsazure.com/en-us/develop/net/how-to-guides/service-bus-queues/http://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/17/an-introduction-to-service-bus-queues.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspxhttp://blogs.msdn.com/b/appfabric/archive/2011/05/25/an-introduction-to-service-bus-topics.aspx


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Items covered if time allows

Dead Lettering

PrefetchCount You can use PrefetchCount to fetch multiple messages

from the server in the same round-trip. This can be useful

in scenarios that need lower latency for receiving existingmessages from a queue or subscription. Prefetch can alsoimprove throughput depending upon the scenarios as thenumber of round-trips to the server are reduced.

Prefetch is disabled by default. You can enable it by usingthis property on the client. You mustset PrefetchCount before receiving the first message.

Defer Support

Session Support

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