Windows Azure Service BusAnton Boyko.NET developer

Service Bus Relay

OnewayNetOnewayRelayBindingAll TCP and HTTP listeners use one-way as internal control channel60KB message-size limitOne-way onlyNo rendezvous overhead

Backend

NamingRouting

Fabric

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FrontendNodes

outbound

connect one-way

net.tcp

outbound connect bidi socket

MsgMsg

NATFirewall

Dynamic IP

NLB TCP/SSL HTTP(S)TCP/SSL HTTP(S)

RouteSubscribe

Rendezvous(TCP & HTTP)

NetTcpRelayBindingWebHttpRelayBindingBasicHttpRelayBindingWS2007RelayBindingRendezvous HandshakeBi-Directional Net.Tcp Full DuplexNo message size limit

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NLB

outbound socket rendezvous

HTTP/SocketForwarder

outbound

socket connect

Ctrl

Ctrl

TCP/SSL or HTTP

Backend

NamingRouting

Fabric

FrontendNodes

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dNamingRouting

Fabric

FrontendNodes

Hybrid ConnectSpecial Mode of NetTcpRelayBindingTcpRelayConnection-Mode.HybridStarts as relayed connectionPerforms NAT probing and behavior predictionEstablishes direct connection and upgrades if possibleUpgrade driven by trafficTakes large transfers off the RelayNo transfer charges, lower latency

relayed connect

NAT Probing

CtrlNAT Probing

NAT Traversal Connection

Upgrade

Upgrade

relayed rendezvous

Oneway RendezvousCtrl Msg

TCP/SSL HTTP(S)

Service Bus Messaging

Relay vs. Message Broker

The Relay routes messages ‘straight through’ with feedback path and network backpressure into sender

Route

AuthN/Z Backpressure Feedback Relay

Query FilterPull

AuthN/Z Broker

Brokers hold messages for retrieval and querying

Push vs. Pull

‘Push’ is a sender initiated activity that results in delivery of a message to a receiver without the receiver explicitly asking for one or a particular message

Intermediary

Broker

‘Pull’ is a receiver initiated activity that delivers stored messages to the receiver in a context that the receiver controls. The context is decoupled from the ‘Push’ style send operation

Ways to PullReceive and DeleteFastest. Message lost if receiver crashes or transmission fails.

Peek LockMessage is locked when retrieved. Reappears on broker when not deleted within lock timeout.

TransactionalLocal model

Broker

Broker

Broker

Broker Message

MessagesProperties are key/value pairs that may very well carry payloadsIt’s not uncommon to have messages with empty message bodiesMessage bodies are useful for a single opaque payload not exposed to the broker (e.g. encrypted content)

Body

Properties

Queues

Load LevelingReceiver receives and processes at its own pace. Can never be overloaded. Can add receivers as queue length grows, reduce receiver if queue length is low or zero. Gracefully handles traffic spikes by never stressing out the backend.

Offline/BatchAllows taking the receiver offline for servicing or other reasons. Requests are buffered up until the receiver is available again.

Queue

Queues

Load BalancingMultiple receivers compete for messages on the same queue (or subscription). Provides automatic load balancing of work to receivers volunteering for jobs.Observing the queue length allows to determine whether more receivers are required.

Queue

TopicsTopic Sub

SubSub

Message DistributionEach receiver gets its own copy of each message. Subscriptions are independent. Allows for many independent ‘taps’ into a message stream. Subscriber can filter down by interest.

Constrained Message Distribution (Partitioning)Receiver get mutually exclusive slices of the message stream by creating appropriate filter expressions.

Subscription FiltersFilter conditions operate on message properties and are expressed in SQL’92 syntax InvoiceTotal > 10000.00 OR ClientRating <3ShipDestCtry = ‘USA’ AND ShipDestState=‘WA’LastName LIKE ‘V%’

Filters actions may modify/add/remove properties as message is selectedSET AuditRequired = 1

Service Bus Best PracticesClient object lifecycle management• Cache QueueClient, SubscriptionClient, TopicClient• Close clients when no longer needed. Close() method may throw an

exception. Wrap it with try/catch.

Handling transient errors• Implement consistent retry pattern• Consider Transient Fault Handling Framework (EntLib6)

Reliable message handling (Peeklock)• Always finalize successfully processed message by calling Complete()• Always abandon unprocessed message by calling Abandon()• Ensure message is processed within designated lock period

Service Bus Best Practices (cont.)Improve Performance• Reuse client objects• Choose Service Bus client protocol over HTTP• Use asynchronous send/receive• Use ReceiveAndDelete when appropriate• Use multiple queues

Storage Queue vs. Service Bus QueueStorage Queue• TTL 7 days max• Max queue size 100 TB• Max message size 64 KB• Authentication via

symmetric key• No WCF integration

Service Bus Queue• TTL unlimited• Max queue size 5GB• Max message size 256 KB• Authentication via

ACS claims• WCF Integration out-of-the-

box

more details http://msdn.microsoft.com/en-us/library/windowsazure/hh767287.aspx