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ISUG SSB Lior King

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ISUG SSB Lior King

  1. 1. Introduction to Service Broker inSQL Server 2005/2008<br />Lior King<br />Database & Infrastructure Group Manager<br />SRL Group<br />
  2. 2. 2<br />Agenda<br />Messaging, SOA, SODA.<br />What is Service Broker (SB) and is it good for.<br />Microsoft’s alternatives to Service Broker.<br />Messaging Basics: Conversation, Dialogs, Conversation Groups, Service<br />SB building blocks: Message types, Contracts, Queues, Service programs.<br />Messaging flow.<br />Handling errors and poison messages.<br />Internal & External activation<br />Using conversations group lock.<br />Routing and security<br />
  3. 3. 3<br />Why Messaging?<br />Asynchronous message processing <br />Decoupling long duration business processes from the client app. For example: Sending a letter or an email.<br />Getting scalability.<br />Benefits of deferred message processing:<br />The receiver controls when messages are processed.<br />Load balancing occurs during peak times.<br />Fault tolerance on the receiving side.<br />Vital for Distributed Systems.<br />Software components are running on different servers on the network<br />Enabling scalability<br />Handling security issues: Authentication, Encryption.<br />
  4. 4. 4<br />What is SOA?<br />SOA = Service Oriented Architecture.<br />Explicit Service boundaries<br />Exposing the available operations to other clients.<br />Autonomous services.<br />Minimum dependency on other services – loosely coupled.<br />Explicit data contracts<br />A contract defines the contents of a message sent in both directions. <br />Interoperability<br />Ability to work with any platform, including non-windows.<br />Service broker is exposed to other clients through XML web services. Even Java clients can interact with Service broker.<br />
  5. 5. 5<br />What is SODA? <br />SODA – Service Oriented DATABASE Architecture<br />Natively implementing messages (data) inside the database.<br />To implement SODA, SQL Server offers:<br />Integration into .NET (SQLCLR)<br />Query Notifications<br />Service Broker<br />XML support<br />Web Services support<br />Business functionality - with SQLCLR stored procedures<br />Message bus – with Service Broker<br />Publishing – with SQL Server Web Service support.<br />
  6. 6. What Is Service Broker?<br />6<br />
  7. 7. 7<br />What is Service Broker (SB)<br />A platform for building asynchronous, scalable database applications.<br />Three features that distinguish SSB are reliable, ordered, and asynchronous delivery of messaging.<br />Supports queuing out of the box which includes features like locking, ordering, and multithreading.<br />We can use SB with a single instance or scale out across multiple instances<br />
  8. 8. 8<br />Messaging complications solved by Service Broker (1)<br />Performance<br />With service broker, the queue is a database object and thus distributed transaction and operations are usually not needed.<br />Queue Reader Management <br />With multiple queues – like a supermarket. What happens when a new line in open? Queue balancing has a cost!<br />The Service broker way – like an airport check in. Using one queue with multiple queue readers.<br />
  9. 9. 9<br />Messaging complications solved by Service Broker (2)<br />Transaction Management<br />Determine how queue readers are coordinated against one queue. Example: An order header record and some order items records. <br />Service broker uses "Conversation Group Locking" which ensures that the same queue reader processes messages from the same conservation group.<br />Message Sequencing<br />When there are several messages, each of which depends on a previous message.<br />SB includes a sequence number with every sent message.<br />In SQL 2008, SB includes built in support for conversation priorities.<br />
  10. 10. 10<br />Messaging complications solved by Service Broker (3)<br />Message Correlation.<br />When a client sends a few messages and gets back a few responses. How can a client know which response is for which request?<br />SB associates a "Conversation ID" to each message which the client can use to correlate responses to requests.<br />Maintenance<br />With MSMQ, messages are stored in the file system and data in the database. A "sync" backup will require stopping the MSMQ while performing the backup!!!<br />With SB, when performing a database backup, you backup also the queues with the messages.Everything is IN SYNC.<br />
  11. 11. What Service Broker is NOT?<br />Not a general purpose messaging system – it only works for SQL Server.<br />Supports only transactional messaging – <br />if transactional messaging is not required this is unnecessary overhead.<br />Not just a messaging system, we can use the queuing features on a single SQL Server instance or multiple instances.<br />11<br />
  12. 12. 12<br />MS Messaging alternatives (1)<br />MSMQ – Microsoft Message Queuing.<br />Since the first version of Windows NT<br />Comes with Windows for free.<br />Not bound to a specific DB<br />Message size – up to 4MB<br />For distributed transaction – MSMQ needs touse DTC.<br />Message ordering is NOT guaranteed.<br />Message correlation – not supported.<br />Queue readers are implemented manually.<br />Synching and locking between queue readers - are implemented manually.<br />Problem with backup consistency.<br />
  13. 13. 13<br />MS Messaging alternatives (2)<br />Queued Components<br />Part of Component Object Model (COM+) infrastructure.<br />Can enqueue a user request to a COM+ app and execute it asynchronously.<br />Internally- it uses MSMQ to enqueue the message.<br />On the server side, a component named "listener" is used to dequeue the message and calls the specified COM+ object.<br />Used in projects that already uses the COM+ infrastructure.<br />
  14. 14. 14<br />MS Messaging alternatives (3)<br />BizTalk is a Microsoft product for Business Process Management (BPM).<br />Enables to automate, orchestrate and optimize business processes.<br />Includes tools for design, develop, deploy, and manage those processes.<br />BizTalk can also manipulate the contents of messages over multiple transports, map message formats, manage workflows etc.<br />Uses its own messaging for Enterprise Application Integration (EAI).<br />High licensing cost (especially where scale out is needed).<br />If your app just requires reliable messaging from one SQL Server instance to another - SSB is probably a better choice.<br />
  15. 15. 15<br />MS Messaging alternatives (4)<br />XML Web Services<br />Based upon open standards such as SOAP and WSDL.<br />Since .NET 1.0 - full support for creation of web services.<br />Easy to design, implement, publish and reuse.<br />No native queuing.<br />
  16. 16. 16<br />MS Messaging alternatives (5)<br />WCF =<br />Windows Communication Foundation<br />Since .NET 3.0.<br />Based on standards.<br />Provides the same API across different communication technologies.<br />The WCF API enables to write apps in a communication-independent way.<br />No native queuing.<br />We can combine SB and WCF in applications.<br />
  17. 17. 17<br />Service Broker Basics<br />
  18. 18. 18<br />Conversation<br />A conversation is a reliable, ordered exchange of messages between two SB services.<br />Dialog – 2 way conversation between exactly two SB services<br />Service 1 = Initiator service<br />Service 2 = Target service<br />Monologue – A one way conversation between a single publisher service and several subscriber services. It's a version of "publish-subscribe" paradigm.<br />Only Dialogs are supported in SQL Server 2005/8. <br />
  19. 19. 19<br />Dialog<br />Guaranteed delivery – even if the receiver is currently offline.<br />Long lived – From a few seconds to several years.<br />Exactly once – No need to resend messages.<br />In order delivery – SB ensures the messages are received in the same order.<br />Persistence – Survives restarts of the DB server.<br />Dialog lifetime:<br />Each participant can end the conversation<br />The Initiator can optionally specify a maximum lifetime for the dialog expiration). Both participants will track the lifetime.<br />Conversations never live beyond their maximum lifetime (if specified).<br />
  20. 20. 20<br />Conversation Groups<br />Identifies one or more related conversations.<br />Allow the SB to coordinate conversations involved in a specific task.<br />A conversation can belong to one group only (one-to-many).<br />Conversation Group Lock - When a message is initiated, SB locks the conversation group. Only one session at a time can receive message of the conversation group.<br />Example: Books ordering on the internet:<br />Credit card validation.<br />Inventory service<br />Accounting service<br />Shipping service.<br />
  21. 21. 21<br />Conversation Groups<br />
  22. 22. 22<br />Message sequencing<br />Each message in the conversation gets a sequence number starting at #1.<br />The target tries to dequeue message #1, then #2 and so on.<br />When a message is lost during the sending process, the target waits until the message is successfully re-sent.<br />Reliable Delivery across the network<br />Resending and acknowledgement is built in SB.<br />
  23. 23. 23<br />Service<br />A SB Service is a named endpoint to which messages from other services are sent. A SB service is a SQL Server object<br />The interface is defined through the messages.<br />Services contain the logic (code) and the state (data)<br />Services communicate through conversions.<br />Services are mapped to queues. Messages send to a service are stored in its associated queue.<br />Each SB service consist of 4 DB objects:<br />Message types<br />Contracts<br />Queue<br />Service program<br />The first three are DB objects. <br />The Service program can be implemented:<br />Internally – as a stored procedure.<br />Externally – as a separate application.<br />
  24. 24. 24<br />
  25. 25. 25<br />Services deployment<br />On the same SQL Server DB<br />On the same SQL instance but on separate DBs.<br />On different SQL instances and on separate DBs – on a different DB Servers.<br />The services location is transparent during the development.<br />
  26. 26. 26<br />ואחרי כל ההקדמה התיאורית <br />הגיע זמן לקצת "תכל'ס"<br />
  27. 27. 27<br />Message Types<br />Defines the type of data that a message contains.<br />Must be created in each DB that participates in a conversation<br />Can perform the following validations:<br />Optional XML validation against XML schema definition (XSD).<br />Well formed XML<br />No validation (for example: when there is binary data)<br />Empty (the message body MUST be empty).<br />NOTE: XML validations can impact the overall performance (due to parsing).<br />Recommended for developing and testing only.<br />
  28. 28. 28<br />Message Types<br />Beware of message type conflicts.<br />It’s conventional to prefix each message type and contract with your own internet domain.<br />Use the DDL command CREATE MESSAGE TYPE. Example: <br /> CREATE MESSAGE TYPE [http://mydomain/SBMessages/RequestMessage] Validation=NONE<br />Use sys.service_message_types catalog view to get information about the defined message types.<br />To change a message type, use the command ALTER MESSAGE TYPE.<br />A [DEFAULT] message type exists in every database.<br />
  29. 29. 29<br />Contracts<br />An agreement between two SB services.<br />Defines the message types a SB service uses.<br />Service Broker ensures that only message types that are defined in the contract are processed.<br />Determines which message type is use by the initiator and which by the target (or used by both):<br />SENT BY INITIATOR<br />SENT BY TARGET<br />SENT BY ANY<br />
  30. 30. 30<br />Contracts<br />Use the DDL command: CREATE CONTRACT. Example: <br />CREATE CONTRACT <br /> [http://mydomain/SBMessages/DemoContract]<br /> ([http://mydomain/SBMessages/RequestMessage] <br /> SENT BY INITIATOR,<br /> [http://mydomain/SBMessages/RequestMessage] <br /> SENT BY TARGET)<br />Use sys.service_contracts and sys.service_contract_message_usages to get the contracts and the message types associated to each contract.<br />To change a contract – use DROP CONTRACT and CREATE CONTRACT again (ALTER will not work).<br />A [DEFAULT] contract exists in every database.<br />
  31. 31. 31<br />Queues<br />A queue – a storage provider for messages that are sent/received.<br />Must be defined for the initiator and for the target services.<br />When a message is sent to a target, it is enqueued in the target's queue.<br />The target service dequeues the message and processes it.<br />When the processing is done – the transaction is committed and the message is removed from the queue.<br />The queue is implemented by hidden tables. <br />Queues can be only queried for monitoring.<br />
  32. 32. 32<br />Queues<br />Use the DDL command: CREATE QUEUE. A simple example: <br />CREATE QUEUE InitiatorQueue WITH STATUS= ON<br /> CREATE QUEUE TargetQueue WITH STATUS= ON<br />Use the sys.service_queues catalog view to get information about the queues defined.<br />
  33. 33. 33<br />Service Programs<br />Service programs process incoming messages from the queue.<br />SB can activate a service program automatically when a message arrives.<br />Service programs activation can also be scheduled.<br />The Response to the initiator is a part of the message's conversation.<br />
  34. 34. 34<br />Service Programs<br />Use the DDL command CREATE SERVICE. Example:<br />CREATE SERVICE InitiatorService ON QUEUE InitiatorQueue <br /> ( [http://mydomain/SBMessages/DemoContract])<br /> CREATE SERVICE TargetService ON QUEUE TargetQueue <br /> ( [http://mydomain/SBMessages/DemoContract])<br />Use the sys.services catalog view to get information about the services defined.<br />Use the ALTER SERVICE to change the service definition. Example:<br />ALTER SERVICE TargetService ON QUEUE MyNewTagetQueue (<br /> ADD CONTRACT [MyNewContract] <br /> DROP CONTRACT [http://mydomain/SBMessages/DemoContract])<br />
  35. 35. 35<br />Sending & Receiving messages<br />Sending Message<br />In order to start the messaging, you need to:<br />Create a new conversation between 2 SB services with <br /> BEGIN DIALOG command.<br />Send a message of the required message type with <br /> SEND ON CONVERSATION command.<br />Receiving a Message<br />Use the RECEIVE command.<br />Using RECEIVE is like doing a “SELECT FROM QUEUE” command.<br />Changes the @@ROWCOUNT system variable.<br />Can be combined with WAITFOR… TIMEOUT command for a limiting the waiting time.<br />
  36. 36. 36<br />Ending a conversation<br />Use the END CONVERSATION command.<br />SB sends a message of the “built-in” message type [http://schemas.microsoft.com/SQL/ServiceBroker/EndDialog]<br />You must explicitly end SB conversations on both service sides. If you forget to end a conversation on one side, the conversation will remain open.<br />Can use WITH CLEAN clause to remove all messages and information without notifying the other side. This is useful if the remote service has been suddenly removed.<br />
  37. 37. 37<br />Poison messages<br />A poison message is a message that will always cause the receiver to fail with its processing.<br />Example: A primary key violation.<br />A deadlock – is NOT a poison message. A retry might eventually succeed.<br />SB disables a queue that experiences 5 rollbacks in a row. It can be resolves manually or automatically with an application that subscribes to the poison message notification, using CREATE EVENT NOTIFICATION. <br />Re-enable the queue with:<br /> ALTER QUEUE <queuename> WITH STATUS = ON<br />
  38. 38. 38<br />Error Messaging (1)<br /> Use END CONVERSATION error message to send an error and end the conversation at the same time. Example:<br /> END CONVERSATION @ch <br /> WITH ERROR = 1234 DESCRIPTION = 'My error msg'<br /> The actual XML sent is:<br /><Error xmlns="http://schemas.microsoft.com/SQL/ServiceBroker/Error"><br /> <Code>1234</Code><br /> <Description>My error message</Description><br /> </Error><br />
  39. 39. 39<br />Error Messaging (2)<br />The service that receives the error can check for an error:<br />IF (@messagetypename =<br /> 'http://schemas.microsoft.com/SQL/ServiceBroker/Error')<br /> BEGIN<br /> SET @errorcode = <br /> (SELECT @messagebody.value(<br /> N'declare namespace brokerns=<br /> "http://schemas.microsoft.com/SQL/ServiceBroker/Error";<br /> (/brokerns:Error/brokerns:Code)[1]', 'int'));<br /> SET @errormessage = (SELECT @messagebody.value(<br /> N'declare namespace brokerns=<br /> "http://schemas.microsoft.com/SQL/ServiceBroker/Error";<br /> (/brokerns:Error/brokerns:Description)[1]', <br /> 'nvarchar(3000)'));<br /> END<br />
  40. 40. 40<br />DEMO<br />
  41. 41. 41<br />Activation<br />Polling the queue to see if messages had arrived wastes a lot of resources when few messages are arriving on the queue.<br />Activation allows you to start a service program as soon as a new message arrives in the service queue:<br />Internal activation: For activating a stored procedure.<br />External activation: For activating an external application.<br />Parallel activation: For starting more than one stored procedure simultaneously.<br />Troubleshooting activation.<br />Activation is performed using “queue monitors” which determine how and when to activate the service.<br />
  42. 42. 42<br />Internal activation - steps<br />Configure a service queue according to your requirements <br />Create (or alter) a queue that enables activation. Example:<br />CREATE QUEUE [TargetQueue] WITH ACTIVATION (<br /> STATUS=ON, <br /> PROCEDURE_NAME = [YourServiceProcName], MAX_QUEUE_READERS=1, EXECUTE AS SELF)<br />MAX_QUEUE_READERS – maximum instances of the stored proc that the queue starts at the same time. This is actually the level of parallelism by which messages in the queue are processed.<br />EXECUTE AS – The DB account under which the activated stored proc runs. Using EXECUTE AS SELF means that the stored proc executes as the current user.<br />
  43. 43. 43<br />Activating a service on a different DB<br />The activation procedure needs to call a stored procedure on another database.<br />The activation procedure might not have sufficient privileges to call another database.<br />To fix this, you must sign the activated stored procedure with a certificate and map a user with the needed permission to this certificate.<br />Another option is to set the database as trustworthy (not recommended for production environment): <br />ALTER DATABASE <db> SET TRUSTWORTHY ON<br />
  44. 44. 44<br />Processing many queues with a single procedure<br />Create the necessary queues with the associated services.<br />Set up internal activation on each queue and point to the same procedure.<br />Write a procedure that determines which queue you’ll use to get messages from. <br />To determine from which queue has activated the procedure:<br />SELECT @queue_name = sq.[name] <br /> FROM sys.service_queues sq <br /> INNER JOIN sys.dm_broker_activated_tasks bat <br /> ON bat.spid=@@spid and <br /> sq.object_id = bat.queue_id<br />
  45. 45. 45<br />DEMO<br />
  46. 46. 46<br />External Activation<br />External activation activates all kinds of windows applications (console apps, windows services, win forms etc).<br />Internal activation is not recommended for long-duration work inside a stored procedure.<br />External activation uses SQL Server event notification mechanism.<br />Use CREATE EVENT NOTIFICATION command.<br />
  47. 47. Why use event notification<br />Needed for external service that should be activated by more than one queue<br />47<br />
  48. 48. 48<br />External Activation – Steps example<br />CREATE QUEUE ExternalActivatorQueue<br />CREATE SERVICE ExternalActivatorService ON ExternalActivatorQueue (<br /> [http://schemas.microsoft.com/SQL/Notifications<br /> /PostEventNotification] )<br />CREATE EVENT NOTIFICATION EventNotifTargetQueue<br /> ON QUEUE TargetQueue <br /> FOR QUEUE_ACTIVATION<br /> TO SERVICE 'ExternalActivatorService', <br /> 'current database'<br />
  49. 49. 49<br />Using managed code<br />Use the ServiceBrokerInterface solution that can be found in the samples directory of SQL Server 2008<br />Contains classes such as Conversation, Message, Service.<br />You can build a service class derived from the class “Service”.<br />c#<br />
  50. 50. 50<br />DEMO<br />
  51. 51. 51<br />Conversation Groups<br />Ensures ordered message processing and supports synchronization support for multiple queue readers.<br />Multiple queue readers can gain SCALABILITY.<br />Ensures that only one task can read messages from a particular conversation at the same time.<br />Every conversation belongs to a conversation group.<br />A conversation group can contain one or more conversations.<br />Use the WITH RELATED_CONVERSATION clause when creating a new dialog<br />You might need to create an application state table for more complex business logic and monitoring.<br />
  52. 52. 52<br />Using Conversation Groups<br />Use the WITH RELATED_CONVERSATION clause when creating a new dialog.<br />BEGIN DIALOG @ch1<br />FROM SERVICE [InitiatorService]<br />TO SERVICE 'TargetService1'<br />WITH ENCRYPTION = OFF;<br />BEGIN DIALOG @ch2<br />FROM SERVICE [InitiatorService]<br />TO SERVICE 'TargetService2'<br />WITH RELATED_CONVERSATION = @ch1,<br />ENCRYPTION = OFF;<br />
  53. 53. Distributed Architecture<br />You’ll need to set up the following:<br />Remote Service Bindings<br />Routes<br />Service Broker Endpoints<br />53<br />
  54. 54. Remote Service Binding<br />A remote service bindingestablishes a relationship between:<br />Local database user<br />The certificate for the user<br />The name of a remote service. <br />A remote service binding specifies the identity to be used to authenticate to the remote service.<br />Use T-SQL command:<br />CREATE REMOTE SERVICE BINDING<br />54<br />
  55. 55. 55<br />Routes<br />SQL Server objects that specify on which IP a SB service is located.<br />By default, each database contains a route that specifies that messages for any service which does not have an explicit route are delivered within the SQL Server instance. <br />Enables flexible deployment.<br />Development can be on the same DB and on the same instance.<br />On production, can be on different DB servers.<br />
  56. 56. Routes<br />56<br />
  57. 57. Endpoints<br />A SB endpoint configures SQL Server to send and receive Service Broker messages over the network. <br />Endpoints are specified using service names.<br />Listens on a specific port.<br />Options for transport security and message forwarding.<br />57<br />
  58. 58. 58<br />Security<br />SB allows services to communicated even when the instances are on different machines, have no trusted relationship and on different networks.<br />2 levels of security:<br />Transport security <br />Dialog security<br />
  59. 59. Transport security <br />Windows-based authentication - using NTLM or Kerberos. Can be used only on servers of the same domain or server on different domains that are trusted.<br />Certificate-based authentication – using certificates. Usually used with services that reside on different physical networks on distrusted domains.<br />Dialog security<br />Service Broker supports "forwarders". A forwarder is a SQL Server instance that accepts service broker messages and forwards them to the next hop on the route to the target service.<br />Using a forwarder requires the decryption of the message and encrypting it again. Causes slower performance.<br />59<br />
  60. 60. Dialog security<br />Secures each individual dialog between two dialog endpoints, regardless of how many networks the messages traverse as the travel between the conversation endpoints.<br />Dialog security establishes authenticated and encrypted communication between two services.<br />Dialog security provides encryption, remote authentication, and remote authorization for a specific conversation. <br />60<br />
  61. 61. 61<br />Summary<br />Service Broker is a good choice for transactional, data processing based messaging solution.<br />Service broker database objects such as: Message types, Contracts, Queues and Services can be easily built using T-SQL.<br />SB can Handling errors and poison messages.<br />SB can maintain a logical connection between messages using conversation groups.<br />SB supports Internal activation as well as external activation.<br />SB can support distributed application architecture using routes.<br />SB can secure the messages payload with the excellent encryption algorithms SQL Server provides.<br />
  62. 62. 62<br />Thank you for listening<br />Lior King<br />Database & Infrastructure Group Manager<br />SRL Group<br />Download this presentation from my Blog: KingLior.WordPress.Com<br />My Email: LiorK@SRL.co.il<br />

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