Service BrokerService BrokerLesson 11

Skills MatrixSkills Matrix

Service BrokerService Broker

• Service Broker, provides a solution to common problems with message delivery and consistency that occur when transferring transactional messages or data from one server to another.

• This technology allows SQL Server to implement its own architecture to create a queue-based message delivery system that guarantees delivery.

Service BrokerService Broker• Service Broker includes the infrastructure

for asynchronous programming, which can be used for applications within a single database or a single instance, as well as for distributed applications.

• Service Broker also makes it easy to scale your application up or down to accommodate the amount of traffic it receives. – When a number of requests are queued

up, you actually can implement more queue readers to process requests.

Queue MechanismQueue Mechanism

• The notable feature of this queue mechanism means that SQL Server guarantees that messages will be submitted to and processed from the queue in the correct order.

Broker ArchitectureBroker Architecture

Service BrokerService Broker• Most of the messages in a Service Broker

conversation are the application-defined messages used to communicate between services. – Each message must comply with a

message type format that was defined by a CREATE MESSAGE TYPE statement.

– The set of message types allowed for a conversation is defined by the contract specified in the BEGIN DIALOG CONVERSATION statement.

Service BrokerService Broker

• When designing a broker architecture, you must first define which messages you need in the application.

• You can specify which message type can be sent by the initiator and what can be returned by the target or destination.

Service BrokerService Broker

• The messages sent will be submitted to a queue and processed by a service program. – To communicate from one service to

the other, you also have to specify the route to get to that destination.

– When defining which service can send and receive information from each other, you have to set up an agreement, called a contract.

Creating a Message TypeCreating a Message Type

• You can create a message type using the CREATE MESSAGE TYPE statement.

• In creating these message types, you can define different types, depending on how you structure the message body.

Creating a Message TypeCreating a Message Type• The SQL Server Service Broker architecture

supports the following message bodies:– None: No validation on the content takes

place; you can send whatever you like in the body.

– Header only: empty: This includes the header only; you send a message with an empty body.

– Well-formed XML: The data in the message body needs to be well-formed XML.

– Schema-bound XML: The data in the message body needs to be schema-validated XML. This means the message-body XML schema must exist on the server.

Creating a QueueCreating a Queue

• You must create a queue as the next step in configuring a broker architecture.

• You can specify what should happen to the queue when you submit a message, which you can do by configuring its status and activation properties.CREATE QUEUE <object>

Creating a ContractCreating a Contract

• In a contract, you set up the agreement between the sender of a message and the recipient. – This contract defines which message

type can be sent by the initiator and what can be returned by the target.

CREATE CONTRACT contract_name

Creating a ServiceCreating a Service• Now that you have configured queues,

message types, and a contract, you can set up the service.

• A service references a contract. • Service Broker uses the name of the service

to route messages, deliver messages to the correct queue within a database, and enforce the contract for a conversation.

• If you are targeting multiple services to participate in the broker service, you need to create the routes between them.

Creating a ServiceCreating a Service

• You can assign multiple contracts to a service, as well.

• Service programs initiate conversations to this service using the contracts specified.

• If no contracts are specified, the service may only initiate conversations.

Create a ServiceCreate a Service

• Once the services are configured, you can specify the route between them if you communicate over multiple services.

• When not configured, you use the local database service and default service route.

• The CREATE SERVICE statement follows this syntax:CREATE SERVICE service_name

Creating a RouteCreating a Route

• For outgoing messages, Service Broker determines the routing by checking the routing table in the local database.

• In a route, you specify the communication settings between services.

• Before creating a route, you should configure the HTTP endpoints by using the CREATE ENDPOINT statement.

Creating a PriorityCreating a Priority

• SQL Server 2008 offers a new conversation priority feature.

• The message priority may be set from 1 (lowest) to 10 (highest) with a default of 5.

• First you must enable the priority feature, then set the priority:

Using Service BrokerUsing Service Broker

• After successfully configuring the broker service, you can start sending messages over the broker instance.

• Key components in this process are the queue and the service program.

Sending MessagesSending Messages

• You manage messages using a queue. • To group messages, you initiate a

dialog, in which you forward related messages.

• To identify a conversation, you use a unique identifier.

• You then have to end the conversation so the messages can be processed by the queue.

Receiving MessagesReceiving Messages

• Once you have the message submitted to the recipient, you have to retrieve it from the receiving queue.

• Retrieving a message from a queue, however, uses the RECEIVE statement, which processes every message.

• This message retrieval process may be complex, because you may want to retrieve messages from the queue one by one or all at once.

Receiving MessagesReceiving Messages• The RECEIVE statement processes the

message from the queue and stores it in the variable. – If the message type received is

TicketRequest, you proceed by executing a stored procedure to which you pass the message.

– The WAITFOR statement waits until receiving a message in the queue, while the RECEIVE statement with the TOP clause specifies how many messages you process at once.

Automating the Queue ProcessingAutomating the Queue Processing

• To automate the queue processing, you can change the status of a queue (or specify this when you create the queue).

• When making changes to the queue, you execute the ALTER QUEUE statement,

SQL Server Service Broker ArchitectureSQL Server Service Broker Architecture

• As you probably noticed, the SQL Server Service Broker architecture requires a lot of syntax and SQL Server does not provide a graphical interface to configure queues, and so on. – However, you can review created

queues and other related broker service objects in Object Explorer.

SummarySummary

• In this lesson, you learned how to configure a Service Broker architecture. – A Service Broker architecture proves

useful in an environment where you need a message-based system or a queue-based system.

• Since SQL Server disables features by default, you need to enable Service Broker on the database level before you can start using it.

SummarySummary

• Because of security reasons, Service Broker, by default, communicates only on local servers. – If you want to allow external access, you

need to configure an endpoint for Service Broker.

– You learned how to do this in this lesson. – HTTP can use endpoints for SOAP

requests, and endpoints can provide access to the database from any client that can explore and use a Web service.

SummarySummary

• Service Broker works with message types, contracts, queues, and service programs. – On a queue, you can specify how an

endpoint should be activated. – The entire configuration of the Web

service, including the permissions and IP restrictions, are managed within SQL Server.

– Users need to be granted permissions before they can connect to an endpoint.

Summary for Certification ExaminationSummary for Certification Examination• Know how to enable, configure and work with the

Service Broker. – Understand the Service Broker architecture and the

components it consists of in terms of services, service programs, contracts, message types, and routing.

• Understand how to create a service. Know how to create a service by identifying which contract is used, and be able to configure and identify the CREATE SERVICE syntax.

• Understand how to create a queue. On a queue, you have the possibility to initiate the activation of the queue and specify the service program to use (stored procedure).

Summary for Certification ExaminationSummary for Certification Examination• Understand how to create a contract. In a

contract, you identify what message types the initiator can send and what can be returned by the sender.

• Understand how to create a message type. Message type bodies can be empty (i.e., header-only messages), or they may need to be well-formed XML or match an XML schema collection.

• Know how to initiate a conversation. When submitting messages to a queue, you need to create a conversation. Within a conversation, you can submit multiple messages that relate to each other.

Summary for Certification ExaminationSummary for Certification Examination

• Understand how to send and receive messages. – When sending and receiving

messages, you use the SEND and RECEIVE keywords.

– You need to fully understand the syntax, how to retrieve messages from a queue, and how to close the conversation when it has concluded.

Summary for Certification ExaminationSummary for Certification Examination

• Understand how to create and secure HTTP endpoints.

• When creating endpoints, you need to identify the virtual directory or path on the server, as well as configure the methods that can be used by the endpoint.

• Know that you manage within the endpoint configuration and that a user must have the appropriate permissions to connect to an endpoint.

SummarySummary

• You can partition views in the same way you can partition tables and for the same reasons: store parts of your views on different spindles or even different servers.