Q) What is Proxy Service ?
A) It is exposed to the calling applications or services. Proxy services are Oracle Service Bus definitions of intermediary Web services that Oracle Service Bus implements locally on WebLogic Server.
A) It is exposed to the calling applications or services. Proxy services are Oracle Service Bus definitions of intermediary Web services that Oracle Service Bus implements locally on WebLogic Server.
Q) What is Business Service?
A) It connects to the EIS layer. Business services are Oracle Service Bus definitions of the enterprise services that exchange messages during business processes.
A) It connects to the EIS layer. Business services are Oracle Service Bus definitions of the enterprise services that exchange messages during business processes.
Q) What is the EAI architecture OSB follows ?
A) OSB follows the BUS architecture in EAI.
A) OSB follows the BUS architecture in EAI.
Q) What does it mean by VETRO concept?
A) VETRO stands for
V – Virtualisation
E – Enrichment
T – Transform
R – Route
O – Operate
A) VETRO stands for
V – Virtualisation
E – Enrichment
T – Transform
R – Route
O – Operate
Q) Can we expose any Business Service to external clients or subscribers?
A) No, we cannot expose Business Services to external clients or subscribers. We need Proxy Services to expose to external world.
A) No, we cannot expose Business Services to external clients or subscribers. We need Proxy Services to expose to external world.
Q) Can we have Proxy Services without Business Services?
A) Yes we can have Proxy Services without Business Services , but that will be just a dummy service. EIS layer cannot be connected using that Proxy Service.
A) Yes we can have Proxy Services without Business Services , but that will be just a dummy service. EIS layer cannot be connected using that Proxy Service.
Q) What is the message flow in Proxy Services ?
A) Message flow in OSB is the most important part. It defines the request message flow from Start Node to Route activity and also defines the response message flow from Route to Start Node. It contains Pipeline Pairs, Branch Nodes, Route Nodes , Stages, Actions etc.
A) Message flow in OSB is the most important part. It defines the request message flow from Start Node to Route activity and also defines the response message flow from Route to Start Node. It contains Pipeline Pairs, Branch Nodes, Route Nodes , Stages, Actions etc.
Q) What are stages ?
A) Stages are OSB Message Flow component to contain the actions.
A) Stages are OSB Message Flow component to contain the actions.
Q) How we can connect to Database from OSB?
A) We need to first create one JCA based DB adapter to connect to the database. Then we need to create that JCA based Business Service. We need to call that Business Service to perform database operations.
A) We need to first create one JCA based DB adapter to connect to the database. Then we need to create that JCA based Business Service. We need to call that Business Service to perform database operations.
Q) Is there any other way to connect to Database without using JCA adapters?
A) Yes we can use XQuery execute-sql() function to connect to database. But it is better to use JCA adapters.
A) Yes we can use XQuery execute-sql() function to connect to database. But it is better to use JCA adapters.
Q) How we can achieve parallel processing in OSB?
A) SPLIT JOINS are meant for parallel processing. So we need to implement Split – Join resources to achieve parallel processing.
A) SPLIT JOINS are meant for parallel processing. So we need to implement Split – Join resources to achieve parallel processing.
Q) What are the transformation resources available in OSB?
A) In OSB we can use XQuery or XSLT for transforming messages.
A) In OSB we can use XQuery or XSLT for transforming messages.
Q) How to poll file in OSB?
A) The proxy service should be using file transport, and also define the required components like File Mask,Polling Interval, Read Limit, Post Read Action etc.
A) The proxy service should be using file transport, and also define the required components like File Mask,Polling Interval, Read Limit, Post Read Action etc.
Q) Can we achieve REST implementation in OSB?
A) Yes we can achieve REST service implementation in OSB. It can be implemented using Branch Nodes.
A) Yes we can achieve REST service implementation in OSB. It can be implemented using Branch Nodes.
Q) What is Pipeline Error Handler?
A) Pipeline Error Handlers are used to handle the errors occurred in Request or Response Pipleline.
A) Pipeline Error Handlers are used to handle the errors occurred in Request or Response Pipleline.
Q) How can you end a Proxy flow without using if then else logic ?
A) You have to use Reply (with Success)action to end the Proxy Flow where you want.
A) You have to use Reply (with Success)action to end the Proxy Flow where you want.
Q) For a JMS Queue Subscriber Proxy Service how can you ensure that the JMS Message is retried if an error occurs during processing?
A) One XA Connection Factory should be created to access that JMS queue and that Connection Factory should be used in the URL.
A) One XA Connection Factory should be created to access that JMS queue and that Connection Factory should be used in the URL.
Q)How can you jump control from one stage to next stage without using if then else logic?
A) You have to use Skip action at the end of the stage.
A) You have to use Skip action at the end of the stage.
Question : What is Oracle Service Bus (OSB)?
Answer :Oracle Service Bus allows you to manage Web services and deliver authentic message brokering through the configuration of proxy services in the Oracle Service Bus design-time environment. Oracle Service Bus manages the routing and transformation of messages in an enterprise system to promote seamless application integration.
Oracle Service Bus is a market-leading enterprise service bus built from the ground up for Service Oriented Architecture (SOA) life cycle management. It provides foundation capabilities for service discovery and intermediation, rapid service provisioning and deployment, and governance. This service-infrastructure software adheres to the SOA principles of building coarse-grained, loosely coupled, and standards-based services, creating a neutral container in which business functions may connect service consumers and back-end business services, regardless of underlying infrastructure.
Oracle Service Bus is a market-leading enterprise service bus built from the ground up for Service Oriented Architecture (SOA) life cycle management. It provides foundation capabilities for service discovery and intermediation, rapid service provisioning and deployment, and governance. This service-infrastructure software adheres to the SOA principles of building coarse-grained, loosely coupled, and standards-based services, creating a neutral container in which business functions may connect service consumers and back-end business services, regardless of underlying infrastructure.
Question : What is Oracle Service Bus Console?
Answer :Oracle Service Bus Console is a Web services management dashboard that allows you to monitor Web services and servers and perform service management tasks. The console enables you to perform operational tasks such as configuring proxy and business services, setting up security, managing resources, and capturing data for tracking or regulatory auditing. It provides views to monitor current state and health of the Oracle Service Bus environment by displaying detailed statistics about servers, services, and alerts. The Oracle Service Bus Console also enables you respond rapidly and effectively to changes in your service-oriented environment.
Question : What is Proxy Services and Business Services in Oracle Service Bus (OSB) ?
Answer :Oracle Service Bus provides intelligent message brokering between business services (such as enterprise services and databases) and service clients (such as presentation applications or other business services) through proxy services that you can configure using Oracle Service Bus development and run-time tooling. Proxy services are Oracle Service Bus definitions of intermediary Web services that Oracle Service Bus implements locally on Oracle WebLogic Server. With Oracle Service Bus message brokering, service clients exchange messages with an intermediary proxy service rather than working directly with a business service.
Oracle Service Bus lets you implement proxy services independently and configure them dynamically, as driven by your business needs, without requiring costly infrastructure development and re-deployment efforts. The configuration functions are separated from the management functions in Oracle Service Bus.
Oracle Service Bus lets you implement proxy services independently and configure them dynamically, as driven by your business needs, without requiring costly infrastructure development and re-deployment efforts. The configuration functions are separated from the management functions in Oracle Service Bus.
A proxy service can route messages to multiple business services; you can choose to configure a proxy service with an interface that is independent of the business services with which the proxy service communicates. In such cases, you can configure a proxy service message flow definition to route a message to the appropriate business service and map the message data into the format required by the business service interface.
Business services are Oracle Service Bus definitions of the enterprise services that exchange messages during business processes. A business service and its interface can be defined and configured using the Oracle Service Bus design-time tooling. To configure a business service, you must specify its interface, the type of transport it uses, its security requirements, and other characteristics.
A business service definition is similar to that of a proxy service, but it does not have pipelines (a message flow).
Business services are Oracle Service Bus definitions of the enterprise services that exchange messages during business processes. A business service and its interface can be defined and configured using the Oracle Service Bus design-time tooling. To configure a business service, you must specify its interface, the type of transport it uses, its security requirements, and other characteristics.
A business service definition is similar to that of a proxy service, but it does not have pipelines (a message flow).
Question : What is WSDL? Explain the steps to import WSDL .
Answer :A WSDL defines the public contract (interface specification) between a client and a service, whether the service is a proxy service or a business service. It is the formal description of a Web service. A WSDL is used to describe what a Web service´s interface is, where it resides, and how to invoke it. You create the WSDL resource first since subsequent service registration tasks depend on it. The WSDL is subsequently used to register the business service with the proxy service.
Question : Explain the concept of message flow and pipelines in OSB.
Answer :In Oracle Service Bus, a message flow is the implementation of a proxy service. You configure the logic for the manipulation of messages using proxy service message flow definitions. This logic includes such activities as transformation, publishing, and reporting, which are implemented as individual actions within the stages of a pipeline.
Pipelines are one-way processing paths that include no branching. A pipeline is a named sequence of stages containing actions, representing a non-branching one-way processing path. It is used to specify the message flow for service requests and responses. A stage is a user-configured processing step. Messages fed into the pipelines are accompanied by a set of message context variables that contain the message contents. They can be accessed or modified by actions in the pipeline stages.
Pipelines are one-way processing paths that include no branching. A pipeline is a named sequence of stages containing actions, representing a non-branching one-way processing path. It is used to specify the message flow for service requests and responses. A stage is a user-configured processing step. Messages fed into the pipelines are accompanied by a set of message context variables that contain the message contents. They can be accessed or modified by actions in the pipeline stages.
Question : Explain Pipeline pairs.
Answer :Pipeline pairs are request and response pipelines. The request pipeline definition specifies the actions that Oracle Service Bus performs on request messages to the proxy service before invoking a business service or another proxy service. The response pipeline definition specifies the processing that Oracle Service Bus performs on responses from the business or proxy service that the proxy service invokes before returning a response to a client.
Each pipeline consists of a sequence of stages, each stage containing actions. However, a single service-level request pipeline might optionally branch out into operational pipelines (you can configure one default operational pipeline at most one per operation). The determination of the operation is done through user-selected criteria. The response processing starts with the relevant operation pipeline which then joins into a single service-level response pipeline.
Each pipeline consists of a sequence of stages, each stage containing actions. However, a single service-level request pipeline might optionally branch out into operational pipelines (you can configure one default operational pipeline at most one per operation). The determination of the operation is done through user-selected criteria. The response processing starts with the relevant operation pipeline which then joins into a single service-level response pipeline.
Question : What is Customization File?
Answer :Customization files are XML files and you can open these files in any editor and substitute the required environment values. In addition, you can search for specific environment values (that are not complex XML types) in Oracle Service Bus Console or in a customization file and replace them with the new values. You can fine-tune the scope of the search by filtering these environment values based on variable type or project.
An Administrator uses customization files to make changes to environment values as well as to change references within resources. Customization files can include customizations for all the environment values found in the selected resources, including complex environment values types defined inside the EnvValueTypes class. In addition, it includes a reference customization type for changing resource references inside resources with dependencies.
An Administrator uses customization files to make changes to environment values as well as to change references within resources. Customization files can include customizations for all the environment values found in the selected resources, including complex environment values types defined inside the EnvValueTypes class. In addition, it includes a reference customization type for changing resource references inside resources with dependencies.
Question : Summary of recommended best practices for deployment of Oracle Service Bus resources.
Answer :
• Avoid project renames. If projects need to be renamed, do so concurrently across development, QA, stage and production systems before the next deployment.
• Operations on environment specific resources are best filtered out at import time. Administrators may define these resources (referenced in the import file) in the target system before starting the import process. Alternatively, new environment-specific resources may be deployed and customized for the environment after the import.
• Operational resources controlled by the operator should not be impacted by the import. A naming convention or a dedicated folder could be used to identify such resources during import.
• When the customization file contains the customizations of all project resources in a single file, apply customizations only to resources that are imported. An alternative is to preserve environment values on import and only apply customizations to resources that are added during import.
• At export-time, the exporter needs to know if resources have been deleted, renamed, or moved; and if there have been project reorganizations of artifacts since the last export. If yes, complete deployment should be done. If no, the exporter can select only those resources that need to be exported and an incremental deployment can be done.
• Avoid project renames. If projects need to be renamed, do so concurrently across development, QA, stage and production systems before the next deployment.
• Operations on environment specific resources are best filtered out at import time. Administrators may define these resources (referenced in the import file) in the target system before starting the import process. Alternatively, new environment-specific resources may be deployed and customized for the environment after the import.
• Operational resources controlled by the operator should not be impacted by the import. A naming convention or a dedicated folder could be used to identify such resources during import.
• When the customization file contains the customizations of all project resources in a single file, apply customizations only to resources that are imported. An alternative is to preserve environment values on import and only apply customizations to resources that are added during import.
• At export-time, the exporter needs to know if resources have been deleted, renamed, or moved; and if there have been project reorganizations of artifacts since the last export. If yes, complete deployment should be done. If no, the exporter can select only those resources that need to be exported and an incremental deployment can be done.
Question : What service types are supported by Oracle Service Bus?
Answer :Oracle Service Bus supports varied service types ranging from conventional Web services (using XML or SOAP bindings in WSDLs) to non-XML (generic) services. The service type is selected by the individual doing the service registration when the business and proxy services are created, and it defines the protocols that can be used to communicate with the service end point. Oracle Service Bus service types include:
• SOAP services: SOAP messages are constructed by wrapping the contents of the header and body variables inside an element. If the body variable contains a piece of reference XML, it is sent as is. In other words, the referenced content is not substituted into the message. If attachments are defined in the attachments variable, a MIME package is created from the main message and the attachment data. Content handling for each attachment part is similar to how it is handled for messaging services.
• XML services (non-SOAP): Messages to XML-based services are XML, but can be of any type the proxy service configuration allows. In messages that include attachments, their content is a MIME package that includes the primary XML payload as one of its parts—typically the first part or the one identified by the top-level content-type header.
• Messaging services: Messaging services are those that can receive messages of one data type and respond with messages of a different data type. Supported data types include XML, Message Format Language (MFL), text, untyped, binary and attachments where interface is not described by WSDL.
Oracle Service Bus supports request and response as well as one-way paradigms, for both the HTTP and the JMS asynchronous transport protocols. If the underlying transport supports ordered delivery of messages, Oracle Service Bus also extends the same support.
• SOAP services: SOAP messages are constructed by wrapping the contents of the header and body variables inside an element. If the body variable contains a piece of reference XML, it is sent as is. In other words, the referenced content is not substituted into the message. If attachments are defined in the attachments variable, a MIME package is created from the main message and the attachment data. Content handling for each attachment part is similar to how it is handled for messaging services.
• XML services (non-SOAP): Messages to XML-based services are XML, but can be of any type the proxy service configuration allows. In messages that include attachments, their content is a MIME package that includes the primary XML payload as one of its parts—typically the first part or the one identified by the top-level content-type header.
• Messaging services: Messaging services are those that can receive messages of one data type and respond with messages of a different data type. Supported data types include XML, Message Format Language (MFL), text, untyped, binary and attachments where interface is not described by WSDL.
Oracle Service Bus supports request and response as well as one-way paradigms, for both the HTTP and the JMS asynchronous transport protocols. If the underlying transport supports ordered delivery of messages, Oracle Service Bus also extends the same support.
Question : What is Message Context?
Answer :All messages sent to and received by the proxy service are defined internally in the proxy service by a set of properties that holds the message data and meta-data related to that message. This set of properties is known as the Message Context (context) and is implemented using Context Variables. It is defined by an XML schema. Each Context Variable relates to a different property. Some Context Variables are predefined and others are user defined. The heart of the proxy service is the Message context. For a complete description of the Message Context and context variables used in the message flow.
Predefined context variables contain information about the message, transport headers, security principals, metadata for the current proxy service, and metadata for the primary routing and publish services invoked by the proxy service. You typically use an XQuery expression to manipulate context variables in a message flow. You can also modify context variables using transformation and in-place update actions.
The message-related context variables $header, $body, and $attachments represent the canonical format of the message in the message flow. These are wrapper variables that contain the SOAP header elements, the SOAP body element, and the MIME attachments, respectively. The context gives the impression that all messages are SOAP messages, and non-SOAP messages are mapped to this paradigm.
In the case of attachments, $attachments contains the following for each attachment:
• attachment, if the attachment is XML
• a reference XML, if the attachment is binary
• text, if the attachment is text
Predefined context variables contain information about the message, transport headers, security principals, metadata for the current proxy service, and metadata for the primary routing and publish services invoked by the proxy service. You typically use an XQuery expression to manipulate context variables in a message flow. You can also modify context variables using transformation and in-place update actions.
The message-related context variables $header, $body, and $attachments represent the canonical format of the message in the message flow. These are wrapper variables that contain the SOAP header elements, the SOAP body element, and the MIME attachments, respectively. The context gives the impression that all messages are SOAP messages, and non-SOAP messages are mapped to this paradigm.
In the case of attachments, $attachments contains the following for each attachment:
• attachment, if the attachment is XML
• a reference XML, if the attachment is binary
• text, if the attachment is text
Question : What is Alert Destination?
Answer :Alert Destination resources capture a list of recipients that can receive alert notifications from the Oracle Service Bus. They are used by Alert actions configured in the message flow, and by SLA alert rules. An Alert destination could include one or more of the following types of destinations: Reporting Data stream, SNMP trap, E-mail, JMS queue, or JMS topic. In the case of E-mail and JMS destinations, a destination resource could include a list of E-mail addresses or JMS URIs, respectively. Alert Destinations can be re-used across alert configurations for services.
Question : Explain Web Services Policy (WS-Policy)? Also explain both types of WS-Policy statements that are recognized by WebLogic Web Services runtime environment.
Answer :Web Services Policy (WS-Policy) is a standards-based framework for defining a Web service´s security constraints and requirements. It expresses security constraints and requirements in a collection of XML statements called policies, each of which contains one or more assertions. In Oracle Service Bus, WS-Policy assertions are used to specify a Web service´s requirements for digital signatures and encryption, along with the security algorithms and authentication mechanisms that it requires.
WS-Policy policies may be included directly in a WSDL document or included by reference, and a WSDL document may import other WSDL documents that contain or refer to WS-Policy policies. An XML file that contains these policies can be used by multiple proxy services or business services. The WebLogic Web Services runtime environment recognizes two types of WS-Policy statements:
• Concrete WS-Policy statements: specify the security tokens that are used for authentication, encryption, and digital signatures. These WS-Policy statements are created if the type of authentication required (such as using X.509 or SAML tokens), multiple private key and certificate pairs from the keystore used for encryption and digital signatures, are known at run-time.
• Abstract WS-Policy statements: that do not specify security tokens.
WS-Policy policies may be included directly in a WSDL document or included by reference, and a WSDL document may import other WSDL documents that contain or refer to WS-Policy policies. An XML file that contains these policies can be used by multiple proxy services or business services. The WebLogic Web Services runtime environment recognizes two types of WS-Policy statements:
• Concrete WS-Policy statements: specify the security tokens that are used for authentication, encryption, and digital signatures. These WS-Policy statements are created if the type of authentication required (such as using X.509 or SAML tokens), multiple private key and certificate pairs from the keystore used for encryption and digital signatures, are known at run-time.
• Abstract WS-Policy statements: that do not specify security tokens.
Question : Explain types of client authentication required for HTTP(S) proxy services or business services . Also list down all transports other than HTTP that are supported in Oracle Service Bus.
Answer :Oracle Service Bus supports transport-level confidentiality, message integrity, and client authentication for one-way requests or request/response transactions (from clients to Oracle Service Bus) over HTTPS. It allows HTTP(S) proxy services or business services to be configured to require one of the following types of client authentication:
• BASIC (username/password) client authentication
• CLIENT CERT (two-way SSL) client authentication
• No client authentication
When a proxy service is activated, Oracle Service Bus generates and deploys a thin Web application. Oracle Service Bus relies on Oracle WebLogic Server for server-side SSL support, including session management, client certificate validation and authentication, trust management and server SSL key/certificate manipulation.
Transport security for transports other than HTTP is supported in Oracle Service Bus as follows:
• For the E-mail and FTP transports, security is provided using credentials to connect to a FTP or E-mail server.
• For the file transport, security is provided using a login control to the machine on which the files are located.
• BASIC (username/password) client authentication
• CLIENT CERT (two-way SSL) client authentication
• No client authentication
When a proxy service is activated, Oracle Service Bus generates and deploys a thin Web application. Oracle Service Bus relies on Oracle WebLogic Server for server-side SSL support, including session management, client certificate validation and authentication, trust management and server SSL key/certificate manipulation.
Transport security for transports other than HTTP is supported in Oracle Service Bus as follows:
• For the E-mail and FTP transports, security is provided using credentials to connect to a FTP or E-mail server.
• For the file transport, security is provided using a login control to the machine on which the files are located.
Question : What is UDDI ?
Answer :Universal Description, Discovery and Integration (UDDI) registries are used in an enterprise to share Web Services. UDDI provides a framework in which to classify your business, its services, and the technical details about the services you want to expose.
Publishing a service to a registry requires knowledge of the service type and the data structure representing that service in the registry. A registry entry has certain properties associated with it and these property types are defined when the registry is created. You can publish your service to a registry and make it available for other organizations to discover and use. Proxy services developed in Oracle Service Bus can be published to a UDDI registry. Oracle Service Bus can interact with any UDDI version 3.0-compliant registry.
Publishing a service to a registry requires knowledge of the service type and the data structure representing that service in the registry. A registry entry has certain properties associated with it and these property types are defined when the registry is created. You can publish your service to a registry and make it available for other organizations to discover and use. Proxy services developed in Oracle Service Bus can be published to a UDDI registry. Oracle Service Bus can interact with any UDDI version 3.0-compliant registry.
Question : What are Branch Nodes and Route Nodes?
Answer :A branch node allows processing to proceed down exactly one of several possible paths. Branching is driven by a simple lookup table with each branch tagged with a simple but unique string value. A variable in the message context is designated as the lookup variable for that node, and its value is used to determine which branch to follow. If no branch matches the value of the lookup variable, then a default branch is followed. The value of the lookup variable must be set before reaching the branch node. This approach ensures that exceptions do not occur within the branch node itself. A branch node may have several descendants in the message flow tree: one for each branch including the default branch.
The route node is used to perform request and response communication with another service. It represents the boundary between request and response processing for the proxy service, and therefore, cannot have any descendants in the message flow tree. When the route node dispatches a request message, request processing is considered finished. When the route node receives a response message, response processing begins.
The route node is very flexible in its specification and supports conditional routing as well as outbound and response transformations. It allows if structures and case structures to be combined (and nested) to define a single endpoint and operation to route the message.
The route node is used to perform request and response communication with another service. It represents the boundary between request and response processing for the proxy service, and therefore, cannot have any descendants in the message flow tree. When the route node dispatches a request message, request processing is considered finished. When the route node receives a response message, response processing begins.
The route node is very flexible in its specification and supports conditional routing as well as outbound and response transformations. It allows if structures and case structures to be combined (and nested) to define a single endpoint and operation to route the message.
Question : What is use of Service Callouts Action?
Answer :Oracle Service Bus provides a service callout action that offers greater flexibility for more sophisticated message flows. Service Callouts are message processing request actions from one message flow, that invoke other services registered within Oracle Service Bus. This action is generally used in response to decisions made in complex dynamic-routing processing, or to perform message enrichment. The service callout action is used inside a message flow routing stage, to call on the destination service to perform some action on the message. The destination service returns a response to the message flow, which gets assigned to a local variable. The variable may be used within the current message flow for conditional branching.
Service callouts allow custom Java code to be invoked from within proxy services. Oracle Service Bus supports a Java exit mechanism via a Java Callout action that allows call out to a Plain Old Java Object (POJO). Static methods can be accessed from any POJO. The POJO and its parameters are visible in the Oracle Service Bus Administration Console at design time; the parameters can be mapped to message context variables.
Service callouts allow custom Java code to be invoked from within proxy services. Oracle Service Bus supports a Java exit mechanism via a Java Callout action that allows call out to a Plain Old Java Object (POJO). Static methods can be accessed from any POJO. The POJO and its parameters are visible in the Oracle Service Bus Administration Console at design time; the parameters can be mapped to message context variables.
Question : What are different ways of error handling available in oracle service bus?
Answer :Oracle Service Bus provides robust and flexible error handling for configured services. It can handle errors in the following ways:
• Testing whether an assertion is true and sending a reply with failure in the request or response pipeline.
• Configuring the service to catch and handle the error at multiple levels including the stage, route node, pipeline, or service levels. The level configured to catch the error depends on the service behavior desired.
• Letting the default system error handler handle the error.
• Testing whether an assertion is true and sending a reply with failure in the request or response pipeline.
• Configuring the service to catch and handle the error at multiple levels including the stage, route node, pipeline, or service levels. The level configured to catch the error depends on the service behavior desired.
• Letting the default system error handler handle the error.
Question : What is Error Handler? How does error pipeline allows you to handle the error ?
Answer :An error handler is a pipeline that allows various actions such as logging, transformation, and publishing to be performed to handle errors appropriately. If an error occurs within a stage a sequence of steps are executed. This sequence of steps constitutes an error pipeline for that stage.
The error pipeline allows you to handle the error in the following ways:
• Publish the original message to an alternate endpoint
• Formulate an error response message to be returned to the invoker of the proxy service
• Log the message
• Continue processing the message through the pipeline after modifying the context
• Raise an exception. Raising an exception transfers control to the next higher scoped error pipeline.
Errors can occur during message flow processing for various reasons. For example, security errors occur if a username is not correctly validated or authorized; transformation errors occur if Oracle Service Bus is unable to successfully transform or validate a message; a routing error is raised if a routing service is unavailable, and so on. Typically, these errors originate from a specific stage, route node or from the proxy service, as this is where most of the message flow logic is implemented.
Each stage can have a sequence of steps to execute if an error occurs in that stage. This sequence of steps constitute an error pipeline for that stage. In addition, an error pipeline can be defined for a pipeline (request or response) or for an entire proxy service. The lowest scoped error pipeline that exists is invoked on an error.
The error pipeline allows you to handle the error in the following ways:
• Publish the original message to an alternate endpoint
• Formulate an error response message to be returned to the invoker of the proxy service
• Log the message
• Continue processing the message through the pipeline after modifying the context
• Raise an exception. Raising an exception transfers control to the next higher scoped error pipeline.
Errors can occur during message flow processing for various reasons. For example, security errors occur if a username is not correctly validated or authorized; transformation errors occur if Oracle Service Bus is unable to successfully transform or validate a message; a routing error is raised if a routing service is unavailable, and so on. Typically, these errors originate from a specific stage, route node or from the proxy service, as this is where most of the message flow logic is implemented.
Each stage can have a sequence of steps to execute if an error occurs in that stage. This sequence of steps constitute an error pipeline for that stage. In addition, an error pipeline can be defined for a pipeline (request or response) or for an entire proxy service. The lowest scoped error pipeline that exists is invoked on an error.
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