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 Now , after having a look at at the ESB fundamentals and some other fundamental concepts , let us have a look at the ESB capabilities .

ESB – Capabilities

We approach this questions as – “ If I have an ESB deployed in my IT landscape,what are the capabilities which are added to my landscape? ”.

The added capabilities can be examined under the following classifications –

  1. Integration

  2. Communication

  3. Mediation

  4. Management

Lets look into each in detail .

Integration – Web Services

One of the primary features of ESB is its support for Services (especially Web Services).In fact , the number of web services in any landscape play a vital role in deciding whether we should use ESB as an Integration medium or other medums line Message Brokers etc. We will revisit this point in ESB Design Decisions.

  1. ESB Exposes the abstract endpoint of the registered integrated service so that service is consumed by sending a message to the ESB endpoint                   

  2.  Uses the awareness of interface, protocol and data format and uses internal Service Invocation framework to translates message send/receive into a call to the underlying service.

  3. Achieves Service Virtualization by exposing service endpointsfor discovery

  4. Maintains an internal registryused for routing and storing service metadata

  5. Provides Light weight service orchestration i.e. Coordinationof multiple implementation services to expose as a single, aggregate service that in turn can be used by service orchestration layer of a composite application.

  6. Provides Error Handling – ability to capture and process faults at service, pipeline and other stages

  7. Provides authentication and authorization features,transport and message level security, auditing of activities on services and Single sign on.

 Integration – Protocol Transformations

  1. Maps and transforms into appropriate protocol required by the end-point service, allowing for dynamic run-time protocol switching

Integration – Adaptors

  1. Use of Adapters, to enable connectivity into packaged and custom enterprise applications, as well as leading technologies. For example, Legacy , Packaged Applications, technologies such as EJB  can mr made to communicate via adaptors.                                                                                                     

  2. ESB also achieves protocol and data transformation required by the connected enterprise system

 image

In the diagram above,  we see ESB integrating with four EIS systems.There are fours  tpyes of adaptors here .The top most adaptor is in-build in the EIS system itself(provided by the software vendor), second adaptor is third party vendor , third adaptor is build using ESB while the fourth adaptor is available out of the box with ESB itself.

Communication – Addressing

  1. ESB can interpret the Physical location or network address of the service and facilitate routing

Communication – Transportation

  1. Support for a range of protocols (JMS, WS, FILE, FTP, HTTP(S), SMTP, EMAIL)

  2. Can match the requestor to a provider of service based on protocol supported

  3. IIf need be performs protocol switch when a providers functionality and QoS meets the needs of the requestor

Communication – Bindings

  1. ESB provides Support for a range of bindings (XML/SOAP/Text/Binary/MFL/Attachments)

Communication – Routings

  1. ESB outes of requests to the relevant service provider. Involves find/bind/invoke operations i.e. identifying and locating the next service in the chain, binding to it, and invocation of it

  2. It maintains location transparency from the perspective of a requestor.

  3. Provides Static Routing by looking up service endpoint in ESB Namespace Directory or Routing information table in database where the Itinerary defining which endpoint to visit is mentioned in the message

  4. Provides Dynamic Routing by examining message content and configured rules for content based routing

  5. Updates externalized routing directory shields the requester of any changes to the provider location

  6. Provides Intelligent routing based on infrastructure intelligence (availability, workload) or detection of error situations is also feasible but complex

  7. It provides Synchronous & Asynchronous Message Processing,Multiple message exchange patterns (request/response, publish/subscribe, fire-and-forget) , Validation, Transformation, Enrichment and  Persistence.

Mediation

Mediation is the capability that facilitates systematic and seamless service based interaction between requestor and provider.It consists of Flows or Logic that are applied on or operate on messages as they flow through the system. Typically they satisfy the integration and operational requirements

 image

 

The Contract between the requestor and provider of the service are realized by using a set of mediation modules

In any ESB , set of pre-built mediation modules(e.g. transformation, lookup, filter, logging) are usually available and the capability to build custom mediationfunctions is also provided

ESB serves as the Service Mediation layer and enables –

  1. Transport Protocol–Interaction with services over multipletransport protocols.    

  2. Data Conversion–Data transformationbetween interacting services.               Runtime Policy Enforcement-Point of enforcementof runtime rules(like security etc.) on interacting services.

  3. Pipeline Processing–Application offilters and routing ruleson messages that are easily configurable to facilitate service interaction.  

  4. Loose Coupling–De-coupling of service consumer(client) and service provider, so that any changes to either of them is masked from rest of the interacting services

Mediations can be inserted at different points on a service interaction link

  1. At requestor end – Mediation performed irrespective of which provider the requestor interacts with e.g. encryption of sensitive information or intelligent routing

  2. At provider end –  Mediation performed irrespective of which requestor send the request e.g. Protocol or format conversion based on provider‟s requirements

  3. With a particular interaction link –  Mediation performed for interactions that occur through this link e.g. audit logs creation

Management

ESB provides the following management featues

  1. Administration

    1. ESB endpoint and registry integration, management, and publication preferably with an Administration Console

    2. Managing changes and versions of services being published

    3. Configuring audit on message saves, edits and resubmits and maintaining the log history

  2. Monitoring

    1. Identify dependencies that exist between different services, trace service interactions, and identify root causes of performance bottlenecks or failures

  3. Exception Mediation

    1. View of the messages that raised faults through the console

    2. Message repair options to edit the faulty message and resubmit

    3. Alert subscription and Notifications on error for user groups

  4. Service Levels

    1. Provide visibility into service utilization and other service metrics like response time and faults

 

 

 
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