05.02.03 Middleware Terms and Definitions

Source: https://developer.salesforce.com/docs/atlas.en-us.integration_patterns_and_practices.meta/integration_patterns_and_practices/integ_pat_middleware_definitions.htm

• Event Handling
  • is the receipt of an identifiable occurrence at a designated receiver
  • The key processes involved are
    • Identifying where an event should be forwarded
    • Executing the forwarding actions
    • Receiving a forwarded event
    • Taking some kind of appropriate action in response, such as writing to a log
  • The event handler might ultimately forward the event to an event consumer
  • Common uses include “publisher/subscriber”
• Protocol Conversion
  • is typically a software application that converts the protocol of one device to another to achieve interoperability
  • Salesforce does not support native protocol conversion. Any such requirements have to be handled by the Middleware or the endpoint
• Translation and Transformation
  • Transformation is the ability to map one data format to another, insuring interoperability
• Queuing and Buffering
  • rely on asynchronous messaging as opposed to request-response architecture
  • message queues provide temporary storage while the destination program is busy
  • key benefit is that if the receiver fails – the sender application can continue, passing new message into the queue
• Synchronous Transport Protocols
  • single thread activity.
    • Caller sends request message
    • ….waits for reply message, blocking everything else
    • then processes the reply
  • Appears as if there is only a single request at a time
• Asynchronous Transport Protocols
  • one thread in the caller send the request message and sets up a callback
  • A separate thread listens for the replay message
  • The reply message invokes the appropriate callback with reestablishes the callers context and process
  • Enables multiple outstanding requests to share a single reply thread
• Mediation Routing
  • is the specification of a complex “flow” from one component to the next component
  • Mediators coordinate with a group of objects so that the objects don’t have to know how to coordinate with each other.
  • Makes sure the right message gets to the right consumer
• Process Choreography and Service Orchestrations
  • forms of “service composition” where any number of endpoints and capabilities are being coordinated
  • Difference
    • Choreography:
      • behavior resulting from a group of interacting individual entities with no central authority
      • combines the interface behavior description of each service
    • Orchestration:
      • behavior resulting from a central conductor coordinating the behavior of individual entities performing tasks independent of each other
      • shows the complete behavior of each service
  • Salesforce Recommended: All complex orchestrations be implemented in the middleware layer because of governor limits and timeouts
• Transactionality (encryption, signing, reliable, delivery, transaction management)
  • ability to support global transactions that encompass all necessary operations against each required resource
  • Implies support for the four ACID propertities that guarantees all-or-nothing outcomes
    • Atomicity, Consistency, Isolation, Durability
  • Salesforce is not able to participate in distributed transactions or transactions initiated outside of Salesforce, therefore transactionality should be implemented in the middleware
• Routing
  • Specifying the complex flow of messages from component to component
  • Salesforce Recommends: Message Routing should be done in the middleware or at the end points
• Extract,Transform, and Load (ETL)
  • Extracting data from the source(s)
  • Transforming data
    • Cleaning
    • Filtering
    • Formatting
  • Loading data into target system