The Power of Mediators: API Call Transformation and Orchestration

Sometimes you are lucky and the backend web services match exactly your desired public API design. But what if they do not? What if you need to change formats on the fly? Or do XSLT transformation? Or orchestrate multiple backend services called and joined into a single API? Fear not! WSO2 API Cloud comes with a powerful mediation engine that can transform and orchestrate API calls on the fly. You can create your mediation sequences and apply them on the fly both on the way to the backend (In Flow) and back to the invoker (Out Flow): API Cloud's mediation engine is built on industry-fastest enterprise service bus (ESB) engine and supports amazing variety of mediators that you can use as building blocks for your sequences: https://docs.wso2.com/display/ESB490/Mediators WSO2 Developer Studio can then be used to build your sequences: And then you simply upload the sequences to the gateway and select which of them you want used in your APIs. There are a couple tutorials that we published to illustrate the process: Using Property Mediator to turn YQL-based Yahoo Weather API into nice REST format: [embed]https://www.youtube.com/watch?v=Mx5qIHQG-_I[/embed] This is the step-by-step tutorial if you want to follow along: https://docs.wso2.com/display/APICloud/Change+the+Default+Mediation+Flow+of+API+Requests And here is another one on turning a SOAP backend into a proper JSON REST frontend API. Here's the full list of mediators supported and links to detailed documentation:

Category	Name	Description
Core	Call	Invoke a service in non blocking synchronous manner
	Sequence	Inserts a reference to a sequence
	Drop	Drops a message
	Enrich	Enriches a message
	Property	Sets or remove properties associated with the message
	Log	Logs a message
Filter	Filter	Filters a message using XPath, if-else kind of logic
	Validate	Validates XML messages against a specified schema.
	Switch	Filters messages using XPath, switch logic
	Conditional Router	Implements complex routing rules (Header based routing, content based routing and other rules)
Transform	XSLT	Performs XSLT transformations on the XML payload
	FastXSLT	Performs XSLT transformations on the message stream
	URLRewrite	Modifies and rewrites URLs or URL fragments
	XQuery	Performs XQuery transformation
	Header	Sets or removes SOAP headers
	Fault (also called Makefault)	Create SOAP Faults
	PayloadFactory	Transforms or replaces message content in between the client and the backend server
Advanced	Cache	Evaluates messages based on whether the same message came to the ESB
	ForEach	Splits a message into a number of different messages by finding matching elements in an XPath expression of the original message.
	Clone	Clones a message
	Iterate	Splits a message
	Aggregate	Combines a message
	Callout	Blocks web services calls
	Transaction	Executes a set of mediators transactionally
	DBReport	Writes data to database
	DBLookup	Retrieves information from database
	Entitlement	Evaluates user actions against a XACML policy
Extension	Class	Creates and executes a custom mediator
	Script	Executes a mediator written in Scripting language

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