Servis-Rhino 4211B Betriebsanweisung PDF herunterladen (Seite 72)

commonly interacting with the back-end server through some other protocol.

When we define the adapter, we define one or more procedures that can be called by the client. For

each procedure, we need to create a corresponding function definition in the JavaScript. For

example, if we define that an adapter will expose a procedure called "getGreeting" then we need to

build a function definition in the JavaScript source file also called "getGreeting". This means that

when the client invokes the adapter's procedure the correspondingly named function will be

invoked.

A procedure function must return a JavaScript object. It is that object that is returned to the client

caller. The object is augmented with a property called "isSuccesful".

Adapter Types

An adapter used by a client app must be of one of the following types:

HTTP Adapter

The HTTP Adapter provides the ability for a Worklight client app to connect to a back-end system

via the HTTP protocol. Calling back-end systems via HTTP outside of the scope of Worklight is a

very common activity. Typically, this concept is called "REST programming" or "AJAX

programming". There is nothing to prevent the client application from calling a target back-end

directly using a JavaScript framework's REST calling APIs directly, however, doing so will not take

advantage of the Worklight adapter architecture and all its relative values.

The high-level architectural overview of using the HTTP Adapter is shown in the following

diagram:

An instance of an HTTP Adapter is created and deployed to the Worklight Server. The Client app

uses the Worklight Client API to invoke a procedure exposed by the adapter. This procedure then

makes the actual request to the back-end server using HTTP.

When an instance of an HTTP Adapter is defined in Worklight Studio, the Connection Policy

options look as follows:

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Servis-Rhino 4211B Betriebsanweisung Seite 72