What is the use of GateWayScripts in DataPower?

Question

Could you please let me know Any useful online resource to learns and implement some scenarios to explore more about it. Thanks.

Answer 1

Datapowers are historically, in order:

• XML Tranformation acceleration Devices (that used to be a thing, XSLT was too slow to process)
• SSL offloading devices (again, that used to be a thing, same reason)
• Web site and Applications Gateways. Both web sites and web services security, concentrated around HTTP and SOAP/XML application layer mechanisms and standards (SSL/TLS, WS-S, SAML, etc.), but also token management, security conversion ... think "super SSO" + application security gateway
• More specialized integration tools : Transformation of XML (with XSLT), Transformation to/from non-XML format (like CSV), Database connections, integration patterns (like routing, composing, and a LOT more). Some called the Datapower a lightweight ESB.
• More specialized uses : B2B(EDI), JSON processing, REST/JSON support, API Mgmt (when used as deployment point for API Connect)

Notice that all later features needs the former ones (ESB is based on WS Security, etc.)

As you may know, most of Datapower devlopement is done with tranformations. The default, established language for them is XSLT (XQuery is also and historic, less popular option).

XSLT is both one of the most powerful and most horrible language to work with. Kind of like the Perl+REGEX of the XML world...

... but there is another problem with XSLT. It is not designed to work with JSON. Making the Datapower of 10 years ago heading for a fats retirement.

At first, IBM designed pseudo-XML ways of dealing with JSON. You could convert inbound JSON to XML and work with the JSON AS XML in XSLT. The inverse operation was to use XSLT to generate JSON... it worked perfectly but kind a looked like old school HTML/PHP merging code.

So IBM came up with a good idea: GatewayScript. (Mostly based on many other good ideas) GatewayScript is basically ECMAScript 2015 (ES6) + CommonJS 1.0 + Many super popular JS crypto libraries. ECMAScript is obviously more known as JavaScript.

Pertaining to your question, the main advantage of GatewayScript is to enabled easier JSON Web Services Development of all the features in the list above, for modern REST/JSON APIs, instead of older (but still good) SOAP/XML Web Services.

GatewayScript has now been present for years, no longer a "beta" option.

Here are some other neat GatewayScript features:

• Access to a DOM model, representing the incoming and outgoing version of the document, in simple JS notation.
• Better errors in the logs when something does not work (you get the .js line number, unlike with the XSLT errors)
• Better debugging options (you can enable a line-by-line debugger)
• Some examples from the web written in Node.js and other JS frameworks can work... which is amazing
• A very useful IBM site (Datapower Playground) where you can learn and test GatewayScripts examples without your own Datapower, à-la-w3cschool
• And more.

I hope this helps.

Answer 2

GhislainCote's answer is very complete but basically GatewayScript is Node.js with an added framework for handling the session object which will contain your data/payload. There are also some special objects, e.g. service-metadata and header-metadata that will contain DataPower variables and headers.

Sample scripts are available in the store:///gatewayscript/ directory and as the store:///healthcheck.js for example.

Also review the Knowledgecenter, it contains a lot of help and information about GatewayScript: https://www.ibm.com/support/knowledgecenter/SS9H2Y_7.7.0/com.ibm.dp.doc/gatewayscript_model.html

GatewayScript is very powerful, I've coded support for AS2 de-/en-veloping (for customers not having the B2B Module option) and RosettaNet handling in GatewayScript so there is pretty much no limit to what you can achieve!