Calling CICS services

If the Node.js application is running within CICS then the invoke request causes CICS to start a new task to run the target JSON service; data is passed between the application and CICS in JSON format, the response is then returned to the application. The following example has a common start, and then has two options to call a CICS service. You can either use callback functions, or you can use promises.

const cics = require('ibm-cics-api');

let uri = "http://winmvs2c.hursley.ibm.com/exampleApp/json_inquireCatalogWrapper";
let requestData = 
{
"inquireCatalogRequest": 
    {
    "startItemRef": 10,
    "itemCount": 774
    }
};

//Version using callback
cics.invoke(uri,requestData,function(err, data) 
{
if (err) 
    {
    ... do something with error ....
    } 
else 
    {
    .... do something with response data
    }
});

//Version using promises

cics.invoke(uri,data).then
(
function(response) 
    {
    ... do something with response ...
    },
function(err) 
    {
    console.log(err);
    }
);

There are three parameters used to call a CICS service:

• A URI (string) - this identifies the target service. It's used to match a URIMAP in CICS, which then maps to the WEBSERVICE, PIPELINE and eventually target PROGRAM.
• Request data (JavaScript object or string) - the data that is sent to the CICS service as the request body. This data must be in the JSON format expected by the target service in CICS.
• A callback function - this function is called by CICS when a response is ready to processed by the Node.js application. This function is not applied if you are using promises.

The parameters that are passed to the callback function are:

• An error object. This is null if the request succeeds. If it fails, this is a JavaScript Error object that describes the error.
• A response object. This is a JavaScript object which represents the response from CICS.