How to configure Service REST in pega

What is REST?

Nowadays we are using REST integration interface to interact with external systems through web service in Pega, basically to make calls between machines.

REST stands for Representational State Transfer Protocol.

What is REST in Pega?

Pega is proving a service (response) to the external system by processing the request received from an external system.

Basically, we will receive a request from external system/machine to Pega, Pega will process that request and provides a response back to an external system.

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The request will be in different types XML/JSON. Let’s consider the request type is JSON.

JSON - JavaScript Object Notation, it is like standard file format and interchange format, a layman can understand this format. Below is the Sample JSON request, using to create a case for Instawit customers for their online clients based on the account number.

Request JSON

{

                "serviceHeader": {

                                "channelID": "IW-Online",

                                "userId": "iw12345",

                                "serviceName": "IW"

                },             "serviceBody": {

                                "serviceRequest": {

                                                "context": {

                                                                "custInfo": {

                                                                                "Name" : "IWcutomer

                                                                                "Description" : "Instant Pega Knowledge",

                                                                                "AccountNumber" : "ABC15797531" }

                                                                  }} } }

How Pega will process this JSON request, see simple data flow below:

Response JSON: will look like

{

                "serviceHeader": {

                                "channelID": "IW-Online",

                                "userId": "iw12345",

                                "serviceName": "IW"

                                "statusMsg":"SUCCESS",

                                "statusCode":"00"

                },             "serviceBody": {

                                "serviceResponse": {

                                                "context": {

                                                                "custInfo": {

                                                                                "Name" : "IWcutomer

                                                                                "Description" : "Instant Pega Knowledge",

                                                                                "AccountNumber" : "ABC15797531"

“caseId” : “IW-57”}

                                                                      }   } } }

How do I create a service rest in PEGA?

What is the PEGA service package?

Let’s see the technical things behind this process: Service Package

1.       We should have a service package rule, it is the heart of all Service rules like

SOAP Rule-Service-SOAP

HTTP Rule-Service-HTTP

SAP  Rule-Service-SAP

REST Rule-Service-REST

2.       The service package is a Data instance (Data-Admin-ServicePackage).

3.       What is the processing mode, stateless or Stateful?

Stateless: From the requestor pool, if any requestor can run the services defined in this service package, even if the requestor is processed earlier.

Stateful: otherwise chooseStateful.

4.       Service access group, this is a required field.

We need to provide access group value for the service package rule, basically to provide the context, and Rule resolution will sue this access group to find and execute correct Service rule.

5.       Requires authentication check box: If authentication is required for the service request select the check box. If checked, will be having Basic, OAuth 2.0, and custom(where we can create authentication service rule)

6.       Suppress Show-HTML check box: to skip the Show-HTML step in any activity, which is executing in any service rule that references this service package.

7.       Methods tab will show all the Service (REST, SOAP, HTML, and SAP) rules which are using this service package.

8.       Pools Tab: requestors pool for the services in this service package, like a requestor’s bench.

a.       Specify how many requestors can be in Idle in this pool to perform the services from this package.

b.      Specify how many active requestor we can have in this pool to perform the services from this package.

c.       Specify how much time (in seconds) should the system waits for each requestor to return to this pool when a service request arrives.

We have the service package ready and it has our Service REST rule in Methods section drop down in context tab of service package rule.

1.       The external system will send a request (JSON format), our service package will receive and locate all the rules based on the access group and will assign a requestor to perform this service from the requestor pool.

2.       Service REST rule will be invoked and will see the Service tab, where we have Page class and Page Name.

Let’s say Page class is “IW-Work-XYZ” and Page name like “CaseReqPage”.

3.       Service REST will be executing on the “CaseReqPage’ of class “IW-Work-XYZ” and Service activity will be invoked by using the same class.

4.       Pega will do Inbound Mapping where Request JSON string will be copied to “CaseReqPage”  to a property identified in “Map to key” the field in Request tab.

5.       Service activity will be invoked as identified from the POST method tab.

6.       This is the Service activity were actually processing the request and response.

a.       Use Data Transform to map the inbound requests to the clipboard.

b.      We have requested as JSON string in the CaseReqPage, we can use pega OOTB function to convert JSON string to clipboard Page ----remember we are on the CaseReqPage context only…

c.       Pega will convert JSON string to clipboard page by using @(Pega-RULES:Page).pxConvertStringToPage(tools, Primary.Service, CaseRequestPage.RequestJSONString,"json")

d.      Once the conversion is a success we can map required or necessary properties to “CaseReqPage”, conversion page will look like below:

a.       We can copy whatever the JSON properties required on to the CaseReqPage, we can do that here.

b.      We will identify the pyWorkPage class by using Decision table or Data transform or DCR (dynamic class referencing) -----context will be pyWorkPage----

c.       We will call the OOTB Call Work-.svcAddWorkObject activity to create the case using values from CaseReqPage. We need to pass parameters to this activity

d.      svcAddWorkObject will create the Case to the particular case type based on the class of pyWorkPage.

e.      Pega will create a case and will enter into the Particular Case type and perform the stages and will return to the svc activity.

f.        We will have all the case type related values onto the pyWorkPage.

1.       Main service activity, will call another data transform to construct the response by using pyWorkPage and other pages. ----context will be CaseRegPage-----

2.       Once, response construction is complete, we need to map the response values to a JSON Response string.

3.       Mapping of outbound value will begin here, where we are setting all our response pages into a property (string).

Final CaseReqPage may look like below: