Handle dynamic paging for OData Services using Looping Process call

Introduction:

This scenario was a result of a query raised by one of our community colleagues regarding handling paging dynamically, so I thought of putting it into a short blog post.

Business Requirement:

Customer wants to make a generic API design which could cater to any one of the below requirements:

• Dynamically fetch records from OData service/entity.
• Setting Dynamic call back URL.
• Setting  the page-size dynamically.

Scenario:

I am going to fetch customer details from a available Northwind ODATA service.

In order to achieve this I am fetching the pagesize, Serivce URL/Query and Push back URL dynamically from the request payload.

I am using below tools & services:

• Cloud Platform Integration
• Postman or any ThirdParty-Client tool to push the request.
• OData service{ Northwind services }
• Webhook or any service which could receive data.

Create Integration flow in SAP Cloud Platform Integration:

def body = message.getBody(java.lang.String)
def slurper = new JsonSlurper().parseText(body)

def addURL = slurper.RequestODATAURL
def topVal = slurper.DynamicPageSize
def pushBackURL = slurper.CallBackUrl
def queryFilter = slurper.QueryFilter

message.setProperty("queryFilter",queryFilter)
message.setProperty("addURL",addURL)
message.setProperty("topVal",topVal)
message.setProperty("pushBackURL",pushBackURL)

message.setBody("")

return message;

String totalCount = message.getBody(java.lang.String);

message.setProperty("totalCount",totalCount)

message.setBody("")

return message;

def map = message.getProperties();
def exitFlag = "false"

def topVal = map.get("topVal") 
def skipVal = map.get("skipVal")
def totalCount = map.get("totalCount")

def tempSkipVal = skipVal.toInteger() + topVal.toInteger()
if(totalCount.toInteger()/tempSkipVal < 1) 
exitFlag = "true"


skipVal = tempSkipVal.toString()

message.setProperty("exitFlag",exitFlag);
message.setProperty("topVal",topVal);
message.setProperty("skipVal", skipVal);

return message;

OData Service

• { Northwind service }

Webhook

• For setting up of web-hook, refer to the blog post from Raffael Herrmann [ Use Requestcatcher]

Testing:

Using Postman I have posted the request as shown in the sample request.

Sample Request:

{
"RequestODATAURL" : "https://services.odata.org/Northwind/Northwind.svc/Customers",
"DynamicPageSize" : "100",
"QueryFilter" : "",
"CallBackUrl" : "https://dynamicpaging.requestcatcher.com/test"
}

I have received below response on the web hook.

Since the page size was set to 50 and the total no of records were 91 so I had 2 post responses to the call back URL as shown above in the request catcher screen below.

If I change the page size to 100 I will get only one post response.

Sample Response:

Sample Response fetched & formatted.

Conclusion:

So I have achieved three things using this use case:

1. I was able to set the page-size dynamically.[“DynamicPageSize” : “100” ] I could change the page size in request payload and could notice that there is a difference in output.
2. I could change the resource name [ Northwind.svc/Customers ]  to [ Northwind.svc/Orders ] or even I can change the API URL but have to handle the authentication internally.
3. I could change the query parameters changing the input segment [QueryFilter ]
4. At last could change the Call Back/ PushBack URL based on the requirement [ “CallBackUrl” : “https://dynamicpaging.requestcatcher.com/test” ]

References:

{ SAP CPI Looping Process }

{ Use Request Catcher }

Hope this helps !

thanks and regards,

Praveen T