How to use Informatica Power Center as a RESTful Web Service Client?

REST Overview

Web Service provides a common platform that allows two different applications on various platforms to communicate and exchange messages between them over HTTP protocol. Web Services can be accessed using different methods or styles. In Web Service world REpresentational State T ransfer(REST) is a stateless client-server architecture in which Web Services are exposed as URLs. The typical method of accessing Web resource in a RESTful system is through various HTTP methods such as GET, POST, PUT and DELETE.

High-Level REST Architecture

REST call using Informatica Power Center

Let us explain with the help of a sample web service which is used in a Retail Industry. In a Retail industry, customer can purchase various items from the retailer through online and offline and we need a centralized repository called a Data Warehouse where all the transactional data is fed into. The item details are then further normalized into Data Marts to form a common schema which will have facts and dimensions. On a large scale environment, this could be a cumbersome task in designing a data model.

Pre-requisites to configure REST call using HTTP Transformation

  • Valid REST based URL supporting either XML or JSON
  • Valid SSL certificates to connect to REST URL outside of the network
  • Basic Authentication Mechanism(User Name and Password)

Step by Step Process

Creating a Source File

Create a source file which specifies the search parameters to be passed as input to the HTTP transformation.

Create HTTP Transformation

Create HTTP transformation with the following input ports:

  • Username
  • Password
  • OrderNumber

Base URL

Set the Base URL to get the Order details based on the input parameters passed from the source file.

Set the HTTP Header parameters

Header parameters in HTTP transformation contain header data for request and response in a specified format such as XML or JSON. Following are the parameters:

  • Default Value: Specify the acceptable values supported by the web service. By default, the response will be in JSON. If you need XML you need to specify as ‘text/xml’
  • HTTP Name: For REST API the default value is “Accept”

HTTP Method Selection Type

Specify the type of HTTP method on the URL. In our example we are trying to get the order detail information, so specify the type as “GET”

HTTP Output

Pass the HTTP output to either a flat file or an XML parser to parse the information and load it into the target table. In this example, we write the output of the HTTP to a flat file.

Create a connection in Workflow manager and run the workflow

Navigate to Workflow manager ->Connections-> Applications->HTTP Transformation

Issues faced while connecting to HTTP Transformation

While using HTTP Transformation the most common issue is “SSL Certificate Error”. So when you run the workflow which is using the final URL you will get the below errors in session logs

Root Cause

This error is caused because the connection to the web service URL or Rest API does not include the certificate data that is needed to authenticate the connection from the certificate provider’s end. The certificate bundle does not contain a certificate from a Certificate Authority that the Web service Provider uses.

Resolution

Download the SSL certificates for the URL and add to the certificate files located under $INFA_HOME/server/bin/ca-bundle.crt

Conclusion

This concludes how to create a Power Center Workflow using REST based methods to access a web service using HTTP Transformation, invoke HTTP commands to get data from the web service resource.

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