How to Invoke REST Web services from DataStage Designer

 Overview:

 The blog provides the information on new capability of DataStage Designer and few  

  example usages

 InfoSphere Information Server Designer provides a stage called Hierarchical Data stage  

 (which was called XML Stage in prior releases to V11.3) that has the capability to parse  

 and compose the hierarchical data formats like JSON and XML. Along with that, it  

  provides the capability to invoke the REST Web services.

 It supports the REST Web services that are configured in different ways as below:

 1. That provides the responses in different formats like JSON, XML, HTML, JPEG, Audio  

     etc.

 2. Supports different authentication mechanisms like BASIC, DIGEST, LTPA, OAUTH

 3. Configured with SSL (Server and Client authentication)

 4. Headers and Cookies

 5. Different HTTP methods like GET, POST, PUT, DELETE, PATCH etc.

 Scenario:

 There is so much data on the social media sites, which you want to pull, transform and 
 send for the  analytics. Here I am taking an example of the IBM Facebook page. From 
 which, I want to retrieve the details for how many likes does IBM page have, which 
 all websites talk about IBM, To fulfill the above requirement, You can use our new 
 capability called REST step from the Hierarchical Datastage stage in DataStage Designer.

  Extracting data from Facebook Page

  The Figure 1 illustrates the DataStage job which retrieves the data from Facebook using 
  REST step  and parses the response data from Facebook to fetch the required data for the
 analytics.

 Figure 1: Extract_And_Parse_DataFromFaceBookPage

 

The figure 2 shows the assembly design of the Hierarchical datastage. The data

is obtained from Facebook by invoking the REST API using REST step. As the 

data provided by Facebook is in format of JSON, JSON parser step is used to parse 

the data. The REST Step “GetFBPageData” and JSON Parser step called 

“ParseFBData” are added to the Assembly Outline.

Figure 2 : Assembly Editor Design

 The Rest Step “GetFBPageData“ is configured as below:

1.In the General tab: The HTTP Method “GET” is selected , URL of the IBM Facebook

   page is mentioned in the “URL” field. The URL is https://graph.facebook.com/IBM as 

   in  figure 3.

2. In the Security tab: As Facebook is configured with SSL, select the checkbox Enable the  

    the SSL and Accept the Self signed certificate as shown in figure 4.

3. In the Request tab: Facebook returns the response in different formats. Here we need in  

    the JSON format. So Specify the Content-Type as application/json under the custom 

    header. As shown in figure 5.

4. In the Response tab : Select the check box “ Pass the received body to” and a radio

    button   “A text node named body in the Output Schema” and specify text/javascript  

    under  the content type as shown in figure 6.

Figure 3: General tab of Rest Step "GetFBPageData"

 Figure 4 : Security tab of Rest Step “GetFBpageData”

 

 Figure 5 : Request tab of Rest Step “GetFBPageData”

 Figure 6 : Response tab of Rest Step “GetFBPageData”

The Output of the REST call which is invoked in the “GetFBPageData” REST step is available in the body element in the output schema tab. The output schema of the REST step is as in figure 7.

Figure 7 : The Output Schema of the Rest Step "GetFBPageData"

 The JSON parser step “ParseFBData” is configured as below:

1.Under the JSON Source tab : Select the String set option, and from the drop down 

   select the bodyelement coming from the REST step “GetFBPageData” as shown in the   

   figure 8.  

2.Under the Document root: Browse and select the schema which conforms with the json

   data retrieved from earlier REST step as shown in figure 9.  

3.Under Validation tab: Minimal Validation is selected by default.  

Figure 8 : JSON Source tab of JSON Parser step “ParseFBData”  

 

 Figure 9 : Document root of JSON Parser step “ParseFBData”

The Output step is configured as below: 

Under the Mappings tab, the target link “DETAILS” is mapped to the top to fetch the parsed details of IBM Facebook page as shown in figure 10.

Figure 10 : Mappings tab of Output step

 

Compile and Execute the job to fetch the required details of the IBM Facebook page shown in figure 11:

Figure 11 : Data from IBM facebook page.

 

 

The output describes the details like ID of the Page, what it is about , when it is founded, 

 how many likes it got, the count talking about this page, username, websites where it is  

 talked etc. This data can be used in the analytics.

Conclusion : The REST capability in the hierarchical Datastage stage can be used to fetch 

 the data like social media data from different applications like Facebook, LinkedIn, 

 Twitter etc which exposes the services using REST

We have articles published on developer works for the integration scenarios with SOFT 

Layer, Cloudant and Information Governance Catalog Glossary using DataStage.

 http://www.ibm.com/developerworks/data/library/techarticle/dm-1407governrest/index.html 

http://www.ibm.com/developerworks/data/library/techarticle/dm-1407-softlayer-obj-storage/index.html 

http://www.ibm.com/developerworks/data/library/techarticle/dm-1407cloudant/index.html 

 Disclaimer: “The postings on this site are my own and don’t necessarily represent IBM’s positions, strategies or opinions.”