Many time you have to use Dynamic SQL in your Stored Procedure but some tools (e.g. Tableau) may reject it because metadata is not returned when sp_describe_first_result_set is called in SQL Prepare phase. You may see error like below in that case.

Metadata Prepare Call

exec sp_describe_first_result_set N'EXEC [dbo].[usp_GetInvoicesByCountry] @country=''Germany'''

Error due to Dynamic SQL

Msg 11514, Level 16, State 1, Procedure sp_describe_first_result_set, Line 1 [Batch Start Line 29]
The metadata could not be determined because statement 'EXECUTE (@sqlFull)' in procedure 'usp_GetInvoicesByCountry' contains dynamic SQL. Consider using the WITH RESULT SETS clause to explicitly describe the result set.

Here is example Stored Procedure which may throw above error. We will re-write same stored proc in later section.

Example of Dynamic SQL in Stored Procedure

--DROP PROC dbo.usp_GetInvoicesByCountry
--GO
/*
Purpose: Parameterize REST API call via SQL. Call ZappySys Drivers inside SQL Server.
*/
CREATE PROC dbo.usp_GetInvoicesByCountry
	@country varchar(100) 
AS 

DECLARE @sql varchar(max)
--//Escape single ticks carefully
SET @sql =  'SELECT OrderID,CustomerID,Country,Quantity FROM $
WITH (Src=''https://services.odata.org/V3/Northwind/Northwind.svc/Invoices?$format=json&filter=Country eq '+ @country +'''
	 ,Filter=''$.value[*]''
	 ,DataFormat=''OData''
)'

DECLARE @sqlFull varchar(max)
SET @sqlFull='SELECT * FROM OPENQUERY( LS , ''' + REPLACE( @sql, '''', '''''' ) + ''' )'
PRINT @sqlFull --//For DEBUG purpose
EXECUTE (@sqlFull)

GO
-- Example call
EXEC dbo.usp_GetInvoicesByCountry @country='Germany'

How to Fix Metadata error for Dynamic SQL

To fix metadata error due to dynamic SQL you have add WITH RESULT SETS statement after EXECUTE call. This feature was added in SQL 2012 and later. There are two ways to describe Stored Procedure / using Dynamic SQL

Method-1

Add  WITH RESULT SETS clause inside Stored Proc if you are using EXECUTE or sp_Executesql like below.

--DROP PROC dbo.usp_GetInvoicesByCountry
--GO
/*
Purpose: Parameterize REST API call via SQL. Call ZappySys Drivers inside SQL Server.
*/
ALTER PROC dbo.usp_GetInvoicesByCountry
	@country varchar(100) 
AS 

DECLARE @sql varchar(max)
--//Escape single ticks carefully
SET @sql =  'SELECT OrderID,CustomerID,Country,Quantity FROM $
WITH (Src=''https://services.odata.org/V3/Northwind/Northwind.svc/Invoices?$format=json&filter=Country eq '+ @country +'''
	 ,Filter=''$.value[*]''
	 ,DataFormat=''OData''
)'

DECLARE @sqlFull varchar(max)
SET @sqlFull='SELECT * FROM OPENQUERY( LS , ''' + REPLACE( @sql, '''', '''''' ) + ''' )'
PRINT @sqlFull --//For DEBUG purpose

EXECUTE (@sqlFull)
WITH RESULT SETS
(
	(OrderID int,CustomerID varchar(100),Country varchar(100),Quantity int) --//describe first result
)
GO

Method-2

Another way to describe resultset is add WITH RESULT SETS statement right after you call Stored proc each time from any client tool (see below). This way you don’t have to touch Source stored Proc. First method is still preferred way.

EXEC [dbo].[usp_GetInvoicesByCountry] @country='Germany' WITH RESULT SETS ( (OrderID int,CustomerID varchar(100),Country varchar(100),Quantity int))

How to generate column names and field datatypes for WITH RESULT SETS

If you have many columns to describe then it becomes tedious to type 200 columns by hand. Lets see how to make it simple.

1. First step is you need to load your result into some static table.
   

   SELECT * INTO _tmp FROM ( some sub query ) t

2. Once you have data we can use it few ways to get datatypes. Lets create a view to query metadata
   

   CREATE VIEW dbo.vwDataTypes
   AS
   SELECT 
      c.name as ColumnName,
      t.name +
      CASE WHEN t.name IN ('char', 'varchar','nchar','nvarchar') THEN '('+
                CASE WHEN c.max_length=-1 THEN 'MAX'
                     ELSE CONVERT(VARCHAR(4),
                                  CASE WHEN t.name IN ('nchar','nvarchar')
                                  THEN  c.max_length/2 ELSE c.max_length END )
                     END +')'
             WHEN t.name IN ('decimal','numeric')
                     THEN '('+ CONVERT(VARCHAR(4),c.precision)+','
                             + CONVERT(VARCHAR(4),c.Scale)+')'
                     ELSE '' END
   	      as FriendlyDataType,
      t.name as DataType,
      c.[object_id] as [TblObjectId],
      c.max_length MaxLengthBytes,
      c.precision as [Precision],
      c.scale  as [Scale],
      c.is_nullable as IsNullable,
      ISNULL(i.is_primary_key, 0) as IsPrimaryKey
   FROM    
      sys.columns c
   INNER JOIN 
      sys.types t ON c.user_type_id = t.user_type_id
   LEFT OUTER JOIN 
      sys.index_columns ic ON ic.object_id = c.object_id AND ic.column_id = c.column_id
   LEFT OUTER JOIN 
      sys.indexes i ON ic.object_id = i.object_id AND ic.index_id = i.index_id
   --WHERE    c.object_id = OBJECT_ID('_tmp')
   go

3. Now you can write below query to generate Comma separated list of columns names and datatypes
   

   DECLARE @csv VARCHAR(MAX)
   SELECT @csv = COALESCE(@csv+', ' ,'') + '[' + ColumnName + '] ' + FriendlyDataType
   FROM vwDataTypes WHERE [TblObjectId]= OBJECT_ID('_tmp')
   SELECT @csv

   Example : 
   

   [CustomerID] nvarchar(10), [CustomerName] nvarchar(68), ......... [Freight] nvarchar(16)

4. Use result of above query and paste in WITH RESULT SETS as below
   

   EXECUTE( @sqlFull )
   WITH RESULT SETS
   (
     (  your-comma-separated-list-goes-here )
   )

The post Tableau Parameters – Fix Metadata / Dynamic SQL Columns Issue appeared first on ZappySys Blog.

Tableau is one of the most popular Reporting / Visualization tool for BI / Data analytics. It comes with many out-of the box connectors to pull data from some popular data sources but still it seriously lakes capability to consume data from millions of other REST / SOAP data sources out there for which Tableau not going to create native connectors.

In this article we will cover how to import REST API in Tableau, We will also look at various examples to read from Files or any JSON / XML SOAP / CSV API in few clicks. We will use ZappySys API Drivers to read data from Web API or Local XML / JSON / CSV Files without doing any coding or ETL.

ZappySys API drivers are most advanced API drivers available in the market with many options to connect to virtually any REST / SOAP API data source. For demo purpose we will load ODATA API (JSON Format) using ZappySys JSON Driver. Concepts / steps listed in this articles are mostly same for other type of API formats too (e.g. XML API or CSV API).

Requirements

Before we get started for step by step tutorial, make sure following requirements are met.

1. You have installed Tableau Desktop
2. Make sure SQL Server Instance is installed somewhere. We will use Linked Server to access REST API. You can download FREE SQL Express Version (DB Server) and SSMS from here (Client).
3. Download and Install ZappySys ODBC PowerPack (API Drivers) – These drivers must be installed on Windows Machine (Can be different than Tableau Desktop / Server)

Step By Step – Loading REST API data in Tableau

Now let’s get started. To load REST API data in Tableau using ZappySys drivers basically there are two approaches.

Approach#1 You can use direct ODBC Connection to call ZappySys Drivers
Approach#2 Use SQL Server Connection in Tableau to send ZappySys Driver queries to ZappySys Data Gateway (using Linked Server OPENQUERY).

We recommend Approach#2 for any ZappySys driver use case in Tableau.  Now you must be wondering why use approach#2 and not #1 ? Tableau doesn’t play well when it comes to 3rd party ODBC drivers because behind the scene Tableau generate complex SQL statements which may not be supported by ODBC driver its trying to call (e.g. JOIN Syntax, CAST functions, Sub queries). See some issues like this and this one.  So if we use SQL Server to wrap those complex queries then it becomes much simpler because Tableau has very good support for SQL Server compared to 3rd party ODBC Drivers.

To access REST API in tableau using SQL Server Connection, you have to perform the following high level steps.

1. Make sure you have access to Microsoft SQL Server instance. If you don’t have one you can always use lightweight FREE SQL Express Edition (Download). This is free for Production use too.
2. Install ZappySys ODBC PowerPack (API Drivers)
3. Configure ZappySys Data Gateway (Create API connection) – We will see in depth, later in this article.
4. Create Linked Server in Microsoft SQL Server and connect to ZappySys Data Gateway
5. Import API data in Tableau using Microsoft SQL Server Connector by calling Linked Server SQL Queries

Assuming you have already done first step lets get started with remaining steps. You can also read this article for other example of calling SQL Server Queries via ZappySys Data Gateway.

Configure ZappySys Data Gateway

Create Linked Server in SQL Server

Once REST API Data source is configured in ZappySys Data Gateway, we can move forward to creating Linked Server part. At this point, you must be wondering why I have to use SQL Server to call ZappySys ODBC Driver? Why can’t I directly use ZappySys ODBC Driver in Tableau?

Technically, you can use Generic ODBC Connector in Tableau to call ZappySys ODBC Drivers for JSON API / XML API or CSV API but there are many problems with it.

Tableau Generic ODBC Connection option generates many unsupported SQL Syntax (e.g. Temp tables, Subqueries, date functions) which may not be supported by most non-relational ODBC drivers (e.g. ZappySys API drivers). Using SQL Server Linked Server we can bridge between ZappySys Drivers and Tableau to access any REST API. So let’s see how to do this.

Import REST API data in Tableau using Microsoft SQL Server Connector

Now we are ready to call REST API in Tableau. Perform following steps to Connect REST API to Tableau.

1. Open Tableau Desktop and click File > New
2. To create new Connection click More > Microsoft SQL Server > Enter your credentials to connect to SQL Server.
   

   Connect to REST API in Tableau using Microsoft SQL Server (Linked Server OPENQUERY approach)

3. Once connection is created for SQL Server we can read REST API data 3 different ways
   1. Query View which contains OPENQUERY to Linked Server for REST API data
   2. Use direct SQL Query using OPENQUERY
   3. Use Stored Procedure (Mostly useful to parameterize calls
4. See below example to pull data from REST API in Tableau using SQL View approach
   

   Create new Data Source in Tableau to Query REST API or file data (JSON / XML / CSV )

5. Here is how to Create Data Source using direct SQL Query. You can enter following Example Query.
   

   SELECT * FROM OPENQUERY( YOUR_LINKED_SERVER , 
   'SELECT * FROM $
   WITH (Src=''https://services.odata.org/V3/Northwind/Northwind.svc/Customers?$format=json''
   	 ,Filter=''$.value[*]''
   )');

    
   

   Create Tableau REST API Datasource using direct SQL Query

6. Once your data sources are created you can click on Sheet1 and drag fields to create visualizations for Tableau Dashboard.
   

   Create Tableau Dashboard from REST API data (JSON / XML / CSV)

Passing Parameters to REST API calls in Tableau (Dynamic SQL)

Now let’s look at scenario where you have to pass parameters to build Dynamic Dashboard. You can try to insert Parameters in your Direct SQL when you build Dynamic SQL but we found some issues with that so we are going to suggest Stored Procedure approach. For more information on Known issue on Dynamic Metadata Check this post.

1. First lets create a stored procedure in SQL Server for Parameter Example. Notice how we added WITH RESULT SETS in the code to describe metadata.
   

   --DROP PROC dbo.usp_GetInvoicesByCountry
   --GO
   /*
   Purpose: Parameterize REST API call via SQL. Call ZappySys Drivers inside SQL Server.
   */
   CREATE PROC dbo.usp_GetInvoicesByCountry
   	@country varchar(100) 
   AS 
   
   DECLARE @sql varchar(max)
   --//Escape single ticks carefully
   SET @sql =  'SELECT OrderID,CustomerID,Country,Quantity FROM $
   WITH (Src=''https://services.odata.org/V3/Northwind/Northwind.svc/Invoices?$format=json&filter=Country eq '+ @country +'''
   	 ,Filter=''$.value[*]''
   	 ,DataFormat=''OData''
   )'
   
   DECLARE @sqlFull varchar(max)
   SET @sqlFull='SELECT * FROM OPENQUERY( LS , ''' + REPLACE( @sql, '''', '''''' ) + ''' )'
   PRINT @sqlFull --//For DEBUG purpose
   
   EXECUTE (@sqlFull) 
   WITH RESULT SETS ( 
    (OrderID int,CustomerID varchar(100),Country varchar(100),Quantity int) --//describe first result. If you don't do this then wont work in Tableau 
   )
   GO
   -- Example call
   EXEC dbo.usp_GetInvoicesByCountry @country='Germany'

2. Once you create a stored procedure go to Tableau datasource and select Database which contains the stored procedure we just created.
3. Now find your stored proc and drag it on the datasource pane. You will see parameters UI as below. You can create new parameter – Select New Parameter under Value Column.
   

   Parameterize Tableau REST API datasource (Stored Procedure Parameters)

4. Thats it now you can reuse your parameterized datasource anywhere in Dashboard.
5. If you have need to select Parameters from predefined values rather than free text then edit your parameter and select List option. Define values you like to select from as below.
   

   Allow Tableau Parameter selection from multiple values

6. When you create Tableau Dashboard you will see Parameter dropdown (If you selected List) elase you may see Textbox to enter custom value.
   

   Tableau Dashboard Example – REST API Source with Parameterized Datasource

Read data from JSON Files in Tableau (Single or Multiple)

So far we have seen how to read data from REST API but there will be a time to read data from JSON Files (Single or Multiple). Also files may be compressed (GZip or Zip). Regardless no worries if you are using ZappySys drivers. See below sample query you can submit via SQL Linked Server to read JSON files stored on network share.

Single File Example

SELECT * FROM OPENQUERY([MY_LINKED_SERVER]
, 'SELECT * FROM $
WITH(
   Src=''c:\ssis\large_2018.json''
  ,Filter=''$.Branches[*]''
)')

Multiple Files Example

SELECT * FROM OPENQUERY([MY_LINKED_SERVER]
, 'SELECT * FROM $
WITH(
   Src=''c:\ssis\large_*.json''
  ,Filter=''$.Branches[*]''
)')

Read Compressed Files (GZip / Zip Format)

SELECT * FROM OPENQUERY([MY_LINKED_SERVER]
, 'SELECT * FROM $
WITH(
   Src=''c:\ssis\large_*.json.gz''
  --Src=''https://zappysys.com/downloads/files/test/large_file_10k.json.gz''
  ,Filter=''$.Branches[*]''
  ,FileCompressionType=''GZip''  --OR-- Zip --OR-- None
)')

Read CSV Files or URL in Tableau

If you like to read data from CSV files or URL then you can use ZappySys CSV Driver same way.

Here is sample query for CSV data.

Reading Compressed CSV Files in Tableau

SELECT * FROM OPENQUERY([MY_API_SERVICE]
, 'SELECT * FROM $
WITH(
  Src=''https://zappysys.com/downloads/files/test/customerdata.csv.gz''
  ,FileCompressionType=''GZip''  --OR-- Zip --OR-- None
  ,ColumnDelimiter=''|''
  ,HasColumnHeaderRow=''False''
)')

Read multiple files (TAB delimited) in Tableau

SELECT * FROM OPENQUERY([MY_API_SERVICE]
, 'SELECT * FROM $
WITH(
  Src=''''c:\ssis\customerdata_*.csv''''
  ,ColumnDelimiter=''{tab}'' --or use \t for tab delimited files
  ,HasColumnHeaderRow=''True''
)')

Read XML Files or API in Tableau

If you like to read data from XML files or URL then you can use ZappySys XML Driver same way. See below example to read some data from XML Web API. We have also passed credentials along with it for demo purpose.

SELECT * FROM OPENQUERY([MY_API_SERVICE]
, 'SELECT * FROM $
WITH(
	 ElementsToTreatAsArray=''item,slide''
	,Src=''http://httpbin.org/xml''
	,DataConnectionType=''HTTP''
	,UserName=''user1''
	,CredentialType=''Basic''
	,Password=''P@11s#''
	,Filter=''$.slideshow.slide[*]''
)')

Read local XML files

SELECT * FROM OPENQUERY([MY_API_SERVICE]
, 'SELECT * FROM $ WITH (
 SRC=''C:\Data\CustomerData.xml''
, Filter=''$.Root.Row[*]''
, ElementsToTreatAsArray=''Row''
)')

Call POST REST API in Tableau

There will be a time when you like to submit API request as POST rather than GET. See below example how to write POST API Request to send Body along with Custom Headers and Method.

POST Body, Set Method, Headers

SELECT * FROM OPENQUERY([MY_API_SERVICE]
, 'SELECT * FROM $
WITH 
(METHOD=''POST'', HEADER=''Content-Type: text/plain || x-hdr1: AAA''
,SRC=''http://httpbin.org/post''
,BODY=''
{
    id:1,
    notes:"Line1\r\nLine2"
}''
)')

Call SOAP API using XML Driver (POST data) – Token based Authentication

Here is another interesting example to call XML SOAP API. It first authenticates and get Token from SOAP Response. Then use that token for API call. To read more about Dynamic Token Method check this article.

SELECT * FROM OPENQUERY([MY_API_SERVICE]
, 'SELECT * FROM $
WITH(
	 ElementsToTreatAsArray=''urn:Row''
	,Src=''https://zappysys.com/downloads/files/test/soap-getdata.aspx''
	,DataConnectionType=''HTTP''
	,AuthScheme=''{none}''
	,TokenUrl=''https://zappysys.com/downloads/files/test/soap-login.aspx''
	,TokenRequestData=''
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:partner.soap.sforce.com">
   <soapenv:Body>
      <urn:login>
         <urn:username>[$userid$]</urn:username>
         <urn:password>[$password$]</urn:password>
      </urn:login>
   </soapenv:Body>
</soapenv:Envelope>''

	,TokenRequestMethod=''POST''
	,TokenResponseContentFilter=''//*[local-name() = ''''sessionid'''']''
	,TokenRequestHeaders=''Content-Type:text/xml|Accept:*/*|Cache-Control:no-cache''
	,TokenResponseContentType=''Xml''
	,UserName=''MyUser001''
    ,Password=''P@$$w0rdAAc12''
	,CredentialType=''TokenDynamic''
	,Filter=''$.soapenv:Envelope.soapenv:Body.urn:Row[*]''
	,RequestData=''
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:urn="urn:partner.soap.sforce.com">
   <soapenv:Body>
      <urn:sessionid>[$token$]</urn:sessionid>
   </soapenv:Body>
</soapenv:Envelope>''

	,Header=''Content-Type: text/xml;charset=UTF-8 || SOAPAction: "https://zappysys.com/soap-getdata" || Accept: */* || Cache-Control: no-cache''
	,RequestMethod=''POST''
)')

REST API / XML SOAP Pagination Settings for Tableau

SELECT * FROM $
WITH(
SRC=@'https://zappysys.com/downloads/files/test/pagination_nextlink_inarray_1.json'
,NextUrlAttributeOrExpr = '$.nextlink'  --keep reading until this attribute is missing. If attribute name contains dot then use brackets like this $.['my.attr.name']
)

SELECT * FROM $
WITH (
SRC=@'https://zappysys.com/downloads/files/test/page-xml.aspx?page=1&mode=DetectBasedOnResponseStatusCode'
,PagingMode='ByUrlParameter'
,PagingByUrlAttributeName='page'
,PagingByUrlEndStrategy='DetectBasedOnResponseStatusCode'
,PagingByUrlCheckResponseStatusCode=401
,IncrementBy=1
)

SELECT * FROM $
WITH (
SRC=@'https://zappysys.com/downloads/files/test/cust-<%page%>.xml'
,PagingMode='ByUrlPath'
,PagingByUrlAttributeName='<%page%>'
,PagingByUrlEndStrategy='DetectBasedOnRecordCount'
,IncrementBy=1
)

SELECT * FROM $
LIMIT 25
WITH(
	 Src='https://wordpress.org/news/wp-json/wp/v2/categories?per_page=10'
	,PagingMode='ByResponseHeaderRfc5988'
	,WaitTimeMs='200' --//wait 200 ms after each request
)

REST API / SOAP Web Service Connection Settings for Tableau

If you need to authenticate or authorize your user to access a web resource, you will need to use one of the Connections:

• HTTP
• OAuth

HTTP Connection

Use HTTP Connection for simple Windows, Basic, NTLM or Kerberos authentication. Just fill in a username and a password and you are good to go!

You can also use HTTP Connection for more sophisticated authentication like:

• SOAP WSS (when accessing a SOAP WebService)
• Static Token / API Key (when need to pass an API key in HTTP header)
• Dynamic Token (same as Static Token method except that each time you need to log in and retrieve a fresh API key)
• JWT Token (As per RFC 7519)

OAuth

If you are trying to access REST API resource, it is a huge chance, you will need to use OAuth Connection. Read this article to understand how OAuth authentication and authorization works and how to use it (article originally was written for SSIS PowerPack, but the concepts and UI stay the same): 
https://zappysys.com/blog/rest-api-authentication-with-oauth-2-0-using-ssis/

Other settings for REST API / SOAP XML Call in Tableau

REST API / XML SOAP Performance Tips for Tableau

SELECT * FROM value
WITH(
	 Src='https://services.odata.org/V3/Northwind/Northwind.svc/Customers?$format=json&$filter=Country eq ''USA'''
	,DataFormat='Odata'
)

-- Slow query - Client-side filtering
SELECT * FROM value
WHERE Country ='USA'
WITH(
	 Src='https://services.odata.org/V3/Northwind/Northwind.svc/Customers?$format=json'
	,DataFormat='Odata'
)

SELECT * FROM $
WITH 
(  SRC='https://myhost.com/some-api'
  ,CachingMode='All'  --cache metadata and data rows both
  ,CacheStorage='File' --or Memory
  ,CacheFileLocation='c:\temp\myquery.cache'
  ,CacheEntryTtl=300 --cache for 300 seconds
)

SELECT * FROM $ 
LIMIT 10 --//add this just to test how fast you can get 10 rows
WITH(
  Filter='$.LargeArray[*]--FAST' --//Adding --FAST option turn on STREAM mode (large files)
 ,SRC='https://zappysys.com/downloads/files/test/large_file_100k_largearray_prop.json.gz'
 --,SRC='c:\data\large_file.json.gz'
 ,IncludeParentColumns='False'  --//This Must be OFF for STREAM mode (read very large files)
 ,FileCompressionType='GZip' --Zip or None (Zip format only available for Local files)
)

Calling SOAP Web Service in Tableau

To call SOAP API you need to know Request XML Body Structure. If you are not sure how to create SOAP Request body then no worries. Check this article to learn how to generate SOAP Request body using the Free tool SoapUI. Basically, you have to use SoapUI to generate Request XML and after that, you can replace parameters as needed in the generated body.

What is SOAP Web Service?

If you are new to SOAP Web Service sometimes referred as XML Web Service then please read some concept about SOAP Web service standard from this link There are two important aspects in SOAP Web service.

1. Getting WSDL file or URL
2. Knowing exact Web Service URL

What is WSDL

In very simple term WSDL (often pronounced as whiz-dull) is nothing but a document which describes Service metadata (e.g. Functions you can call, Request parameters, response structure etc). Some service simply give you WSDL as xml file you can download on local machine and then analyze or sometimes you may get direct URL (e.g. http://api.mycompany.com/hr-soap-service/?wsdl )

Example SQL Query for SOAP API call using ZappySys XML Driver

Here is an example SQL query you can write to call SOAP API. If you not sure about many details then check next few sections on how to use XML Driver User Interface to build desired SQL query to POST data to XML SOAP Web Service without any coding.

SELECT * FROM $
WITH(
	 Src='http://www.holidaywebservice.com/HolidayService_v2/HolidayService2.asmx'
	,DataConnectionType='HTTP'
	,CredentialType='Basic' --OR SoapWss
	,SoapWssPasswordType='PasswordText'
	,UserName='myuser'
	,Password='pass$$w123'
	,Filter='$.soap:Envelope.soap:Body.GetHolidaysAvailableResponse.GetHolidaysAvailableResult.HolidayCode[*]'
	,ElementsToTreatAsArray='HolidayCode'	
	,RequestMethod='POST'	
	,Header='Content-Type: text/xml;charset=UTF-8 || SOAPAction: "http://www.holidaywebservice.com/HolidayService_v2/GetHolidaysAvailable"'
	,RequestData='
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:hol="http://www.holidaywebservice.com/HolidayService_v2/">
   <soapenv:Header/>
   <soapenv:Body>
      <hol:GetHolidaysAvailable>
         <!--type: Country - enumeration: [Canada,GreatBritain,IrelandNorthern,IrelandRepublicOf,Scotland,UnitedStates]-->
         <hol:countryCode>UnitedStates</hol:countryCode>
      </hol:GetHolidaysAvailable>
   </soapenv:Body>
</soapenv:Envelope>'
)

Now let's look at steps to create SQL query to call SOAP API. Later we will see how to generate code for your desired programming language (e.g. C# or SQL Server)

Video Tutorial - Introduction to SOAP Web Service and SoapUI tool

Before we dive into details about calling SOAP API using ZappySys XML Driver, lets first understand what is SOAP API and how to create SOAP requests using SoapUI tool. You will learn more about this process in the later section. The video contains some fragment about using SOAP API in SSIS but just ignore that part because we will be calling Soap API using ZappySys ODBC Driver rather than SSIS Components.  

Using SoapUI to test SOAP API call / Create Request Body XML

Assuming you have downloaded and installed SoapUI from here, now we are ready to use WSDL for your SOAP Web Service Calls. If you do not have WSDL file or URL handy then contact your API provider (sometimes you just have to add ?wsdl at the end of your Service URL to get WSDL so try that. Example: http://mycompany/myservice?wsdl ). If you don't know what is WSDL then in short, WSDL is Web service Description Language (i.e. XML file which describes your SOAP Service). WSDL helps to craft SOAP API request Body for ZappySys XML Driver. So Let's get started.

1. Open SoapUI and click SOAP button to create new SOAP Project
2. Enter WSDL URL or File Path of WSDLFor example WSDL for our sample service can be accessed via this URL

   http://www.dneonline.com/calculator.asmx?wsdl

   
   Create new SOAP API Project in SoapUI tool for SOAP API Testing
3. Once WSDL is loaded you will see possible operations you can call for your SOAP Web Service.
4. If your web service requires credentials then you have to configure it. There are two common credential types for public services (SOAP WSS or BASIC )
   1. To use SOAP WSS Credentials select request node and enter UserId, Password, and WSS-PasswordType (PasswordText or PasswordHash)
      
      Configure SOAP WSS Credentials for SoapUI (SOAP API Testing Tool)
   2. To use BASIC Auth Credentials select request node and double-click it. At the bottom click on Auth (Basic) and From Authorization dropdown click Add New and Select Basic.
      Configure Basic Authorization for SoapUI (SOAP API Testing Tool)
5. Now you can test your request first Double-click on the request node to open request editor.
6. Change necessary parameters, remove optional or unwanted parameters. If you want to regenerate request you can click on Recreate default request toolbar icon.
   Create SOAP Request XML (With Optional Parameters)
7. Once your SOAP Request XML is ready, Click the Play button in the toolbar to execute SOAP API Request and Response will appear in Right side panel. Test SOAP API using SoapUI Tool (Change Default XML Body / Parameters, Execute and See Response)

Create DSN using ZappySys XML Driver to call SOAP API

Once you have tested your SOAP API in SoapUI tool, we are ready to use ZappySys XML driver to call SOAP API in your preferred BI tool or Programming language.

1. First open ODBC Data Sources (search ODBC in your start menu or go under ZappySys > ODBC PowerPack > ODBC 64 bit)
2. Goto System DSN Tab (or User DSN which is not used by Service account)
3. Click Add and Select ZappySys XML Driver ZappySys ODBC Driver for XML / SOAP API
4. Configure API URL, Request Method and Request Body as below ZappySys XML Driver - Calling SOAP API - Configure URL, Method, Body
5. (This step is Optional) If your SOAP API requires credentials then Select Connection Type to HTTP and configure as below.
   ZappySys XML Driver - Configure SOAP WSS Credentials or Basic Authorization (Userid, Password)
6. Configure-Request Headers as below (You can get it from Request > Raw tab from SoapUI after you test the request by clicking the Play button) Configure SOAP API Request Headers - ZappySys XML Driver
7. Once credentials entered you can select Filter to extract data from the desired node. Make sure to select array node (see special icon) or select the node which contains all necessary columns if you don't have array node. Select Filter - Extract data from nested XML / SOAP API Response (Denormalize Hierarchy)
8. If prompted select yes to treat selected node as Array (This is helpful when you expect one or more record for selected node) Treat selected node as XML Array Option for SOAP API Response XML

Preview SOAP API Response / Generate SQL Code for SOAP API Call

Once you configure settings for XML Driver now you can preview data or generate example code for desired language (e.g. C#, Python, Java, SQL Server). Go to Preview tab and you will see default query generated based on settings you entered in previous sections. Attributes listed in WITH clause are optional. If you omit attribute in WITH clause it will use it from Properties tab.

Preview Data

Preview SOAP API Response in ZappySys XML Driver

Generate Code Option

Generate Example Code for ZappySys Driver

Conclusion

Tableau has no out of the box features to consume many Web API / JSON / XML data sources out there. ZappySys has developed most innovative drivers which can connect to virtually any REST API / SOAP data sources in Tableau. These drivers also capable reading local files in JSON / CSV or XML format. Feel free to download  ZappySys Drivers here and try yourself . You can always contact ZappySys Support Team here if you need any API integration help.

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