![\"\"](\"https:\/\/zappysys.com\/blog\/wp-content\/uploads\/2018\/06\/tableau-integration-logo.png\"){kind=logo}
<\/a>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.<\/p>\nIn 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<\/a>\u00a0to read data from Web API or Local XML \/ JSON \/ CSV Files without doing any coding or ETL.<\/p>\n 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.\u00a0For demo purpose we will load ODATA API (JSON Format) using ZappySys JSON Driver<\/a>. Concepts \/ steps listed in this articles are mostly same for other type of API formats too (e.g. XML API or CSV API).<\/p>\n Before we get started for step by step tutorial, make sure following requirements are met.<\/p>\n Now let’s get started. To load REST API data in Tableau using ZappySys drivers basically there are two approaches.<\/p>\n Approach#1<\/strong> You can use direct ODBC Connection to call ZappySys Drivers We recommend Approach#2<\/span><\/span> for any ZappySys driver use case in Tableau.\u00a0 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<\/a> and this one<\/a>.\u00a0 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.<\/p>\n To access REST API in tableau using SQL Server Connection, you have to perform the following high level steps.<\/p>\n 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<\/a>.<\/p>\n Open ZappySys Data Gateway<\/p>\r\n\r\n<\/div><\/li>\r\n \t Port Number setting on ZappySys Data Gateway<\/p>\r\n\r\n<\/div><\/li>\r\n \t Add Data Gateway User<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n \r\n Add Gateway Data Source (Native JSON Driver)<\/p>\r\n\r\n<\/div><\/li>\r\n \t Configure JSON API Data source<\/p>\r\n\r\n<\/div><\/li>\r\n<\/ol>\r\n JSON \/ REST API Driver Query Preview \/ Query Examples (Read REST API or JSON Files)<\/p>\r\n\r\n<\/div><\/li>\r\n \t Using SQL Query Builder (For Files or REST \/ SOAP API - JSON \/ XML \/ CSV Format)<\/p>\r\n\r\n<\/div><\/li>\r\n \t Generate Example Code for ZappySys Driver<\/p>\r\n\r\n<\/div><\/li>\r\n \t 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?<\/p>\n Technically, you can use Generic ODBC Connector in Tableau<\/a>\u00a0to call ZappySys ODBC Drivers for JSON API \/ XML API or CSV API but there are many problems with it.<\/p>\n Tableau Generic ODBC Connection option generates many unsupported SQL Syntax<\/a>\u00a0(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.<\/p>\n Add Linked Server in SQL Server<\/p>\r\n\r\n<\/div><\/li>\r\n \t Configure Linked Server Provider, Catalog, Server, Port for ZappySys Data Gateway Connection<\/p>\r\n<\/div>\r\n Optional: Under the Server Options Tab, Enable RPC<\/b> and RPC Out<\/b> and Disable Promotion of Distributed Transactions(MSDTC)<\/b>.<\/p>\r\n\t\t RPC and MSDTC Settings<\/p>\r\n\t\t<\/div>\r\n \r\n You need to enable RPC Out if you plan to use EXEC(...) AT [MY_LINKED_SERVER_NAME]<\/i><\/b> rather than OPENQUERY.\r\n \r\n Query Example:\r\n \r\n If you plan to use 'INSERT INTO...EXEC(....) AT [MY_LINKED_SERVER_NAME]'<\/i><\/b> in that case you need to Disable Promotion of Distributed Transactions(MSDTC).\r\n \r\n Query Example:\r\n SSMS Output - Query REST API via Linked Server OPENQUERY statement (Connect to ZappySys Data Gateway)<\/p>\r\n\r\n<\/div><\/li>\r\n \t Now we are ready to call REST API in Tableau. Perform following steps to Connect REST API to Tableau.<\/p>\n Connect to REST API in Tableau using Microsoft SQL Server (Linked Server OPENQUERY approach)<\/p><\/div><\/li>\n Create new Data Source in Tableau to Query REST API or file data (JSON \/ XML \/ CSV )<\/p><\/div><\/li>\n <\/p>\n Create Tableau REST API Datasource using direct SQL Query<\/p><\/div><\/li>\n Create Tableau Dashboard from REST API data (JSON \/ XML \/ CSV)<\/p><\/div><\/li>\n<\/ol>\n 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<\/a>.<\/p>\n Parameterize Tableau REST API datasource (Stored Procedure Parameters)<\/p><\/div><\/li>\n Allow Tableau Parameter selection from multiple values<\/p><\/div><\/li>\n Tableau Dashboard Example – REST API Source with Parameterized Datasource<\/p><\/div><\/li>\n<\/ol>\n 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.<\/p>\n Single File Example<\/strong><\/p>\n Multiple Files Example<\/strong><\/p>\n Read Compressed Files (GZip \/ Zip Format)<\/strong><\/p>\n <\/p>\n If you like to read data from CSV files or URL then you can use ZappySys CSV Driver<\/a> same way.<\/p>\n Here is sample query for CSV data.<\/p>\n Reading Compressed CSV Files in Tableau<\/strong><\/p>\n Read multiple files (TAB delimited) in Tableau<\/strong><\/p>\n If you like to read data from XML files or URL then you can use ZappySys XML Driver<\/a> same way. See below example to read some data from XML Web API. We have also passed credentials along with it for demo purpose.<\/p>\n Read local XML files<\/strong><\/p>\n <\/p>\n 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.<\/p>\n POST Body, Set Method, Headers<\/strong><\/p>\n Call SOAP API using XML Driver (POST data) – Token based Authentication<\/strong><\/p>\n 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<\/a>.<\/p>\n <\/p>\n <\/p>\nRequirements<\/h2>\n
\n
Step By Step – Loading REST API data in Tableau<\/h2>\n
\nApproach#2<\/strong>\u00a0Use SQL Server Connection in Tableau to send ZappySys Driver queries to\u00a0ZappySys Data Gateway<\/a>\u00a0(using Linked Server OPENQUERY).<\/p>\n\n
Configure ZappySys Data Gateway<\/h3>\n
Configure Data Gateway User \/ Port<\/span><\/h4>\r\nNow let's look at steps to configure Data Gateway after installation. We will also create a sample data source for ODATA API (i.e. JSON based REST API Service).\r\n
\r\n \t
<\/a>\r\n<\/a>\r\n<\/a>\r\nConfigure Data Source<\/span><\/h4>\r\n
\r\n \t
NOTE:<\/strong> Whenever possible use native driver option for better performance \/ security and ease of use.<\/pre>\r\n
<\/a>\r\nhttps:\/\/services.odata.org\/V3\/Northwind\/Northwind.svc\/Invoices?$format=json<\/pre>\r\n<\/li>\r\n \t
<\/a>\r\nTest SQL Query \/ Preview Data<\/span><\/h4>\r\n
\r\n \t
<\/a>\r\n<\/a>\r\n<\/a>\r\nCreate Linked Server in SQL Server<\/h3>\n
\r\n \t
\r\n<\/a>\r\n\r\n<\/a>\r\n\r\n
\r\n\t\t\t
\r\n
\r\n If don't enabled it, you will encounter the 'Server \"MY_LINKED_SERVER_NAME\" is not configured for RPC'<\/i> error.\r\n <\/p>\r\n EXEC('Select * from Products') AT [MY_LINKED_SERVER_NAME]<\/code>\r\n <\/p>\r\n
\r\n
\r\n If don't disabled it, you will encounter the 'The operation could not be performed because OLE DB provider \"SQLNCLI11\/MSOLEDBSQL\" for linked server \"MY_LINKED_SERVER_NAME\" was unable to begin a distributed transaction.'<\/i> error.\r\n <\/p>\r\n Insert Into dbo.Products \r\nEXEC('Select * from Products') AT [MY_LINKED_SERVER_NAME]<\/pre>\r\n <\/p>\r\n
\r\n<\/li>\r\n \tSELECT * FROM OPENQUERY( MY_LINKED_SERVER_NAME, 'SELECT * FROM $')<\/pre>\r\n--OR--\r\n
SELECT * FROM OPENQUERY( MY_LINKED_SERVER_NAME, \r\n'SELECT * FROM $\r\n WITH (Src=''https:\/\/services.odata.org\/V3\/Northwind\/Northwind.svc\/Customers?$format=json''\r\n ,Filter=''$.value[*]''\r\n ,DataFormat=''OData''\r\n)');<\/pre>\r\n<\/li>\r\n \t
\r\n<\/a>\r\nCREATE VIEW dbo.vwApiInvoices \r\nAS \r\n\/*Call REST API inside SQL Server View*\/\r\nSELECT * FROM OPENQUERY( LS , \r\n'SELECT * FROM $\r\nWITH (Src=''https:\/\/services.odata.org\/V3\/Northwind\/Northwind.svc\/Invoices?$format=json''\r\n\t ,Filter=''$.value[*]''\r\n\t ,DataFormat=''OData''\r\n)');\r\n\r\nGO\r\n<\/pre>\r\n <\/li>\r\n \t
Import REST API data in Tableau using Microsoft SQL Server Connector<\/h3>\n
\n
<\/a>\n
<\/a>SELECT * FROM OPENQUERY( YOUR_LINKED_SERVER , \r\n'SELECT * FROM $\r\nWITH (Src=''https:\/\/services.odata.org\/V3\/Northwind\/Northwind.svc\/Customers?$format=json''\r\n\t ,Filter=''$.value[*]''\r\n)');<\/pre>\n
<\/a><\/a>Passing Parameters to REST API calls in Tableau (Dynamic SQL)<\/h2>\n
\n
--DROP PROC dbo.usp_GetInvoicesByCountry\r\n--GO\r\n\/*\r\nPurpose: Parameterize REST API call via SQL. Call ZappySys Drivers inside SQL Server.\r\n*\/\r\nCREATE PROC dbo.usp_GetInvoicesByCountry\r\n\t@country varchar(100) \r\nAS \r\n\r\nDECLARE @sql varchar(max)\r\n--\/\/Escape single ticks carefully\r\nSET @sql = 'SELECT OrderID,CustomerID,Country,Quantity FROM $\r\nWITH (Src=''https:\/\/services.odata.org\/V3\/Northwind\/Northwind.svc\/Invoices?$format=json&filter=Country eq '+ @country +'''\r\n\t ,Filter=''$.value[*]''\r\n\t ,DataFormat=''OData''\r\n)'\r\n\r\nDECLARE @sqlFull varchar(max)\r\nSET @sqlFull='SELECT * FROM OPENQUERY( LS , ''' + REPLACE( @sql, '''', '''''' ) + ''' )'\r\nPRINT @sqlFull --\/\/For DEBUG purpose\r\n\r\nEXECUTE (@sqlFull) \r\nWITH RESULT SETS ( \r\n (OrderID int,CustomerID varchar(100),Country varchar(100),Quantity int) --\/\/describe first result. If you don't do this then wont work in Tableau \r\n)\r\nGO\r\n-- Example call\r\nEXEC dbo.usp_GetInvoicesByCountry @country='Germany'<\/pre>\n<\/li>\n
<\/a><\/a><\/a><\/h2>\n
Read data from JSON Files in Tableau (Single or Multiple)<\/h2>\n
SELECT * FROM OPENQUERY([MY_LINKED_SERVER]\r\n, 'SELECT * FROM $\r\nWITH(\r\n Src=''c:\\ssis\\large_2018.json''\r\n ,Filter=''$.Branches[*]''\r\n)')<\/pre>\n
SELECT * FROM OPENQUERY([MY_LINKED_SERVER]\r\n, 'SELECT * FROM $\r\nWITH(\r\n Src=''c:\\ssis\\large_*.json''\r\n ,Filter=''$.Branches[*]''\r\n)')<\/pre>\n
SELECT * FROM OPENQUERY([MY_LINKED_SERVER]\r\n, 'SELECT * FROM $\r\nWITH(\r\n Src=''c:\\ssis\\large_*.json.gz''\r\n --Src=''https:\/\/zappysys.com\/downloads\/files\/test\/large_file_10k.json.gz''\r\n ,Filter=''$.Branches[*]''\r\n ,FileCompressionType=''GZip'' --OR-- Zip --OR-- None\r\n)')<\/pre>\n
Read CSV Files or URL in Tableau<\/h2>\n
SELECT * FROM OPENQUERY([MY_API_SERVICE]\r\n, 'SELECT * FROM $\r\nWITH(\r\n Src=''https:\/\/zappysys.com\/downloads\/files\/test\/customerdata.csv.gz''\r\n ,FileCompressionType=''GZip'' --OR-- Zip --OR-- None\r\n ,ColumnDelimiter=''|''\r\n ,HasColumnHeaderRow=''False''\r\n)')<\/pre>\n
SELECT * FROM OPENQUERY([MY_API_SERVICE]\r\n, 'SELECT * FROM $\r\nWITH(\r\n Src=''''c:\\ssis\\customerdata_*.csv''''\r\n ,ColumnDelimiter=''{tab}'' --or use \\t for tab delimited files\r\n ,HasColumnHeaderRow=''True''\r\n)')<\/pre>\nRead XML Files or API in Tableau<\/h2>\n
SELECT * FROM OPENQUERY([MY_API_SERVICE]\r\n, 'SELECT * FROM $\r\nWITH(\r\n\t ElementsToTreatAsArray=''item,slide''\r\n\t,Src=''http:\/\/httpbin.org\/xml''\r\n\t,DataConnectionType=''HTTP''\r\n\t,UserName=''user1''\r\n\t,CredentialType=''Basic''\r\n\t,Password=''P@11s#''\r\n\t,Filter=''$.slideshow.slide[*]''\r\n)')<\/pre>\n
SELECT * FROM OPENQUERY([MY_API_SERVICE]\r\n, 'SELECT * FROM $ WITH (\r\n SRC=''C:\\Data\\CustomerData.xml''\r\n, Filter=''$.Root.Row[*]''\r\n, ElementsToTreatAsArray=''Row''\r\n)')<\/pre>\n
Call POST REST API in Tableau<\/h2>\n
SELECT * FROM OPENQUERY([MY_API_SERVICE]\r\n, 'SELECT * FROM $\r\nWITH \r\n(METHOD=''POST'', HEADER=''Content-Type: text\/plain || x-hdr1: AAA''\r\n,SRC=''http:\/\/httpbin.org\/post''\r\n,BODY=''\r\n{\r\n id:1,\r\n notes:\"Line1\\r\\nLine2\"\r\n}''\r\n)')<\/pre>\nSELECT * FROM OPENQUERY([MY_API_SERVICE]\r\n, 'SELECT * FROM $\r\nWITH(\r\n\t ElementsToTreatAsArray=''urn:Row''\r\n\t,Src=''https:\/\/zappysys.com\/downloads\/files\/test\/soap-getdata.aspx''\r\n\t,DataConnectionType=''HTTP''\r\n\t,AuthScheme=''{none}''\r\n\t,TokenUrl=''https:\/\/zappysys.com\/downloads\/files\/test\/soap-login.aspx''\r\n\t,TokenRequestData=''\r\n<soapenv:Envelope xmlns:soapenv=\"http:\/\/schemas.xmlsoap.org\/soap\/envelope\/\" xmlns:urn=\"urn:partner.soap.sforce.com\">\r\n <soapenv:Body>\r\n <urn:login>\r\n <urn:username>[$userid$]<\/urn:username>\r\n <urn:password>[$password$]<\/urn:password>\r\n <\/urn:login>\r\n <\/soapenv:Body>\r\n<\/soapenv:Envelope>''\r\n\r\n\t,TokenRequestMethod=''POST''\r\n\t,TokenResponseContentFilter=''\/\/*[local-name() = ''''sessionid'''']''\r\n\t,TokenRequestHeaders=''Content-Type:text\/xml|Accept:*\/*|Cache-Control:no-cache''\r\n\t,TokenResponseContentType=''Xml''\r\n\t,UserName=''MyUser001''\r\n ,Password=''P@$$w0rdAAc12''\r\n\t,CredentialType=''TokenDynamic''\r\n\t,Filter=''$.soapenv:Envelope.soapenv:Body.urn:Row[*]''\r\n\t,RequestData=''\r\n<soapenv:Envelope xmlns:soapenv=\"http:\/\/schemas.xmlsoap.org\/soap\/envelope\/\" xmlns:urn=\"urn:partner.soap.sforce.com\">\r\n <soapenv:Body>\r\n <urn:sessionid>[$token$]<\/urn:sessionid>\r\n <\/soapenv:Body>\r\n<\/soapenv:Envelope>''\r\n\r\n\t,Header=''Content-Type: text\/xml;charset=UTF-8 || SOAPAction: \"https:\/\/zappysys.com\/soap-getdata\" || Accept: *\/* || Cache-Control: no-cache''\r\n\t,RequestMethod=''POST''\r\n)')<\/pre>\nREST API \/ XML SOAP Pagination Settings for Tableau<\/h2>\n
Paginate by Response Attribute<\/h3>\r\nThis example shows how to paginate API calls where you need to paginate until the last page detected. In this example, next page is indicated by some attribute called nextlink (found in response). If this attribute is missing or null then it stops fetching the next page.\r\n
SELECT * FROM $\r\nWITH(\r\nSRC=@'https:\/\/zappysys.com\/downloads\/files\/test\/pagination_nextlink_inarray_1.json'\r\n,NextUrlAttributeOrExpr = '$.nextlink' --keep reading until this attribute is missing. If attribute name contains dot then use brackets like this $.['my.attr.name']\r\n)<\/pre>\r\n
Paginate by URL Parameter (Loop until certain StatusCode)<\/h3>\r\nThis example shows how to paginate API calls where you need to pass page number via URL. The driver keeps incrementing page number and calls next URL until the last page detected (401 error). There are few ways to indicate the last page (e.g. By status code, By row count, By response size). If you don't specify end detection then it will use the default (i.e. No records found).\r\n
SELECT * FROM $\r\nWITH (\r\nSRC=@'https:\/\/zappysys.com\/downloads\/files\/test\/page-xml.aspx?page=1&mode=DetectBasedOnResponseStatusCode'\r\n,PagingMode='ByUrlParameter'\r\n,PagingByUrlAttributeName='page'\r\n,PagingByUrlEndStrategy='DetectBasedOnResponseStatusCode'\r\n,PagingByUrlCheckResponseStatusCode=401\r\n,IncrementBy=1\r\n)<\/pre>\r\n
Paginate by URL Path (Loop until no record)<\/h3>\r\nThis example shows how to paginate API calls where you need to pass page number via URL Path. The driver keeps incrementing page number and calls next URL until the last page is detected. There are few ways to indicate the last page (e.g. By status code, By row count, By response size). If you don't specify end detection then it will use the default (i.e. No records found).\r\n
SELECT * FROM $\r\nWITH (\r\nSRC=@'https:\/\/zappysys.com\/downloads\/files\/test\/cust-<%page%>.xml'\r\n,PagingMode='ByUrlPath'\r\n,PagingByUrlAttributeName='<%page%>'\r\n,PagingByUrlEndStrategy='DetectBasedOnRecordCount'\r\n,IncrementBy=1\r\n)<\/pre>\r\n
Paginate by Header Link (RFC 5988)<\/h3>\r\nAPI like GitHub \/ Wordpress use Next link in Headers (RFC 5988<\/a>)\r\n
SELECT * FROM $\r\nLIMIT 25\r\nWITH(\r\n\t Src='https:\/\/wordpress.org\/news\/wp-json\/wp\/v2\/categories?per_page=10'\r\n\t,PagingMode='ByResponseHeaderRfc5988'\r\n\t,WaitTimeMs='200' --\/\/wait 200 ms after each request\r\n)<\/pre>\r\n <\/div>\n
REST API \/ SOAP Web Service Connection Settings for Tableau<\/h2>\n
\r\n \t
\r\nHTTP Connection<\/h3>\r\n
\r\n \t
\r\nOAuth<\/h3>\r\nIf you are trying to access REST API resource, it is a huge chance, you will need to use OAuth Connection<\/em>. Read this article<\/a> to understand how OAuth authentication and authorization works and how to use it (article originally was written for SSIS PowerPack<\/a>, but the concepts and UI stay the same):\u00a0
<\/div>\nOther settings for REST API \/ SOAP XML Call in Tableau<\/h2>\n
API Limit \/ Throttling<\/strong><\/h3>\r\nWhile calling public API or other external web services one important aspect you have to check,\u00a0 how many requests are allowed by your API. Especially when you use API pagination options to pull many records you have to slow down based on API limits. For example, your API may allow you only 5 requests per second. Use Throttling Tab on Driver UI to set delay after each request.\r\n
2D Array Transformation<\/strong><\/h3>\r\nIf you are using JSON or XML API Driver then possible you may have to transform your data using 2D array transformation feature. Check this link<\/a> for more information.\r\n\r\n <\/div>\n
REST API \/ XML SOAP Performance Tips for Tableau<\/h2>\n
Use Server-side filtering if possible in URL or Body Parameters<\/strong><\/span><\/h4>\r\nMany API supports filtering your data by URL parameters or via Body. Whenever possible try to use such features.\u00a0 Here is an example of odata\u00a0API<\/a>, In the below query the first query is faster than the second query because\u00a0in the first query we filter at the\u00a0server.\r\n
SELECT * FROM value\r\nWITH(\r\n\t Src='https:\/\/services.odata.org\/V3\/Northwind\/Northwind.svc\/Customers?$format=json&$filter=Country eq ''USA'''\r\n\t,DataFormat='Odata'\r\n)\r\n\r\n-- Slow query - Client-side filtering\r\nSELECT * FROM value\r\nWHERE Country ='USA'\r\nWITH(\r\n\t Src='https:\/\/services.odata.org\/V3\/Northwind\/Northwind.svc\/Customers?$format=json'\r\n\t,DataFormat='Odata'\r\n)<\/pre>\r\n
Avoid Special features in SQL Query (e.g. WHERE, Group By, Order By)<\/strong><\/span><\/h4>\r\nZappySys API engine triggers client-side processing\u00a0if special features are used in Query. Following SQL Features will trigger Client-Side processing which is several times slower than server-side processing. So always try to use simple query (Select col1, col2 ....\u00a0from mytable\u00a0)\r\n
\r\n \t
Consider using pre-generated Metadata \/ Cache File<\/strong><\/span><\/h4>\r\nUse META option in WITH Clause to use static metadata (Pre-Generated)There are two more options to speedup query processing time. Check this article<\/a> for details.\r\n
\r\n \t
select * from value WITH( meta='c:\\temp\\meta.txt' )\r\n--OR--\r\nselect * from value WITH( meta='my-meta-name' )\r\n--OR--\r\nselect * from value WITH( meta='[ {\"Name\": \"col1\", \"Type\": \"String\", Length: 100}, {\"Name\": \"col2\", \"Type\": \"Int32\"} ...... ]' )<\/pre>\r\n<\/li>\r\n \t