REST API Connector for JAVA

In this article you will learn how to integrate REST API data in JAVA (live / bi-directional connection to REST API). REST API Connector can be used to extract and output JSON/XML/CSV/String data coming from REST API web service calls (Web URL)..

Using REST API Connector you will be able to connect, read, and write data from within JAVA. Follow the steps below to see how we would accomplish that.

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If your API is JSON Type and responding the json string response, in that case using ZappySys JSON Driver we can make the JSON API call and parse the json string. Let's configure the API call in the JSON Driver

Create Data Source in ZappySys Data Gateway based on JSON Driver

  1. Download and install ZappySys ODBC PowerPack.

  2. Search for gateway in start menu and Open ZappySys Data Gateway:
    Open ZappySys Data Gateway

  3. Go to Users Tab to add our first Gateway user. Click Add; we will give it a name tdsuser and enter password you like to give. Check Admin option and click OK to save. We will use these details later when we create linked server:
    ZappySys Data Gateway - Add User

  4. Now we are ready to add a data source. Click Add, give data source a name (Copy this name somewhere, we will need it later) and then select Native - ZappySys JSON Driver. Finally, click OK. And it will create the Data Set for it and open the ZS driver UI.

    ZappySys Data Gateway - Add JSON Data Source

  5. Select Url or File and paste the following Url for this example OR you can load existing connection string as per this article.

    NOTE: Here for demo, We are using odata API, but you need to refer your own API documentation and based on that you need to use your own API URL and need to configure connection based on API Authentication type

  6. Now enter JSONPath expression in Array Filter textbox to extract only specific part of JSON file as below ($.value[*] will get content of value attribute from JSON document. Value attribute is array of JSON documents so we have to use [*] to indicate we want all records of that array)

    NOTE: Here, We are using our desired filter, but you need to select your desired filter based on your requirement.


    Click on Test Connection button to view whether the Test Connection is SUCCESSFUL or Not.

    $.value[*]
    ZappySys ODBC Driver - Configure JSON Driver
  7. Once you configured a data source, you can preview data. Hit Preview tab, and use similar settings to preview data:
    ZappySys ODBC Driver - Preview JSON Driver

  8. Click OK to finish creating the data source

  9. That's it; we are done. In a few clicks we configured the call to JSON API using ZappySys JSON Connector.

In upper section we check how to make the JSON API call using JSON Driver and parse the json string response. Same way if your API is XML/SOAP Type and responding the xml string response, in that case using ZappySys XML Driver we can make the XML/SOAP API call and parse the xml string. Let's configure the API call in the XML Driver.

Create Data Source in ZappySys Data Gateway based on XML Driver

  1. Download and install ZappySys ODBC PowerPack.

  2. Search for gateway in start menu and Open ZappySys Data Gateway:
    Open ZappySys Data Gateway

  3. Go to Users Tab to add our first Gateway user. Click Add; we will give it a name tdsuser and enter password you like to give. Check Admin option and click OK to save. We will use these details later when we create linked server:
    ZappySys Data Gateway - Add User

  4. Now we are ready to add a data source. Click Add, give data source a name (Copy this name somewhere, we will need it later) and then select Native - ZappySys XML Driver. Finally, click OK. And it will create the Data Set for it and open the ZS driver UI.

    ZappySys Data Gateway - Add XML Data Source

  5. Select Url or File and paste the following Url for this example OR you can load existing connection string as per this article.

    NOTE: Here for demo, We are using odata API, but you need to refer your own API documentation and based on that you need to use your own API URL and need to configure connection based on API Authentication type

  6. Now enter Path expression in Array Filter textbox to extract only specific part of XML file as below ($.feed.entry[*] will get content of entry attribute from XML document. Entry attribute is array of XML documents so we have to use [*] to indicate we want all records of that array)

    NOTE: Here, We are using our desired filter, but you need to select your desired filter based on your requirement.


    Click on Test Connection button to view whether the Test Connection is SUCCESSFUL or Not.

    $.feed.entry[*]
    ZappySys ODBC Driver - Configure XML Driver
  7. Once you configured a data source, you can preview data. Hit Preview tab, and use similar settings to preview data:
    ZappySys ODBC Driver - Preview XML Driver

  8. Click OK to finish creating the data source.

  9. That's it; we are done. In a few clicks we configured the call to XML API using ZappySys XML Connector.

In upper section we check how to make the XML/Soap API call using XML Driver and parse the xml string response. Same way if your API is csv Type or want to parse the CSV file data, in that case using ZappySys CSV Driver we can make the API call or read the CSV file data.

Create Data Source in ZappySys Data Gateway based on CSV Driver

  1. Download and install ZappySys ODBC PowerPack.

  2. Search for gateway in start menu and Open ZappySys Data Gateway:
    Open ZappySys Data Gateway

  3. Go to Users Tab to add our first Gateway user. Click Add; we will give it a name tdsuser and enter password you like to give. Check Admin option and click OK to save. We will use these details later when we create linked server:
    ZappySys Data Gateway - Add User

  4. Now we are ready to add a data source. Click Add, give data source a name (Copy this name somewhere, we will need it later) and then select Native - ZappySys CSV Driver. Finally, click OK. And it will create the Data Set for it and open the ZS driver UI.

    CSVDSN
    Native - ZappySys CSV Driver
    ZappySys Data Gateway - Add CSV Data Source

  5. Select Url or File.

    Read CSV API in JAVA

    • Paste the following Url. In this example, We are using Zip format CSV File URL, but you need to refer your CSV File/URL.

      https://zappysys.com/downloads/files/test/cust-1.csv.zip
      Click on Test Connection button to view whether the Test Connection is SUCCESSFUL or Not. ZappySys ODBC Driver - Configure CSV Driver

    Read CSV File in JAVA

    • You can use pass single file or multiple file path using wildcard pattern in path and you can use select single file by clicking [...] path button or multiple file using wildcard pattern in path.

      Note: If you want to operation with multiple files then use wild card pattern as below
      (when you use wild card pattern in source path then system will treat target path as folder regardless you end with slash)
      
      C:\SSIS\Test\reponse.csv (will read only single reponse.csv file)
      C:\SSIS\Test\j*.csv (all files starting with file name j)
      C:\SSIS\Test\*.csv (all files with .csv Extension and located under folder subfolder)
      
      Click on Test Connection button to view whether the Test Connection is SUCCESSFUL or Not. ZappySys ODBC Driver - Configure CSV Driver

  6. Once you configured a data source, you can preview data. Hit Preview tab, and use similar settings to preview data:
    ZappySys ODBC Driver - Preview CSV Driver

  7. Click OK to finish creating the data source

  8. That's it; we are done. In a few clicks we configured the read the CSV data using ZappySys CSV Connector.

Read data in Java from the DSN

  1. Java code to get the data:

    "jdbc:sqlserver://localhost:5000;databasename=RestapiDSN;user=tdsuser;password=test"
    Java code to Make ZappySys Driver Data Source Call

  2. When you run the code it will make the API call and read the data:
    Java code ZappySys Driver Data Source Results

  3. Here is Java program's code in text format:

    
    //Step-1: Install ZappySys ODBC PowerPack and Configure Data Gateway
    
    //Step-2:Assuming the Microsoft SQL Server JDBC Driver is in below folder
    //C:\Program Files\Microsoft Jdbc Driver 6.0 for SQL Server\sqljdbc_6.0\enu\auth\x64
    package padaone;
    
    import java.sql.*;
    
    public class zappy {
    
        public static void main(String[] args) {
    
            // Create a variable for the connection string.
            String connectionUrl = "jdbc:sqlserver://localhost:5000;databasename=RestapiDSN;user=test;password=test";
    
            // Declare the JDBC objects.
            Connection con = null;
            Statement stmt = null;
            ResultSet rs = null;
    
                try {
                    // Establish the connection.
                    Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
                    con = DriverManager.getConnection(connectionUrl);
    
                    // Create and execute an SQL statement that returns some data.
                    String SQL = "SELECT Country , SUM(UnitPrice * Quantity) Total " 
                               + "FROM value " 
                               + "GROUP BY Country "
                               + "WITH (SRC='https://services.odata.org/V3/Northwind/Northwind.svc/Invoices?$format=json')";
                    stmt = con.createStatement();
                    rs = stmt.executeQuery(SQL);
    
                    // Iterate through the data in the result set and display it.
                    while (rs.next()) {
                        System.out.println(rs.getString(1) + " " + rs.getString(2));
                    }
                }
    
            // Handle any errors that may have occurred.
            catch (Exception e) {
                e.printStackTrace();
            } 
            
            finally {
                if (rs != null) try { rs.close(); } catch (Exception e) {}
                if (stmt != null) try { stmt.close(); } catch (Exception e) {}
                if (con != null) try { con.close(); } catch (Exception e) {}
            }
        }
    }

Configuring pagination in the REST API Driver

ZappySys REST API Driver equips users with powerful tools for seamless data extraction and management from REST APIs, leveraging advanced pagination methods for enhanced efficiency. These options are designed to handle various types of pagination structures commonly used in APIs. Below are the detailed descriptions of these options:

  1. Page-based Pagination: This method works by retrieving data in fixed-size pages from the Rest API. It allows you to specify the page size and navigate through the results by requesting different page numbers, ensuring that you can access all the data in a structured manner.

  2. Offset-based Pagination: With this approach, you can extract data by specifying the starting point or offset from which to begin retrieving data. It allows you to define the number of records to skip and fetch subsequent data accordingly, providing precise control over the data extraction process.

  3. Cursor-based Pagination: This technique involves using a cursor or a marker that points to a specific position in the dataset. It enables you to retrieve data starting from the position indicated by the cursor and proceed to subsequent segments, ensuring that you capture all the relevant information without missing any records.

  4. Token-based Pagination: In this method, a token serves as a unique identifier for a specific data segment. It allows you to access the next set of data by using the token provided in the response from the previous request. This ensures that you can systematically retrieve all the data segments without duplication or omission.

Utilizing these comprehensive pagination features in the ZappySys REST API Driver facilitates efficient data management and extraction from REST APIs, optimizing the integration and analysis of extensive datasets.

For more detailed steps, please refer to this link: How to do REST API Pagination in SSIS / ODBC Drivers

Authentication

ZappySys offers various authentication methods to securely access data from various sources. These authentication methods include OAuth, Basic Authentication, Token-based Authentication, and more, allowing users to connect to a wide range of data sources securely.

ZappySys Authentication is a robust system that facilitates secure access to data from a diverse range of sources. It includes a variety of authentication methods tailored to meet the specific requirements of different data platforms and services. These authentication methods may involve:

  1. OAuth: ZappySys supports OAuth for authentication, which allows users to grant limited access to their data without revealing their credentials. It's commonly used for applications that require access to user account information.

  2. Basic Authentication: This method involves sending a username and password with every request. ZappySys allows users to securely access data using this traditional authentication approach.

  3. Token-based Authentication: ZappySys enables users to utilize tokens for authentication. This method involves exchanging a unique token with each request to authenticate the user's identity without revealing sensitive information.

By implementing these authentication methods, ZappySys ensures the secure and reliable retrieval of data from various sources, providing users with the necessary tools to access and integrate data securely and efficiently. For more comprehensive details on the authentication process, please refer to the official ZappySys documentation or reach out to their support team for further assistance.

For more details, please refer to this link: ZappySys Connections

Advanced topics

Create Custom Stored Procedure in ZappySys Driver

You can create procedures to encapsulate custom logic and then only pass handful parameters rather than long SQL to execute your API call.

Steps to create Custom Stored Procedure in ZappySys Driver. You can insert Placeholders anywhere inside Procedure Body. Read more about placeholders here

  1. Go to Custom Objects Tab and Click on Add button and Select Add Procedure:
    ZappySys Driver - Add Stored Procedure

  2. Enter the desired Procedure name and click on OK:
    ZappySys Driver - Add Stored Procedure Name

  3. Select the created Stored Procedure and write the your desired stored procedure and Save it and it will create the custom stored procedure in the ZappySys Driver:
    Here is an example stored procedure for ZappySys Driver. You can insert Placeholders anywhere inside Procedure Body. Read more about placeholders here

    CREATE PROCEDURE [usp_get_orders]
        @fromdate = '<<yyyy-MM-dd,FUN_TODAY>>'
     AS
        SELECT * FROM Orders where OrderDate >= '<@fromdate>';
    

    ZappySys Driver - Create Custom Stored Procedure

  4. That's it now go to Preview Tab and Execute your Stored Procedure using Exec Command. In this example it will extract the orders from the date 1996-01-01:

    Exec usp_get_orders '1996-01-01';

    ZappySys Driver - Execute Custom Stored Procedure

  5. Let's generate the SQL Server Query Code to make the API call using stored procedure. Go to Code Generator Tab, select language as SQL Server and click on Generate button the generate the code.
    As we already created the linked server for this Data Source, in that you just need to copy the Select Query and need to use the linked server name which we have apply on the place of [MY_API_SERVICE] placeholder.

    SELECT * FROM OPENQUERY([MY_API_SERVICE], 'EXEC usp_get_orders @fromdate=''1996-07-30''')

    ZappySys Driver - Generate SQL Server Query

  6. Now go to SQL served and execute that query and it will make the API call using stored procedure and provide you the response.
    ZappySys Driver - Generate SQL Server Query

Create Custom Virtual Table in ZappySys Driver

ZappySys API Drivers support flexible Query language so you can override Default Properties you configured on Data Source such as URL, Body. This way you don't have to create multiple Data Sources if you like to read data from multiple EndPoints. However not every application support supplying custom SQL to driver so you can only select Table from list returned from driver.

If you're dealing with Microsoft Access and need to import data from an SQL query, it's important to note that Access doesn't allow direct import of SQL queries. Instead, you can create custom objects (Virtual Tables) to handle the import process.

Many applications like MS Access, Informatica Designer wont give you option to specify custom SQL when you import Objects. In such case Virtual Table is very useful. You can create many Virtual Tables on the same Data Source (e.g. If you have 50 URLs with slight variations you can create virtual tables with just URL as Parameter setting.

  1. Go to Custom Objects Tab and Click on Add button and Select Add Table:
    ZappySys Driver - Add Table

  2. Enter the desired Table name and click on OK:
    ZappySys Driver - Add Table Name

  3. And it will open the New Query Window Click on Cancel to close that window and go to Custom Objects Tab.

  4. Select the created table, Select Text Type AS SQL and write the your desired SQL Query and Save it and it will create the custom table in the ZappySys Driver:
    Here is an example SQL query for ZappySys Driver. You can insert Placeholders also. Read more about placeholders here

    SELECT
      "ShipCountry",
      "OrderID",
      "CustomerID",
      "EmployeeID",
      "OrderDate",
      "RequiredDate",
      "ShippedDate",
      "ShipVia",
      "Freight",
      "ShipName",
      "ShipAddress",
      "ShipCity",
      "ShipRegion",
      "ShipPostalCode"
    FROM "Orders"
    Where "ShipCountry"='USA'

    ZappySys Driver - Create Custom Table

  5. That's it now go to Preview Tab and Execute your custom virtual table query. In this example it will extract the orders for the USA Shipping Country only:

    SELECT * FROM "vt__usa_orders_only"

    ZappySys Driver - Execute Custom Virtual Table Query

  6. Let's generate the SQL Server Query Code to make the API call using stored procedure. Go to Code Generator Tab, select language as SQL Server and click on Generate button the generate the code.
    As we already created the linked server for this Data Source, in that you just need to copy the Select Query and need to use the linked server name which we have apply on the place of [MY_API_SERVICE] placeholder.

    SELECT * FROM OPENQUERY([MY_API_SERVICE], 'EXEC [usp_get_orders] ''1996-01-01''')

    ZappySys Driver - Generate SQL Server Query

  7. Now go to SQL served and execute that query and it will make the API call using stored procedure and provide you the response.
    ZappySys Driver - Generate SQL Server Query

Conclusion

In this article we discussed how to connect to REST API in JAVA and integrate data without any coding. Click here to Download REST API Connector for JAVA and try yourself see how easy it is. If you still have any question(s) then ask here or simply click on live chat icon below and ask our expert (see bottom-right corner of this page).

Download REST API Connector for JAVA Documentation 

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