Web Applications

The database instances are not thread-safe, so each thread needs a own instance. All the database instances will share the same connection to the storage for the same URL. For more information look at Java Multi threads and databases.

Java WebApp runs inside a Servlet container with a pool of threads that work the requests.

There are mainly 2 solutions:

  • Manual control of the database instances from Servlets (or any other server-side technology like Apache Struts Actions, Spring MVC, etc.)
  • Automatic control using Servlet Filters

Manual control

Graph API

  1. package com.orientechnologies.test;
  2. import javax.servlet.*;
  4. public class Example extends HttpServlet {
  5.   public void doGet(HttpServletRequest request,
  6.                     HttpServletResponse response)
  7.         throws IOException, ServletException
  8.   {
  9.     OrientBaseGraph graph = new OrientGraph("plocal:/temp/db", "admin", "admin");
  11.     try {
  12.      // USER CODE
  14.     } finally {
  15.       graph.shutdown();
  16.     }
  17.   }
  18. }

Document API

  1. package com.orientechnologies.test;
  2. import javax.servlet.*;
  4. public class Example extends HttpServlet {
  5.   public void doGet(HttpServletRequest request,
  6.                     HttpServletResponse response)
  7.         throws IOException, ServletException
  8.   {
  9.     ODatabaseDocumentTx database = new ODatabaseDocumentTx("plocal:/temp/db").open("admin", "admin");
  11.     try {
  12.      // USER CODE
  14.     } finally {
  15.       database.close();
  16.     }
  17.   }
  18. }

Automatic control using Servlet Filters

Servlets are the best way to automatise database control inside WebApps. The trick is to create a Filter that get a reference of the graph and binds it in the current ThreadLocal before to execute the Servlet code. Once returned the ThreadLocal is cleared and graph instance released.

JaveEE Servlets

Create a Filter class

Filter with Graph API

In this example a new graph instance is created per request, opened and at the end closed.

  1. package com.orientechnologies.test;
  2. import javax.servlet.*;
  4. public class OrientDBFilter implements Filter {
  6.   public void doFilter(ServletRequest request, ServletResponse response,
  7.           FilterChain chain) {
  8.       OrientBaseGraph graph = new OrientGraph("plocal:/temp/db", "admin", "admin");
  9.       try{
  10.         chain.doFilter(request, response);
  11.       } finally {
  12.         graph.shutdown();
  13.       }
  14.   }
  15. }

Filter with Document API

In this example a new graph instance is created per request, opened and at the end closed.

  1. package com.orientechnologies.test;
  2. import javax.servlet.*;
  4. public class OrientDBFilter implements Filter {
  6.   public void doFilter(ServletRequest request, ServletResponse response,
  7.           FilterChain chain) {
  8.       ODatabaseDocumentTx database = new ODatabaseDocumentTx("plocal:/temp/db").open("admin", "admin");
  9.       try{
  10.         chain.doFilter(request, response);
  11.       } finally {
  12.         database.close();
  13.       }
  14.   }
  15. }

Register the filter

Now we’ve create the filter class it needs to be registered in the web.xml file:

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <web-app xmlns="http://java.sun.com/xml/ns/j2ee"
  3.          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.          xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
  5.          http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
  6.          version="2.4">
  7.   <filter>
  8.     <filter-name>OrientDB</filter-name>
  9.     <filter-class>com.orientechnologies.test.OrientDBFilter</filter-class>
  10.   </filter>
  11.     <filter-mapping>
  12.       <filter-name>OrientDB</filter-name>
  13.       <url-pattern>/*</url-pattern>
  14.     </filter-mapping>
  15.     <session-config>
  16.       <session-timeout>30</session-timeout>
  17.     </session-config>
  18. </web-app>