Spring MVC: Multiple dataSources: select DB schema based on user selection from UI - spring

Question

I'm working on a web app which works fine. But recently from management request we need to serve our web app to multiple teams. So what we decided is to create a separate copy of DB schema for each team.
Let's say our team uses TEAM_A schema & other team uses TEAM_B schema. Both DB schema's are exactly same only difference is data in them.
So I used AbstractRoutingDataSource in my application like this:
package com.company.app.utils.datasource;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
public class DynamicDataSource extends AbstractRoutingDataSource {
#Override
protected Object determineCurrentLookupKey() {
return TeamContextHolder.getTeamType();
}
}
And TeamContextHolder as:
package com.company.app.utils.datasource;
public class TeamContextHolder{
public static final String TEAM_A_DATA_SOURCE = "aTeamDataSource";
public static final String TEAM_B_DATA_SOURCE = "bTeamDataSource";
private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
public static void setTeamType(String teamType) {
contextHolder.set(teamType);
}
public static String getTeamType() {
return contextHolder.get();
}
public static void clearTeamType() {
contextHolder.remove();
}
}
Spring configuration file have below bean definition for data-sources:
<bean id="aTeamDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" >
<property name="url" value="jdbc:mysql://localhost.com:3306/TEAM_A?autoReconnect=true&verifyServerCertificate=false&useSSL=true" />
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="username" value="welcome" />
<property name="password" value="welcome" />
</bean>
<bean id="bTeamDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" >
<property name="url" value="jdbc:mysql://localhost.com:3306/TEAM_B?autoReconnect=true&verifyServerCertificate=false&useSSL=true" />
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="username" value="welcome" />
<property name="password" value="welcome" />
</bean>
<bean primary="true" id="dynamicDataSource" class="com.company.app.utils.datasource.DynamicDataSource" >
<property name="targetDataSources">
<map key-type="java.lang.String">
<entry value-ref="aTeamDataSource" key="aTeamDataSource"></entry>
<entry value-ref="bTeamDataSource" key="bTeamDataSource"></entry>
</map>
</property>
<property name="defaultTargetDataSource" ref="aTeamDataSource" >
</property>
</bean>
My home controller:
package com.company.app.web;
import org.apache.log4j.Logger;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.servlet.ModelAndView;
import java.util.HashMap;
import java.util.Map;
#Controller
#SessionAttributes("team")
public class Home {
/**
* Logger
*/
private static final Logger logger = Logger.getLogger(Home.class);
#RequestMapping(value="/home")
public ModelAndView mainHomePage() {
logger.info("Landing on main home page");
Map<String, Object> model = new HashMap<>();
return new ModelAndView("/home", "model", model);
}
#RequestMapping(value="/setteam")
public ModelAndView rememberTeam(#RequestParam String product) {
logger.info("Setting product info: " + product);
Map<String, Object> model = new HashMap<>();
model.put("team", team);
return new ModelAndView("/home", "model", model);
}
}
From home controller, I'm passing team session variable to other controllers via JSP file.
My home.jsp has below form:
<form action="./setproduct" method="POST" class="p-a-4">
<fieldset class="page-signup-form-group form-group form-group-lg">
<select class="page-signup-form-control form-control" id="grid-input-lg-2" name="product">
<option value="Not selected">Not selected</option>
<option value="TEAM_A">TEAM_A</option>
<option value="TEAM_B">TEAM_B</option>
</select>
</fieldset>
<button type="submit" class="btn btn-block btn-lg btn-primary m-t-3">Submit</button>
</form>
And then finally I'm setting datasource to use in my DaoImpl classes as:
if (filters.getTeam().equalsIgnoreCase("TEAM_B")){
TeamContextHolder.setTeamType(TeamContextHolder.TEAM_B_DATA_SOURCE);
}
And it works as expected as I thought. But blown in production as all the time TEAM_B datasource is selected.
So my questions:
Is it possible the on single tomcat webserver (where we deployed our
app) few users can select TEAM_A and work with TEAM_A_DATA_SOURCE
and few users select TEAM_B and work with TEAM_B_DATA_SOURCE?
Initially I thought it is doable but after this kaboom on production
I'm not sure if it's possible in spring.
If it's NOT possible then
how should I handle my case where end users can select their teams
and work simultaneous on two different DB schema's on same web-app.

Answer 1

I resolved this issue by changing contextHolder from ThreadLocal to HttpSession, that way I was able to connect to a team's DB schema for a entire browser session. Also now I don't have to pass session variable to other controllers and no need to set datasource to use in my DaoImpl classes as I was doing earlier. So now my updated TeamContextHolder looks like this:
package com.company.app.utils.datasource;
import org.apache.log4j.Logger;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import javax.servlet.http.HttpSession;
public class TeamContextHolder {
private static final Logger logger = Logger.getLogger(TeamContextHolder.class);
public static HttpSession getCurrentSession() {
ServletRequestAttributes attr = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();
return attr.getRequest().getSession(true);
}
public static void setTeamType(String teamType) {
TeamContextHolder.getCurrentSession().setAttribute("team", teamType);
}
public static String getTeamType() {
logger.info("Session attribute product: " + TeamContextHolder.getCurrentSession().getAttribute("team"));
return (String) TeamContextHolder.getCurrentSession().getAttribute("team");
}
}
Session variable is set from home controller as:
package com.company.app.web;
import org.apache.log4j.Logger;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.SessionAttributes;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import java.util.HashMap;
import java.util.Map;
#Controller
#SessionAttributes("team")
public class HomeController {
private static final Logger logger = Logger.getLogger(HomeController.class);
#RequestMapping(value="/home")
public ModelAndView home() {
logger.info("Landing on main home page");
Map<String, Object> model = new HashMap<>();
return new ModelAndView("/home", "model", model);
}
#RequestMapping(value="/setteam")
public ModelAndView setteam(#RequestParam String team,
HttpServletRequest request) {
// Setting session attribute:
request.getSession().setAttribute("team", team);
logger.info("Setting team: " + team);
Map<String, Object> model = new HashMap<>();
model.put("team", team);
return new ModelAndView("/home", "model", model);
}
}

Answer 2

You can have multiple entity managers which will be scanning the different set of repositories and you can switch those entity managers depending upon your cookie.