Monday, July 9, 2012

OSGi Services

Full system(carbon core + products) is built as a combination of OSGi bundles. Some of theses bundles expose services at OSGi level. I have to use them to get the tenant usage plan.

There is a service in manager which gives the usage plan of the tenant. To use it first I have to catch them, unluckily those manager component that is needed for the service it not there in the DSS, so we have to add them to DSS temporary as a feature. core and mgt are placed in DSS as a feature. First we thought is putting those to into droppings. But it didn't work as mgt package tried to start before core which is not possible as it requires core. Because of that we have to make it as a feature.

After putting them we have catch that service. Those are normally catches at serviceComponents(one class with 'activate' method). Below is how I did it. There are some methods that is used to bind and unbind the service objects we have to have them where we catch the service

I added the osgi comments as below  
 * @scr.component name="org.wso2.carbon.rssmanager" immediate="true" 
 * @scr.reference name="default.tenant.billing.service" 
 *                interface="org.wso2.carbon.stratos.common.TenantBillingService" 
 *                cardinality="1..1" policy="dynamic" 
 *                bind="setTenantBillingService" 
 *                unbind="unsetTenantBillingService" 
 * @scr.reference name="user.realmservice.default" 
 *                  interface="org.wso2.carbon.user.core.service.RealmService" 
 *                  cardinality="1..1" policy="dynamic" 
 *                  bind="setRealmService" 
 *                  unbind="unsetRealmService" 
then I added following methods
     * osgi bind method for RealmService 
     * @param tenantBillingService 
    protected void setRealmService(RealmService realmService) { 
        this.realmService = realmService; 

     * osgi unbind method for RealmService 
     * @param tenantBillingService 
    protected void unsetRealmService(RealmService realmService) { 
        this.realmService =null; 
     * returns a RealmService objects that is used to get the tenant list. 
     * @param tenantBillingService 
    private RealmService getRealmService() { 
        return realmService; 
After catching it I can use it as below,
        TenantManager tenantManager = getRealmService().getTenantManager(); 
        Tenant[] tenants; 
        try { 
            tenants = (Tenant[]) tenantManager.getAllTenants(); 
            for (int i = 0; i < tenants.length; i++) { 
               // check for each tenant 
        } catch (UserStoreException e1) { 
            // TODO Auto-generated catch block 
            System.out.println("realmService NULL"); 
Problems came across Service was not available in DSS First I tried to catch this in my own java class (not in RSSManagerServiceComponent) which was OK but was not the standard. Standard is to catch it in RSSManagerServiceComponent. Anyway it should work, on matter how we do it. In my case it didn't work for tenant.billing.service . Problem was same service (tenant.billing.service not realmservice) was caught in RSSManagerServiceComponent before coming in to my class. This is where I figured out the importance of that standard. Had to include lot of other jar files in droppings.

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