boSession & EboContext

Each time a user logs to a XEO application a boSession instance is created to represent the session of the user whithin the application

boSession

The boSession instance

When using XEO's Web Component Layer, the login is made through a web form which will automatically create a boSession instance for the user (and EboContext instances as well), so there's usually no need to explicitely create boSession instances, unless you're creating a custom JSP/Servlet and need to programatically connect to the XEO Application.

EboContext

Every request made to a XEO Application to load/create boObject instances must be contained in a context. EboContext is the class that implements that "context" and is where instances of boObjects are stored wheneved they are created/loaded. EboContext is also the place where transactional control can happen (there's another alternative in boObject (getUpdateQueue).Transactions created by using EboContext methods are JTA ( Java Transactional API) transactions which means you can mix DML statements with your object creation and update inside a transaction and commit on success/rollback on failure, see an example bellow.

EboContext instances are generally created by the XEO Runtime and can be accessed from several places, such as from any instance of a boObject throught the getEboContext() method. If you recall from the methods generated by XEO Studio for the required/defaultValue and such methods, one of the parameters was the boObject instance. Bellow, see the table of important methods in the EboContext class.

Method Name	Description	Parameters	Return type	Notes
beginContainterTransaction	Initiates a JTA Transaction, this is the prefered method if you want to mix database DML statements with Object updates	-	void
commitContainerTransaction	Commits a previously created JTA transaction (initiated with beginContainerTransaction)	-	void
rollbackContainerTransaction	Rollback of a previously created JTA transaction (initiated with beginContainerTransaction)	-	void
close	Closes the current context	-	void	It's very important to close an open context whenever you don't need one as each context has an open data conection associated.
getConnection	Retrieves a JDBC database connection (allows to make queries to the database)	-	java.sql.Connection
setModeBatch	Sets the context to operate in batch mode (turns events and validations off)	-	void	Can be usefull to process large batches of instances, since it disables events and validations
setModeBatch	Sets the context to operate in batch mode, acceppts a parameter to indicate the type of batch being used (validate objects, execute certain events, etc...)	int mode	void	See above

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Safe Ebo Context Usage Example

        boSession session = null;
        EboContext context = null;
        boApplication xeoApp = boApplication.getDefaultApplication();
        try {
                session = xeoApp.boLogin("USERNAME", "PASSWORD");        
                context = xeoApp.createContext(session);
                  
                //Your code in here

        } catch (Exception e) {
                 //Process the exception in case of error
        } finally {
            if (context!=null)
                context.close();
            if (session!=null)
                session.closeSession();
        }

Using JTA Transactions Example

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//Declare variables
        boApplication app = null;
        boSession session = null;
        EboContext ctx = null;
        
        try{
                //Get the application instance
                app = boApplication.getDefaultApplication();
                //Login a user
                session = app.boLogin("SYSUSER", "ABC");
                //Create a context
                ctx = app.createContext(session);
        
                //Start Transaction 
                ctx.beginContainerTransaction();
            
                try{
                    
                    //Create Object, set an attribute and save
                    boObject obj = app.getObjectManager().createObject(ctx, "MyObj");
                    obj.getAttribute("att").setValueString("foo");
                    obj.update();
                    
                    //Make a DML statement to insert some values in database
                    Connection conn = null;
                    Statement stmt = null;
                    
                    //Retrieve the connection and execute the query
                    conn = ctx.getConnectionData();
                    stmt = conn.createStatement(
                            ResultSet.TYPE_SCROLL_SENSITIVE,
                            ResultSet.CONCUR_READ_ONLY);
                    stmt.executeQuery("INSERT INTO MY_TABLE VALUES('foo','bar')");
                    
                    //Commit the changes
                    ctx.commitContainerTransaction();
                }
                catch (Exception e){
                    //If anything goes wrong roll back the transaction
                    ctx.rollbackContainerTransaction();
                }
        }
        catch (boRuntimeException e ){
            //Deal with the exception during execution
        } catch (boLoginException e) {
            // Deal with login exception 
        }finally{
            //Close all used resources
            if (ctx != null) ctx.close();
            if (session != null) session.closeSession();
        }

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