Hi Rainer,
thanks for pointing me to 'Empire-Struts2 Example Application'. Will look at this, but provided
descrition seems to be obvious.
Anothoner question :-) In FAQ is said, that there is schema migration available. How does it
work/can be used? Does it work automticly in some way or is there any docs about it?
Thanks once again,
David
Rainer Döbele wrote:
Hi David,
in a web-application you should ideally work with connection pooling, which is
usually done by the application server (i.e. Apache-Tomcat).
We recommend the following:
1. create an Application object which is instantiated and initialized once when
the web-application is loaded in the web application server. This can be done
via a custom filter class registered in the web.xml definition file of your
web-application. The application object is a singleton.
2. use a JNDI context to access a datasource provided by the application
server. When initializing your application obtain a Connection from the data
source and initialize your DB-Objects (create the driver, open the database,
check the schema, etc.)
3. for each request, obtain a connection from the pool which you can then pass
to the appropriate Empire-db function. When the request finished close the
connection which will effectively return it to the pool.
I recommend downloading and looking at our Empire-Struts2 Example Application
called DBWebSample provided with the distribution of the
empire-struts2-extentions. Even if you don't intend to use Struts2 as your web
application framework it gives a good idea on how to use Empire-db in a web
application. You should particularly look the init() method of the
SampleApplication class. However the sample application does not implement
connection pooling - but it can be easily added.
Hope this is the kind of answer you expected.
Regards
Rainer
David Marko wrote:
Hello,
can anyone share some common scenario on how to initialise necessary
things in web application using
e.g. SpringFramework?
##### Using the code from the EmpireDB Site:
config.init((args.length > 0 ? args[0] : "config.xml"));
// STEP 1: Get a JDBC Connection
Connection conn = getJDBCConnection();
In step two the sample creates and initializes a database driver object
for the target DBMS. This is
HSQLDB by default.
// STEP 2: Choose a driver
DBDatabaseDriver driver = getDatabaseDriver(config.getDatabaseProvider());
Then in step three the database object is opened using the driver. Only
when opened, other methods
of the database object may be used. Finally we check whether or not our
database objects exist.
// STEP 3: Open Database and check if tables exist
db.open(driver, conn);
databaseExists(conn);
In order to check existence of the database the sample simply performs a
query on the Departments
table ("select count(*) from DEPARTMENTS") using the following code:
DBCommand cmd = db.createCommand();
cmd.select(db.DEPARTMENTS.count());
db.querySingleInt(cmd.getSelect(), -1, conn);
###
... should/can be the conn and db initialised using some singleton pattern
and used within the
application in this way?
Thanks for info,
David
