I am building a java REST APIs based website whose function is to connect to any user entered database and get the schemas, tables, indexes etc and the user can pick whatever schemas / tables / indexes they want and send to another system.
So the site takes the database details, then shows the schemas - user selects the schemas they need- then the site brings back the corresponding tables etc. So in the backend I have separate calls for getting schema/tables/indexes.
I am using plain JDBC calls in the server to do this. Each time I am opening the connection, getting the metadata(schema/table/index), closing the connection. I think performance can be improved if I keep the database connection open between requests.
Since the database details are dynamic and each user is connecting to a different database,I cannot use the connection pool facility provided in the (play) framework. Is there a better way to do this? Thanks in advance!
I am using play framework 2.x with Angular JS.
You can use a singleton or static Map of JDBC DataSource and get the connexion from it. The datasource will manage the connexion pull.
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So i have a problem. Currently my application connects with single database and supports multi user. So for different landscapes, we deploy different application all together.
I need a solution that my application remains the same (single WAR deployment) but is able to connect to different DB across different landscapes.
For example a user in UK is using same application but underlying DB is in UK and subsequently another user logs in from Bangladesh and he sees the data of DB schema for Bangladesh and so on.
Currently we are creating JDBC connections in a connection pool created out of java and taking the same through out the application. Also we load static datas in hashmaps during the start up of server. But the same would not be possible with multiple DB since one would overwrite the other static data.
I have been scratching here and there , If some one can point me in the right direction, would be grateful.
You have to understand that your application start up and a user's geography are not connected attributes. You simply need to switch / pick correct DB connection while doing CRUD operations for a user of a particular geography.
So in my opinion, your app's memory requirement is going to be bigger now ( than previous ) but rest of set up would be simple.
At app start up, You need to initialize DB Connection pools for all databases and load static data for all geographies and then use / pick connection & static data as per logged in user's geography.
There might be multiple ways to implement this switching / choosing logic and this very much dependent on what frameworks & libraries you are using.
I am intending to have a console on my web app so I can run queries directly from my browser. I can only find guides on how to connect the h2console to an in-memory DB instance. Is this possible? Security isn't an issue, this is strictly for testing purposes, only my ip address will be allowed to connect to the site (for now).
I think you are confusing some things here: h2 is an in-memory-database. There is NO persistent storage. MySQL is a proper RDBMS. I would not expect you to be able to connect to mysql through that interface.
If you just need to be able to execute queries from your web application, and it is not going to go public, simply create a page with a textarea, send that to the backend using JDBC. If I have misunderstood your question, please add additional details to it so we cn provide a better answer.
We have a command and control system which persists historical data in a database. We'd like to make the system independent of the database. So if the database is there, great we will persist data there, if it is not, we will do some backup storage to files and memory until the database is back. The command and control functionality must be able to continue uninterrupted by the loss or restoration of the database; it should not even know the database exists. So the database and DAO functionality needs to be decoupled from the rest of the application.
We are using RESTful service calls, Spring framework, ActiveMQ, JDBCTemplate with SQL Server database. Currently following standard connection practices using Hikari datasource and JTDS driver. The problem is that if the database goes down or the database connection is lost we start to have data issues as too many service calls (mainly the getters) are still too dependent on the database existence for processing. This dependence is what we'd like to eliminate.
What are the best practices/technologies for totally decoupling the database from the application? We are considering using AMQ to broadcast data updates and have the DAO listen for those messages and then do the update to the database if it is available or flat files as a backup. Then for the getters, provide replies based on what is available either from the actual database or from the short-term backup.
My team has little experience with this and we want to know what others have done that works well.
I have seen many solutions which all make you first configure statically via XML the different datasources and then use AbstractRoutingDataSource to return back a key which you consume while defining the datasource.
As here: dynamic datasource routing
But my case is different. I dont know how many databases there could be in my web application. I am building an app where each user uploads a small h2 db dump from a desktop app. The web app will download the h2 db dump and then connect to it.
So to make things simple to understand. Each user will have his/her own database file that I need to connect to once the user logs in. Since the number of users are not fixed, I dont know how many databases I will need to connect to, hence I cannot statically configure them in an XML file.
How to go about doing this in Spring? Also, not sure if it helps, these h2 dbs are read only. I am not going to write to them.
This is my configuration.
Maven, Spring MVC, JOOQ, H2 DBs
If you like to change the database changes dynamically, you have to write the UI for database source information and set to the spring config files in version-4.0.
I'm using JDBC to connect to a PostgreSQL database. We are trying to block access to the database for the users themselves; instead they should be forced to use our frontend. We blocked access to any table, and gave only procedures, which do all the work for users, still not giving them any opportunity to access data directly. We tried to block access to schema pg_catalog, which limits users to procedures we created, but it seems that this access is needed for JDBC to call any procedure.
Anyway, the question is either how to use JDBC without access to pg_catalog, or how to authorize only connections made by application, not user.
There is no fool proof way but the simplest is to use a username and password for the connection that you do not give to your users. Store the password in an encrypted configuration file. Ofcourse the encryption key can be retrieved from the application by a smart person.
For a really save system it would probably be best to put a service in front of the database that handles all security and provides a high level API to access the data and let the client connect to this.
The DBMS is being presented with a Catch-22 situation:
When a user runs a specific JDBC program to access the database, let it do its stuff.
When a user runs any other JDBC program to access the database, do not let it do its stuff.
How can the DBMS tell the difference between the two programs? As far as it is concerned, they are both clients that are using the correct protocol to communicate with the DBMS, and have identified themselves as a legitimate user of the database.
To make it work, you have to find a non-subvertible way to distinguish between the two applications. That is not trivial - to say the least.
There are kludges, but there isn't a clean solution. It is a generic problem that any DBMS faces when the problem is presented as in the question.
Well, just don't give your users an account on your postgresql database and create only an postgresql account for your application.