It used to be that you could use Connector/MXJ to embed a MySQL Database in to a Java Application, however the Connector/MXJ project has been EOL'd by Oracle (thanks Larry) so I am looking for the best way to accomplish my goal.
Our application ships with an embedded Tomcat and JRE and we would like to embed the MySQL database as well (don't ask if we can use some other database engine - it has to be MySQL). I can't find any good documentation or answers on the best way to do this so here are the thoughts that I have come up with:
Simply launch the executable to startup mysqld as part of the application's startup script
Write/Use a JNI wrapper around libmysqld to startup the server at application start and stop it at application stop (this would be the preferred method)
For the second (preferred) option, I don't think writing a JNI wrapper around the libmysqld calls would be too difficult, however I am wondering if that would even work since libmysqld only provides access to code running in the same process (no named pipes or tcp access). Would a process kicked off within a running java app allow the parent application to access the database?
Perhaps try this. It's for MariaDB, which may be ok, or it might even work with MySQL since they should be largely compatible.
https://github.com/vorburger/MariaDB4j
Related
I am in a situation where I am being asked to make a single WAR file that runs Wordpress. Using Quercus, Tomcat and httpd+mod_rewrite I was able to make a WAR file containing everything except the database, which I ran externally. However, I'm not sure how I might go about removing the dependency upon an external database (and, frankly, this whole endeavor seems like a bad idea to me).
This article describes how Wordpress has been successfully deployed on the Google App Engine and hence without needing MySQL, but this was done using JPA.
Instead of embedding a MySQL instance, if I could use an external MSSQL database connection instead that would be fine too. (This is an old post, but it seems to suggest that real MySQL is the only supported database for Wordpress.) Is the most viable option to attempt to replace each MySQL call in the Wordpress source code to a MSSQL call? Is there some kind of compatibility/translation layer that I could use instead? (I saw this question, but the solution will not work in my case.)
UPDATE: I came across MySQL-JE, but it looks out of date and not quite complete enough (not sure how I would tell Quercus/PHP to communicate with it). Has anyone used it? If so, do you think it would help solve this problem?
Embedded Database
According to this chart, MySQL is not built for embedded use.
I can point you to two pure Java database engines for embedding in a Java app. Both are open-source, free of cost, and under active development. Both have a good pedigree with a long line of database development history behind them.
H2
Derby
WordPress Requires MySQL
According to this WordPress Requirements page, specifically MySQL is required. That's annoying. The main point of SQL is to avoid database-vendor lock-in.
I have a jar file which contains two Java classes. Using the javamail API I have developed these classes to read and edit my mail, then send to another mail id.
I am able to execute this through my standalone system via Eclipse. Now I want to host this jar file somewhere remotely so that it would fetch the data in real time and execute the job regularly. I have contacted couple of hosting sites and they are saying that they require a war file instead.
Does anyone have any suggestions to this problem?
To give you another point of view and to be constructive, I would go with embedding your jar into a war application and you get some things for free, the most important I think is that you gain a managed application lifecycle so with a standard web application context listener you can start and stop your program in a managed way. Besides you have more hosting options and it is less work.
Good luck with that.
As I don't know of any services specifically for plain execution of executables, your best bet is probably getting a cheap VPS. With some searching you can probably find one that would work for around $5 USD/month. For a single simple app you'd only need around 128MB of memory.
Pick one up, install Java (whatever Linux distro you get probably has OpenJDK in the repositories), copy your files over, and set up a cron job to run the executable at a set interval.
For easier administration, install something like webmin and use that to configure the cron job. The command would likely just be java -jar /path/to/my/App.jar, and you can use the web interface to configure the intervals for the command to be executed.
For an app like this, I would avoid anything related to a war file. You aren't making an application with a web interface (like a PHP app or some such) so it really wouldn't be appropriate. You would have to write some extra code to make it compatible with a container like Tomcat, and on top of that the memory requirements for running the application server would be a lot higher.
Problem: I have a standalone Java app (henceforth known as "the agent") that runs as a service on internal company servers. It acts as a remote agent for some central servers. As the agent gets deployed in more places, managing them is getting more complicated. Specifically: pushing updates is painful because it's a fairly manual process, and getting access to the logs and other info about the environments where the agents are running is problematic, making debugging difficult. The servers under discussion are headless and unattended, meaning that this has to be a fully automated process with no manual intervention, hence Java Web Start isn't a viable solution.
Proposed solution: Make the agent phone home (to the central servers) periodically to provide agent status and check for updates.
I'm open to other suggested solutions to the problem, but I've already got a working prototype for the "status and self-updates" idea, which is what this question is focused on.
What I came up with is actually a separate project that acts as a wrapper for the agent. The wrapper periodically calls the central server via HTTP to check for an updated version of the agent. Upon finding an update, it downloads the new version, shuts down the running agent, and starts the new one. If that seems like an odd or roundabout solution, here are a few other considerations/constraints worth noting:
When the wrapper gets a new version of the agent, there may be new JAR dependencies, meaning class path changes, meaning I probably want to spawn a separate Java process instead of fiddling with ClassLoaders and running the risk of a permanent generation memory leak, which would require manual intervention--exactly what I'm trying to get away from. This is why I ended up with a separate, "wrapper" process to manage the agent updates in my prototype.
Some servers where the agents are deployed are resource-limited, so any solution needs to be low on CPU and memory usage. That makes me want a solution that doesn't involve spinning up a new JVM and is a stroke against having a separate wrapper process.
The agent is already deployed to both Windows and RHEL servers, so the solution must be cross-platform, though I wouldn't have a problem duplicating a reasonable amount of the process in batch and bash scripts to get things rolling.
Question: As stated, I want to know how to make a self-updating Java app. More specifically, are there any frameworks/libraries out there that would help me with this? Can someone with experience in this area give me some pointers?
If your application is OSGi based, you could let OSGi handle bundle updates for you. It is similar to the wrapper approach you suggest, in that the OSGi container itself is "the wrapper" and some of it won't be updated. Here's a discussion on this
Different solution: use (and pay for) install4j. Check out the auto-update features here
No need for wrapper (save memory) or java web start (adds more restrictions on your application), simply let a thread in you application check periodically for updates (e.g. from cloud) and download updates if available, then code these two calls in you application:
launch a shell script (.sh or .cmd) to update your artifacts and launch your application after few seconds pause in the script(to avoid having two instances of your application at the same time).
Terminate your application (first instance)
The script can overwrite needed artifacts and re-launch your application.
enjoy !
Have a look at Java Web Start.
It is technology that's been part of Java since... 1.5? maybe 1.4? and allows deployment and install of standalone Java-based apps through a web browswer. It also enables you to always run the latest app.
http://www.oracle.com/technetwork/java/javase/overview-137531.html
http://en.wikipedia.org/wiki/JNLP#Java_Network_Launching_Protocol_.28JNLP.29
also see this question: What's the best way to add a self-update feature to a Java Swing application?
It appears as though Webstart is the only built in way to do this at the moment.
Recently I made an application in using Swing, AWT and JDBC that manages some database. I used PostgreSQL as the backend with JDBC drivers to connect to the database. What I want to do is create a setup/installer program so that the application can be installed and used on any pc. My problem is I dont know how to integrate the database along?
Any help would be appreciated.
Take a lesson from most commercial applications that have a database component. Usually they require that the database be installed/configured beforehand and provide db scripts for their supported vendors. There are a lot of reasons for this. Most of these are related to the fact that organization's like to manage their own databases. This is often because they have company restrictions regarding security, maintenance, etc. Also a single database process may be shared between many different programs(if you install two instances of your application do you want to have to two installations of the database?).
Most folks(especially network admins) wouldn't want an application that ran around installing rogue DMBS's on their machine.
I wouldn't spend a ton of time attempting to install the database during your install process. Why re-invent the wheel when the vendor has already created an installation process for you? Instead install the database ahead of time and focus your installer instead on running the necessary scripts such that your application can connect to it on the first start up. What it does means is having your installer have the necessary drivers, connection information, and credentials to communicate with the database to get it initialized. After the DB is initialized then you can have additional routines that configure your application install such that it points to the database you initialized during the install. Taking this approach will not only be easier, but it will allow your application to do more interesting things like connect to remote databases or skip database initialization all together and connect to an existing database.
Writing an installer that also manages DB installation is a project in and of itself. The big question is do you need to install PostgreSQL from scratch or will you tell the user to install it themselves first?
I have attempted to do something similar and what I eventually did was build an installer with NSIS that includes Postgres and a JRE in the install bundle along with my program. The installer copies everything to the user's install location and creates all the required config files.
The biggest issue I had was that I had a number of config options to present to the user that would have taken a lot of programming in NSIS. So, I modified the ANT build scripts I already had written to build the project. What NSIS does then is copy the JRE to a temp location and start a Java installer GUI I wrote instead that gathers up all the config info and launches ANT in the background.
If you don't have much to configure or what you need to configure doesn't have many options, then you can probably do everything in NSIS directly. But, keep in mind that you need to be security conscious too. How are you creating a new user to run Postgres? What about directory permissions for you install? Who can start and stop the DB, who can read the db files, etc?
Maybe you may try a pure java database, like hsql, or h2, or derby....
i am not clear about steps/configuration details about how i can embed mysql in a Java desktop application so that it(application) can be installed on any machine through a single executable file and doing so sets up database and also provides an exe to run the app.Till now i have built my app using netbeans and i have used mysql to set up database.plz guide me further.
MySQL isn't an embedded database - the only JAR related to it is the JDBC driver. It requires a installation process, which might be able to be scripted via Java, but the process will definitely function outside of the Java application you intend it to support. Meaning, you can turn off your Java application but the MySQL service/daemon will still be running.
Only the libmysqld is embeddable.
There are embedded databases - SQLite, Firebird - and embedded databases made in Java - HSQL, Derby/(can't remember what it was called before). I believe SQL Server Compact Edition is embeddable, while SQL Server Express/MSDE is not. I don't know if Oracle has an embeddable version....
I would strongly recommend H2. It is a very fast embedded database written in Java and I've found it easier to use than some of the others mentioned such as HSQL.
Edit:
On the H2 website, you can see a speed comparison of H2 vs Derby, HSQL, MySql, etc...
Here's information on how to backup the database.
While theoritcaly possable it would not be easy. The standard MySql distributions assume you want to set up a general purpose database server with separate from the client applications cominicating via odbc etc.
You may be better looking at the "pure java" options like HSQL or JavaDB which are designed to be embedded in a java application, and need little or no "setup".
Another possibility is Sqlite which only needs a single binary plus the sqljbbc jar file. This is again designed from scratch to be embedded inside an application and requires zero admin apart from allocating a file for the database.
Take a look at http://dev.mysql.com/doc/refman/5.0/en/connector-mxj.html. I do not remember the exact details but I was able to embed MySQL db in desktop application without user needing to install it separately.
The key class is com.mysql.management.MysqldResource.
Here is the example, http://dev.mysql.com/doc/refman/5.0/en/connector-mxj-configuration-java-object.html
The mysql-connector-mxj-gpl-db-files.jar file contains MySQL installation files for all the platforms. If you know which is your target platform, you can strip other platform versions from jar, to reduce download size for end user.
If you want an embedded database with java, then use one written in Java designed to be embedded. I know Apache Derby Can be embedded and apparently H2 too.
How big amount of data dó you need the database to handle?