Re: Tomcat 7 JDBC Connection Pool - question about usage from Java code
Hey Ric, Thanks for asking these questions. Hopefully, this discussion will benefit many on this list. Here's the summary of your options obtaining connections in your application. As you suggested, database connections are typically obtained through a javax.sql.DataSource object (wrapped pool of database connections). There are few ways that database connections could be managed in a Tomcat web application, e.g. (1) NOT MANAGED. Database connections are created on demand, they are not pooled, and typically not a great way to get database connections, especially in a web app where you have 1000s of users/requests. For simplicity, we might use this for batch applications, since we typically control how often and how many times the code is executed, i.e. not in 1000s of requests, as with web application requests. Here's the code for that ... Class.forName(some.jdbc.driver.here); Connection c = DriverManager.getConnection(); ... So, don't use this if you are in a context of web application. (2) CONTAINER-MANAGED CONNECTION POOL. This is a typical JEE way to manage and pool your resources. Connection pool is implemented as part of the application server (Tomcat, WebSphere, Weblogic, JBoss, etc...) and each appserver has its own way to configure and implement connection pools. In Tomcat, you need to define a Resource ... / element somewhere in your appserver configuration (GlobalNamingResources will be in global context, or per application in Context element of particular application). See more details here: http://tomcat.apache.org/tomcat-7.0-doc/config/resources.html On Tomcat, this is now implemented by Tomcat JDBC Connection Pool ( http://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html) and has replaced the older traditional Apache Commons DBCP project ( http://commons.apache.org/proper/commons-dbcp). Here's an example configuration: http://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html#As_a_Resource In order to configure this, you also need to add specific database JDBC drivers (e.g. postgresql JDBC drivers) to the server class path, typically just copying them to CATALINA_HOME/lib directory. Once it is configured, the connection pool will be created and registered with JNDI on the startup of the server. You would then get the reference to this connection pool through standard JNDI lookups: (a) using container injection @Resource(name=) private DataSource datasource (b) traditional JNDI lookup Context naming = new InitialContext(); DataSource datasource = (DataSource) naming.lookup(); (c) or even using Spring JEE context, e.g. jee:jndi-lookup id=mydatasource jndi-name=/ For each database (schema), you will need to create a separate JDBC connection pool. Each one will have a separate JNDI name that you can use to lookup/inject into your code. And finally, third way that developers manage their connections is: (3) APPLICATION-MANAGED CONNECTION POOL. This way, connection pools are created per application. Container doesn't know about the connection pool. This is very typical in Spring applications, where you define your own datasources. Here, you can to use any of the connection pool implementations. You could use Tomcat JDBC Connection Pool or any other third-party connection pools, e.g. - C3P0 (http://www.mchange.com/projects/c3p0/) - HikariCP (http://brettwooldridge.github.io/HikariCP/) - Apache Commons DBCP (http://commons.apache.org/proper/commons-dbcp/) or many other ones. Spring also provides a simple JDBC wrapper class (org.springframework.jdbc.datasource.DriverManagerDataSource) that is not really implementing a connection pool, but rather simplification for the lack of better connection pool implementation. We often use this connection pool in development, as it is simple to configure and no need for other connection pool libraries. More details here: http://docs.spring.io/spring-framework/docs/4.1.1.RELEASE/javadoc-api/org/springframework/jdbc/datasource/DriverManagerDataSource.html The connection pool is managed by the application, typically created at the application deployment. Since the drivers are isolated to a particular application, you don't have to place drivers in shared library folder (CATALINA_HOME/lib) as in (2) CONTAINER-MANAGED, but rather can include drivers in the application, e.g. WEB-INF/lib folder. It is important that the creation of the connection pool is done at some application-scoped level, not per request! Because, the pool itself is putting the limits on the total number of connections to a database. Each connection pool is independent of other connection pools that might exist. So, in this third way - connection pool management and configuration is done by the developer, not administrator like in CONTAINER-MANAGED CONNECTION POOLS. Hopefully, this sheds some light on the options we have when we need a connection pool. I will try to answer your other specific questions in a separate email. Cheers! Neven
Re: Tomcat 7 JDBC Connection Pool - question about usage from Java code
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Ric, On 10/25/14 9:06 PM, Ric Bernat wrote: Thanks. That makes sense. Pooling for the duration of that single web service call is not our main goal. However, JAX-RS allows me to persist objects in memory across web service calls, so I can keep a collection of DataSource instances (e.g., by database name, in a ConcurrentHashMap). No problem keeping DataSource instances in memory for an extended period of time, is there? btw, I have worked with Microsoft tools in the past, including SQL Server ADO.NET connection pooling. There, you get one connection pool per connection string, regardless of what object instance you use to instantiate your connection objects. That is doubtlessly why I came to Tomcat connection pooling with a connection-URL-equals-connection-pool mindset. On a tangent, I am very eager to monitor Tomcat connection pooling so that I can see what is going on with the connection pools. To that end, I have configured both the JMXProxyServlet (via the manage webapp), and PSI Probe. And I have set poolProperties.setJmxEnabled(true). However, neither of these monitoring tools let me see any information about Tomcat connection pool state. Perhaps these tools required that I JNDI to configure my database connections, and cannot monitor connection pools created via Java code? Unless I am using those two monitoring tools incorrectly (quite possible), and they really do offer a view of connection pool state, it seems that my only choice is to configure JMX monitoring, which seems non-trivial. (I am assuming that JMX will give me a view of connection pool state.) Or perhaps I should go the JNDI route (guessing that my two current monitoring apps can show connection pooling information for JNDI-created connection pools). However, since we create databases at runtime, I'm not sure that I would be able to create JNDI declarations for just-created databases on the fly. I haven't used non-JNDI connection pools, so I'm not absolutely sure about this. - From the tomcat-pool documentation[1]: The connection pool object exposes an MBean that can be registered. In order for the connection pool object to create the MBean, the flag jmxEnabled has to be set to true. This doesn't imply that the pool will be registered with an MBean server, merely that the MBean is created. In a container like Tomcat, Tomcat itself registers the DataSource with the MBean server, the org.apache.tomcat.jdbc.pool.DataSource object will then register the actual connection pool MBean. If you're running outside of a container, you can register the DataSource yourself under any object name you specify, and it propagates the registration to the underlying pool. To do this you would call mBeanServer.registerMBean(dataSource.getPool().getJmxPool(),objectname). Prior to this call, ensure that the pool has been created by calling dataSource.createPool(). So, the JMX bean is being created, but it's not registered with the JMX server so you can't see the bean remotely. You'll have to register it yourself as described above. That one-line call isn't entirely straightforward, so let me refer you to a presentation on monitoring Tomcat via JMX which shows you how to register your own beans. (In your case, the bean exists already, so you'll just be registering the bean from tomcat-pool): http://people.apache.org/~schultz/ApacheCon%20NA%202014/Monitoring%20Apache%20Tomcat%20with%20JMX.pdf Hope that helps, - -chris [1] http://tomcat.apache.org/tomcat-8.0-doc/jdbc-pool.html#JMX -BEGIN PGP SIGNATURE- Version: GnuPG v1 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJUTPLAAAoJEBzwKT+lPKRYJ1wP/0FhZoL/VgASr3rKUps61ocX SV1DKdwtUalt8f++MuPODJflBEkxsjeO6tmHLlHi1Ew5yCUVDz6/GQFPJDM0j16v tCv0veB6H+5AR4AcSvIvHZLdwnocYN3NY0mIAuxHCwfMNDxgZ5fg6m6r05/7lc6h Q0ZZyIEpx3NT1DpwJ6Qy/4junQ0IkwkVgFaB2NY07M9Ec00uujbn2eMdFiqk0LEo P/qTPTui0V8Y3Pe45NSwgjWzO66O6CrwB2lpt5gZyOcdQ4FQ8RCkaUw4KyPB6xjk cbFl+Lxz7PnpXOu6OTLrVEDbhvevPKdrYUl4wk7/GL5aeIextY4pfV8VeLl6eddj lu5gKNV0kEjgt8j+6HUP4ItGQVKxndYWBm7+TCSdAb+Md0/X9TuJISmYinniK6Mw 93ygRx2M9oSSiqR+LCUz+fXDkDcRNpEMY196OI2T077Gxyyejjsn6238f9p/Uuwr 5Q+9LA8jqHgE00bXl03ZMa8Yq5mc15W+OVG08rPqE7FQmSV6sezTClct+SJ9Jj73 vxoEDFTa0aLQu9SWaZ2V/3md0ydqeVqzBDwehSo6W33+3cau+xIG8+Kkv7RDlQJr QPHCDAnpHmMmbcD4Lwleuua8mxqsq+RGw1X9j4aJB8cTroEvMIvd2DhW70W9O0Fm +PWW7OpOvMQ3NffY01ZF =bYDS -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: tomcat websocket communication with external java program
-BEGIN PGP SIGNED MESSAGE- Hash: SHA256 Jason, On 10/25/14 3:41 PM, Jason Ricles wrote: I have a tomcat webpage with a websocket server written in java to communicate with the webpage. I want this websocket server to be able to communicate with an external java program without an sockets, so something like this webpagewebsocket serverexternal java program However I am having trouble getting that to work, since to use the websocket server I need to make an instance of it and thus it thinks there are no session. What do you mean websocket session? Are you trying to use the HttpSession from a websocket call? Or only for the HTTP call that precedes the websocket upgrade? If you just want to inherit the session, then make sure you send a JSESSIONID cookie or ;jsessionid path parameter in your URL with your initial connection. Are you launching your own Websocket server, or are you allowing Tomcat to host the Websocket server like in a normal configuration? So currently I have done it the following way webpage-websocket server--socket---external java program This is kinda messy however, so is there some way to get my external java program and my webpage to communicate through websockets without a socket go between? I don't think this extra step is necessary, but it's pretty tough to understand what you are trying to do. Thanks, - -chris -BEGIN PGP SIGNATURE- Version: GnuPG v1 Comment: GPGTools - http://gpgtools.org iQIcBAEBCAAGBQJUTPOPAAoJEBzwKT+lPKRYAhAQAJghL4HjgjuEWBIbO0NQSRa7 D5i+raJCmN2dQSC0sfnsEW5NrMpKr6I0KWVBp3kjBYjXzXZ1VDbU1vPYP+O391xK kCSqEWmwz642uCHC060DES2u9AaWkJ9RoLMRKv2LcQ0VwEFeudxe1GP8Mjjk7kYq WtfsF0e1XU4ncYr6p1qUR0jK3Ipk4UrfnxTkU5//eqy10478uLvCIE+mdOSEjfS5 bzBy3ZMIQ0teTVkNNT4WxfUX5gxieYBsXWPLcoup01Rn1FCXwrf2x+YEZwRVJxl3 j40vWMj3O+oHCfhJcJTFhUlpeCU8kTZZdNV29qP4NKLgH7v6x+lkNor7THhNznLE ei0t4j5pX0KeLRRA+3K+tPMRLTE514aFwmrsCmw1zyE8SKrUxl8flxwcftJUMgBO 6gyGbm8drkdqmTSusDMBquuDi+TaGkaBGftAWMPH2ev5Cvklu+YS0JwWJ8N9/8NF lZ2hT2YabXmac+7n0PyDWT3d1CquuE/mxrtGAMZ8OP5ji6U00uStrUZiWLiFuKkX ikX0tGgsvYvVs9Hjpwjiy+zPGx231qnsfnJzrjiA0L3TxT/l7nnUMqWDlt9E3JgM dJy34nk49z6ic3JyC1vdOztJc/M1SzrkZBSwqk+A922JBSI8CZz0p3sYS03ePcjv 3fb4POPO8ilqsHskSLcX =oalw -END PGP SIGNATURE- - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
HTTPS / URLs with no port number / Tomcat only
Hello and thank you for reading my post. I was willing to run only a Tomcat server and not a Tomcat server + an Apache HTTP server. Mostly because: - an article like this one: http://www.tomcatexpert.com/blog/2011/11/02/best-practices-securing-apache-tomcat-7 says, if I understand properly, that Tomcat is secure enough with what it basically implements, - and because, if possible, I don't want to have to secure an Apache HTTP server in addition to the rest of the architecture... (Actually I already made a solution work with an Apache server but I was wondering if I could do without it). So, I am willing to serve HTTPS pages only with Tomcat and with URLs not including a port number. I did some config (mostly taken from http://tomcat.apache.org/tomcat-7.0-doc/ssl-howto.html and http://java.dzone.com/articles/setting-ssl-tomcat-5-minutes) I could make this work: https://localhost:8443/my_webapp/a_page.jsp And this: http://localhost/my_webapp/a_page.jsp automatically redirects to: https://localhost:8443/my_webapp/a_page.jsp Now, in all possible cases, I would like to have this URL instead: https://localhost/my_webapp/a_page.jsp (which doesn't work presently). Can this be achieved with Tomcat ONLY? And how? Best regards. -- View this message in context: http://tomcat.10.x6.nabble.com/HTTPS-URLs-with-no-port-number-Tomcat-only-tp5024482.html Sent from the Tomcat - User mailing list archive at Nabble.com. - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
RE: Tomcat 7 JDBC Connection Pool - question about usage from Java code
Thanks, Nevin. I certainly appreciate your deep treatment of my question/issue! I would like to ask for clarification about a point in your #2: (2) CONTAINER-MANAGED CONNECTION POOL. (a) using container injection @Resource(name=) private DataSource datasource (b) traditional JNDI lookup Context naming = new InitialContext(); DataSource datasource = (DataSource) naming.lookup(); With either 2a or 2b, for a given JNDI resource name, regardless of where in my JAX-RS Java code I get the DataSource, I can be certain that I am getting a DataSource/connection from a container-managed connection pool, and so there is no need to cache anything within my application, right? The only stumbling block for me is that in our application, databases are added at runtime, and I don't believe there is a way to add a JNDI Resource definition at runtime (i.e., GlobalNamingResources or Context element of particular application). Since databases are not added rapid-fire, I suppose each time one is added I could dynamically generate a new server configuration file under a temporary name, adding Resources for all databases, then run a script that shuts down Tomcat, replaces the server configuration copy with the newly generated one, and restart Tomcat. A little clumsy, I suppose, but the benefit would be significant. (3) APPLICATION-MANAGED CONNECTION POOL. Alternatively, I can manage my own cache of connection pools (i.e., org.apache.tomcat.jdbc.pool.DataSource instances), keyed off of database name in a HashMap, for example, and storing that cache in an object that is persisted across web service calls (using JAX-RS Features). Do you see any problem with retaining org.apache.tomcat.jdbc.pool.DataSource instances in memory and re-using them for extended periods of time? - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: HTTPS / URLs with no port number / Tomcat only
On Sun, Oct 26, 2014 at 9:04 AM, Léa Massiot lmhe...@orange.fr wrote: Now, in all possible cases, I would like to have this URL instead: https://localhost/my_webapp/a_page.jsp (which doesn't work presently). Can this be achieved with Tomcat ONLY? And how? Configure your https connector to use port 443 and start with jsvc -- see the Apache Commons Daemon section of the RUNNING.txt file in the distribution. You *could* run as root, but that's definitely NOT RECOMMENDED :-) Alternatively, use iptables to route port 443 requests to your current port 8443 connector. HTH, -- Hassan Schroeder hassan.schroe...@gmail.com http://about.me/hassanschroeder twitter: @hassan - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Tomcat 7 JDBC Connection Pool - question about usage from Java code
Hey Ric,
Here's another thing you could do:
http://stackoverflow.com/questions/7195556/how-to-manage-connections-to-dynamically-created-databases
If your databases are all on the same db instance, but different
schema/database name, you could avoid connecting to the specific database
name, but rather set that up on the connection object, e.g.
@Resource(name=)
private DataSource datasource;
public void someMethod() {
try
(
Connection c = datasource.getConnection();
c.setCatalog(dynamic_dbname);
PreparedStatement ps = c.prepareStatement(SOME SQL HERE);
)
{
...
} catch (SQLException sqle) {
...
}
}
I haven't tried this myself, but I guess this could work. Off course,
working with Spring JdbcTemplate makes it even nicer :))
How long do these dbs live? How often do you create them? Why do you have a
need for that many databases? etc...
Hope that helps!
Cheers!
Neven
INFO: TLD skipped Messages in logs
Hi, I am getting below messages in the logs, Oct 26, 2014 4:05:46 PM org.apache.catalina.startup.TaglibUriRule body INFO: TLD skipped. URI: http://java.sun.com/jstl/xml_rt is already defined Oct 26, 2014 4:05:46 PM org.apache.catalina.startup.TaglibUriRule body INFO: TLD skipped. URI: http://java.sun.com/jstl/xml is already defined Oct 26, 2014 4:05:46 PM org.apache.catalina.startup.TaglibUriRule body INFO: TLD skipped. URI: http://java.sun.com/jsp/jstl/xml is already defined I have jstl.jar in web/lib app folder and probably have jstl jar in the tomcat lib directory. I wanted to understand if this messages are related to duplicate jstl jar or something else . - Kiran Badi - - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
