FWD » Core Development » Database

Issue #3930 added session level control over database connections (in the 4GL sense, not the JDBC sense). These connections are similar to explicit connections made by the 4GL CONNECT statement, but they occur implicitly when a session (i.e., user context) begins, and are terminated implicitly when that session ends. Explicit connections and disconnections are still possible, as before. In fact, these two types of connections should be the same in every sense, except their implicit/explicit nature.

The new implementation left behind an internal distinction between implicit and explicit connections which needs to be cleaned up. Both types of connections should be accounted for the same way internally, and should be cleaned up properly, whether the disconnect occurs:

• explicitly (via DISCONNECT statement);
• implicitly by session termination, whether or not the original connection was made implicitly or explicitly (the latter case may occur if application code does not properly pair a DISCONNECT statement with its corresponding CONNECT statement).

I had been attempting to configure a project for multiple databases, and had (incorrectly) configured the directory with:

    <node class="container" name="server">
      <node class="container" name="default">
        <node class="container" name="runtime">
          <node class="container" name="default">
            <node class="strings" name="database-connections.server">
              <node-attribute name="values" value="db1,db2,db3,db4,db5,db6,db7"/>
            </node>

I received the below... we should probably handle more gracefully.

[12/06/2021 10:25:52 EST] (com.goldencode.p2j.persist.DatabaseManager:INFO) Connecting to [db1,db2,db3,db4,db5,db6,db7]
[12/06/2021 10:25:52 EST] (ErrorManager:SEVERE) {0000000E:00000027:projAS1} stack trace follows
com.goldencode.p2j.persist.PersistenceException: java.lang.NullPointerException
Caused by: java.lang.NullPointerException
        at com.goldencode.p2j.net.RouterSessionManager.connectVirtual(RouterSessionManager.java:426)
        at com.goldencode.p2j.net.SessionManager.connectVirtual(SessionManager.java:730)
        at com.goldencode.p2j.persist.ConnectionManager.makeConnection(ConnectionManager.java:3492)
        at com.goldencode.p2j.persist.ConnectionManager.connect(ConnectionManager.java:3313)
        at com.goldencode.p2j.persist.ConnectionManager.connectDbImpl(ConnectionManager.java:2994)
        at com.goldencode.p2j.persist.ConnectionManager.connect_(ConnectionManager.java:663)
        at com.goldencode.p2j.persist.ConnectionManager.connect(ConnectionManager.java:564)
        at com.goldencode.p2j.persist.DatabaseManager.autoConnect(DatabaseManager.java:878)
        at com.goldencode.p2j.util.Agent.prepare(Agent.java:2555)
        at com.goldencode.p2j.util.Agent.listen(Agent.java:423)
        at com.goldencode.p2j.util.AgentPool.start(AgentPool.java:551)
        at com.goldencode.p2j.util.AppServerManager.startAppServer(AppServerManager.java:1482)
        at com.goldencode.p2j.main.StandardServer.standardEntry(StandardServer.java:429)
        at com.goldencode.p2j.main.StandardServerMethodAccess.invoke(Unknown Source)
        at com.goldencode.p2j.util.MethodInvoker.invoke(MethodInvoker.java:156)
        at com.goldencode.p2j.net.Dispatcher.processInbound(Dispatcher.java:783)
        at com.goldencode.p2j.net.Conversation.block(Conversation.java:422)
        at com.goldencode.p2j.net.Conversation.run(Conversation.java:232)
        at java.lang.Thread.run(Thread.java:748)
[12/06/2021 10:25:52 EST] (com.goldencode.p2j.persist.ConnectionManager:SEVERE) CONNECT failed
com.goldencode.p2j.util.ErrorConditionException: com.goldencode.p2j.persist.PersistenceException: java.lang.NullPointerException
Caused by: com.goldencode.p2j.persist.PersistenceException: java.lang.NullPointerException
Caused by: java.lang.NullPointerException
        at com.goldencode.p2j.net.RouterSessionManager.connectVirtual(RouterSessionManager.java:426)
        at com.goldencode.p2j.net.SessionManager.connectVirtual(SessionManager.java:730)
        at com.goldencode.p2j.persist.ConnectionManager.makeConnection(ConnectionManager.java:3492)
        at com.goldencode.p2j.persist.ConnectionManager.connect(ConnectionManager.java:3313)
        at com.goldencode.p2j.persist.ConnectionManager.connectDbImpl(ConnectionManager.java:2994)
        at com.goldencode.p2j.persist.ConnectionManager.connect_(ConnectionManager.java:663)
        at com.goldencode.p2j.persist.ConnectionManager.connect(ConnectionManager.java:564)
        at com.goldencode.p2j.persist.DatabaseManager.autoConnect(DatabaseManager.java:878)
        at com.goldencode.p2j.util.Agent.prepare(Agent.java:2555)
        at com.goldencode.p2j.util.Agent.listen(Agent.java:423)
        at com.goldencode.p2j.util.AgentPool.start(AgentPool.java:551)
        at com.goldencode.p2j.util.AppServerManager.startAppServer(AppServerManager.java:1482)
        at com.goldencode.p2j.main.StandardServer.standardEntry(StandardServer.java:429)
        at com.goldencode.p2j.main.StandardServerMethodAccess.invoke(Unknown Source)
        at com.goldencode.p2j.util.MethodInvoker.invoke(MethodInvoker.java:156)
        at com.goldencode.p2j.net.Dispatcher.processInbound(Dispatcher.java:783)
        at com.goldencode.p2j.net.Conversation.block(Conversation.java:422)
        at com.goldencode.p2j.net.Conversation.run(Conversation.java:232)
        at java.lang.Thread.run(Thread.java:748)