Example 1. Not very useful work-list handler

First line of this example configures engine using conf/Shark.conf file. Then after getting a connection and successfully connecting it asks Resource object how many assignments there are for this user (in line 4).

      Shark.configure("conf/Shark.conf");
      SharkConnection sConn = Shark.getInstance().getSharkConnection();
      sConn.connect("qq", "lele", "shark", "");
      if (0 < sConn.getResourceObject().how_many_work_item()) {
          System.err.println("Oh, let these tasks wait until tomorrow!");
      }
      System.out.println("Job done!");
			       

Example 2. User group management

This example won't work if you set Shark to use LDAP user-group component, but database based component starts empty, and to do anything usefull you'll need to define at least one group and user.

      Shark.configure();
      UserGroupAdministration ugAdmin = Shark.getInstance()
         .getAdminInterface()
         .getUserGroupAdministration();
      ugAdmin.createGroup("developers", "sweat-shop");
      ugAdmin.createUser("developers",
                         "user",
                         "secret",
                         "Jane",
                         "Doe",
                         "some@email.address");
      System.out.println("Group and user created!");
			       

Example 3. Loading package into Shark library

The location of the package's XPDL file is relative to the root of the package repository. Before you perform this operation, you might want to get all the package relative paths by calling method getDefinedPackagesPath() on your client object. First you need the location of the package's XPDL file relative to the root of the package repository, then you need a PackageAdministation instance.

      String xpdlName = "test.xpdl";
      Properties props = new Properties();
      props.setProperty("enginename", "testSharkInstance");
      props.setProperty("EXTERNAL_PACKAGES_REPOSITORY",
                        "c:/Shark/repository/xpdls");
      Shark.configure(props);
      String pkgId = Shark.getInstance()
         .getRepositoryManager()
         .getPackageId(xpdlName);
      PackageAdministration pa = Shark.getInstance()
         .getAdminInterface()
         .getPackageAdministration();
      if (!pa.isPackageOpened(pkgId)) {
         pa.openPackage(xpdlName);
      }
      System.out.println("Package " + xpdlName + " is loaded");
			       

Example 4. Creating and starting process

After loading XPDL into shark, lets create, fill with initial variable values, and start some processes based on their XPDL definitions.

      String pkgId = "test";
      String pDefId1 = "basic";
      String pDefId2 = "complex";

      SharkConnection sConn = Shark.getInstance().getSharkConnection();

      sConn.connect("user", "secret", "", "");

      WfProcess proc1 = sConn.createProcess(pkgId, pDefId1);
      WfProcess proc2 = sConn.createProcess(pkgId, pDefId2);

      Map m1 = new HashMap();
      m1.put("test_var",
            "This is String variable defined in XPDL for the process basic");
      proc1.set_process_context(m1);
      Map m2 = new HashMap();
      m2.put("counter", new Long(55));
      proc2.set_process_context(m2);

      proc1.start();
      proc2.start();
			       

Example 5. Setting a variable

After successfully connecting to Shark, and acquiring list of assignments, lets do something useful, like setting a variable and completing the activity.

      /*
      SharkConnection sConn;
      String activityId;
      String vName;
      String vValue;
       */
      WfAssignment a = null;
      WfAssignment[] ar = sConn.getResourceObject().get_sequence_work_item(0);
      for (int i = 0; i < ar.length; ++i) {
         if (activityId.equals(ar[i].activity().key())) {
            a = ar[i];
            break;
         }
      }
      if (null == a)
         throw new BaseException("Activity:"
                                 + activityId
                                 +" not found in "
                                 + sConn.getResourceObject().resource_key()
                                 +"'s worklist");
      if (!a.get_accepted_status())
         throw new BaseException("I don't own activity "+ activityId);
      Map _m = new HashMap();
      WfActivity activity = a.activity();
      Object c = activity.process_context().get(vName);
      if (c instanceof Long) {
         c = new Long(vValue);
      } else {
         c = vValue;
      }
      _m.put(vName, c);
      activity.set_result(_m);
      activity.complete();
			       

Example 6. Getting process managers based on some criteria

This example shows how to get process managers based on some criteria. It'll try to get all process managers which package Id is "test", and which state is enabled.

      ExecutionAdministration eAdmin = Shark.getInstance()
         .getAdminInterface()
         .getExecutionAdministration();
      eAdmin.connect("user", "secret", "", "");

      WfProcessMgrIterator pmi = eAdmin.get_iterator_processmgr();
      String query = "packageId.equals(\"test\") && enabled.booleanValue()";
      pmi.set_query_expression(query);
      WfProcessMgr[] procs = pmi.get_next_n_sequence(0);
			       

Example 7. Getting processes based on some criteria

This example shows how to get processes created by some process manager based on some criteria. It'll try to get all processes which state is "open.running", which are started in last 10 minutes, which have more than 3 active activities, and which String variable called "myvariable" has value "test".

      /*
      WfProcessMgr mgr;
       */
      WfProcessIterator wpi = mgr.get_iterator_process();
      String query = "state.equals(\"open.running\") && "
                     + "startTime.longValue()>(java.lang.System.currentTimeMillis()-10*60*1000) && "
                     + "activeActivitiesNo.longValue()>3 && "
                     + "context_myvariable.equals(\"test\")";
      wpi.set_query_expression(query);
      WfProcess[] procs = wpi.get_next_n_sequence(0);
			       

Example 8. Using external transactions

Each method of Shark API invocation presents separate transaction: engine internally creates, uses, optionally commits, and eventually releases transaction. This means that even quite simple code utilizing Shark may unknowingly use many transactions.

Sometimes, it is required to do things a differently, therefore SharkTransaction is introduced. An application('s developer) may choose to use external transactions for number of reasons including usage of the same database to store application (non work-flow related) data, to avoid constantly creating/discarding transactions, ...

Of course, this approach comes with a price: you must obey the rules of usage. Transactions are created calling Shark.getInstance().createTransaction();, just before you release one, your application must call Shark.getInstance().unlockProcesses(st); notifying Shark to do it's internal bookkeeping. If anything goes awry, you must catch a Throwable and call Shark.getInstance().emptyCaches(st);. Yes, you've read it right even Error's must be caught, otherwise you'll leave the engine in undefined state.

Here is the variable setting example modified to use a single transaction.

      /*
      SharkConnection sConn;
      String activityId;
      String vName;
      String vValue;
       */
      SharkTransaction st = Shark.getInstance().createTransaction();
      try {
         WfAssignment a = null;
         WfAssignment[] ar = sConn.getResourceObject(st)
            .get_sequence_work_item(st, 0);
         for (int i = 0; i < ar.length; ++i) {
            if (activityId.equals(ar[i].activity(st).key(st))) {
               a = ar[i];
               break;
            }
         }
         if (null == a) throw new BaseException("Activity:"
                                                + activityId
                                                + " not found in "
                                                + sConn.getResourceObject(st)
                                                   .resource_key(st)
                                                + "'s worklist");
         if (!a.get_accepted_status(st)) throw new BaseException("I don't own activity "
                                                                 + activityId);
         Map _m = new HashMap();
         WfActivity activity = a.activity(st);
         Object c = activity.process_context(st).get(vName);
         if (c instanceof Long) {
            c = new Long(vValue);
         } else {
            c = vValue;
         }
         _m.put(vName, c);
         activity.set_result(st, _m);
         activity.complete(st);
         st.commit();
      } catch (Throwable t) {
         Shark.getInstance().emptyCaches(st);
         st.rollback();
         if (t instanceof RootException)
            throw (RootException) t;
         else
            throw new RootException(t);
      } finally {
         try {
            Shark.getInstance().unlockProcesses(st);
         } catch (Exception _) {}
         st.release();
      }