7.8 Class
7.8 Class === https://tinurll.com/2tD7eT
A class indicator determines what class of object each database record represents. A class indicator is only necessary when a persistent class can be extended by other persistent classes.The class indicator is always placed on the base class. Subclasses inherit the class indicator of their parent class.
In Kodo JDO, class indicators extend the basekodo.jdbc.meta.ClassIndicator class. The concrete class indicators Kodo JDO provides are described in the sections below. By default, themapping tool usesthe in-class-name class indicator for all persistent classes. You can change the default class indicator type with the kodo.jdbc.ClassIndicator configurationproperty. You can also instruct the mapping tool to use a specificindicator for an individual class with the jdbc-class-ind-name JDO metadata extension.
The in-class-name indicator stores the full class name of persistentobjects in a special database column. When you query for objectsof certain classes, the indicator appends a SQL IN clause to theend of the query to make sure each record's class name column matches one of target class names.
The metadata-value indicator maps persistent classes to symbolicconstants stored in a database column. Each class in theinheritance tree using the metadata value indicator uses thejdbc-class-ind-value metadata extension to specify the database valuethat indicates a row is a member of that class. The extension isrequired. When you query for objects of certain classes, the indicator appends a SQL IN clause to the end of the query to make sure each record's class indicator column value matches the symbolic constant mapped to one of those classes.
Unlike the in-class-name indicator, this indicator cannot calculateall the subclasses for a given class by examining the databasecontents. If you use this indicator, you must list all of yourpersistent classes in the kodo.PersistentClasses property, or make sure all classes in inheritance trees that use thisindicator have been referenced in code by the time you performpersistent operations on any of them.
The jdbc-class-ind-name JDO metadata extension tells the mapping toolwhich class indicator to install. If you write mappings by hand rather than with the mapping tool, simply specify the full class name of your custom indicator in the type attribute of the mapping XML.
Scan classes dictate the rate of execution of tags, and therefore play a crucial role in the design of large and high-performance systems. It will often make sense to have more than one scan class as usually not all of your tags will need to be subscribed at the same rate. Some tags you may wish to see updated at 250-500ms, while others may not be so crucial and may only need to be subscribed at 1500ms.
Creating different scan classes allow you to organize your tags into groups that subscribe at different rates. It is good practice to put some forethought and planning into the organization of your Tags and scan classes.
Tags are executed by scan classes inside of a tag provider. In a typical system, there are a number of scan classes and one or two tag providers: the internal tag provider and possibly an external tag provider.
Tags stored in an external provider are available to all Ignition installations that have access to that database. One of the installations can be specified as the tag's driver. The driving system has a copy of the scan class that it executes, which in turn evaluates the tag. The value is stored to the database and all of the other installations are notified of the new value.
You can add and edit scan classes by clicking on the Edit Scan Classes icon in the Tag Browser. The Scan Class Editor window is displayed showing a list of already configured Scan Classes on the left, and configuration settings on the right. To add a scan class, simply click the green + icon on the lower-left of the Scan Class Editor and then specify the name and the properties for it.
DirectThe scan class executes at a fixed rate, defined by the slow rate setting.LeasedThe scan class executes at the fast rate when any of the tags it contains are subscribed and visible in a Client window. If no tags are subscribed, the scan class runs at the slow rate.DrivenThe rate of the scan class is based on the value of a driving tag. The condition is a simple comparison between a tag value and a number. If the condition is true, the scan class will execute at the fast rate. If false, it will run at the slow rate. There are two exceptions to this: the Any Change operator, and One-shot mode. Using either of these, the scan class will not run at a rate. Instead, it will be triggered by a change in the driving tag's value. Keep in mind that the driving tag can be an Expression tag that performs complex calculations and references other tags. In this way, it's possible to create robust scan class triggering.
Used by the Driven and Leased modes, this is the faster rate that the tags will be executed at when those modes are active.Note: If the rate is set to 0, the scan class will not be executed.
How long to wait before the tags in the scan class are determined to be stale (not running). This is calculated off of the last expected execution time of the scan class, and is particularly important for scan classes executed by other drivers through the external Tags provider. This property is not used by internal providers.
The Driving Tag should not use this same scan class. The Driving Tag should be on a separate scan class that runs at a faster rate than the Driven scan class. This means that changes to the Driving Tag will be recognized by the system faster, and the change in rate on the Driven scan class will occur faster.
The Any Change operator works differently than the other operators: The scan class will execute immediately whenever the driving tag changes value. Using the Any Change operator means that the scan class no longer uses the Slow Rate or Fast Rate properties.
ReadTags will not be subscribed, but will instead be synchronously read each time the scan class executes. This operation is less efficient, but allows more precise control over when values are obtained. This mode is particularly useful when collecting data over a slow or expensive connection for display. When combined with the one-shot execution mode above, and a static tag tied to a momentary button, it's easy to create a manual refresh button on a screen that pulls data on-demand.
Enabling this property is less efficient as a single write to a tag becomes two separate requests. This is especially helpful with slower scanclasses as it the tags will show the latest value quicker than the normal execution would allow.
Historical scan classes are simply standard scan classes used by Tags to store history. By using separate scan classes for status and history, it's possible to maintain a tag's status at a fast rate, without storing large amounts of history unnecessarily.
Despite the fact that there is not a technical differentiation between standard and historical scan classes, it is recommended that you create separate scan classes for each purpose and name them in a manner that indicates their usage. It is common to modify scan classes in order to affect a large number of tags, and without a consistent distinction it may be possible to affect tag execution in unexpected ways.
It depends. There are deadlines that are enforced from dropping classes, and students may need to maintain a certain number of units for various reasons (scholarships, visa compliance, etc.) so may need to add new course if one is dropped - when possible.
Once the class begins, there is a period in which students may drop the class. It will still show up in UAccess records, but not on the transcript (no grade is awarded). The deadline to drop without a grade depends on the session in which the course is offered; for full-semester classes, it is about 2 weeks into the semester.
Version 7.8 Sep 25th: Sub Version 200625: a) Added 2 more returned fields 'u_tel_number as string' and 'u_tel_extension as string' in the class 'AuthenticateResponse' for the WS 'Authenticate', requested by Jeff Doan b) Set the textbox of password to not readable, type = password
Version 7.8 Sep 25th: a) New field DescriptionOfFormatOfInmateID in the class ActiveSourceCode for WS /API/GetActiveSourceCodePerStore which is Tab 2 b) Fill in both the values DescriptionOfFormatOfInmateID and FormatOfInmateID in the class ActiveSourceCode for WS /API/GetActiveSourceCodePerStore which is Tab 2 c) Return the SKU_Description together with the SKU in the WishList, Tab 8 d) Add a button to add 1 item of WishList to Cart, Tab 8 e) Add new Web Service called WSChangePassword in tab 16 to change password, this requires the user already logged in
The deprecated com.teamdev.jxbrowser.view.javafx.BitmapUtil and com.teamdev.jxbrowser.view.swing.BitmapUtil classes have been removed. Use the com.teamdev.jxbrowser.view.swing.graphics.BitmapImage and com.teamdev.jxbrowser.view.javafx.graphics.BitmapImage classes instead.
Lists also differ from arrays in that you can have an array of any of the primitive types: int, double, or boolean, but you can only put objects in a list. You can use the wrapper classes Integer, Double, and Boolean to wrap a primitive value in an object so that you can put it in a list. Java will also do this automatically for you if you try to add a primitive value to a list or set a primitive variable to an item of a list. This is called autoboxing and unboxing.
Autoboxing - Automatically wrapping a primitive type in a wrapper class object. For instance if you try to add an int value to a list, it will automatically be converted to an Integer object. 781b155fdc