Sharing of user classloaded classes metadata support. Each jav all pass consists of an opcode followed by its operands. Instead, they depend on a JVM to perform these operations. Casting for porn makes Yui Satonaka to act really nasty - More at javhd. Ability of the jav all pass collector and memory manager to deal with the demands of the click to see more running This can not be determined often. Interfaces are similar to classes.
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Tiket untuk pertunjukan khusus tersedia secara terpisah. Beli Tiket. Selain Daily Pass, Anda akan memerlukan tiket special show untuk melihat pertunjukan khusus. Tiket special show ini hanya memberi Anda tiket masuk ke pertunjukan unik dan bukan ke festival. Ticket Info. Only those who have received a complete primary dose of COVID Vaccine as demonstrated by your account in the PeduliLindungi mobile application are eligible to purchase event tickets.
You agree to and are bound by this Event Ticket Policy by purchasing event tickets. Daily Pass Ticket This sort of ticket allows you to enter the festival area for one day only Friday, Saturday, or Sunday. Special Show Ticket In addition to your daily pass, you'll need a special show ticket to see a special show. All classes in Java inherit from the Object class at some level, as you walk up through the inheritance chain of superclasses. Figure illustrates a generic Java class hierarchy.
The FullTimeEmployee class contains the id and lastName fields defined in the Employee class, because it inherits from the Employee class. In the example, the FullTimeEmployee instance can call methods defined only in the FullTimeEmployee class and methods defined in the Employee class. Instances of Class B can be substituted for instances of Class A, which makes inheritance another powerful construct of object-oriented languages for improving code reuse.
You can create classes that define behavior and state where it makes sense in the hierarchy, yet make use of preexisting functionality in class libraries. You can write and load Java applications within the database because it is a safe language with a lot of security features. Java has been developed to prevent anyone from tampering with the operating system where the Java code resides in.
Some languages, such as C, can introduce security problems within the database. However, Java, because of its design, is a robust language that can be used within the database. Although the Java language presents many advantages to developers, providing an implementation of a JVM that supports Java server applications in a scalable manner is a challenge. This section discusses the following challenges:. Oracle Database provides Java applications with a dynamic data-processing engine that supports complex queries and different views of the same data.
All client requests are assembled as data queries for immediate processing, and query results are generated dynamically. The combination of Java and Oracle Database helps you to create component-based, network-centric applications that can be easily updated as business needs change.
In addition, you can move applications and data stores off the desktop and onto intelligent networks and network-centric servers. More important, you can access those applications and data stores from any client device.
The figure also shows how Oracle Net Services Connection Manager can combine many network connections into a single database connection. This enables Oracle Database to support a large number of concurrent users. Multithreading is one of the key scalability features of the Java language. The Java language and class libraries make it simpler to write multithreaded applications in Java than many other languages, but it is still a daunting task in any language to write reliable, scalable multithreaded code.
Oracle Database server efficiently schedules work for thousands of users. The Oracle JVM takes advantage of the session architecture of Oracle database to concurrently run Java applications for hundreds to thousands of users. Although Oracle Database supports Java language-level threads required by the JLS and JCK, scalability will not increase by using threads within the scope of the database.
By using the embedded scalability of the database, the need for writing multithreaded Java servers is eliminated. You should use the facilities of Oracle Database for scheduling users by writing single-threaded Java applications.
The database can schedule processes between each application, and thus, you achieve scalability without having to manage threads. You can still write multithreaded Java applications, but multiple Java threads will not increase the performance of the server.
One complication multithreading creates is the interaction of threads and automated storage management or garbage collection. The garbage collector running in a generic JVM has no knowledge of which Java language threads are running or how the underlying operating system schedules them. A single user maps to a single Java thread and a single garbage collector manages all garbage from all users. Different techniques typically deal with allocation and collection of objects of varying lifetimes and sizes.
The result in a heavily multithreaded application is, at best, dependent upon operating system support for native threads, which can be unreliable and limited in scalability. High levels of scalability for such implementations have not been convincingly demonstrated.
Even when thousands of users connect to the server and run the same Java code, each user experiences it as if he or she is running his or her own Java code on his or her own JVM.
The responsibility of an Oracle JVM is to make use of operating system processes and threads and the scalable approach of Oracle Database. As a result of this approach, the garbage collector of the Oracle JVM is more reliable and efficient because it never collects garbage from more than one user at any time.
Garbage collection is a major function of the automated storage management feature of Java, eliminating the need for Java developers to allocate and free memory explicitly. However, garbage collection contributes to the overhead of program execution speed and footprint.
Garbage collection imposes a challenge to the JVM developer seeking to supply a highly scalable and fast Java platform. An Oracle JVM meets these challenges in the following ways:. Garbage collection is performed consistently for multiple users, because garbage collection is focused on a single user within a single session. The Oracle JVM has an advantage, because the burden and complexity of the job of the memory manager does not increase as the number of users increases.
The memory manager performs the allocation and collection of objects within a single session, which typically translates to the activity of a single user. The Oracle JVM uses different garbage collection techniques depending on the type of memory used. These techniques provide high efficiency and low overhead. Figure illustrates the different actions performed by the garbage collector. Scavenging occurs at a set interval. Some programmers create objects frequently for only a short duration.
These types of objects are created and garbage-collected quickly within the new call space. This is known as scavenging. Any objects that have survived several iterations of scavenging are considered to be objects that can exist for a while.
These objects are moved out of new call space into old call space. During the move, they are also compacted. Old call space is scavenged or garbage collected less often and, therefore, provides better performance.
At the end of the call, any objects that are to exist beyond the call are moved into session space. Figure illustrates the steps listed in the preceding text. This approach applies sophisticated allocation and collection schemes tuned to the types and lifetimes of objects. For example, new objects are allocated in fast and inexpensive call memory, designed for quick allocation and access.
Objects held in Java static fields are migrated to the more precious and expensive session space. The size of the program depends on the number of classes and methods and how much code they contain. The complexity of the program depends on the number of core class libraries that the Oracle JVM uses as the program runs, as opposed to the program itself. The amount of space the JVM uses depends on the number of objects the JVM allocates, how large these objects are, and how many objects must be retained across calls.
Ability of the garbage collector and memory manager to deal with the demands of the program running. This can not be determined often. The speed with which objects are allocated and the way they are held on to by other objects influences the importance of this factor. From a scalability perspective, the key to supporting multiple clients concurrently is a minimum per-user session footprint.
The Oracle JVM keeps the per-user session footprint to a minimum by placing all read-only data for users, such as Java bytecodes, in shared memory. Appropriate garbage collection algorithms are applied against call and session memories to maintain a small footprint for the user's session. The Oracle JVM uses the following types of garbage collection algorithms to maintain the user's session memory:.
Copying collector for long-lived objects, that is, objects that live across calls within a session. Any time you add levels within software, the performance is degraded.
Because Java requires going through an intermediary to interpret the bytecodes, a degree of inefficiency exists for Java applications as compared to applications developed using a platform-dependent language, such as C. To address this issue, several JVM suppliers create native compilers.
Native compilers translate Java bytecodes into platform-dependent native code, which eliminates the interpreter step and improves performance. The JIT compiler is enabled without the support of any plug-ins and it is applicable across all the platforms that Oracle supports. Figure illustrates how natively compiled code runs up to 10 times faster than interpreted code. As a result, the more native code your program uses, the faster it runs. Another strong feature of Java is dynamic class loading.
The class loader loads classes from the disk and places them in the JVM-specific memory structures necessary for interpretation. This approach, which works well for applets, poses the following problems in a server environment:. In addition, Oracle Database adheres to standard Java language semantics, including dynamic class loading at run time.
A session is typically, although not necessarily, bounded by the time a single user connects to the server. As a user who calls a Java code, you must establish a session in the server. When a user causes a Java code to run within a session, it is termed as a call.
A call can be started in the following different ways:. In a standard Java environment, you run a Java application through the interpreter by issuing the following command on the command line, where classname is the name of the class that you want the JVM to interpret first:.
When using the Oracle JVM, you must load the application into the database, publish the interface, and then run the application within a database session. The database session is the environment in which the Oracle JVM runs and as such is the analog of the operating system process in which a standard client JVM runs. Standard client-based Java applications declare a single, top-level method, public static void main String args.
This method is executed once and the instantiation of the Java Virtual Machine lasts for the duration of that call. But, Oracle Java applications are not restricted to a single top-level main entrypoint, and the duration of the Oracle JVM instantiation is not determined by a single call and the exit of the call from this entrypoint. Each client begins a session, calls its server-side logic modules through top-level entry points, and eventually ends the session.
The same JVM instance remains in place for the entire duration of the session, so data state such as static variable values can be used across multiple calls to multiple top-level entry points. Class definitions that have been loaded and published in the database are generally available to all sessions in that database. This data is present for the duration of the session and may be used by multiple calls within the lifetime of that session. But, neither this data is visible to other sessions nor the data can be shared in any way with other sessions.
This is analogous to how in a standard client Java application separate invocations of the main method share the same class definitions, but the data created and used during those invocations are separate. A server cannot provide GUIs, but it can provide the logic that drives them. You can write and test applications on any preferred integrated development environment IDE , such as Oracle JDeveloper, and then deploy them within the database for the clients to access and run them.
The binary compatibility of Java enables you to work on any IDE and then upload the Java class files to the server. You need not move your Java source files to the database. Instead, you can use powerful client-side IDEs to maintain Java applications that are deployed on the server.
The primary benefit of IPv6 is a large address space, derived from the use of bit addresses. IPv6 also improves upon IPv4 in areas such as routing, network autoconfiguration, security, quality of service, and so on. If IPv6 is available on the operating system, then the underlying native socket will be an IPv6 socket. If you have an application that has a preference to use only IPv4 sockets, then you can set this property to true. If you set the property to true , then it implies that the application will not be able to communicate with IPv6 hosts.
Even if IPv6 is available on the operating system, then for backward compatibility reasons, the addresses are mapped to IPv4. For example, applications that depend on access to only an IPv4 service, benefit from this type of mapping. If you want to change the preferences to use IPv6 addresses over IPv4 addresses, then you can set the java. This allows applications to be tested and deployed in environments, where the application is expected to connect to IPv6 services.
Table lists the features of Oracle JVM and the versions in which they were first supported. This section briefly describes the main components of an Oracle JVM and some of the facilities they provide. It runs in the same process space and address space as the database kernel by sharing its memory heaps and directly accessing its relational data.
This design optimizes memory use and increases throughput. It fully supports Java data structures, method dispatch, exception handling, and language-level threads. It also supports all the core Java class libraries, including java. This feature lets Java programs access Java objects stored in Oracle Database and application servers across the enterprise. In addition, the Oracle JVM is tightly integrated with the scalable, shared memory architecture of the database.
Java programs use call, session, and object lifetimes efficiently without user intervention. As a result, the Oracle JVM and middle-tier Java business objects can be scaled, even when they have session-long state. Each bytecode consists of an opcode followed by its operands. The resulting Java class files, which conform fully to the Java standard, are submitted to the interpreter at run time. The interpreter and the associated Java run-time system run standard Java class files.
The run-time system supports native methods and call-in and call-out from the host environment. In response to requests from the run-time system, the Java class loader locates, loads, and initializes Java classes stored in the database. The class loader reads the class and generates the data structures needed to run it.
Immutable data and metadata are loaded into initialize-once shared memory. As a result, less memory is required for each session.
The class loader attempts to resolve external references when necessary. In addition, if the source files are available, then the class loader calls the Java compiler automatically when Java class files must be recompiled. Java class files are fully portable and conform to a well-defined format. The verifier prevents the inadvertent use of spoofed Java class files, which might alter program flow or violate access restrictions. Oracle security and Java security work with the verifier to protect your applications and data.
JDBC is a standard and defines a set of Java classes providing vendor-independent access to relational data. Using low-level entry points, a specially tuned JDBC driver runs directly inside Oracle Database, providing fast access to Oracle data from Java stored procedures. Tightly integrated with the database, the JDBC driver supports Oracle-specific data types, globalization character sets, and stored procedures.
It is more concise than JDBC and more responsive to static analysis and type checking. The Java type system ensures that objects of those classes are called with the correct arguments. SQLJ forms can include queries, data manipulation language DML statements, data definition language DDL statements, transaction control statements, and calls to stored procedures. A set of classes that constitute a significant portion of the implementation of Java in Oracle Database environment is known as the System classes.
These classes are defined in the SYS schema and exported for all users by public synonym. A class with the same name as one of the System classes can be defined in a schema other than the SYS schema Foot 1. But, this is a bad practice because the alternate version of the class may behave in a manner that violates assumptions about the semantics of that class that are present in other System classes or in the underlying implementation of Java Virtual Machine.
Oracle strongly discourages this practice. Oracle provides enterprise application developers an end-to-end Java solution for creating, deploying, and managing Java applications. The total solution consists of client-side and server-side programmatic interfaces, tools to support Java development, and a JVM integrated with Oracle Database. All these products are fully compatible with Java standards. This section covers the following topics:. Oracle Database provides a complete implementation of the standard Java programming language and a fully compliant JVM.
Both these APIs are available on the client and the server. As a result, you can deploy your applications on the client and server, without modifying the code.
JDBC is a database access protocol that enables you to connect to a database and run SQL statements and queries to the database. However, JDBC is designed to enable vendors to supply drivers that offer the necessary specialization for a particular database.
Oracle provides the following distinct JDBC drivers:. This work has resulted in a new standard, ANSI x. At run time, the program can communicate with multi-vendor databases using standard JDBC drivers. SQLJ provides a simple, but powerful, way to develop both client-side and middle-tier applications that access databases from Java.
Oracle Database 11g provides a complete Java environment, so you cannot compile SQLJ programs on a client that will run on the server. Instead, you can compile them directly on the server. The adherence of Oracle Database to the Internet standards enables you to choose the development style as per your requirements. JPublisher provides a simple and convenient tool to create Java programs that access existing Oracle relational database tables.
The adherence of Oracle Database to the Java standards and specifications and the open Internet standards and protocols ensures that your Java programs work successfully, when you deploy them on Oracle Database. Oracle provides many tools or utilities that are written in Java making development and deployment of Java server applications easier.
Since Oracle Database 10 g , the Oracle JVM has a new memory model for sessions that connect to the database through a dedicated server.
The basic memory structures associated with Oracle include:. The SGA is shared by all server and background processes. A PGA is a memory region that contains data and control information for a server process. It is nonshared memory created by Oracle when a server process is started. Access to the PGA is exclusive to the server process. There is one PGA for each server process. Background processes also allocate their own PGAs. The total PGA memory allocated for all background and server processes attached to an Oracle instance is referred to as the aggregate PGA.
The simplest way to manage memory is to allow the database to automatically manage and tune it for you. Because the target memory initialization parameter is dynamic, you can change the target memory size at any time without restarting the database. The maximum memory size serves as an upper limit so that you cannot accidentally set the target memory size too high.
Because certain SGA components either cannot easily shrink or must remain at a minimum size, the database also prevents you from setting the target memory size too low. Some of the important concepts of Java include: A Java virtual machine JVM , which provides the fundamental basis for platform independence Automated storage management techniques, such as garbage collection Language syntax that is similar to that of the C language The result is a language that is object-oriented and efficient for application programming.
Each class can define the following: Fie lds Fields are variables that are present in each object or instance of a particular class, or are variables that are global and common to all instances. Meth ods Methods are procedures associated with a class.
Ob jects A Java object is an instance of a class and is analogous to a relational table row. Inheri tance Inheritance is an important feature of object-oriented programming languages.
Interf aces Java supports only single inheritance, that is, each class can inherit fields and methods of only one class. Enc apsulation Encapsulation describes the ability of an object to hide its data and methods from the rest of the world and is one of the fundamental principles of object-oriented programming.
Poly morphism Polymorphism is the ability for different objects to respond differently to the same message. Compensation is computed differently for different types of employees: Full-time employees are eligible for a bonus. Non-exempt employees get overtime pay. In procedural languages, you write a switch statement, with the different possible cases defined, as follows: switch: employee.
Key Features of the Java Language The Java language provides certain key features that make it ideal for developing server applications. These features include: Simplicity Java is simpler than most other languages that are used to create server applications, because of its consistent enforcement of the object model.
Portability Java is portable across platforms. See Also: "Java Virtual Machine".