Estd: 1994 Department of Computer Science and Engineering Subject code : IT1402 Year/Sem: IV/VII Subject Name JAYARAM COLLEGE OF ENGINEERING AND TECHNOLOGY Pagalavadi, Tiruchirappalli - 621014 (An approved by AICTE and Affiliated to Anna University) : Middleware Technologies UNIT I ISO 9001:2000 Certified 1. What is CORBA? CORBA stands for the common object request broker Architecture. It is a set of standard mechanisms for naming, locating and defining objects in a distributed computing environment. 2. What is a database server? With a database server, the client passes SQL requests as messages to the database server. The results of each SQL command are returned over the network. The server uses its own processing power to find the request data instead data instead of processing all the records back to the client and then getting if find its own data. The result is a much more efficient use of distributed processing power. It is also known as SQL engine. 3. What is File Server? File servers are useful for sharing files across a network with a file server, the client passes requests for file records over network to file server. 4. What is web server? This new model of Client/Server consists of thin,portable, universal clients that talk to super fat servers. In the simplest form, a web server returns document when clients ask for them by name. the clients and server communicating using an RPC Like protocol called HTTP.
5. What is meant by 2 tier architecture? In 2 tier client server systems, the application logic is either buried inside the user interface on the client or within the database on the server. Example : file servers and database servers with stored procedures. 6. What is meant by Middleware? Middleware is distributed software needed to support interaction between clients and server. In short, it is the software that is in the middle of the client/server systems and It acts as a bridge between the clients and server. It starts with the API set on the client side that is used to invoke a service and it covers the transmission of the request over the network and the resulting response. It neither includes the software that provides the actual service that is in the servers domain not the user interface or the application login that s in clients domain. 7. What are the two board classes of middleware? General middleware Service specific middleware 8. What is group ware Server? Group server addresses the management of semi-structured information such as text, image, tesmail, bulletin boards and the flow of work. These client/server systems have people in direct contact with other people. 9. What are the characteristics of client /Server? Service Shared resources Asymmentrical protocols Transparency of location Mix and match Message based exchanges Encapsulation of services Scalability Integrity
Client /server computing is the ultimate open platform it gives the freedom to mix and match components of almost any level. Clients and servers are loosely coupled systems that interact through a message passing mechanism. 10. What is ACID Property? ACID is a term coined by Andrew Reuter in 1983, which stands for atomicity, consistence, isolation and durability. 11. What are the classifications of clients? Non GUI clients two types are Non GUI clients that do not need multi tasking (Example automatic teller machines, cell phone) Non GUI Clients that need multi tasking Example ROBOTs GUI clients OOUI clients 12. What are stored procedures? A stored procedures is a named collection of SQL statements and procedural logic that is complied verified and stored in a sever database. It is typically treated like any other database object. Stored procedures accept input parameters so that a single procedure can be used over the network by multiple clients using different input data. A single remote message triggers the execution of a collection of stored SQL statements. The results are a reduction of network traffic and better performance. 13. What are the five major technologies that can be used to create client/server applications? Database Servers TP monitors Groupware Distributed objects Intranets
14.What is meant by Mix and match? The ideal client server software is independent of hardware and operating system software platform. It should be able to mix match client and server platforms. 15. What is a Transaction server? With a transaction server, the client invokes remote procedures that reside on the server with an SQL database engine. These remote procedures on the server execute a group of SQL statements. The network exchange consists of a single request reply message. The SQL statements either all succeed or fail as a unit. 16. What is an object server? With an object server, the client server application is written as a set of communicating objects. Client object commnunicate with server objects using an object request broker. The client invokes a method on a remote object. The ORB locates an instance of that object server class, invokes the requested method and returns the results to the client object. Server objects must provide support for concurrency and sharing. The ORB brings it all together. 17. What are the called fat clients and fat servers? If the bulk of the application runs on the client side, then it is fat clients, it is used for decision support and personal software. If the bulk of the application runs on the server side, then it is fat servers. It tries to minimize network interchanges by creating more abstract levels of services. 18. What is message oriented middleware? MOM allows general purpose messages to be exchanged in a client/server system using message queues. Application communicate over networks by simply putting messages in the queues and getting messages form queue. It typically provides and server can run at different times. It is a post office like metaphor.
19. What is structured query language (SQL) SQL is a powerful set oriented language which was developed by ibm research for the databases that adhere to the relational model. It consists of a short list of powerful, yet highly flexible commands that can be used to manipulate information collected in tables. Through SQL. We can manipulate and control sets of record sets a time. 20. What are the three types of SQL database server architectuer? Process per client architecture. Example oracle6, Informix) Multithreaded architecture. Example Sybase, SQL server) Hybrid architecture example oracle UNIT I BIG QUESTIONS 1. Explain the architecture of MOM? How is it different from other types of Middleware. 2. Define Middleware and types of middleware in detail. 3. How is RPC implemented in client server environment? Explain in detail the various issues involved while implementing with diagram. 4. How are the servers classified? Describe each type in detail. 5. What are the most typical functional units of the client /server applications?
UNIT II 1. What is EJB? EJB stands for Enterprise JavaBeans and is widely-adopted server side component architecture for J2EE. It enables rapid development of ission-critical application that are versatile, reusable and portable across middleware while protecting IT investment and preventing vendor lock-in. 2. What is session Facade? Session Facade is a design pattern to access the Entity bean through local interface than accessing directly. It increases the performance over the network. In this case we call session bean which on turn call entity bean. 3. What is EJB role in J2EE? EJB technology is the core of J2EE. It enables developers to write reusable and portable server-side business logic for the J2EE platform. 4. What is the difference between EJB and Java beans? EJB is a specification for J2EE server, not a product; Java beans may be a graphical component in IDE. 5. What are the key features of the EJB technology? 1. EJB components are server-side components written entirely in the Java programming language 2. EJB components contain business logic only - no system-level programming & services, such as transactions, security, life-cycle, threading, persistence, etc. are automatically managed for the EJB component by the EJB server. 3. EJB architecture is inherently transactional, distributed, portable multi-tier, scalable and secure. 4. EJB components are fully portable across any EJB server and any OS. 5. EJB architecture is wire-protocol neutral--any protocol can be utilized like IIOP, JRMP, HTTP, DCOM, etc.
6. What are the key benefits of the EJB technology? 1. Rapid application development 2. Broad industry adoption 3. Application portability 4. Protection of IT investment 7. How many enterprise beans? There are three kinds of enterprise beans: 1. session beans, 2. entity beans, and 3. message-driven beans. 8. What is message-driven bean? A message-driven bean combines features of a session bean and a Java Message Service (JMS) message listener, allowing a business component to receive JMS. A message-driven bean enables asynchronous clients to access the business logic in the EJB tier. 9. How can I call one EJB from inside of another EJB? EJBs can be clients of other EJBs. It just works. Use JNDI to locate the Home Interface of the other bean, then acquire an instance reference, and so forth. 10. Can a Session Bean be defined without ejbcreate() method? The ejbcreate() methods is part of the bean's lifecycle, so, the compiler will not return an error because there is no ejbcreate() method. However, the J2EE spec is explicit: the home interface of a Stateless Session Bean must have a single create() method with no arguments, while the session bean class must contain exactly one ejbcreate() method, also without arguments. Stateful Session Beans can have arguments (more than one create method)
11. Why would a session bean use bean-managed transactions? In some situations, it's necessary for a (stateful) session bean to selectively control which methods participate in transactions, and then take over the bundling of operations that form a logical unit of work. 12. Is method overloading allowed in EJB? Yes you can overload methods. 13. How can JMS be used from EJB 1.1? The same as any client would use JMS. At this point there is no integration, but it is planned for a future release of the EJB spec. 14. Can primary keys contain more than one field? Yes, a primary key can have as many fields as the developer feels is necessary, just make sure that each field you specify as the primary key, you also specify a matching field in the bean class. A primary key is simply one or more attributes which uniquely identify a specific element in a database. Also, remember to account for all fields in the equals() and hashcode() methods. 15. Which fields in beans should be public? All Container Managed Fields in an Entity Bean must be public. Ejb 1.1 spec section 9.4.1 - "The fields must be defined in the entity bean class as public, and must not be defined as transient." 16. How do I automatically generate primary keys? A common way to do it is to use a stateless session bean to retrieve the ID that you wish to use as the primary key. This stateless session bean can then execute an Oracle sequencer or procedure etc. to retrieve the ID value used as the primary key. 17 What are the different type of Enterprise JavaBeans? There are 3 types of enterprise beans, namely: Session bean, Entity beans and Message driven beans.
BIG QUESTIONS: UNIT II 1. Draw the architecture and explain the functions of various entities involved. 2. Discuss the roles in EJB. 3. Draw the life cycle of Entity bean and explain 4. List the Constraints on using Session beans. 5. Explain the concept of session bean and It type in detail.
Unit III 1. What is Session Bean? Session bean represents a single client inside the J2EE server. To access the application deployed in the server the client invokes methods on the session bean. The session bean performs the task shielding the client from the complexity of the business logic. Session bean components implement the javax.ejb.sessionbean interface. Session beans can act as agents modeling workflow or provide access to special transient business services. Session beans do not normally represent persistent business concepts. A session bean corresponds to a client server session. The session bean is created when a client requests some query on the database and exists as long as the client server session exists. 2. What are different types of session bean? There are two types of session beans, namely: Stateful and Stateless. 3. What is an Entity Bean? An entity bean represents a business object in a persistent storage mechanism. An entity bean typically represents a table in a relational database and each instance represents a row in the table. Entity bean differs from session bean by: persistence, shared access, relationship and primary key. 4. What are different types of entity beans? There are two types of entity beans available. Container Managed Persistence (CMP), Bean managed persistence (BMP). 5. What is abstract schema? In order to generate the data access calls, the container needs information that you provide in the entity bean's abstract schema. It is a part of Deployment Descriptor. It is used to define the bean's persistent fields and relation ships.
6. When we should use Entity Bean? When the bean represents a business entity, not a procedure. we should use an entity bean. Also when the bean's state must be persistent we should use an entity bean. If the bean instance terminates or if the J2EE server is shut down, the bean's state still exists in persistent storage (a database). 7. When to Use Session Beans? At any given time, only one client has access to the bean instance. The state of the bean is not persistent, existing only for a short period (perhaps a few hours). The bean implements a web service. Under all the above circumstances we can use session beans. 8. When to use Stateful session bean? The bean's state represents the interaction between the bean and a specific client. The bean needs to hold information about the client across method invocations. The bean mediates between the client and the other components of the application, presenting a simplified view to the client. Under all the above circumstances we can use a stateful session bean. 9. When to use a stateless session bean? The bean's state has no data for a specific client. In a single method invocation, the bean performs a generic task for all clients. For example, you might use a stateless session bean to send an email that confirms an online order. The bean fetches from a database a set of read-only data that is often used by clients. Such a bean, for example, could retrieve the table rows that represent the products that are on sale this month. Under all the above circumstance we can use a stateless session bean. 10. Why Use EJB? EJB helps in building enterprise applications easily. Developers of EJB needs to focus on business logic only. All other features like transaction, persistence etc will be managed by the container. EJB provides developers architectural independence.
11. What are the different methods of Entity Bean? An entity bean consists of 4 type of methods: create methods, finder methods, remove methods and home methods. 12. What is the difference between EJB and Java beans? EJB is a specification for J2EE server, not a product; Java beans may be a graphical component in IDE. 13. What is EJB role in J2EE? EJB technology is the core of J2EE. It enables developers to write reusable and portable server-side business logic for the J2EE platform. 14. What are the key benefits of the EJB technology? <!--[if!supportlists]-->1. <!--[endif]-->rapid application development <!--[if!supportlists]-->2. <!--[endif]-->broad industry adoption <!--[if!supportlists]-->3. <!--[endif]-->application portability <!--[if!supportlists]-->4. <!--[endif]-->protection of IT investment 15. How many enterprise beans? There are three kinds of enterprise beans: <!--[if!supportlists]-->1. <!--[endif]-->session beans, <!--[if!supportlists]-->2. <!--[endif]-->entity beans, and <!--[if!supportlists]-->3. <!--[endif]-->message-driven beans. 16. What is message-driven bean? A message-driven bean combines features of a session bean and a Java Message Service (JMS) message listener, allowing a business component to receive JMS. A message-driven bean enables asynchronous clients to access the business logic in the EJB tier. 17. What is the difference between session and entity beans? An entity bean represents persistent global data from the database; a session bean represents transient user-specific data that will die when the user disconnects (ends his session). Generally, the session beans implement business methods (e.g. Bank.transferFunds) that call entity beans (e.g. Account.deposit, Account.withdraw)
18. How many EJB Objects are created for a Bean? For a Session bean one EJB object for one bean instance. For entity bean it depends, if two users are accessing one row at time then one EJB object is used for both the beans other wise for each bean one EJB object. 19. What is EJB container? An EJB container is a run-time environment that manages one or more enterprise beans. The EJB container manages the life cycles of enterprise bean objects, coordinates distributed transactions, and implements object security. Generally, each EJB container is provided by an EJB server and contains a set of enterprise beans that run on the server. 20. What is the difference between ejbcreate() and ejbpostcreate? The purpose of ejbpostcreate() is to perform clean-up database operations after SQL INSERTs (which occur when ejbcreate() is called) when working with CMP entity beans. ejbcreate() is called before database INSERT operations. You need to use ejbpostcreate() to define operations, like set a flag, after INSERT completes successfully UNIT III BIG QUESTIONS 1. Explain Life Cycle of session bean with diagram. 2. Explain detail about Entity beans and its deployment. 3. (i) Draw the life cycle of entity bean and explain. (ii) List the constraints on using session beans.
UNIT IV 1. Why we need CORBA? It is used to solve one fundamental problem- how can distributed object oriented systems implemented in different languages and running on different platforms? 2. What are the essential parts of CORBA? Invocation Interfaces Object Request Broker Object Adapters 3. What are the requirements need to work invocation interfaces and object adapters? All object interfaces need to be described in a common language. All languages used must have bindings to the common language. 4. What is the use ORB? An ORB is capable of loading and starting an object servant which receiving invocation requests for an object of that servant. 5. What is responsible of object adapter? An object adapter is responsible for which servant serves telling an ORB which new object. 6. Differentiate stubs and skeletons. Sl.no Stubs Skeletons 1. 2. Called client side proxy objects. It forwards all invocations through the ORB to the real target object. Called server side stubs It directly invokes the target method. 7. Specify the features of SOM. Meta programming Binary compatibility
8. Specify any four services supporting enterprise distributed computing. Naming and trader service. Event and notification service Object transaction service Security service 9. Specify any four services supporting architecture using fine-grained objects? _ Concurrency control service _ Licensing service _ Lifecycle service _ Relationship service _ Persistent state service 10. What is naming service? It allows arbitrary names to be associated with an object. Names are unique within a naming context and naming contexts from a hierarchy. 11. What is push model? In push model the event supplier calls a push method on the event channel, which reacts by calling the push method of all registered consumers. 12. What is pull model? In pull model the consumers call the pull method of the event channel, effectively pooling the channel for events. 13. What is the life cycle service? This service supports creation, copying, moving and deletion of objects and related group of objects. 14. What are the features of CCM components? Ports that are classified into facets, receptacles, event sources and event sinks. Primary keys, which are values that instances of entity components
Attributes and configuration Home interfaces 15. What is facet? A special of CCM components is the equivalent interface, which enables navigation between the different facts of a CCM component. 16. What is Receptacles? Receptacles provide connect and disconnect operations and internally correspond to object references top other objects of appropriate type. 17. What is home interface? The home interface is provided by a component, not its instances, and supports the creation of new instances. 18. What is the use of primary keys? Primary keys which are values that instances of entity components provide to allow client identification of the instances. 19. What is attribute and configuration? Configuration interfaces support initial configuration of new component instances. They are described as IDL attributes with set and get operations. 20. What is MDA? The OMG architecture board introduced a new approach called model driven architecture for all forthcoming OMG specifications.
UNIT IV BIG QUESTIONS: 1. Explain briefly about the CORBA services Services supporting enterprise distributed computing. Services supporting architecture using fine-grained objects. 2. Explain the CORBA component model. Portable object adapter CCM components CCM containers 3. Write short notes on SOM and MDA. SOM Meta programming Binary compatibility MDA 4. Explain briefly about IDL interface. _ IDL interface _ Modules _ Data types 5. Explain briefly about CCM components. _ Features _ Diagram
UNIT-V 1. Define COM? COM is binary standard, it specifies nothing about how a particular programming language may be bound to it. COM does not specify what a component or an object is. 2. Draw the binary representation of a COM interface. Client variable 3. Name and two interfaces that is used in COM? Query interface Iunknown interface 4. What is the use of Query interface method? Query interface takes the name of an interface, checks if the current COM object supports it, and if so returns the corresponding interface reference. 5. What is the use of Iunknown interface? The identity of the Iunknown interface can serve to identify the entire COM object with out requiring any specific functionality. 6. What are the methods supported by Iunknown interface? Query Interface AddRef AddRelease 7.Specify the use of HRESULT type. The type HRESULT is used by most COM interface methods to indicate success or failure to call. It may also indicate network failure. Interface node OP1 OP2 OPn Component
8. What is AddRef and Release? On creation of an object or node, the reference count is initialized to 1 before handling out a first reference. Each time a copy of a reference is created the count must be incremented (AddRef). Each time a reference is given up, the count must be decremented (Release). 9. Specify the two forms of object reuse. Containment Aggregation 10. What is containment? Containment is a form of object reuse. It is just the simple object composition technique. One object holds an exclusive reference to another. Here the call is forwarded and handled by another object. 11. What is aggregation? Aggregation is a form of object reuse. Here instead of forwarding requests, an inner object s interface reference could be handed out directly to another object s client. 12. When we use Aggregation? Aggregation is only useful where the outer object does not wish to intercept calls to perform some filtering or additional processing. 13. Compare COM and DCOM. DCOM transparently expands the concepts and services of COM. DCOM builds on the client-side proxy objects and the server side stub objects already present in COM. 14. What is outgoing interface? An outgoing interface is an interface that a COM object would use if it were connected to an object that provides this interface. 15. Name the interface that is declared within outgoing interface. IConnectionPointContainer IConectionPoint
16. Specify the use of IConnectionPointContainer? Using IConnectionPointContainer,the various connection point objects of a connectable object can be found and enumerated. 17. Specify the use oficonnectionpoint? IConnectionPoint can be used to establish, enumerate and tear down connections. 18. How the connectable objects implement change propagation? Connectable objects provide a uniform way to implement change propagation. As outgoing and incoming interfaces are matched, the propagation can take the form of regular method invocations instead of requiring the creation of event objects. 19. Specify the policies that are used to determine the shared assemblies in GAC. Publisher policy Application policy Machine policy 20. What is Appdomains? The CLR execution engine partitions a process into one or more AppDomains. An AppDomain isolates sets of object from all objects in other appdomain, but is more light weight and cheaper than operating systems. 21. What are contexts? A context is a partition of an appdomain the member objects, objects of which share the propreties of their contexts. 22. What is reflection? The CLI reflection support grants full access to the type structure of loaded assemblies including all attributes defined on these types. 23. What is remoting? The CLI remoting support combines context and reflection infrastructure with flexible support for proxies, channels and messages provide building blocks for a wide variety of communication styles and patterns.
UNIT V BIG QUESTIONS: 1. Explain the COM services in detail. Dispatch interfaces Connectable objects 2. Explain in detail the compound document and OLE. OLE containers and services Controls-ActiveXcontrols 3. Explain briefly about the.net components. Assemblies Single application Shared application Policies 4. Write short notes on AppDomains, contexts, reflection,remoting AppDomains o Loading o Unloading Contexts o Context bound o Context Agile Reflection Remoting 5. Explain about dual interface and outgoing interfaces. o Dual interface _ Idispatch method _ DispID o Outgoing interface _ IConnectionPointContainer _ IConnectionPoint