Interview Q&A

• What do I need to run AppleScript?

  You need at least a 68020 (a Mac II or LC, for example) to run AppleScript 1.1.

• What is SLIP (Serial Line Interface Protocol)? »

  It is a very simple protocol used for transmission of IP datagrams across a serial line.

• What is SLIP (Serial Line Interface Protocol)? »

  It is a very simple protocol used for transmission of IP datagrams across a serial line.

• What is OSPF?

  It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet’s topology to make accurate routing decisions

• What is a Multi-homed Host?

  It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.

• What is NVT (Network Virtual Terminal)? »

  It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

• Name of seven layers in Open System Interconnection model.

  They are Application, Presentation, Session, Transport, Network, Data link, and Physical.

• SHOULD ALL MY OBJECTS BE DISTRIBUTED?

  Not every business object should be distributed. Distribution implies network overhead and management overhead. Distribution of all business objects can lead to severe performance problems. Distribution can provide many benefits, but should...

• What are the similarities and differences between RMI and CORBA?

  Similarities * Hide communication to remote objects behind method calls * Use stub/skeleton approach * Provide a Naming Service

• What is the purpose of a mapping?

  A mapping allows a compiler to translate an interface defined in IDL into a specific programming language. It allows the compiler to generate stubs, skeletons and various helper classes which can be used to develop implementations of the in...

• What is the purpose of IDL?

  Interface Definition Language (IDL) is a programming language-independent language for specifying the names, parameters and return types of the interface methods. A module may contain several interfaces and may define constants to be used w...

• What is the purpose of a request in CORBA?

  A request is used to transfer the name of the method (the service) and the parameters between the client and the server.

• What is the purpose of a request in CORBA?

  A request is used to transfer the name of the method (the service) and the parameters between the client and the server.

• What is an ORB?

  An ORB or Object Request Broker is software that allows servers to register the objects they provide and clients to find objects providing the services they want and then to interact with them.

• What is a heterogeneous distributed system?

  A collection of communicating machines running different operating systems

• What are the goals of CORBA?

  CORBA aims to allow interaction between potentially distributed component objects created by different manufacturers in different languages (location transparency and language transparency).

• What is CORBA?

  Common Object Request Broker Architecture - provides services to support intercommunication between objects. It is a framework and a specification for object collaboration and sharing across a heterogeneous distributed network of machines a...

• What is optional dependency

  plug-in prerequisite elements can be made optional by adding the optional="true" attribute in Manifest file(see below for an example). Marking an import as optional simply states that if the specified plug-in is not found at runtime, the de...

• What are the differences between 'Require-Bundle' and 'Import-Package'

  There are two complementary ways of depending on something from outside a given plug-in; Require-Bundle and Import-Package.

• How can I change the window icon in my application?

  Define a product via the products extension point and specify the windowImages property to refer to two image files, a 16x16 one and a 32x32 one.

• What is included in the Rich Client Platform?

  Eclipse Runtime, SWt, JFace, Workbench

• Is there a built-in facility to check whether a given value is valid compared to the effective facets of its type?

  To determine if a literal is valid with respect to a simple type, you can use either XSDSimpleTypeDefinition.isValidLiteral or XSDSimpleTypeDefinition.assess.

• What is EMF?

  The Eclipse Modeling Framework is a Java/XML framework for generating tools and other applications based on simple class models. EMF helps you rapidly turn models into efficient, correct, and easily customizable Java code. It is intended to...

• How to resize my shell to get my changed widgets to lay out again?

  A layout is only performed automatically on a Composite's children when the Composite is resized, including when it is initially shown. To make a Composite lay out its children under any other circumstances, such as when children are create...

• Why do I get the error "org.eclipse.swt.SWTException: Invalid thread access"?

  SWT implements a single-threaded UI model often called apartment threading. In this model, only the UI-thread can invoke UI operations. SWT strictly enforces this rule. If you try and access an SWT object from outside the UI-thread, you get...

• What is Display, what is Shell?

  The Display class respresents the GUI process(thread), the Shell class represents windows.

• How to fire a key event in my test code to make the program act as if a user pressed a key?

  Two ways to implement it in code: generating OS level key event use Display.post(Event) or use Widge.notifyListeners(...) to just notify a widget's listeners.

• Do we need to explicitly invoke org.eclipse.swt.graphics.Image.dispose()?

  Application code must explicitly invoke the Image.dispose() method to release the operating system resources managed by each instance when those instances are no longer required. This is because that the Java finalization is too weak to rel...

• How to access UI objects from a non-ui thread?

  Use Display.getDefault().asyncExec(new Runnable()...) Display.asyncExec causes the run() method of the runnable to be invoked by the user-interface thread at the next reasonable opportunity. The caller of this method continues to run in par...

• What is the classpath of a plug-in?

  The OSGi parent class loader. (Java boot class loader by default); The exported libraries of all imported plug-ins; The declared libraries of the plug-in and all its fragments.

• What are extensions and extension points?

  Loose coupling in Eclipse is achieved partially through the mechanism of extensions and extension points. When a plug-in wants to allow other plug-ins to extend or customize portions of its functionality, it will declare an extension point....

• How to config a plugin to start automatically during platform starts up?

  Define the 'Eclipse-AutoStart=true' header in Manifest file.

• When does a plugin get started?

  Each plug-in can be viewed as having a declarative section and a code section. The declarative part is contained in the plugin.xml file. This file is loaded into a registry when the platform starts up and so is always available, regardless...

• How can you generate debugging output from PL/SQL?

  There are 12 types of triggers in PL/SQL that consist of combinations of the BEFORE, AFTER, ROW, TABLE, INSERT, UPDATE, DELETE and ALL key words: BEFORE ALL ROW INSERT AFTER ALL ROW INSERT BEFORE INSERT AFTER INSERT etc.

• . How can you find within a PL/SQL block, if a cursor is open?

  Use the %ISOPEN cursor status variable.

• What are SQLCODE and SQLERRM and why are they important for PL/SQL developers?

  SQLCODE returns the value of the error number for the last error encountered. The SQLERRM returns the actual error message for the last error encountered. They can be used in exception handling to report, or, store in an error log table, th...

• In what order should a open/fetch/loop set of commands in a PL/SQL block be implemented if you use the NOTFOUND cursor variable in the exit when statement? Why?

  OPEN then FETCH then LOOP followed by the exit when. If not specified in this order will result in the final return being done twice because of the way the %NOTFOUND is handled by PL/SQL.

• When is a declare statement needed ?

  The DECLARE statement is used in PL/SQL anonymous blocks such as with stand alone, non-stored PL/SQL procedures. It must come first in a PL/SQL stand alone file if it is used.

• Describe the use of PL/SQL tables

  PL/SQL tables are scalar arrays that can be referenced by a binary integer. They can be used to hold values for use in later queries or calculations. In Oracle 8 they will be able to be of the %ROWTYPE designation, or RECORD.

• What packages (if any) has Oracle provided for use by developers?

  Oracle provides the DBMS_ series of packages. There are many which developers should be aware of such as DBMS_SQL, DBMS_PIPE, DBMS_TRANSACTION, DBMS_LOCK, DBMS_ALERT, DBMS_OUTPUT, DBMS_JOB, DBMS_UTILITY, DBMS_DDL, UTL_FILE

• escribe the use of %ROWTYPE and %TYPE in PL/SQL

  %ROWTYPE allows you to associate a variable with an entire table row. The %TYPE associates a variable with a single column type.

• What is a mutating table error and how can you get around it?

  his happens with triggers. It occurs because the trigger is trying to update a row it is currently using. The usual fix involves either use of views or temporary tables so the database is selecting from one while updating the other.

• Describe the difference between a procedure, function and anonymous pl/sql block.

  a function must return a value while a procedure doesn't have to.

• How do I update an existing copy of the source to the current version?

  As the common code changes, you might want to update your copy to contain the lastest version. To do that, use: cvs -q update Any changes will be merged into the files on your disk, and you should then be up-to-date with your own changes st...

• What are these messages about .DS_Store files?

  If you're using MacOS X, CVS may give you messages about ".DS_Store" files. These are used to keep track of window layouts, etc. To suppress these messages, just create a file in your home directory called ".cvsignore" and add a line of ".D...

• . How can I bring my copy of the JMRI code up to date?

  People contribute updates to the JMRI code almost every week. Your local copy doesn't get these changes until you ask for them, so that you've got something stable to work with. If you have an existing copy of the code and want to update it...

• How can I get my own copy of the JMRI code?

  To get a copy of the source for your own use, you can use "anonymous checkout". For a command line cvs client, make a new directory for the project, change to it, and tell CVS you exist with cvs -d:pserver:[email protected]...

• How do I get a copy of CVS?

  Many computers come with CVS installed, including Linux and MacOS X. If you're using Windows, you will need to install a CVS "client" program like WinCVS. A recent version can be downloaded from: http://prdownloads.sourceforge.net/cvsgui/Wi...

• How can I bring my copy of the JMRI code up to date?

  People contribute updates to the JMRI code almost every week. Your local copy doesn't get these changes until you ask for them, so that you've got something stable to work with. If you have an existing copy of the code and want to update it...

• How do I make a MIDI file?

  There are many programs and equipment for making MIDIs. Again, as I am not a musician or sequencer myself, I really do not know all that is required. Check out the following company sites for starters. Also Check Out The MIDI CHAT Discussio...