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/* * @(#)Context.java 1.25 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package org.omg.CORBA; /** * An object used in <code>Request</code> operations * to specify the context object in which context strings * must be resolved before being sent along with the request invocation. * A <code>Context</code> object * contains a list of properties in the form of <code>NamedValue</code> * objects. These properties represent information * about the client, the environment, or the circumstances of a request * and generally are properties that might be inconvenient * to pass as parameters. * <P> * A <code>Context</code> object is created by first calling the * <code>ORB</code> method <code>get_default_context</code> * and then calling the method <code>create_child</code> on the * default context. * <P> * Each property in a <code>Context</code> object is represented by * a <code>NamedValue</code> object. The property name is contained * in the <code>NamedValue</code> object's <code>name</code> field, and * the value associated with the name is contained in the <code>Any</code> * object that was assigned to the <code>NamedValue</code> object's * <code>value</code> field. * <P> * <code>Context</code> properties can represent a portion of a client's * or application's environment that is meant to be propagated to * (and made implicitly part of) a server's environment. * (Examples might be a window identifier or user preference information). * Once a server has been invoked (that is, after the properties are * propagated), the server may query its <code>Context</code> object * for these properties using the method <code>get_values</code>. * *<P> * When an operation declaration includes a context clause, * the stubs and skeletons will have an additional argument * added for the context. When an operation invocation occurs, * the ORB causes the properties that were named in the operation * definition in IDL and * that are present in the client's <code>Context</code> object * to be provided in the <code>Context</code> object parameter to * the invoked method. * <P> * <code>Context</code> property names (which are strings) * typically have the form of an OMG IDL identifier or * a series of OMG IDL identifiers separated by periods. * A context property name pattern is either a property name * or a property name followed by a single "*". A property * name pattern without a trailing "*" is said to match only * itself. A property name pattern of the form "<name>*" matches any * property name that starts with <name> and continues with zero * or more additional characters. * <P> * Property name patterns are used in the context clause of * an operation definition and as a parameter for the * method <code>Context.get_values</code>. * <P> * <code>Context</code> objects may be "chained" together to achieve a * particular defaulting behavior. A <code>Context</code> * object created with the method <code>create_child</code> will * be chained to its parent (the <code>Context</code> object * that created it), and that means that the parent will be searched * after the child in a search for property names. *<P> * Properties defined in a particular <code>Context</code> object * effectively override those properties in the next higher level. * The scope used in a search for properties may be restricted by specifying a * starting scope and by using the flag <code>CTX_RESTRICT_SCOPE</code> * when invoking the method <code>get_values</code>. * <P> * A <code>Context</code> object may be named for purposes of specifying * a starting search scope. * * @version 1.11, 09/09/97 * @since JDK1.2 */ public abstract class Context { /** * Retrieves the name of this <code>Context</code> object. * * @return the name of this <code>Context</code> object */ public abstract String context_name(); /** * Retrieves the parent of this <code>Context</code> object. * * @return the <code>Context</code> object that is the * parent of this <code>Context</code> object */ public abstract Context parent(); /** * Creates a <code>Context</code> object with the given string as its * name and with this <code>Context</code> object set as its parent. * <P> * The new <code>Context</code> object is chained into its parent * <code>Context</code> object. This means that in a search for * matching property names, if a match is not found in this context, * the search will continue in the parent. If that is not successful, * the search will continue in the grandparent, if there is one, and * so on. * * * @param child_ctx_name the <code>String</code> object to be set as * the name of the new <code>Context</code> object * @return the newly-created child <code>Context</code> object * initialized with the specified name */ public abstract Context create_child(String child_ctx_name); /** * Creates a <code>NamedValue</code> object and adds it to this * <code>Context</code> object. The <code>name</code> field of the * new <code>NamedValue</code> object is set to the given string, * the <code>value</code> field is set to the given <code>Any</code> * object, and the <code>flags</code> field is set to zero. * * @param propname the name of the property to be set * @param propvalue the <code>Any</code> object to which the * value of the property will be set. The * <code>Any</code> object's <code>value</code> * field contains the value to be associated * with the given propname; the * <code>kind</code> field must be set to * <code>TCKind.tk_string</code>. */ public abstract void set_one_value(String propname, Any propvalue); /** I Sets one or more property values in this <code>Context</code> * object. The <code>NVList</code> supplied to this method * contains one or more <code>NamedValue</code> objects. * In each <code>NamedValue</code> object, * the <code>name</code> field holds the name of the property, and * the <code>flags</code> field must be set to zero. * The <code>NamedValue</code> object's <code>value</code> field * contains an <code>Any</code> object, which, in turn, contains the value * for the property. Since the value is always a string, * the <code>Any</code> object must have the <code>kind</code> * field of its <code>TypeCode</code> set to <code>TCKind.tk_string</code>. * * @param values an NVList containing the property * names and associated values to be set * * @see #get_values * @see org.omg.CORBA.NamedValue * @see org.omg.CORBA.Any */ public abstract void set_values(NVList values); /** * Deletes from this <code>Context</code> object the * <code>NamedValue</code> object(s) whose * <code>name</code> field matches the given property name. * If the <code>String</code> object supplied for * <code>propname</code> has a * trailing wildcard character ("*"), then * all <code>NamedValue</code> objects whose <code>name</code> * fields match will be deleted. The search scope is always * limited to this <code>Context</code> object. * <P> * If no matching property is found, an exception is returned. * * @param propname name of the property to be deleted */ public abstract void delete_values(String propname); /** * Retrieves the <code>NamedValue</code> objects whose * <code>name</code> field matches the given name or name * pattern. This method allows for wildcard searches, * which means that there can be multiple matches and * therefore multiple values returned. If the * property is not found at the indicated level, the search * continues up the context object tree until a match is found or * all <code>Context</code> objects in the chain have been exhausted. * <P> * If no match is found, an error is returned and no property list * is returned. * * @param start_scope a <code>String</code> object indicating the * context object level at which to initiate the * search for the specified properties * (for example, "_USER", "_GROUP", "_SYSTEM"). Valid scope * names are implementation-specific. If a * scope name is omitted, the search * begins with the specified context * object. If the specified scope name is * not found, an exception is returned. * @param op_flags an operation flag. The one flag * that may be specified is <code>CTX_RESTRICT_SCOPE</code>. * If this flag is specified, searching is limited to the * specified <code>start_scope</code> or this * <code>Context</code> object. * @param pattern the property name whose values are to * be retrieved. <code>pattern</code> may be a * name or a name with a * trailing wildcard character ("*"). * * @return an <code>NVList</code> containing all the property values * (in the form of <code>NamedValue</code> objects) * whose associated property name matches the given name or * name pattern * @see #set_values * @see org.omg.CORBA.NamedValue */ abstract public NVList get_values(String start_scope, int op_flags, String pattern); };