Network Working Group Rob Weltman INTERNET-DRAFT Netscape Communications Corp. September 26, 1997 Java LDAP Controls draft-ietf-asid-ldap-java-controls-00.txt Status of this Memo This document is an Internet-Draft. Internet-Drafts are working docu- ments of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as ``work in progress.'' To learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). Abstract This document defines support for the Preferred Language Control, the Server Sorting Control, and the Virtual List Control in the java LDAP API. Controls are an LDAP protocol version 3 extension, to allow pass- ing arbitrary control information along with a standard request to a server, and to receive arbitrary information back with a standard result. 1. Introduction Version 3 of the LDAP protocol provides a means of supplying arbitrary additional information along with a request to an LDAP server, and receiving arbitrary additional response information. A few applications of the Control mechanism have been identified as having general interest, and the protocol defined for their transmission [5] and [6]. This document defines how support for the Preferred Language Control, the Server Sorting Control, and the Virtual List Control are supported in the java LDAP API. The java LDAP API in general is described in [2]. The Control protocol extension is described in [1], section 4.1.12, and applications of it in [5] and [6]. Expires 3/98 [Page 1] JAVA LDAP CONTROLS September 1997 2. Overview of the LDAP Control classes LDAPControl is part of a basic LDAP class package. Specific applications/implementations of Controls are in a subpackage called "controls". The base class LDAPControl is defined in [2] as: public class LDAPControl implements Cloneable An LDAPControl encapsulates optional additional parameters or con- straints to be applied to LDAP operations. If set as a Server Con- trol, it is sent to the server along with operation requests. If set as a Client Control, it is not sent to the server, but rather inter- preted locally by the client. LDAPControl is an LDAPv3 extension, and is not supported in an LDAPv2 environment. Constructors public LDAPControl(String id, boolean critical, byte vals[]) Parameters are: id The type of the Control, as a string. critical True if the LDAP operation should be discarded if the server does not support this Control. vals Control-specific data. getID public String getID() Returns the identifier of the control. isCritical public boolean isCritical() Returns true if the control must be supported for an associated operation to be executed. getValue public byte[] getValue() Expires 3/98 [Page 2] JAVA LDAP CONTROLS September 1997 Returns the control-specific data of the object. The following Controls are defined for the controls subpackage: LDAPLanguageControl Is used to set a preferred language for results from the server. LDAPVirtualListControlEncapsulates requests for a subset of a virtual list of search results, and the response of a server to such a request. LDAPSortControl Encapsulates a requested sorting order for search results returned by a server, and the server's response to the request. 3. The java LDAP Control classes 3.1. public class LDAPLanguageControl extends LDAPControl The LDAPLanguageControl class represents control data for setting a pre- ferred language for results returned by a Directory Server. 3.1.1. Constructors public LDAPLanguageControl(String lang) Constructs a new LDAPLanguageControl object using a a string specifi- cation of language and optionally also country and a variant. public LDAPLanguageControl(Locale locale) Constructs a new LDAPLanguageControl object using a Locale object to select language. Parameters are: lang A string of the form "en" or "ja-JP-kanji". The syn- tax is defined in [3] and [4]. The first two charac- ters are a language specification (as defined in ISO Expires 3/98 [Page 3] JAVA LDAP CONTROLS September 1997 639); they may be followed by a dash and a two char- acter country specification (as defined in ISO 3166); the latter may be followed by a dash and a language variant. Examples: "lang-en" "lang-en-us" "lang-ja-JP-kanji" locale A Locale object to be used to define the preferred language. A control for the default locale language may be created with LDAPLanguageControl lc = new LDAPLanguageControl( Locale.getDefault() ); 3.1.2. public class LDAPVirtualListControl extends LDAPControl LDAPVirtualListControl is a Server Control to specify that results from a search are to be returned in pages, subsets of the entire virtual result set. On success, an updated LDAPVirtualList object is returned as a response Control, containing information on the virtual list size and the actual first index. This object can then be updated by the client with a new requested position or length and sent to the server to obtain a different segment of the virtual list. 3.1.2.1. Constructors public LDAPVirtualListControl( String subFilter, int beforeCount, int afterCount ) Constructs a virtual list control using the specified filter expres- sion, which defines the extent of the virtual search results, and the number of entries before and after a located index to be returned. Parameters are: subFilter A search expression that defines the extent of the virtual search results. The filter expression in the search operation itself may be, for example, "objectclass=person" and the subFilter expression in the virtual list control may be "cn=m*", to retrieve a subset of entries starting at or centered around those with a common name beginning with the letter "M". beforeCount The number of entries before "listIndex" to be Expires 3/98 [Page 4] JAVA LDAP CONTROLS September 1997 returned. afterCount The number of entries after "listIndex" to be returned. 3.1.2.2. getAfterCount public int getAfterCount() Returns the number of entries after the top/center one to return per page of results. 3.1.2.3. getBeforeCount public int getBeforeCount() Returns the number of entries before the top/center one to return per page of results. 3.1.2.4. getListSize public int getListSize() Returns the size of the virtual search results list. For a newly con- structed control - one which is not the result of parseResponse on a control returned by a server - the method returns -1. 3.1.2.5. setRange public void setRange( int listIndex, int beforeCount, int afterCount ) Sets the center or starting list index to return, and the number of results before and after. Parameters are: listIndex The center or starting list index to be returned. beforeCount The number of entries before "listIndex" to be returned. afterCount The number of entries after "listIndex" to be Expires 3/98 [Page 5] JAVA LDAP CONTROLS September 1997 returned. 3.1.2.6. parseResult public LDAPVirtualListControl parseResponse() public static LDAPVirtualListControl parseResponse( LDAPControl[] controls ) When applied to a virtual list control returned by a server, par- seResponse returns a new virtual list control which can be used for subsequent searches using the same substringFilter. The second form processes a list of controls, one of which may or may not be an LDAP- VirtualListControl. The input is typically provided with the LDAPConnection.getResponseControls method. Parameters are: controls An array of controls. It may be null. 3.1.3. public class LDAPSortControl extends LDAPControl LDAPSortControl is a Server Control to specify how search results are to be sorted by the server (see [5]). If a server does not support sorting in general or for a particular query, the results will be returned unsorted, along with a control indicating why they were not sorted (or that sort controls are not supported). If the control was marked "criti- cal", the whole search operation will fail if the sort control is not supported. 3.1.3.1. Constructors public LDAPSortControl( LDAPSortKey key, boolean critical) Constructs a sort control with a single key. public LDAPSortControl( LDAPSortKey[] keys, boolean critical) Constructs a sort control with multiple sort keys. Parameters are: key A sort key object, which specifies attribute, order, Expires 3/98 [Page 6] JAVA LDAP CONTROLS September 1997 and optional matching rule. keys An array of sort key objects, to be processed in order. critical True if the search operation is to fail if the server does not support this control. 3.1.3.2. parseResponse public static String parseResponse( LDAPControl[] controls, int results[] ) Processes an array of Server Controls to determine if sorting was rejected, and if so, why. If sorting was rejected, the return value is the attribute name which caused sorting to fail. results[0] con- tains the result code on return. The result code is one defined in [1], section 4.1.10. Parameters are: controls An array of Server Controls, typically obtained with LDAPConnection.getResponseControls(). It may be null, which is equivalent to no error. 4. Security Considerations See [2] for security considerations in the java LDAP API. Expires 3/98 [Page 7] JAVA LDAP CONTROLS September 1997 5. Bibliography [1] M. Wahl, T. Howes, S. Kille, "Lightweight Directory Access Protocol (v3)", Internet Draft draft-ietf-asid-ldapv3-protocol-06.txt, July 1997. [2] R. Weltman, T. Howes, M. Smith, "The Java LDAP Application Program Interface", Internet Draft draft-ietf-asid-ldap-java-api-01.txt, September 1997. [3] H. Alvestrans, "Tags for the Identification of Languages", Request for Comments 1766, March 1995. [4] M. Wahl, T. Howes, "Use of Language Codes in LDAPv3", Internet Draft draft-ietf-asid-ldapv3-lang-02.txt, June 1997. [5] A. Herron, T. Howes, M. Wahl, "LDAP Control Extension for Server Side Sorting of Search Results", Internet Draft draft-ietf-asid- ldapv3-sorting-00.txt, April 1997. [6] D. Boreham, "LDAP Control Extension for Virtual List View Browsing of Search Results", Internet Draft draft-ietf-asid-ldapv3- virtuallistview-01.txt, October 1997. [7] C. Weider, A Herron, T. Howes, "LDAP Control Extension for Simple Paged Results Manipulation", Internet Draft draft-ietf-asid- ldapv3-simple-paged-01.txt, March 1997. 6. Author's Address Rob Weltman Netscape Communications Corp. 501 E. Middlefield Rd. Mountain View, CA 94043 USA +1 650 937-3301 rweltman@netscape.com 7. Appendix A - Sample usage of the java LDAP controls Doing a search with results sorted on the server import netscape.ldap.*; import netscape.ldap.controls.*; import java.util.*; public class SearchJensenSorted { Expires 3/98 [Page 8] JAVA LDAP CONTROLS September 1997 public static void main( String[] args ) { try { LDAPConnection ld = new LDAPConnection(); /* Connect to server */ String MY_HOST = "localhost"; int MY_PORT = 389; ld.connect( MY_HOST, MY_PORT ); /* search for all entries with surname of Jensen */ String MY_FILTER = "sn=Jensen"; String MY_SEARCHBASE = "o=Ace Industry, c=US"; /* Get the common name, uid, and telephone number */ String[] attrs = new String[3]; attrs[0] = "cn"; attrs[1] = "telephonenumber"; attrs[2] = "uid"; /* Sort by lastname, firstname */ LDAPSortKey[] keys = new LDAPSortKey[2]; keys[0] = new LDAPSortKey( "sn" ); keys[1] = new LDAPSortKey( "givenname" ); LDAPSortControl sort = new LDAPSortControl( keys, true ); ld.setOption( LDAPConnection.SERVERCONTROLS, sort ); LDAPSearchResults res = ld.search( MY_SEARCHBASE, LDAPConnection.SCOPE_ONE, MY_FILTER, attrs, false ); /* Loop on results until finished */ while ( res.hasMoreElements() ) { /* Next directory entry */ LDAPEntry findEntry = (LDAPEntry)res.nextElement(); System.out.println( findEntry.getDN() ); /* Get the attributes of the entry */ LDAPAttributeSet findAttrs = findEntry.getAttributeSet(); Enumeration enumAttrs = findAttrs.getAttributes(); System.out.println( "Attributes: " ); /* Loop on attributes */ while ( enumAttrs.hasMoreElements() ) { LDAPAttribute anAttr = (LDAPAttribute)enumAttrs.nextElement(); Expires 3/98 [Page 9] JAVA LDAP CONTROLS September 1997 String attrName = anAttr.getName(); System.out.println( "" + attrName ); /* Loop on values for this attribute */ Enumeration enumVals = anAttr.getStringValues(); while ( enumVals.hasMoreElements() ) { String aVal = ( String )enumVals.nextElement(); System.out.println( "" + aVal ); } } } /* Check if the server had something to say about the sort request */ LDAPControl[] controls = ld.getResponseControls(); if ( controls != null ) { int[] results = new int[1]; String bad = LDAPSortControl.parseResponse( controls, results ); if ( results[0] != 0 ) { System.out.println( "Error code: " + results[0] ); if ( bad != null ) System.out.println( "Offending attribute: " + bad ); else System.out.println( "No offending attribute + "returned" ); } } } catch( LDAPException e ) { System.out.println( "Error: " + e.toString() ); } /* Done, so disconnect */ if ( ld.isConnected() ) ld.disconnect(); } } Expires 3/98 [Page 10] JAVA LDAP CONTROLS September 1997 Using virtual list controls - excerpts from an application import netscape.ldap.*; import netscape.ldap.controls.*; // Call this to initialize the list box, whenever the search // conditions change. // "filter" may be "objectclass=person", for example, and // "subFilter" might be "cn>=m*" void initListBox( String base, int scope, String filter, String attrs, String subFilter ) { // Record the virtual list box settings beforeCount = 2; afterCount = getScrollVisibleSize() - beforeCount - 1; this.base = base; this.scope = scope; this.filter = filter; this.attrs = attrs; // Create the initial virtual list control pageControls = new LDAPControl[2]; pageControls[0] = new LDAPVirtualListControl( subFilter, beforeCount, afterCount ); // virtual list also require a sort control pageControls[1] = new LDAPSortControl( new LDAPSortKey("cn"), true ); // We have no idea yet how big the virtual list is, so just // hint that there is more than what is visible setScrollRange( 0, 100 ); // Do an initial update of the scroll box onScrollListBox(); } // This is called any time the list box needs to be updated. It // fetches an appropriate page of results from the server. void onScrollListBox() { // Where is the list scrolled to now? int topOfList = getScrollTop(); // Check if we have a control returned from a previous search LDAPVirtualListControl nextCont = LDAPVirtualListControl.parseResponse( ld.getResponseControls() ); // If this is the first search, use the initial settings; // otherwise use the just-retrieved control if ( nextCont != null ) { nextCont.setRange( topOfList, beforeCount, afterCount ); pageControls[0] = nextCont; // Now we know the total size of the virtual list box Expires 3/98 [Page 11] JAVA LDAP CONTROLS September 1997 setScrollRange( 0, nextCont.getListSize() ); } ld.setControls( pageControls ); // Fetch a page of results LDAPSearchResults res = ld.search( base, scope, filter, attrs, false ); // and display them in the list box showResults( res ); } private int beforeCount, afterCount; private String base, filter, attrs; private int scope; private LDAPControl[] pageControls; Expires 3/98 [Page 12] JAVA LDAP CONTROLS September 1997 8. Appendix D - Outstanding issues 8.1. Virtual List Control The described LDAPVirtualListControl does not correspond to the Paged Results Control described in [7], which was found to be less useful than the one described in this document. Expires 3/98 [Page 13] 1. Introduction...................................................1 2. Overview of the LDAP Control classes...........................2 3. The java LDAP Control classes..................................3 3.1. LDAPLanguageControl..........................................3 3.1.1. Constructors.............................................3 3.1.2. LDAPVirtualListControl....................................4 3.1.2.1. Constructors..........................................4 3.1.2.2. getAfterCount.........................................5 3.1.2.3. getBeforeCount........................................5 3.1.2.4. getListSize...........................................5 3.1.2.5. setRange..............................................5 3.1.2.6. parseResult...........................................6 3.1.3. LDAPSortControl...........................................6 3.1.3.1. Constructors..........................................6 4. Security Considerations........................................7 5. Bibliography...................................................8 6. Author's Address...............................................8 7. Appendix A - Sample usage of the java LDAP controls............8 8. Appendix D - Outstanding issues................................13 8.1. Virtual List Control........................................13