Movatterモバイル変換

Network Working Group                                       P. FaltstromRequest for Comments: 1914              Bunyip Information Systems, Inc.Category: Standards Track                                    R. Schoultz                                                                  KTHNOC                                                               C. Weider                                        Bunyip Information Systems, Inc.                                                           February 1996How to Interact with a Whois++ MeshStatus of this Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.1. Overview   In the Whois++ architecture [Deutsch94],[Weider94], mesh traversal is   done by the client, since each server 'refers' the client to the next   appropriate server(s). The protocol is simple. The client opens a   connection to a  server, sends a query, receives a reply, closes the   connection, and after parsing the  response the client decides which   server to contact next, if necessary.   So, the client needs to have an algorithm to follow when it interacts   with the Whois++ mesh so that referral loops can be detected, cost is   minimised, and appropriate servers are rapidly and effectively   contacted.Faltstrom, et al            Standards Track                     [Page 1]

RFC 1914          How to Interact with a Whois++ Mesh      February 19962. Basic functionality   Each Whois++ client should be configured to automatically send   queries to a specific Whois++ server. The deault Whois++ server can   vary depending on which template is desired, and the location of the   client with respect to the WHOIS++ index mesh,  but as a rule the   server should be as local as possible.                        A                       / \                      B   C                     / \   \           Z -----> D   E   F                   / \                  G   H       Fig 1: The client Z is configured to first query server D   After getting responses from a server, the client can act in several   ways. If the number of hits is greater than zero, the response is   just presented to the user. If the client gets one or many servers-   to-ask answers, the client should be able to automatically resolve   these pointers, i.e. query these servers in turn.                        A                       / \                      B   C                     / \   \           Z <----- D   E   F             \     / \              --> G   H   Fig 2: The client Z gets a "servers-to-ask G" response from D and             therefore may automatically queries server G.3. How to navigate in the mesh   A client can use several different strategies when traversing or   navigating around in the mesh. The automatic way of doing this is to   just "expand the search" (described in 3.1) and a second method is to   use the "Directory of Servers" (described in 3.2).3.1. Expansion of searches   If the number of hits is zero, or if the user in some way wants to   expand the search, it is recommended for the client to issue a   'polled-by' and 'polled-for' query to the server. The client can then   repeat the original query to the new servers indicated.Faltstrom, et al            Standards Track                     [Page 2]

RFC 1914          How to Interact with a Whois++ Mesh      February 1996                        A                       / \              /-----> B   C             /       / \   \           Z <----- D   E   F                   / \                  G   H Fig 3: The client Z gets a "polled-by B" response from D and therefore                           queries server B.   The client must always keep track of which servers it has queried   because it must itself detect loops in the mesh by not querying the   same server more than once.                        A                       / \                   /- B   C                  /  / \   \           Z <---/  D   E   F                   / \                  G   H  Fig 4: The client Z gets a "servers-to-ask D" response from B but Z    does not query D because the server D has already been queried.   So, the default expansion of a query by a client causes increasingly   more comprenhensive index servers to be queried; the forward   knowledge contained in the index server mesh allows rapid pruning of   these larger trees.   All loop detection and elimination is done in the client, rather than   in the server mesh. This decision was made because loop detection and   elimination are quite difficult to build into the mesh if we are to   continue to allow each server to participate in multiple hierarchies   within the mesh.3.1.1. Optimising the mesh   If organization A tends to use organization B's WHOIS++ server   frequently, for example if A is cooperating in a project with B, A   may wish to make B's server locally available by creating a local   index server which retrieves the centroid for both organizations.   When A's client then expands a query which is looking for someone at   B, the client can much more rapidly resolve the query, as it does not   have to find the top level servers for the tree to which A and B both   belong.Faltstrom, et al            Standards Track                     [Page 3]

RFC 1914          How to Interact with a Whois++ Mesh      February 1996                        A                       / \                      B   C                     / \   \           Z        D   --> F                   / \                  G   H           Fig 5: The server B gets a centroid from server F                        A                       / \                      B   C                     / \   \           Z <----> D   --- F                   / \                  G   H  Fig 6: The client queries server D, gets zero hits back, expands the             search and gets a "polled-by B" response back.                        A                       / \                 /--> B   C                /    / \   \           Z <-/    D   --- F                   / \                  G   H    Fig 7: The client Z queries server B and gets "servers-to-ask F"                             response back.                        A                       / \                      B   C                     / \   \                    D   --- F <-----> Z                   / \                  G   H       Fig 8: The client Z queries server F and gets the answer.   The example given in Fig 5-8 shows that the algorithm works even   though the Whois++ mesh is not a tree. There are many reasons why a   given index server mesh might be 'short-circuited'. For example, in   the case of a multinational company, the Swedish branch of Acme Inc.,   is polled both by the national server in Sweden and the headquarters   server in the USA. By querying the Swedish server, one finds allFaltstrom, et al            Standards Track                     [Page 4]

RFC 1914          How to Interact with a Whois++ Mesh      February 1996   persons working at the Swedish branch of Acme Inc., but by querying   the Acme Inc.  server in the USA, you will find all employees in the   company, including those in Sweden.   Note that the location of a server does not implicitly narrow the   search, i.e. you have to specify all information when sending a query   to a server. In the example above, one can see that by just querying   a server for companies in the USA, you will not implicitly only get   hits from records in the states, because the Acme Inc. server in the   states has polled a server in Sweden. So, in this case you have to   explicitly include "country=USA" in the query if you are only   interested in those records.   Although the WHOIS++ index service has been designed to make searches   at any location in the index mesh quite effective and efficient,   blindly expanding the query can incur an exponentially growing cost   in resources, and, as charging for responses is implemented in parts   of the WHOIS++ index service mesh, growing cost, automatic expansion   is not recommended. More sophisticated clients  should also be   configurable to "cut off" some servers from a search, i.e. a   blacklist of servers. This might be needed when searching for records   and one server might have a very high cost (in dollars) so one might   want to explicitly forbid the client to send queries to that server.3.1.2. The algorithm used by the client   By following this algorithm a client finds all records in a mesh   which the first Whois++ server queried belongs to.   The algorithm for the client follows:      Query := data to search for;      QueriedServers := {};      AnswerList := {};      OriginalServers := { known servers to this client };      while OriginalServers is not empty do:            ServerList = OriginalServers;            while ServerList is not empty do:                  Server := ServerList[1];                  if Server is not in QueriedServers then do:                        send Query to Server;                        Answer := answer from Server;                        append ServersToAsk to ServerList;                        remove Server from ServerList;                        append Answers to AnswerList;                  end;            done;            if query should be expanded then do:Faltstrom, et al            Standards Track                     [Page 5]

RFC 1914          How to Interact with a Whois++ Mesh      February 1996                  ServerList := OriginalServers;                  OriginalServers := {};                  while ServerList is not empty do:                        Server := ServerList[1];                        send Polled-For-Query to Server;                        Answer := answer from Server;                        append Answer to OriginalServers;                        remove Server from ServerList;                  end;            done;      done;      display AnswerList to user;3.2. The Directory of Servers   A second way of finding the correct server to query is to use a   separate service we call the Directory of Servers. The Directory of   Servers is a special Whois++ server which polls every Whois++ server   for information about common information among the records on that   perticular server.3.2.1. How should a client use the Directory of Servers?   A client that want to very quickly find what servers serves USER   templates in Sweden, should do it this way:   1) The hostname and portnumber of the directory of Servers have      to be preconfigured in the current version of the protocol.   2) Query the Directory of Servers for serverhandle records for      country sweden. This gives information of all these servers.      By presenting this information to the user the user should be      able to start the search at some closer server.   Note that we at this moment doesn't think this should be an autmatic   process in the client. The Directory of Servers should be used for   giving the user information about what Whois++ servers that exists.   In the future a technique might have developed that makes it possible   for a client to do this selection automatically depending on the   query the user issues.Faltstrom, et al            Standards Track                     [Page 6]

RFC 1914          How to Interact with a Whois++ Mesh      February 19963.2.2. What does the serverhandle record look like?   The attributes that must be in all serverhandle records are:   Server-Handle: The handle for this server.   Host-Name:     The (current) hostname of this server.   Host-Port:     The (current) portnumber for this server.   Part from that information, the record can include other attributes   like:   Admin-Name:        Patrik Faltstrom   Admin-Email:       paf@bunyip.com   Admin-Phone:       +1-514-875-8611   Organization-Name: Bunyip Information Systems Inc.   Description:       USER information   Menu-Item:         World (Bunyip Information Systems inc)   City:              Montreal   State:             Quebec   Country:           Canada   :   :   (Other attributes that can identify all records on this server, for   example domainname)   The information in the Navigation record is intended to be presented   to a user.3.2.3. Example   An example of how an interaction with the Directory of Servers is   done follows. The characters '<' and '>' displays if it is the client   ('<') or responding server ('>') which is responsible for the output:> % 220-This is services.bunyip.com running Bunyip-Whois++: DIGGER 1.0.5> % 220 Ready to go!< template=serverhandle and bunyip> % 200 Search is executing> # FULL SERVERHANDLE BUNYIPCOM01 BUNYIPCOM01>  SERVER-HANDLE: BUNYIPCOM01>  HOST-NAME: services.bunyip.com>  HOST-PORT: 63>  ADMIN-NAME: Patrik Faltstrom>  ADMIN-EMAIL: paf@bunyip.com>  ORGANIZATION-NAME: Bunyip Information Systems Inc.>  DESCRIPTION: USER information>  DESCRIPTION: Directory of Servers>  DESCRIPTION: Toplevel Index server in the worldFaltstrom, et al            Standards Track                     [Page 7]

RFC 1914          How to Interact with a Whois++ Mesh      February 1996>  MENU-ITEM: World (Bunyip Information Systems inc)>  CITY: Montreal>  COUNTRY: Canada> # END>> # FULL SERVERHANDLE BUNYIPCOM01 BUNYIPCOM02>  SERVER-HANDLE: BUNYIPCOM02>  HOST-NAME: services.bunyip.com>  HOST-PORT: 7778>  ADMIN-NAME: Patrik Faltstrom>  ADMIN-EMAIL: paf@bunyip.com>  ORGANIZATION-NAME: Bunyip Information Systems Inc.>  DESCRIPTION: USER information>  MENU-ITEM: Bunyip Information Systems>  CITY: Montreal>  COUNTRY: Canada> # END>> % 226 Transaction complete> % 203 Bye, bye4. Caching   A client can cache all information it gets from a server for some   time.  For example records, IP-addresses of Whois++ servers, the   Directory of Services server etc.   A client can itself choose for how long it should cache the   information.   The IP-address of the Directory of Services server might not change   for a day or two, and neither might any other information.4.1. Caching a Whois++ servers hostname   An example of cached information that might change is the chached   hostname, IP-address and portnumber which a client gets back in a   servers-to-ask response. That information is cached in the server   since the last poll, which might occurred several weeks ago.   Therefore, when such a connection fails, the client should fall back   to use the serverhandle insted, which means that it contacts the   Directory of Services server and queries for a server with that   serverhandle.  By doing this, the client should always get the last   known hostname.Faltstrom, et al            Standards Track                     [Page 8]

RFC 1914          How to Interact with a Whois++ Mesh      February 1996   An algorithm for this might be:  response := servers-to-ask response from server A  IP-address := find ip-address for response.hostname in DNS  connect to ip-address at port response.portnumber  if connection fails {     connect to Directory of Services server     query for host with serverhandle response.serverhandle     response := response from Directory of Services server     IP-address := find ip-address for response.hostname in DNS     connect to ip-address at port response.portnumber     if connection fails {         exit with error message     }   }   Query this new server5. Security Considerations   Security considerations when using the Whois++ protocol is described   in [Deutsch94].   A client should be able to have a "blacklist" of servers it should   not query, because it might happen that fake Whois++ servers is put   up on the net. When such a fake Whois++ servers is found, a user   should be able to configure it's client to never query this server.   Note that a client should be careful when expanding a query by either   using normal expansion or using the directory of servers. A query   might take a long time, so a user should be able to quit in the   middle of such a transaction. This is though more a question of user   interaction than a plain security issue.6. References   [Deutsch94]  Deutsch P., Schoultz R., Faltstrom P., and C. Weider,                "Architecture of the Whois++ service",RFC 1835,                August 1995.   [Weider94]   Weider C., Fullton J., and S. Spero, "Architecture of                the WHOIS++ Index Service",RFC 1913, February 1996.Faltstrom, et al            Standards Track                     [Page 9]

RFC 1914          How to Interact with a Whois++ Mesh      February 19967. Authors' Addresses   Patrik Faltstrom   BUNYIP INFORMATION SYSTEMS, inc   310 St Catherine St West, Suite 300   Montreal, Quebec   CANADA H2X 2A1   EMail: paf@bunyip.com   Rickard Schoultz   KTHNOC, SUNET/NORDUnet/Ebone Operations Centre   S-100 44  STOCKHOLM   SWEDEN   EMail: schoultz@sunet.se   Chris Weider   BUNYIP INFORMATION SYSTEMS, inc   310 St Catherine St West, Suite 300   Montreal, Quebec   CANADA H2X 2A1   EMail: clw@bunyip.comFaltstrom, et al            Standards Track                    [Page 10]