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NAME

       httpd -
           HTTP server API

DESCRIPTION

       An  implementation  of  an HTTP 1.1 compliant web server, as defined in RFC 2616. Provides
       web server start options, administrative functions, and an Erlang callback API.

DATA TYPES

       Type definitions that are used more than once in this module:

       boolean() = true | false

       string() = list of ASCII characters

       path() = string() representing a file or a directory path

        ip_address() = {N1,N2,N3,N4} % IPv4 | {K1,K2,K3,K4,K5,K6,K7,K8} % IPv6

       hostname() = string() representing a host, for example, "foo.bar.com"

       property() = atom()

ERLANG HTTP SERVER SERVICE START/STOP

       A web server  can  be  configured  to  start  when  starting  the  Inets  application,  or
       dynamically   in   runtime   by  calling  the  Inets  application  API  inets:start(httpd,
       ServiceConfig)  or  inets:start(httpd,   ServiceConfig,   How),   see   inets(3erl).   The
       configuration options, also called properties, are as follows:

       File Properties

       When the web server is started at application start time, the properties are to be fetched
       from a configuration file that can consist of a regular Erlang  property  list,  that  is,
       [{Option,  Value}],  where   Option  =  property()  and Value = term(), followed by a full
       stop, or for backwards compatibility, an Apache-like configuration file. If the web server
       is  started  dynamically  at  runtime, a file can still be specified but also the complete
       property list.

         {proplist_file, path()}:
           If this property is defined, Inets expects to find all  other  properties  defined  in
           this file. The file must include all properties listed under mandatory properties.

         {file, path()}:
           If  this  property  is  defined, Inets expects to find all other properties defined in
           this file, which uses Apache-like syntax. The file must include all properties  listed
           under  mandatory  properties.  The  Apache-like syntax is the property, written as one
           word where each new word begins with a capital, followed by a white-space, followed by
           the value, followed by a new line.

           Example:

         {server_root, "/urs/local/www"} -> ServerRoot /usr/local/www

           A  few  exceptions  are documented for each property that behaves differently, and the
           special cases  {directory,  {path(),  PropertyList}}  and  {security_directory,  {Dir,
           PropertyList}}, are represented as:

         <Directory Dir>
          <Properties handled as described above>
         </Directory>

   Note:
       The  properties  proplist_file  and file are mutually exclusive. Also newer properties may
       not be supported as Apache-like options, this is a legacy feature.

       Mandatory Properties

         {port, integer()} :
           The port that the HTTP server listen to. If zero is specified as  port,  an  arbitrary
           available port is picked and function httpd:info/2 can be used to determine which port
           was picked.

         {server_name, string()}:
           The name of your server, normally a fully qualified domain name.

         {server_root, path()}:
           Defines the home directory of the server, where log files, and so on, can  be  stored.
           Relative paths specified in other properties refer to this directory.

         {document_root, path()}:
           Defines the top directory for the documents that are available on the HTTP server.

       Communication Properties

         {bind_address, ip_address() | hostname() | any}:
           Default is any. any is denoted * in the Apache-like configuration file.

         {profile, atom()}:
           Used  together with bind_address and port to uniquely identify a HTTP server. This can
           be useful in a virtualized environment, where there can be more that one  server  that
           has  the  same  bind_address  and  port. If this property is not explicitly set, it is
           assumed that the bind_address and portuniquely identifies the HTTP server.

         {socket_type, ip_comm | {ip_comm, Config::proplist()} | {essl, Config::proplist()}}:
           For ip_comm configuration options, see gen_tcp:listen/2, some options  that  are  used
           internally by httpd cannot be set.

           For SSL configuration options, see ssl:listen/2.

           Default is ip_comm.

         {ipfamily, inet | inet6}:
           Default  is  inet, legacy option inet6fb4 no longer makes sense and will be translated
           to inet.

         {minimum_bytes_per_second, integer()}:
           If given, sets a minimum of bytes per second value for connections.

           If the value is unreached, the socket closes for that connection.

           The option is good for reducing the risk of "slow DoS" attacks.

       Erlang Web Server API Modules

         {modules, [atom()]} :
           Defines which modules  the  HTTP  server  uses  when  handling  requests.  Default  is
           [mod_alias,  mod_auth,  mod_esi,  mod_actions,  mod_cgi,  mod_dir,  mod_get, mod_head,
           mod_log, mod_disk_log]. Notice that some mod-modules are dependent on others,  so  the
           order  cannot  be  entirely  arbitrary. See the Inets Web Server Modules in the User's
           Guide for details.

       Limit properties

         {customize, atom()}:
           A callback module to customize the inets HTTP servers behaviour see  httpd_custom_api

         {disable_chunked_transfer_encoding_send, boolean()}:
           Allows you to disable chunked transfer-encoding when sending a response to an HTTP/1.1
           client. Default is false.

         {keep_alive, boolean()}:
           Instructs  the  server whether to use persistent connections when the client claims to
           be HTTP/1.1 compliant. Default is true.

         {keep_alive_timeout, integer()}:
           The number of seconds the server waits for a subsequent request from the client before
           closing the connection. Default is 150.

         {max_body_size, integer()}:
           Limits the size of the message body of an HTTP request. Default is no limit.

         {max_clients, integer()}:
           Limits the number of simultaneous requests that can be supported. Default is 150.

         {max_header_size, integer()}:
           Limits the size of the message header of an HTTP request. Default is 10240.

         {max_content_length, integer()}:
           Maximum  content-length in an incoming request, in bytes. Requests with content larger
           than this are answered with status 413. Default is 100000000 (100 MB).

         {max_uri_size, integer()}:
           Limits the size of the HTTP request URI. Default is no limit.

         {max_keep_alive_request, integer()}:
           The number of requests that a client can do on one connection.  When  the  server  has
           responded  to  the  number  of requests defined by max_keep_alive_requests, the server
           closes the connection. The server closes it even if there are queued request.  Default
           is no limit.

         {max_client_body_chunk, integer()}:
           Enforces  chunking  of  a  HTTP  PUT  or  POST body data to be deliverd to the mod_esi
           callback. Note this is not supported for mod_cgi. Default is no limit  e.i  the  whole
           body is deliverd as one entity, which could be very memory consuming. mod_esi(3erl).

       Administrative Properties

         {mime_types, [{MimeType, Extension}] | path()}:
           MimeType  =  string() and Extension = string(). Files delivered to the client are MIME
           typed according to RFC 1590. File suffixes  are  mapped  to  MIME  types  before  file
           delivery.  The  mapping  between  file  suffixes and MIME types can be specified as an
           Apache-like file or directly in the property list. Such  a  file  can  look  like  the
           follwoing:

         # MIME type    Extension
         text/html html htm
         text/plain     asc txt

           Default is [{"html","text/html"},{"htm","text/html"}].

         {mime_type, string()}:
           When  the  server is asked to provide a document type that cannot be determined by the
           MIME Type Settings, the server uses this default type.

         {server_admin, string()}:
           Defines the email-address of the server administrator to  be  included  in  any  error
           messages returned by the server.

         {server_tokens, none|prod|major|minor|minimal|os|full|{private, string()}}:
           Defines the look of the value of the server header.

           Example:  Assuming the version of Inets is 5.8.1, the server header string can look as
           follows for the different values of server-tokens:

           none:
             "" % A Server: header will not be generated

           prod:
             "inets"

           major:
             "inets/5"

           minor:
             "inets/5.8"

           minimal:
             "inets/5.8.1"

           os:
             "inets/5.8.1 (unix)"

           full:
             "inets/5.8.1 (unix/linux) OTP/R15B"

           {private, "foo/bar"}:
             "foo/bar"

           By default, the value is as before, that is, minimal.

         {log_format, common | combined}:
           Defines if access logs are to be written according to the common  log  format  or  the
           extended  common  log  format.  The  common  format  is  one  line  looking like this:
           remotehost rfc931 authuser [date] "request" status bytes.

           Here:

           remotehost:
             Remote.

           rfc931:
             The remote username of the client (RFC 931).

           authuser:
             The username used for authentication.

           [date]:
             Date and time of the request (RFC 1123).

           "request":
             The request line as it came from the client (RFC 1945).

           status:
             The HTTP status code returned to the client (RFC 1945).

           bytes:
             The content-length of the document transferred.

           The combined format is one line looking like this: remotehost rfc931  authuser  [date]
           "request" status bytes "referer" "user_agent"

           In addition to the earlier:

           "referer":
             The  URL the client was on before requesting the URL (if it could not be determined,
             a minus sign is placed in this field).

           "user_agent":
             The software the client claims to be using (if it could not be determined,  a  minus
             sign is placed in this field).

           This affects the access logs written by mod_log and mod_disk_log.

         {error_log_format, pretty | compact}:
           Default is pretty. If the error log is meant to be read directly by a human, pretty is
           the best option.

           pretty has a format corresponding to:

         io:format("[~s] ~s, reason: ~n ~p ~n~n", [Date, Msg, Reason]).

           compact has a format corresponding to:

         io:format("[~s] ~s, reason: ~w ~n", [Date, Msg, Reason]).

           This affects the error logs written by mod_log and mod_disk_log.

       URL Aliasing Properties - Requires mod_alias

         {alias, {Alias, RealName}}:
           Alias = string() and RealName = string(). alias allows documents to be stored  in  the
           local  file  system  instead of the document_root location. URLs with a path beginning
           with url-path is mapped to local files beginning with directory-filename, for example:

         {alias, {"/image", "/ftp/pub/image"}}

           Access   to   http://your.server.org/image/foo.gif   would   refer   to    the    file
           /ftp/pub/image/foo.gif.

         {re_write, {Re, Replacement}}:
           Re  =  string()  and Replacement = string(). re_write allows documents to be stored in
           the local file system instead of the document_root location.  URLs  are  rewritten  by
           re:replace/3 to produce a path in the local file-system, for example:

         {re_write, {"^/[~]([^/]+)(.*)$", "/home/\\1/public\\2"}}

           Access    to    http://your.server.org/~bob/foo.gif    would   refer   to   the   file
           /home/bob/public/foo.gif. In an Apache-like configuration file, Re is  separated  from
           Replacement  with  one  single  space,  and  as expected backslashes do not need to be
           backslash escaped, the same example would become:

         ReWrite ^/[~]([^/]+)(.*)$ /home/\1/public\2

           Beware of trailing space in Replacement to be used. If you must have a  space  in  Re,
           use, for example, the character encoding \040, see re(3erl).

         {directory_index, [string()]}:
           directory_index  specifies  a  list  of  resources  to look for if a client requests a
           directory using a / at the end of the directory name. file depicts the name of a  file
           in  the  directory.  Several  files can be given, in which case the server returns the
           first it finds, for example:

         {directory_index, ["index.html", "welcome.html"]}

           Access         to          http://your.server.org/docs/          would          return
           http://your.server.org/docs/index.html  or http://your.server.org/docs/welcome.html if
           index.html does not exist.

       CGI Properties - Requires mod_cgi

         {script_alias, {Alias, RealName}}:
           Alias = string() and RealName = string(). Have the same behavior  as  property  alias,
           except that they also mark the target directory as containing CGI scripts. URLs with a
           path beginning with url-path are mapped to scripts beginning with  directory-filename,
           for example:

         {script_alias, {"/cgi-bin/", "/web/cgi-bin/"}}

           Access  to http://your.server.org/cgi-bin/foo would cause the server to run the script
           /web/cgi-bin/foo.

         {script_re_write, {Re, Replacement}}:
           Re = string() and Replacement = string(). Have the same behavior as property re_write,
           except that they also mark the target directory as containing CGI scripts. URLs with a
           path beginning with url-path are mapped to scripts beginning with  directory-filename,
           for example:

         {script_re_write, {"^/cgi-bin/(\\d+)/", "/web/\\1/cgi-bin/"}}

           Access  to  http://your.server.org/cgi-bin/17/foo  would  cause  the server to run the
           script /web/17/cgi-bin/foo.

         {script_nocache, boolean()}:
           If script_nocache is set to true, the HTTP server by default adds  the  header  fields
           necessary  to  prevent  proxies  from  caching  the page. Generally this is preferred.
           Default to false.

         {script_timeout, integer()}:
           The time in seconds the web server waits between each chunk of data from  the  script.
           If  the CGI script does not deliver any data before the timeout, the connection to the
           client is closed. Default is 15.

         {action, {MimeType, CgiScript}} - requires mod_action:
           MimeType = string() and CgiScript = string(). action adds an action activating  a  CGI
           script  whenever a file of a certain MIME type is requested. It propagates the URL and
           file  path  of  the  requested  document  using  the  standard   CGI   PATH_INFO   and
           PATH_TRANSLATED environment variables.

           Example:

         {action, {"text/plain", "/cgi-bin/log_and_deliver_text"}}

         {script, {Method, CgiScript}} - requires mod_action:
           Method  =  string()  and  CgiScript = string(). script adds an action activating a CGI
           script whenever a file is requested using a certain HTTP method. The method is  either
           GET  or  POST,  as  defined  in  RFC  1945. It propagates the URL and file path of the
           requested document using the standard CGI PATH_INFO  and  PATH_TRANSLATED  environment
           variables.

           Example:

         {script, {"PUT", "/cgi-bin/put"}}

       ESI Properties - Requires mod_esi

         {erl_script_alias, {URLPath, [AllowedModule]}}:
           URLPath  =  string()  and  AllowedModule  =  atom().  erl_script_alias  marks all URLs
           matching url-path as erl scheme scripts. A matching URL  is  mapped  into  a  specific
           module and function, for example:

         {erl_script_alias, {"/cgi-bin/example", [httpd_example]}}

           A request to http://your.server.org/cgi-bin/example/httpd_example:yahoo would refer to
           httpd_example:yahoo/3  or,  if  that  does  not   exist,   httpd_example:yahoo/2   and
           http://your.server.org/cgi-bin/example/other:yahoo would not be allowed to execute.

         {erl_script_nocache, boolean()}:
           If  erl_script_nocache  is  set to true, the server adds HTTP header fields preventing
           proxies from caching the page. This is generally a good idea for dynamic  content,  as
           the content often varies between each request. Default is false.

         {erl_script_timeout, integer()}:
           If  erl_script_timeout sets the time in seconds the server waits between each chunk of
           data to be delivered through mod_esi:deliver/2. Default is 15. This is  only  relevant
           for scripts that use the erl scheme.

         {eval_script_alias, {URLPath, [AllowedModule]}}:
           URLPath  =  string()  and  AllowedModule  =  atom().  Same as erl_script_alias but for
           scripts using the eval scheme. This is only supported for backwards compatibility. The
           eval scheme is deprecated.

       Log Properties - Requires mod_log

         {error_log, path()}:
           Defines  the  filename  of  the error log file to be used to log server errors. If the
           filename does not begin with a slash  (/),  it  is  assumed  to  be  relative  to  the
           server_root.

         {security_log, path()}:
           Defines  the filename of the access log file to be used to log security events. If the
           filename does not begin with a slash  (/),  it  is  assumed  to  be  relative  to  the
           server_root.

         {transfer_log, path()}:
           Defines  the  filename  of the access log file to be used to log incoming requests. If
           the filename does not begin with a slash (/), it is assumed  to  be  relative  to  the
           server_root.

       Disk Log Properties - Requires mod_disk_log

         {disk_log_format, internal | external}:
           Defines  the  file  format of the log files. See disk_log for details. If the internal
           file format is used, the log file is repaired after  a  crash.  When  a  log  file  is
           repaired,  data  can  disappear. When the external file format is used, httpd does not
           start if the log file is broken. Default is external.

         {error_disk_log, path()}:
           Defines the filename of the (disk_log(3erl)) error log file to be used to  log  server
           errors.  If the filename does not begin with a slash (/), it is assumed to be relative
           to the server_root.

         {error_disk_log_size, {MaxBytes, MaxFiles}}:
           MaxBytes =  integer()  and  MaxFiles  =  integer().  Defines  the  properties  of  the
           (disk_log(3erl))  error  log  file.  This  file  is  of type wrap log and max bytes is
           written to each file and max files is used before the  first  file  is  truncated  and
           reused.

         {security_disk_log, path()}:
           Defines the filename of the (disk_log(3erl)) access log file logging incoming security
           events, that is, authenticated requests. If the filename does not begin with  a  slash
           (/), it is assumed to be relative to the server_root.

         {security_disk_log_size, {MaxBytes, MaxFiles}}:
           MaxBytes  =  integer()  and  MaxFiles  =  integer().  Defines  the  properties  of the
           disk_log(3erl) access log file. This file is of type wrap log and max bytes is written
           to each file and max files is used before the first file is truncated and reused.

         {transfer_disk_log, path()}:
           Defines  the  filename  of  the  (disk_log(3erl))  access  log  file  logging incoming
           requests. If the filename does not begin with  a  slash  (/),  it  is  assumed  to  be
           relative to the server_root.

         {transfer_disk_log_size, {MaxBytes, MaxFiles}}:
           MaxBytes  =  integer()  and  MaxFiles  =  integer().  Defines  the  properties  of the
           disk_log(3erl) access log file. This file is of type wrap log and max bytes is written
           to each file and max files is used before the first file is truncated and reused.

       Authentication Properties - Requires mod_auth

       {directory, {path(), [{property(), term()}]}}

       The properties for directories are as follows:

         {allow_from, all | [RegxpHostString]}:
           Defines a set of hosts to be granted access to a given directory, for example:

         {allow_from, ["123.34.56.11", "150.100.23"]}

           The host 123.34.56.11 and all machines on the 150.100.23 subnet are allowed access.

         {deny_from, all | [RegxpHostString]}:
           Defines a set of hosts to be denied access to a given directory, for example:

         {deny_from, ["123.34.56.11", "150.100.23"]}

           The  host  123.34.56.11  and  all  machines  on  the 150.100.23 subnet are not allowed
           access.

         {auth_type, plain | dets | mnesia}:
           Sets the type of authentication database that is  used  for  the  directory.  The  key
           difference between the different methods is that dynamic data can be saved when Mnesia
           and Dets are used. This property is called AuthDbType in the Apache-like configuration
           files.

         {auth_user_file, path()}:
           Sets  the  name  of  a  file  containing  the  list  of  users  and passwords for user
           authentication. The filename can be either absolute or relative to the server_root. If
           using  the  plain  storage  method,  this  file  is  a plain text file where each line
           contains a username followed by a colon, followed by the  non-encrypted  password.  If
           usernames are duplicated, the behavior is undefined.

           Example:

          ragnar:s7Xxv7
          edward:wwjau8

           If  the  Dets storage method is used, the user database is maintained by Dets and must
           not be edited by hand. Use the API functions in module  mod_auth  to  create/edit  the
           user  database.  This  directive  is ignored if the Mnesia storage method is used. For
           security reasons, ensure that auth_user_file is stored outside the  document  tree  of
           the  web  server.  If  it  is  placed  in  the directory that it protects, clients can
           download it.

         {auth_group_file, path()}:
           Sets the name of a file containing the list of user groups  for  user  authentication.
           The  filename  can  be  either  absolute  or relative to the server_root. If the plain
           storage method is used, the group file is a plain text file, where each line  contains
           a  group  name  followed  by  a  colon, followed by the members usernames separated by
           spaces.

           Example:

         group1: bob joe ante

           If the Dets storage method is used, the group database is maintained by Dets and  must
           not  be  edited  by  hand.  Use  the  API for module mod_auth to create/edit the group
           database. This directive is ignored if the Mnesia storage method is used. For security
           reasons,  ensure  that  the auth_group_file is stored outside the document tree of the
           web server. If it is placed in the directory that it protects,  clients  can  download
           it.

         {auth_name, string()}:
           Sets  the  name  of the authorization realm (auth-domain) for a directory. This string
           informs the client about which username and password to use.

         {auth_access_password, string()}:
           If set to other than "NoPassword", the password is required for all API calls. If  the
           password  is set to "DummyPassword", the password must be changed before any other API
           calls. To secure the authenticating data, the password must be changed after  the  web
           server is started. Otherwise it is written in clear text in the configuration file.

         {require_user, [string()]}:
           Defines users to grant access to a given directory using a secret password.

         {require_group, [string()]}:
           Defines users to grant access to a given directory using a secret password.

       Htaccess Authentication Properties - Requires mod_htaccess

         {access_files, [path()]}:
           Specifies  the  filenames  that are used for access files. When a request comes, every
           directory in the path to the requested asset are searched after files with  the  names
           specified  by  this  parameter.  If  such  a file is found, the file is parsed and the
           restrictions specified in it are applied to the request.

       Security Properties - Requires mod_security

       {security_directory, {path(), [{property(), term()}]}}

       The properties for the security directories are as follows:

         {data_file, path()}:
           Name of the security data file. The filename can either be absolute or relative to the
           server_root. This file is used to store persistent data for module mod_security.

         {max_retries, integer()}:
           Specifies  the  maximum  number  of attempts to authenticate a user before the user is
           blocked out. If a user successfully authenticates while blocked, the user  receives  a
           403  (Forbidden)  response  from  the server. If the user makes a failed attempt while
           blocked, the server returns 401 (Unauthorized), for security reasons.  Default  is  3.
           Can be set to infinity.

         {block_time, integer()}:
           Specifies the number of minutes a user is blocked. After this timehas passed, the user
           automatically regains access. Default is 60.

         {fail_expire_time, integer()}:
           Specifies the number of minutes a failed user authentication is remembered. If a  user
           authenticates  after  this  time  has  passed, the previous failed authentications are
           forgotten. Default is 30.

         {auth_timeout, integer()}:
            Specifies the number of seconds a successful user authentication is remembered. After
           this time has passed, the authentication is no longer reported. Default is 30.

EXPORTS

       info(Pid) ->
       info(Pid, Properties) -> [{Option, Value}]

              Types:

                 Properties = [property()]
                 Option = property()
                 Value = term()

              Fetches  information  about  the  HTTP  server.  When called with only the pid, all
              properties are fetched. When called with a list of specific  properties,  they  are
              fetched. The available properties are the same as the start options of the server.

          Note:
              Pid  is  the  pid  returned  from  inets:start/[2,3].  Can  also  be retrieved form
              inets:services/0 and inets:services_info/0, see inets(3erl).

       info(Address, Port) ->
       info(Address, Port, Profile) ->
       info(Address, Port, Profile, Properties) -> [{Option, Value}]
       info(Address, Port, Properties) -> [{Option, Value}]

              Types:

                 Address = ip_address()
                 Port = integer()
                 Profile = atom()
                 Properties = [property()]
                 Option = property()
                 Value = term()

              Fetches information about the HTTP server. When called with only Address and  Port,
              all  properties  are  fetched. When called with a list of specific properties, they
              are fetched. The available properties are the same as  the  start  options  of  the
              server.

          Note:
              The address must be the IP address and cannot be the hostname.

       reload_config(Config, Mode) -> ok | {error, Reason}

              Types:

                 Config = path() | [{Option, Value}]
                 Option = property()
                 Value = term()
                 Mode = non_disturbing | disturbing

              Reloads  the  HTTP  server  configuration  without  restarting the server. Incoming
              requests are answered with a temporary down message during the reload time.

          Note:
              Available properties are the same as the start  options  of  the  server,  but  the
              properties bind_address and port cannot be changed.

              If  mode  is  disturbing,  the  server  is blocked forcefully, all ongoing requests
              terminates, and the reload starts immediately. If mode is  non-disturbing,  no  new
              connections  are  accepted, but ongoing requests are allowed to complete before the
              reload is done.

ERLANG WEB SERVER API DATA TYPES

       The Erlang web server API data types are as follows:

             ModData = #mod{}

             -record(mod, {
                 data = [],
                 socket_type = ip_comm,
                 socket,
                 config_db,
                 method,
                 absolute_uri,
                 request_uri,
                 http_version,
                 request_line,
                 parsed_header = [],
                 entity_body,
                 connection
            }).

       To acess the record in your callback-module use:

        -include_lib("inets/include/httpd.hrl").

       The fields of record mod have the following meaning:

         data:
           Type [{InteractionKey,InteractionValue}] is used to propagate  data  between  modules.
           Depicted interaction_data() in function type declarations.

         socket_type:
           socket_type() indicates whether it is an IP socket or an ssl socket.

         socket:
           The socket, in format ip_comm or ssl, depending on socket_type.

         config_db:
           The  config  file  directives  stored  as  key-value  tuples in an ETS table. Depicted
           config_db() in function type declarations.

         method:
           Type "GET" | "POST" | "HEAD" | "TRACE", that is, the HTTP method.

         absolute_uri:
           If the request is an HTTP/1.1 request, the URI can be in the absolute URI  format.  In
           that  case,  httpd saves the absolute URI in this field. An Example of an absolute URI
           is "http://ServerName:Part/cgi-bin/find.pl?person=jocke"

         request_uri:
           The Request-URI as defined in RFC 1945, for example, "/cgi-bin/find.pl?person=jocke".

         http_version:
           The HTTP version of the request, that is, "HTTP/0.9", "HTTP/1.0", or "HTTP/1.1".

         request_line:
           The   Request-Line   as   defined   inRFC    1945,    for    example,    "GET    /cgi-
           bin/find.pl?person=jocke HTTP/1.0".

         parsed_header:
           Type [{HeaderKey,HeaderValue}]. parsed_header contains all HTTP header fields from the
           HTTP request stored in a list as key-value tuples. See RFC 2616 for a listing  of  all
           header  fields.  For  example,  the  date field is stored as {"date","Wed, 15 Oct 1997
           14:35:17 GMT"}. RFC 2616 defines that HTTP is  a  case-insensitive  protocol  and  the
           header  fields can be in lower case or upper case. httpd ensures that all header field
           names are in lower case.

         entity_body:
           The entity-Body as defined in RFC 2616, for example, data sent from a CGI script using
           the POST method.

         connection:
           true  | false. If set to true, the connection to the client is a persistent connection
           and is not closed when the request is served.

ERLANG WEB SERVER API CALLBACK FUNCTIONS

EXPORTS

       Module:do(ModData)-> {proceed, OldData} | {proceed, NewData} | {break, NewData} | done

              Types:

                 OldData = list()
                 NewData = [{response,{StatusCode,Body}}]
                 | [{response,{response,Head,Body}}]
                 | [{response,{already_sent,Statuscode,Size}}]
                 StatusCode = integer()
                 Body = io_list() | nobody | {Fun, Arg}
                 Head = [HeaderOption]
                 HeaderOption = {Option, Value} | {code, StatusCode}
                 Option = accept_ranges | allow
                 | cache_control | content_MD5
                 | content_encoding | content_language
                 | content_length | content_location
                 | content_range | content_type | date
                 | etag | expires | last_modified
                 | location | pragma | retry_after
                 | server | trailer | transfer_encoding
                 Value = string()
                 Fun = fun( Arg ) -> sent| close | Body
                 Arg = [term()]

              When a valid request reaches httpd, it calls do/1 in each module,  defined  by  the
              configuration option of Module. The function can generate data for other modules or
              a response that can be sent back to the client.

              The field data in ModData is a list. This list is the list returned from  the  last
              call to do/1.

              Body  is  the  body  of  the  HTTP  response  that  is  sent back to the client. An
              appropriate header is appended to the message. StatusCode is the status code of the
              response, see RFC 2616 for the appropriate values.

              Head  is  a  key  value  list  of HTTP header fields. The server constructs an HTTP
              header from this data. See RFC 2616 for  the  appropriate  value  for  each  header
              field.  If  the  client  is an HTTP/1.0 client, the server filters the list so that
              only HTTP/1.0 header fields are sent back to the client.

              If Body is returned and equal to {Fun,Arg}, the web server  tries  apply/2  on  Fun
              with  Arg  as  argument.  The web server expects that the fun either returns a list
              (Body) that is an HTTP repsonse, or the atom sent if the HTTP response is sent back
              to  the client. If close is returned from the fun, something has gone wrong and the
              server signals this to the client by closing the connection.

       Module:load(Line, AccIn)-> eof | ok | {ok, AccOut} | {ok, AccOut, {Option, Value}} |  {ok,
       AccOut, [{Option, Value}]} | {error, Reason}

              Types:

                 Line = string()
                 AccIn = [{Option, Value}]
                 AccOut = [{Option, Value}]
                 Option = property()
                 Value = term()
                 Reason = term()

              Converts  a  line in an Apache-like configuration file to an {Option, Value} tuple.
              Some more complex configuration options, such as directory and  security_directory,
              create an accumulator. This function only needs clauses for the options implemented
              by this particular callback module.

       Module:remove(ConfigDB) -> ok | {error, Reason}

              Types:

                 ConfigDB = ets_table()
                 Reason = term()

              When httpd is shut down, it tries to execute remove/1 in  each  Erlang  web  server
              callback module. The programmer can use this function to clean up resources created
              in the store function.

       Module:store({Option, Value}, Config)-> {ok, {Option, NewValue}} | {error, Reason}

              Types:

                 Line = string()
                 Option = property()
                 Config = [{Option, Value}]
                 Value = term()
                 Reason = term()

              Checks the validity of the configuration options before saving them in the internal
              database.  This  function  can also have a side effect, that is, setup of necessary
              extra resources implied by the configuration option. It can also  resolve  possible
              dependencies  among configuration options by changing the value of the option. This
              function only needs clauses for the options implemented by this particular callback
              module.

ERLANG WEB SERVER API HELP FUNCTIONS

EXPORTS

       parse_query(QueryString) -> [{Key,Value}]

              Types:

                 QueryString = string()
                 Key = string()
                 Value = string()

              parse_query/1  parses  incoming data to erl and eval scripts (see mod_esi(3erl)) as
              defined in the standard URL format, that is, '+' becomes 'space'  and  decoding  of
              hexadecimal characters (%xx).

SEE ALSO

       RFC 2616, inets(3erl), ssl(3erl)