%%%---------------------------------------------------------------------- %%% File : yaws_rss.erl %%% Created : 15 Dec 2004 by Torbjorn Tornkvist %%% %%% @doc A Yaws RSS feed interface. %%% %%% @author Torbjörn Törnkvist %%% @end %%% %%% $Id: yaws_rss.erl 1070 2007-01-17 09:43:11Z etnt $ %%%---------------------------------------------------------------------- -module(yaws_rss). -behaviour(gen_server). %% External exports -export([start/0, start_link/0, open/1, open/2, close/0, close/2, insert/5, insert/6, insert/7, retrieve/2]). -export([t_setup/0, t_exp/0, t_xopen/0]). %% gen_server callbacks -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2]). -record(s, { open_apps = [], % activated applications expire = false, % false | days rm_exp = false, % remove expired items max=infinite, % maximum number of elements in DB days=7, % maximum number of days in DB counter}). % item counter -define(SERVER, ?MODULE). -define(DB, ?MODULE). -define(DB_FNAME, "yaws_rss.dets"). -define(ITEM(App, Tag, Counter, Item), {{App, Tag, Counter}, Item}). %%%---------------------------------------------------------------------- %%% API %%%---------------------------------------------------------------------- start_link() -> gen_server:start_link({local, ?SERVER}, ?MODULE, [], []). start() -> gen_server:start({local, ?SERVER}, ?MODULE, [], []). %%% %%% @spec open(App::atom(), Dir::string()) -> %%% {ok, DB::db()} | {error, string()} %%% %%% @type db(). An opaque handle leading to an RSS database. %%% %%% @doc See {@open/2} %%% open(App) -> open(App, []). %%% %%% @spec open(App::atom(), Opts::list()) -> %%% {ok, DB::db()} | {error, string()} %%% %%% @doc Open a RSS database. %%% Per default dets is used as database, %%% but by using the db_mod option it is %%% possible to use your own database.
%%% These are the options: %%%

%%% %%%
{db_mod, Module}
%%%
If specified, the following functions will be %%% called:
    %%%
  • Module:open(Opts)
    • %%%
  • Module:insert(App,Tag,Title,Link,Desc,Creator,GregSec)
    • %%%
  • Module:retrieve(App,Tag) -> {Title, Link, Desc, Creator, GregSecs}
    • %%%
  • Module:close(DbName)
%%% This means that the default DB won't be used, and %%% no expiration handling will be done. Only the producing of %%% XML will thus be done. Also, the whole Opts will be %%% passed un-interpreted to the other DB module.
%%% %%%
{db_dir, Dir}
%%%
Specifies the directory where the database will be created. %%% Default is: /tmp
%%% %%%
{expire, Expire}
%%%
Specifies what method to use to expire items. Possible values %%% are: false, days, meaning %%% never expire, expire after a number of days. %%% Default is to never expire items.
%%% %%%
{days, Number}
%%%
Specifies the number of days befor an item is expired. %%% Default is 7 days.
%%% %%%
{rm_exp, Bool}
%%%
Specifies if expired items should be removed from %%% the database. Default is to not remove any items.
%%% %%%
{max, Number}
%%%
Specifies the maximum number of items that should %%% be stored in the database. The default in infinite
%%%

%%%

If no database exist, a new will be created. %%% The returned database handle is to be used with {@link close/1}. %%% @end %%% open(App, Opts) -> gen_server:call(?SERVER, {open, App, Opts}, infinity). %%% %%% @spec close() -> ok | {error, string()} %%% %%% @doc Close the RSS database. %%% close() -> gen_server:call(?SERVER, {close, ?DB}, infinity). %%% %%% @spec close(DbMod::atom(), DbName::atom()) -> %%% ok | {error, string()} %%% %%% @doc Close the user provided RSS database. %%% A call to; DbMod:close(DbName) will be made. %%% close(DBmod, DBname) -> gen_server:call(?SERVER, {close, DBmod, DBname}, infinity). %%% %%% @spec insert(App::atom(), Tag::atom(), Title::string(), %%% Link::string(), Desc::string()) -> %%% ok | {error, string()} %%% %%% @doc Insert an RSS item into the {App,Tag} RSS feed. %%% An application (App) can maintain several feeds each %%% one refered to with a symbolic name (Tag). %%% Link should be a URL pointing to the item. %%%

In case another database backend is used, the %%% Tag has the format: {DbModule, OpaqueTag} %%% where DbModule is the database backend module %%% to be called, and OpaqueTag the Tag that is %%% used in DbModule:insert(Tag, ...)

%%% @end %%% insert(App, Tag, Title, Link, Desc) -> insert(App, Tag, Title, Link, Desc, ""). %%% %%% @spec insert(App::atom(), Tag::atom(), Title::string(), %%% Link::string(), Desc::string(), %%% Creator::string()) -> %%% ok | {error, string()} %%% %%% @doc Works as {@link insert/5} but takes an extra argument %%% Creator which may contains an identification %%% of who created the item. %%% insert(App, Tag, Title, Link, Desc, Creator) -> GregSecs = calendar:datetime_to_gregorian_seconds({date(),time()}), insert(App, Tag, Title, Link, Desc, Creator, GregSecs). %%% %%% @spec insert(App::atom(), Tag::atom(), Title::string(), %%% Link::string(), Desc::string(), %%% Creator::string(), GregSecs::integer()) -> %%% ok | {error, string()} %%% %%% @doc Works as {@link insert/6} but takes an extra argument %%% GregSecs which is the creation time of the item %%% in Gregorian Seconds. %%% insert(App, Tag, Title, Link, Desc, Creator, GregSecs) -> Args = {App, Tag, Title, Link, Desc, Creator, GregSecs}, gen_server:call(?SERVER, {insert, Args}, infinity). %%% %%% @spec retrieve(App::atom(), Tag::atom()) -> %%% {ok, RSScontent::IoList()} | {error, string()} %%% %%% @type IoList. A deep list of strings and/or binaries. %%% %%% @doc Retrieve the RSScontent (in XML and all...) %%% to be delivered to a RSS client. %%%

In case another database backend is used, the %%% Tag has the format: {DbModule, OpaqueTag} %%% where DbModule is the database backend module %%% to be called, and OpaqueTag the Tag that is %%% used in DbModule:retrieve(Tag) which must return %%% a list of tuples: {Title, Link, Desc, Creator, GregSecs}

%%% retrieve(App, Tag) -> gen_server:call(?SERVER, {retrieve, App, Tag}, infinity). %%%---------------------------------------------------------------------- %%% Callback functions from gen_server %%%---------------------------------------------------------------------- %%---------------------------------------------------------------------- %% Func: init/1 %% Returns: {ok, State} | %% {ok, State, Timeout} | %% ignore | %% {stop, Reason} %%---------------------------------------------------------------------- init([]) -> {ok, #s{}}. %%---------------------------------------------------------------------- %% Func: handle_call/3 %% Returns: {reply, Reply, State} | %% {reply, Reply, State, Timeout} | %% {noreply, State} | %% {noreply, State, Timeout} | %% {stop, Reason, Reply, State} | (terminate/2 is called) %% {stop, Reason, State} (terminate/2 is called) %%---------------------------------------------------------------------- handle_call({open, App, Opts}, _From, State) -> {NewState, Res} = do_open_dir(State, App, Opts), {reply, Res, NewState}; %% handle_call({close, DB}, _From, State) -> dets:close(DB), {reply, ok, State}; %% handle_call({close, DBMod, DBname}, _From, State) -> catch apply(DBMod, close, [DBname]), {reply, ok, State}; %% handle_call({insert, Args}, _From, State) -> {NewState, Res} = do_insert(State, Args), {reply, Res, NewState}; %% handle_call({retrieve, App, Tag}, _From, State) -> {NewState, Res} = do_retrieve(State, App, Tag), {reply, Res, NewState}. %%---------------------------------------------------------------------- %% Func: handle_cast/2 %% Returns: {noreply, State} | %% {noreply, State, Timeout} | %% {stop, Reason, State} (terminate/2 is called) %%---------------------------------------------------------------------- handle_cast(_Msg, State) -> {noreply, State}. %%---------------------------------------------------------------------- %% Func: handle_info/2 %% Returns: {noreply, State} | %% {noreply, State, Timeout} | %% {stop, Reason, State} (terminate/2 is called) %%---------------------------------------------------------------------- handle_info(_Info, State) -> {noreply, State}. %%---------------------------------------------------------------------- %% Func: terminate/2 %% Purpose: Shutdown the server %% Returns: any (ignored by gen_server) %%---------------------------------------------------------------------- terminate(_Reason, _State) -> ok. %%%---------------------------------------------------------------------- %%% Internal functions %%%---------------------------------------------------------------------- %%% %%% Check what database store that should be used. %%% Per default 'dets' is used. %%% do_open_dir(State, App, Opts) -> case get_db_mod(Opts, dets) of dets -> File = get_db_file(Opts), Expire = get_expire(Opts, #s.expire), Max = get_max(Opts, #s.max), Days = get_days(Opts, #s.days), RmExp = get_rm_exp(Opts, #s.rm_exp), case dets:is_dets_file(File) of false -> {State, {error, "not a proper dets file"}}; _ -> case catch dets:open_file(?DB, [{file, File}]) of {ok,DB} = Res -> {State#s{ open_apps = u_insert(App, State#s.open_apps), expire = Expire, days = Days, rm_exp = RmExp, max = Max, counter = init_counter(DB)}, Res}; {error, _Reason} -> {State, {error, "open dets file"}} end end; DBmod -> {State, catch apply(DBmod, open, Opts)} end. get_db_file(Opts) -> Dir = get_db_dir(Opts, "/tmp"), Dir ++ "/" ++ a2l(?DB) ++ ".dets". init_counter(DB) -> case dets:lookup(DB, counter) of [] -> dets:insert(DB, {counter, 0}), 0; [{counter,N}] -> N end. set_counter(DB, N) -> dets:insert(DB, {counter, N}). do_insert(State, {App, {DbMod,Tag}, Title, Link, Desc, Creator, GregSecs}) -> {State, catch apply(DbMod, insert, [App, Tag,Title,Link,Desc,Creator,GregSecs])}; do_insert(State, {App, Tag, Title, Link, Desc, Creator, GregSecs}) -> case lists:member(App, State#s.open_apps) of true -> Counter = if (State#s.max > 0) -> (State#s.counter + 1) rem State#s.max; true -> State#s.counter + 1 end, Item = {Title, Link, Desc, Creator, GregSecs}, Res = dets:insert(?DB, ?ITEM(App, Tag, Counter, Item)), set_counter(?DB, Counter), {State#s{counter = Counter}, Res}; false -> {State, {error, "no open DB"}} end. do_retrieve(State, App, {DbMod,Tag}) -> {State, catch apply(DbMod, retrieve, [App, Tag])}; do_retrieve(State, App, Tag) -> case lists:member(App, State#s.open_apps) of true -> F = fun(?ITEM(Xa, Xt, _Counter, Item), Acc) when Xa == App, Xt == Tag -> [Item|Acc]; (_, Acc) -> Acc end, Items = sort_items(expired(State, dets:foldl(F, [], ?DB))), Xml = to_xml(Items), {State, {ok, Xml}}; false -> {State, {error, "no open DB"}} end. -define(ONE_DAY, 86400). % 24*60*60 seconds -define(X(GregSecs), {Title, Link, Desc, Creator, GregSecs}). %%% Filter away expired items !! expired(State, List) when State#s.expire == days -> Gs = calendar:datetime_to_gregorian_seconds({date(),time()}), Old = Gs - (?ONE_DAY * State#s.days), F = fun(?X(GregSecs), Acc) when GregSecs > Old -> [?X(GregSecs) | Acc]; (_, Acc) -> Acc end, lists:foldl(F, [], List); expired(_State, List) -> List. -undef(X). %%% %%% Sort on creation date !! %%% Item = {Title, Link, Desc, Creator, GregSecs}, %%% sort_items(Is) -> lists:keysort(5,Is). to_xml([{Title, Link, Desc, Creator, GregSecs}|Tail]) -> Date = w3cdtf(GregSecs), [["\n", "", yaws_api:htmlize(Title), "\n", "", Link, "\n", "", Link, "\n", "", yaws_api:htmlize(Desc), "\n", "", Creator, "\n", "", Date, "\n", "\n"] | to_xml(Tail)]; to_xml([]) -> []. %%% %%% Create W3CDTF (http://www.w3.org/TR/NOTE-datetime) formatted date %%% w3cdtf(GregSecs) -> "YYYY-MM-DDThh:mm:ssTZD" %%% w3cdtf(GregSecs) -> Date = calendar:gregorian_seconds_to_datetime(GregSecs), {{Y, Mo, D},{H, Mi, S}} = Date, [UDate|_] = calendar:local_time_to_universal_time_dst(Date), {DiffD,{DiffH,DiffMi,_}}=calendar:time_difference(UDate,Date), w3cdtf_diff(Y, Mo, D, H, Mi, S, DiffD, DiffH, DiffMi). %%% w3cdtf's helper function w3cdtf_diff(Y, Mo, D, H, Mi, S, _DiffD, DiffH, DiffMi) when DiffH < 12, DiffH /= 0 -> i2l(Y) ++ "-" ++ add_zero(Mo) ++ "-" ++ add_zero(D) ++ "T" ++ add_zero(H) ++ ":" ++ add_zero(Mi) ++ ":" ++ add_zero(S) ++ "+" ++ add_zero(DiffH) ++ ":" ++ add_zero(DiffMi); w3cdtf_diff(Y, Mo, D, H, Mi, S, DiffD, DiffH, DiffMi) when DiffH > 12, DiffD == 0 -> i2l(Y) ++ "-" ++ add_zero(Mo) ++ "-" ++ add_zero(D) ++ "T" ++ add_zero(H) ++ ":" ++ add_zero(Mi) ++ ":" ++ add_zero(S) ++ "+" ++ add_zero(DiffH) ++ ":" ++ add_zero(DiffMi); w3cdtf_diff(Y, Mo, D, H, Mi, S, DiffD, DiffH, DiffMi) when DiffH > 12, DiffD /= 0, DiffMi /= 0 -> i2l(Y) ++ "-" ++ add_zero(Mo) ++ "-" ++ add_zero(D) ++ "T" ++ add_zero(H) ++ ":" ++ add_zero(Mi) ++ ":" ++ add_zero(S) ++ "-" ++ add_zero(23-DiffH) ++ ":" ++ add_zero(60-DiffMi); w3cdtf_diff(Y, Mo, D, H, Mi, S, DiffD, DiffH, DiffMi) when DiffH > 12, DiffD /= 0, DiffMi == 0 -> i2l(Y) ++ "-" ++ add_zero(Mo) ++ "-" ++ add_zero(D) ++ "T" ++ add_zero(H) ++ ":" ++ add_zero(Mi) ++ ":" ++ add_zero(S) ++ "-" ++ add_zero(24-DiffH) ++ ":" ++ add_zero(DiffMi); w3cdtf_diff(Y, Mo, D, H, Mi, S, _DiffD, DiffH, _DiffMi) when DiffH == 0 -> i2l(Y) ++ "-" ++ add_zero(Mo) ++ "-" ++ add_zero(D) ++ "T" ++ add_zero(H) ++ ":" ++ add_zero(Mi) ++ ":" ++ add_zero(S) ++ "Z". add_zero(I) when integer(I) -> add_zero(i2l(I)); add_zero([A]) -> [$0,A]; add_zero(L) when list(L) -> L. get_db_mod(Opts, Def) -> lkup(db_mod, Opts, Def). get_db_dir(Opts, Def) -> lkup(db_dir, Opts, Def). get_expire(Opts, Def) -> lkup(expire, Opts, Def). get_max(Opts, Def) -> lkup(max, Opts, Def). get_days(Opts, Def) -> lkup(days, Opts, Def). get_rm_exp(Opts, Def ) -> lkup(rm_exp, Opts, Def). lkup(Key, List, Def) -> case lists:keysearch(Key, 1, List) of {value,{_,Value}} -> Value; _ -> Def end. u_insert(H, [H|T]) -> T; u_insert(E, [H|T]) -> [H|u_insert(E,T)]; u_insert(E, []) -> [E]. i2l(I) when integer(I) -> integer_to_list(I); i2l(L) when list(L) -> L. a2l(A) when atom(A) -> atom_to_list(A); a2l(L) when list(L) -> L. t_setup() -> %%open([{db_file, "yaws_rss.dets"}, {max,7}]), insert(test,xml,"Normalizing XML, Part 2", "http://www.xml.com/pub/a/2002/12/04/normalizing.html", "In this second and final look at applying relational " "normalization techniques to W3C XML Schema data modeling, " "Will Provost discusses when not to normalize, the scope " "of uniqueness and the fourth and fifth normal forms."), insert(test,xml,"The .NET Schema Object Model", "http://www.xml.com/pub/a/2002/12/04/som.html", "Priya Lakshminarayanan describes in detail the use of " "the .NET Schema Object Model for programmatic manipulation " "of W3C XML Schemas."), insert(test,xml,"SVG's Past and Promising Future", "http://www.xml.com/pub/a/2002/12/04/svg.html", "In this month's SVG column, Antoine Quint looks back at " "SVG's journey through 2002 and looks forward to 2003."). t_exp() -> %%open([{db_file, "yaws_rss.dets"}, {expire,days}]), insert(test,xml,"Expired article", "http://www.xml.com/pub/a/2002/12/04/normalizing.html", "In this second and final look at applying relational " "normalization techniques to W3C XML Schema data modeling, " "Will Provost discusses when not to normalize, the scope " "of uniqueness and the fourth and fifth normal forms.", "tobbe", 63269561882). % 6/12-2004 t_xopen() -> open([{db_file, "yaws_rss.dets"}, {expire,days}, {days, 20}]).