diff options
Diffstat (limited to 'system/doc/getting_started/conc_prog.xml')
| -rw-r--r-- | system/doc/getting_started/conc_prog.xml | 46 |
1 files changed, 23 insertions, 23 deletions
diff --git a/system/doc/getting_started/conc_prog.xml b/system/doc/getting_started/conc_prog.xml index e392287ff0..2b64826a93 100644 --- a/system/doc/getting_started/conc_prog.xml +++ b/system/doc/getting_started/conc_prog.xml @@ -95,7 +95,7 @@ goodbye</pre> the second a "goodbye", the first another "hello" and so forth. But where did the <0.63.0> come from? The return value of a function is of course the return value of the last "thing" in - the function. The last thing in the function <c>start</c> is</p> + the function. The last thing in the function <c>start</c> is:</p> <code type="none"> spawn(tut14, say_something, [goodbye, 3]).</code> <p><c>spawn</c> returns a <em>process identifier</em>, or @@ -166,11 +166,11 @@ Pong_PID = spawn(tut15, pong, [])</code> <c>start</c> now creates another process "ping".</p> <code type="none"> spawn(tut15, ping, [3, Pong_PID]),</code> - <p>this process executes</p> + <p>This process executes:</p> <code type="none"> tut15:ping(3, Pong_PID)</code> <p><0.36.0> is the return value from the <c>start</c> function.</p> - <p>The process "pong" now does:</p> + <p>The process "pong" now does:</p> <code type="none"> receive finished -> @@ -235,7 +235,7 @@ Ping_PID ! pong</code> Pid ! Message</code> <p>I.e. <c>Message</c> (any Erlang term) is sent to the process with identity <c>Pid</c>.</p> - <p>After sending the message <c>pong</c>, to the process "ping", + <p>After sending the message <c>pong</c> to the process "ping", "pong" calls the <c>pong</c> function again, which causes it to get back to the <c>receive</c> again and wait for another message. Now let's look at the process "ping". Recall that it was started @@ -253,7 +253,7 @@ Pong_PID ! {ping, self()},</code> <p><c>self()</c> returns the pid of the process which executes <c>self()</c>, in this case the pid of "ping". (Recall the code for "pong", this will land up in the variable <c>Ping_PID</c> in - the <c>receive</c> previously explained).</p> + the <c>receive</c> previously explained.)</p> <p>"Ping" now waits for a reply from "pong":</p> <code type="none"> receive @@ -352,8 +352,8 @@ pong ! {ping, self()},</code> on different computers. Before we do this, there are a few things we need to set up to get this to work. The distributed Erlang implementation provides a basic security mechanism to prevent - unauthorized access to an Erlang system on another computer - (*manual*). Erlang systems which talk to each other must have + unauthorized access to an Erlang system on another computer. + Erlang systems which talk to each other must have the same <em>magic cookie</em>. The easiest way to achieve this is by having a file called <c>.erlang.cookie</c> in your home directory on all machines which on which you are going to run @@ -363,8 +363,8 @@ pong ! {ping, self()},</code> you can safely ignore this and simply create a file called <c>.erlang.cookie</c> in the directory you get to after executing the command <c>cd</c> without any argument). - The <c>.erlang.cookie</c> file should contain on line with - the same atom. For example on Linux or Unix in the OS shell:</p> + The <c>.erlang.cookie</c> file should contain one line with + the same atom. For example, on Linux or Unix in the OS shell:</p> <pre> $ <input>cd</input> $ <input>cat > .erlang.cookie</input> @@ -373,10 +373,10 @@ $ <input>chmod 400 .erlang.cookie</input></pre> <p>The <c>chmod</c> above make the <c>.erlang.cookie</c> file accessible only by the owner of the file. This is a requirement.</p> <p>When you start an Erlang system which is going to talk to other - Erlang systems, you must give it a name, eg: </p> + Erlang systems, you must give it a name, e.g.: </p> <pre> $ <input>erl -sname my_name</input></pre> - <p>We will see more details of this later (*manual*). If you want to + <p>We will see more details of this later. If you want to experiment with distributed Erlang, but you only have one computer to work on, you can start two separate Erlang systems on the same computer but give them different names. Each Erlang @@ -385,7 +385,7 @@ $ <input>erl -sname my_name</input></pre> IP domain and we can use only the first component of the IP address, if we want to use nodes in different domains we use <c>-name</c> instead, but then all IP address must be given in - full (*manual*).</p> + full.)</p> <p>Here is the ping pong example modified to run on two separate nodes:</p> <code type="none"> @@ -538,9 +538,9 @@ ping finished</pre> <p>Before we start, let's note the following:</p> <list type="bulleted"> <item> - <p>This example will just show the message passing logic no + <p>This example will just show the message passing logic - no attempt at all has been made to provide a nice graphical user - interface - this can of course also be done in Erlang - but + interface. This can, of course, also be done in Erlang - but that's another tutorial.</p> </item> <item> @@ -550,8 +550,8 @@ ping finished</pre> tutorial.</p> </item> <item> - <p>The first program we write will contain some inadequacies as - regards handling of nodes which disappear, we will correct + <p>The first program we write will contain some inadequacies + regarding the handling of nodes which disappear. We will correct these in a later version of the program.</p> </item> </list> @@ -571,7 +571,7 @@ ping finished</pre> %%% already logged in at the same node, login will be rejected %%% with a suitable error message. %%% logoff() -%%% Logs off anybody at at node +%%% Logs off anybody at that node %%% message(ToName, Message) %%% sends Message to ToName. Error messages if the user of this %%% function is not logged on or if ToName is not logged on at @@ -734,11 +734,11 @@ await_result() -> <item>copy the compiled code (<c>messenger.beam</c>) to the directory on each computer where you start Erlang.</item> </list> - <p>In the following example of use of this program, I have started + <p>In the following example of use of this program I have started nodes on four different computers, but if you don't have that - many machines available on your network, you could start up + many machines available on your network you could start up several nodes on the same machine.</p> - <p>We start up four Erlang nodes, messenger@super, c1@bilbo, + <p>We start up four Erlang nodes: messenger@super, c1@bilbo, c2@kosken, c3@gollum.</p> <p>First we start up a the server at messenger@super:</p> <pre> @@ -780,19 +780,19 @@ ok receiver_not_found</pre> <p>But this fails as Fred has already logged off.</p> <p>First let's look at some of the new concepts we have introduced.</p> - <p>There are two versions of the <c>server_transfer</c> function, + <p>There are two versions of the <c>server_transfer</c> function: one with four arguments (<c>server_transfer/4</c>) and one with five (<c>server_transfer/5</c>). These are regarded by Erlang as two separate functions.</p> <p>Note how we write the <c>server</c> function so that it calls - itself, <c>server(User_List)</c> and thus creates a loop. + itself, via <c>server(User_List)</c>, and thus creates a loop. The Erlang compiler is "clever" and optimizes the code so that this really is a sort of loop and not a proper function call. But this only works if there is no code after the call, otherwise the compiler will expect the call to return and make a proper function call. This would result in the process getting bigger and bigger for every loop.</p> - <p>We use functions in the <c>lists</c> module. This is a very + <p>We use functions from the <c>lists</c> module. This is a very useful module and a study of the manual page is recommended (<c>erl -man lists</c>). <c>lists:keymember(Key,Position,Lists)</c> looks through a list |