libcgi "go to url"

chris livermore chrisliv at unimelb.edu.au
Tue Oct 9 04:21:52 EDT 2007


outstanding reply, thanks for the continued support Andre

chris

On 08/10/2007, at 5:59 AM, Andre Garzia wrote:

> Hello Chris,
>
> sorry for the late reply, I think I understand what you're trying to
> accomplish and will write some words on the topic, if I understood you
> wrong, then, sorry, english is not my strongest quality.
>
> Let us divide your problem in two topics: "templating" and "answering"
>
> Templating is the act of having a placeholder file or stack that is  
> used by
> the cgi to answer to a request, so you put your presentation layer  
> into one
> of those templates then with some calls, you glue your data into  
> them. We're
> specifically talking about building HTML like files. So you can have a
> default HTML template and just glue your data in it.
>
> When you run a Revolution CGI, the CGI has a "default folder" (global
> property the defaultFolder), all it's file operations are relative  
> to such
> location, you can change it by setting it to a new folder path such  
> as:
>
>     set the defaultfolder to "/mySweetTemplates/"
>
> You can set it to absolute paths (absolute paths are relative too  
> but they
> are relative to the root folder of your file system) or relative  
> path. If
> you set the default folder to a relative path, it will be set using  
> the
> previous known location and then override this location. This in plain
> english means that if the default folder is your cgi folder and you  
> have a
> "template" folder inside it, then executing the following line:
>
>     set the defaultfolder to "templates/"
>
> will set all the file operations to be relative to such child  
> folder. To
> read or write files, the best option is to use URL keywork commands  
> such as
> you're already doing. Now to glue data into your template there are  
> many
> ways, I'll just explore two in here.
>
> First is to use the replace command. You fill your template html  
> file with
> place holders such as "###NAME###", each of those placeholders will be
> replaced with the actual data by using multiple replace calls.  
> Using your
> previous example, let us replace some values, consider that your  
> HTML file
> has something like ###NAME### and ###COLOR### in it, and it is  
> answering the
> name and the  favorite color of the user. You can then call  
> something like:
>
>     replace "###NAME###" with tName in tData
>
>     replace "###COLOR###" with tFavoriteColor in tData
>
> So with each replace call you glue one piece of your data back in  
> the tData
> template. This is a very straight forward way of doing templates in
> Revolution. Another popular way that requires less coding and is more
> flexible is to use the merge command. This command will pick a  
> variable and
> inspect it looking for pre-defines placeholders, it will then  
> replace these
> place holders with the result of their values. Revolution uses double
> brackets as place holders for the merge call, so you just fill your  
> template
> with double brackets and your variables. Using our previous  
> example, imagine
> that your template looks like
>
>     <html>
>
>     <head><title>My Fav Color</title></head>
>
>     <body>
>
>     Hello, [[tName]]
>
>     Your favorite color is [[tFavoriteColor]]
>
>     </body>
>
>     </html>
>
> then if you execute the call:
>
>     put the merge of tData into tAssembledData
>
> The resulting variable called tAssembledData will contain the  
> content of the
> template with those double bracket place holders replaced with the  
> actual
> variable content. This is very flexible because you can change your  
> template
> to display different data without changing your program code.
>
> OBS: the merge call does more than variable glueing. This is just a  
> quick
> note...
>
> So now you should have some mental image of how to glue data into your
> template and end up with a variable that contains the answer you  
> want to
> send back to the browser, let us talk about answering to the  
> browser now.
>
> In your example you try to use RevGoURL. This command is to be used by
> desktop application to open the browser directed to some web page,  
> this is
> not to be used by CGI applications. It's a purelly desktop command  
> that
> opens another program and launches a web page.
>
> Most web servers are running under some kind of unix or follow some
> conventions set by the unix familly of operating systems. To  
> explain how the
> cgi answers back to the browser let me talk a little about the  
> standard i/o
> common to C programs. There are three important standard i/o, they are
> STDIN, STDOUT and STDERR. They mean "standard input", "standard  
> output" and
> "standard error output".
>
> You can think of them as files, three different files used for  
> different
> purposes. STDIN always mean the standard input interface, it may be  
> the
> keyboard or a piped file. When you use a CGI, the STDIN is written  
> by the
> web server to contain the web request, so when you read from STDIN  
> using a
> CGI you should read the raw web request data.
>
>
>
> STDOUT always mean the standard output, in some cases is the  
> screen, in
> others it may be a file. When you talk about CGI, the STDOUT will  
> be grabed
> by the web server and sent back to the browser. So your CGI will  
> write it's
> output to STDOUT and this will be piped back to the browser.
>
> STDERR points to the standard error output, like STDOUT it differs  
> for each
> context, in the cases of CGI, the web server will grab STDERR and  
> log it to
> system log file. So if something wrong happens in your cgi you can  
> have the
> web server to log useful information by writting to STDERR.
>
> Okay, now we know that using these three "files" we're able to  
> interface
> with the web server and thus talk with the web browsers. When  
> executing  a
> revolution CGI, the console becomes STDOUT, so all your put  
> commands that
> would go to the message box when run from the IDE will actually go to
> STDOUT. So to send data back to the browser, you simply use the put  
> command.
> Like this:
>
>     put tAssembledData
>
> This will send tAssembledData to STDOUT. Be aware that the web browser
> expects a fully HTTP compliant answer. Some web servers will  
> inspect what
> you write to STDOUT and fix missing information but most will not.  
> Below I
> give you a very simple output function that your can use to assemble a
> minimal response back to the browser.
>
> on cgiOutput pData
>
>     put "200 OK HTTP/1.0" & cr
>
>     put "Content-type: text/html" & cr
>
>     put "Content-lenght:" && the lenght of pData & cr & cr
>
>     put pData
>
> end cgiOutput
>
> using this simple function you can then call:
>
>     cgiOutput tAssembledData
>
> and have the HTML stored in that variable to display in the web  
> browser. If
> you want to look further into these topics, I advise you to follow  
> Jacques
> CGI tutorial at:
>
>    http://hyperactivesw.com/cgitutorial/index.html
>
> I'll also tell you some buzzwords that you may find userful. Look into
> "XSLT" for your templates, it is a standard way to build HTML  
> templates and
> most server boxes come with "xsltproc" installed so you can very  
> quickly
> assemble and web response by calling xsltproc thru the shell()  
> command. Also
> read JM Marshall "HTTP Made Easy" eBook, it will give you a basic  
> grasp of
> the HTTP protocol. Very useful.
>
> and then use my own RevHTTP server from the Revolution IDE to learn  
> more
> about CGIs. You can learn more about it at
> http://www.andregarzia.com/RevOnRockets
>
> Cheers, I hope this help you.
>
> Andre
>
>
> Hello
>
> On 10/1/07, chris livermore <chrisliv at unimelb.edu.au> wrote:
>>
>> Hi
>> I have libCGI working nicely (thanks for this stack), I'm storing/
>> writing variables to text files all OK. Problem is sending a client
>> back to a web page.
>> So the client clicks 'Submit' button, all parameters are processed;
>> This script:  put url ("file:../test/switchatest/
>> parameters_summary.html") into tData
>> finds the correct page but because the page's links are relative,
>> none of the graphics are shown. I'll convert all to absolute links
>> but there must be an easier way to go to any url?
>> I've tried: get url ("file:../test/switchatest/
>> parameters_summary.html") into tData
>> and: revGoURL "http://www.kipmultimedia.com/test/switchatest/
>> parameters_oral.html"
>> but no luck.
>> I have a feeling this is going to be embarrassingly simple, thanks
>> for a great forum.
>>
>> macintel 10.4.10, rev 2.8.1 (3)
>>
>> regards
>>
>> chris
>>
>>
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