source-git / libxml2

Clone
Source Code
GIT

Blame doc/example.html

c8 c8s master
  1.   8142202cc68380b20fde7dc42bdb7a79003b162b
  2.   doc
  3.   example.html
Blob History Raw
Packit 423ecb
Packit 423ecb
Packit 423ecb 
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css">
Packit 423ecb 
TD {font-family: Verdana,Arial,Helvetica}
Packit 423ecb 
BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em}
Packit 423ecb 
H1 {font-family: Verdana,Arial,Helvetica}
Packit 423ecb 
H2 {font-family: Verdana,Arial,Helvetica}
Packit 423ecb 
H3 {font-family: Verdana,Arial,Helvetica}
Packit 423ecb 
A:link, A:visited, A:active { text-decoration: underline }
Packit 423ecb 
</style><title>A real example</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000">
Action against software patentsGnome2 LogoW3C LogoRed Hat Logo
Made with Libxml2 Logo
The XML C parser and toolkit of Gnome
A real example
<center>Developer Menu</center>
<form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form>
<center>API Indexes</center>
<center>Related links</center>
Here is a real size example, where the actual content of the application
Packit 423ecb 
data is not kept in the DOM tree but uses internal structures. It is based on
Packit 423ecb 
a proposal to keep a database of jobs related to Gnome, with an XML based
Packit 423ecb 
storage structure. Here is an XML encoded jobs
Packit 423ecb 
base:
<?xml version="1.0"?>
Packit 423ecb 
<gjob:Helping xmlns:gjob="http://www.gnome.org/some-location">
Packit 423ecb 
  <gjob:Jobs>
Packit 423ecb
Packit 423ecb 
    <gjob:Job>
Packit 423ecb 
      <gjob:Project ID="3"/>
Packit 423ecb 
      <gjob:Application>GBackup</gjob:Application>
Packit 423ecb 
      <gjob:Category>Development</gjob:Category>
Packit 423ecb
Packit 423ecb 
      <gjob:Update>
Packit 423ecb 
        <gjob:Status>Open</gjob:Status>
Packit 423ecb 
        <gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST</gjob:Modified>
Packit 423ecb 
        <gjob:Salary>USD 0.00</gjob:Salary>
Packit 423ecb 
      </gjob:Update>
Packit 423ecb
Packit 423ecb 
      <gjob:Developers>
Packit 423ecb 
        <gjob:Developer>
Packit 423ecb 
        </gjob:Developer>
Packit 423ecb 
      </gjob:Developers>
Packit 423ecb
Packit 423ecb 
      <gjob:Contact>
Packit 423ecb 
        <gjob:Person>Nathan Clemons</gjob:Person>
Packit 423ecb 
        <gjob:Email>nathan@windsofstorm.net</gjob:Email>
Packit 423ecb 
        <gjob:Company>
Packit 423ecb 
        </gjob:Company>
Packit 423ecb 
        <gjob:Organisation>
Packit 423ecb 
        </gjob:Organisation>
Packit 423ecb 
        <gjob:Webpage>
Packit 423ecb 
        </gjob:Webpage>
Packit 423ecb 
        <gjob:Snailmail>
Packit 423ecb 
        </gjob:Snailmail>
Packit 423ecb 
        <gjob:Phone>
Packit 423ecb 
        </gjob:Phone>
Packit 423ecb 
      </gjob:Contact>
Packit 423ecb
Packit 423ecb 
      <gjob:Requirements>
Packit 423ecb 
      The program should be released as free software, under the GPL.
Packit 423ecb 
      </gjob:Requirements>
Packit 423ecb
Packit 423ecb 
      <gjob:Skills>
Packit 423ecb 
      </gjob:Skills>
Packit 423ecb
Packit 423ecb 
      <gjob:Details>
Packit 423ecb 
      A GNOME based system that will allow a superuser to configure
Packit 423ecb 
      compressed and uncompressed files and/or file systems to be backed
Packit 423ecb 
      up with a supported media in the system.  This should be able to
Packit 423ecb 
      perform via find commands generating a list of files that are passed
Packit 423ecb 
      to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
Packit 423ecb 
      or via operations performed on the filesystem itself. Email
Packit 423ecb 
      notification and GUI status display very important.
Packit 423ecb 
      </gjob:Details>
Packit 423ecb
Packit 423ecb 
    </gjob:Job>
Packit 423ecb
Packit 423ecb 
  </gjob:Jobs>
Packit 423ecb 
</gjob:Helping>
While loading the XML file into an internal DOM tree is a matter of
Packit 423ecb 
calling only a couple of functions, browsing the tree to gather the data and
Packit 423ecb 
generate the internal structures is harder, and more error prone.
The suggested principle is to be tolerant with respect to the input
Packit 423ecb 
structure. For example, the ordering of the attributes is not significant,
Packit 423ecb 
the XML specification is clear about it. It's also usually a good idea not to
Packit 423ecb 
depend on the order of the children of a given node, unless it really makes
Packit 423ecb 
things harder. Here is some code to parse the information for a person:
/*
Packit 423ecb 
 * A person record
Packit 423ecb 
 */
Packit 423ecb 
typedef struct person {
Packit 423ecb 
    char *name;
Packit 423ecb 
    char *email;
Packit 423ecb 
    char *company;
Packit 423ecb 
    char *organisation;
Packit 423ecb 
    char *smail;
Packit 423ecb 
    char *webPage;
Packit 423ecb 
    char *phone;
Packit 423ecb 
} person, *personPtr;
Packit 423ecb
Packit 423ecb 
/*
Packit 423ecb 
 * And the code needed to parse it
Packit 423ecb 
 */
Packit 423ecb 
personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
Packit 423ecb 
    personPtr ret = NULL;
Packit 423ecb
Packit 423ecb 
DEBUG("parsePerson\n");
Packit 423ecb 
    /*
Packit 423ecb 
     * allocate the struct
Packit 423ecb 
     */
Packit 423ecb 
    ret = (personPtr) malloc(sizeof(person));
Packit 423ecb 
    if (ret == NULL) {
Packit 423ecb 
        fprintf(stderr,"out of memory\n");
Packit 423ecb 
        return(NULL);
Packit 423ecb 
    }
Packit 423ecb 
    memset(ret, 0, sizeof(person));
Packit 423ecb
Packit 423ecb 
    /* We don't care what the top level element name is */
Packit 423ecb 
    cur = cur->xmlChildrenNode;
Packit 423ecb 
    while (cur != NULL) {
Packit 423ecb 
        if ((!strcmp(cur->name, "Person")) && (cur->ns == ns))
Packit 423ecb 
            ret->name = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Packit 423ecb 
        if ((!strcmp(cur->name, "Email")) && (cur->ns == ns))
Packit 423ecb 
            ret->email = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
Packit 423ecb 
        cur = cur->next;
Packit 423ecb 
    }
Packit 423ecb
Packit 423ecb 
    return(ret);
Packit 423ecb 
}
Here are a couple of things to notice:
    Packit 423ecb 
      
  • Usually a recursive parsing style is the more convenient one: XML data
    		•
    Packit 423ecb 
        is by nature subject to repetitive constructs and usually exhibits highly
    Packit 423ecb 
        structured patterns.
    Packit 423ecb 
      
  • The two arguments of type xmlDocPtr and xmlNsPtr,
    		•
    Packit 423ecb 
        i.e. the pointer to the global XML document and the namespace reserved to
    Packit 423ecb 
        the application. Document wide information are needed for example to
    Packit 423ecb 
        decode entities and it's a good coding practice to define a namespace for
    Packit 423ecb 
        your application set of data and test that the element and attributes
    Packit 423ecb 
        you're analyzing actually pertains to your application space. This is
    Packit 423ecb 
        done by a simple equality test (cur->ns == ns).
    Packit 423ecb 
      
  • To retrieve text and attributes value, you can use the function
    		•
    Packit 423ecb 
        xmlNodeListGetString to gather all the text and entity reference
    Packit 423ecb 
        nodes generated by the DOM output and produce an single text string.
    Packit 423ecb 
    Here is another piece of code used to parse another level of the
    Packit 423ecb 
    structure:
    #include <libxml/tree.h>
    Packit 423ecb 
    /*
    Packit 423ecb 
     * a Description for a Job
    Packit 423ecb 
     */
    Packit 423ecb 
    typedef struct job {
    Packit 423ecb 
        char *projectID;
    Packit 423ecb 
        char *application;
    Packit 423ecb 
        char *category;
    Packit 423ecb 
        personPtr contact;
    Packit 423ecb 
        int nbDevelopers;
    Packit 423ecb 
        personPtr developers[100]; /* using dynamic alloc is left as an exercise */
    Packit 423ecb 
    } job, *jobPtr;
    Packit 423ecb
    Packit 423ecb 
    /*
    Packit 423ecb 
     * And the code needed to parse it
    Packit 423ecb 
     */
    Packit 423ecb 
    jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
    Packit 423ecb 
        jobPtr ret = NULL;
    Packit 423ecb
    Packit 423ecb 
    DEBUG("parseJob\n");
    Packit 423ecb 
        /*
    Packit 423ecb 
         * allocate the struct
    Packit 423ecb 
         */
    Packit 423ecb 
        ret = (jobPtr) malloc(sizeof(job));
    Packit 423ecb 
        if (ret == NULL) {
    Packit 423ecb 
            fprintf(stderr,"out of memory\n");
    Packit 423ecb 
            return(NULL);
    Packit 423ecb 
        }
    Packit 423ecb 
        memset(ret, 0, sizeof(job));
    Packit 423ecb
    Packit 423ecb 
        /* We don't care what the top level element name is */
    Packit 423ecb 
        cur = cur->xmlChildrenNode;
    Packit 423ecb 
        while (cur != NULL) {
    Packit 423ecb
    Packit 423ecb 
            if ((!strcmp(cur->name, "Project")) && (cur->ns == ns)) {
    Packit 423ecb 
                ret->projectID = xmlGetProp(cur, "ID");
    Packit 423ecb 
                if (ret->projectID == NULL) {
    Packit 423ecb 
                    fprintf(stderr, "Project has no ID\n");
    Packit 423ecb 
                }
    Packit 423ecb 
            }
    Packit 423ecb 
            if ((!strcmp(cur->name, "Application")) && (cur->ns == ns))
    Packit 423ecb 
                ret->application = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
    Packit 423ecb 
            if ((!strcmp(cur->name, "Category")) && (cur->ns == ns))
    Packit 423ecb 
                ret->category = xmlNodeListGetString(doc, cur->xmlChildrenNode, 1);
    Packit 423ecb 
            if ((!strcmp(cur->name, "Contact")) && (cur->ns == ns))
    Packit 423ecb 
                ret->contact = parsePerson(doc, ns, cur);
    Packit 423ecb 
            cur = cur->next;
    Packit 423ecb 
        }
    Packit 423ecb
    Packit 423ecb 
        return(ret);
    Packit 423ecb 
    }
    Once you are used to it, writing this kind of code is quite simple, but
    Packit 423ecb 
    boring. Ultimately, it could be possible to write stubbers taking either C
    Packit 423ecb 
    data structure definitions, a set of XML examples or an XML DTD and produce
    Packit 423ecb 
    the code needed to import and export the content between C data and XML
    Packit 423ecb 
    storage. This is left as an exercise to the reader :-)
    Feel free to use the code for the full C
    Packit 423ecb 
    parsing example as a template, it is also available with Makefile in the
    Packit 423ecb 
    Gnome SVN base under libxml2/example
    Daniel Veillard
    </body></html>

    Powered by Pagure 5.13.3

    SSH Hostkey/Fingerprint | Documentation