SDO XML Data Access Service Functions
Введение
In order to use the XML Data Access Service for Service Data Objects, you will need to understand some of the concepts behind SDO: the data graph, the data object, XPath and property expressions, and so on. If you are not familiar with these ideas, you might want to look first at the section on SDO.
The job of the XML DAS is to move data between the application and an XML data source, which can be either a file or a URL. SDOs are always created and maintained according to a model which defines type names and what property names each type may have. For data which is from XML, this SDO model is built from a schema file written in XML schema language (an xsd file). This schema file is usually passed to the create method when the XMLDAS is initialised. The » SDO 2.0 specification defines the mapping between XML types and SDO types. There are a number of small limitations in the PHP support - not everything which is in the specification can be done - and these limitations are summarised in a later section.
Требования
The SDO XML Data Access Service requires PHP 5.1.0 or higher. It is packaged with the SDO extension and requires SDO to have been installed. See the SDO installation instructions for the details of how to do this.
Установка
The XML Data Access Service is packaged and installed as part of the SDO extension. Please Refer SDO installation instructions.
Примеры
Several of the following examples are based on the letter example described in the SDO documentation. The examples assume the XML Schema for the letter is contained in a file letter.xsd and the letter instance is in the file letter.xml. These two files are reproduced here:
<xsd:schema xmlns:xsd="https://www.w3.org/2001/XMLSchema"
xmlns:letter="https://letterSchema"
targetNamespace="https://letterSchema">
<xsd:element name="letters" type="letter:FormLetter"/>
<xsd:complexType name="FormLetter" mixed="true">
<xsd:sequence>
<xsd:element name="date" minOccurs="0" type="xsd:string"/>
<xsd:element name="firstName" minOccurs="0" type="xsd:string"/>
<xsd:element name="lastName" minOccurs="0" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>
</xsd:schema>
<letter:letters xmlns:letter="https://letterSchema"> <date>March 1, 2005</date> Mutual of Omaha Wild Kingdom, USA Dear <firstName>Casy</firstName> <lastName>Crocodile</lastName> Please buy more shark repellent. Your premium is past due. </letter:letters>
Example#1 Loading, altering, and saving an XML document
The following example shows how an XML document can be loaded from a file, altered, and written back.
<?php
/**
* Load, update, and save an XML document
*/
try {
$xmldas = SDO_DAS_XML::create("letter.xsd");
$document = $xmldas->loadFile("letter.xml");
$root_data_object = $document->getRootDataObject();
$root_data_object->date = "September 03, 2004";
$root_data_object->firstName = "Anantoju";
$root_data_object->lastName = "Madhu";
$xmldas->saveFile($document, "letter-out.xml");
echo "New file has been written:\n";
print file_get_contents("letter-out.xml");
} catch (SDO_Exception $e) {
print($e->getMessage());
}
?>
An instance of the XML DAS is first obtained from the SDO_DAS_XML::create() method, which is a static method of the SDO_DAS_XML class. The location of the xsd is passed as a parameter. Once we have an instance of the XML DAS initialised with a given schema, we can use it to load the instance document using the loadFile() method. There is also a loadString() method if you want to load an XML instance document from a string. If the instance document loads successfully, you will be returned an object of type SDO_DAS_XML_Document, on which you can call the getRootDataObject() method to get the SDO data object which is the root of the SDO data graph. You can then use SDO operations to change the graph. In this example we alter the date, firstName, and lastName properties. Then we use the saveFile() method to write the changed document back to the file system. The saveFile method has an optional extra integer argument which if specified will cause the XML DAS to format the XML, using the integer as the amount to indent by at each change in level on the document.
This will write the following to letter-out.xml.
<?xml version="1.0" encoding="UTF-8"?> <FormLetter xmlns="https://letterSchema" xsi:type="FormLetter" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"> <date>September 03, 2004</date> Mutual of Omaha Wild Kingdom, USA Dear <firstName>Anantoju</firstName> <lastName>Madhu</lastName> Please buy more shark repellent. Your premium is past due. </FormLetter>
Example#2 Creating a new XML document
The previous example loaded the document from a file. This example shows how to create an SDO data graph in memory. In this example it is then saved to an XML string. Furthermore, because the letter contains both structured and unstructured content, it uses the Sequence API as well assignments to properties to construct the data graph.
<?php
/**
* Create an XML document from scratch
*/
try {
$xmldas = SDO_DAS_XML::create("letter.xsd");
try {
$doc = $xmldas->createDocument();
$rdo = $doc->getRootDataObject();
$seq = $rdo->getSequence();
$seq->insert("April 09, 2005", NULL, 'date');
$seq->insert("Acme Inc. ", NULL, NULL);
$seq->insert("United Kingdom. ");
$seq->insert("Dear", NULL, NULL);
$seq->insert("Tarun", NULL, "firstName");
$seq->insert("Nayaraaa", NULL, "lastName");
$rdo->lastName = "Nayar";
$seq->insert("Please note that your order number ");
$seq->insert(12345);
$seq->insert(" has been dispatched today. Thanks for your business with us.");
print($xmldas->saveString($doc));
} catch (SDO_Exception $e) {
print($e);
}
} catch (SDO_Exception $e) {
print("Problem creating an XML document: " . $e->getMessage());
}
?>
The createDocument() method on the XML DAS returns a document object with a single root data object corresponding to an empty document element. The element name of the document element is known from the schema file. If there is any ambiguity about what the document element is, as there can be when more than one schema has been loaded into the same XML DAS, the element name and the namespace URI can be passed to the createDocument() method.
This will emit the following output (line breaks have been inserted for readability):
<?xml version="1.0" encoding="UTF-8"?> <FormLetter xmlns="https://letterSchema" xsi:type="FormLetter" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"> <date>April 09, 2005</date> Acme Inc. United Kingdom. Dear <firstName>Tarun</firstName> <lastName>Nayar</lastName> Please note that your order number 12345 has been dispatched today. Thanks for your business with us. </FormLetter>
Example#3 Setting XML document properties
This third example shows you how to set the XML version and encoding on the document object. These will be used when the XML is written out. If no XML declaration is wanted at all (perhaps you want to generate the XML as a string to embed in something) then you can use the setXMLDeclaration() method to suppress it.
<?php
/**
* Illustrate the calls that control the XML declaration
*/
$xmldas = SDO_DAS_XML::create("letter.xsd");
$document = $xmldas->loadFile("letter.xml");
$document->setXMLVersion("1.1");
$document->setEncoding("ISO-8859-1");
print($xmldas->saveString($document));
?>
The XML version and encoding are set in the XML declaration at the top of the XML document.
<?xml version="1.1" encoding="ISO-8859-1"?> .../...
Example#4 Using an open type
This fourth example illustrates the use of an SDO open type and the use of the createDataObject() method. For this example we use the following two schema:
<schema
xmlns="https://www.w3.org/2001/XMLSchema">
<element name="jungle">
<complexType>
<sequence>
<any minOccurs="0" maxOccurs="unbounded"/>
</sequence>
<