XML Parser for Java. This chapter contains these topics.
Partial validation validates all or part of the input XML document according to the DTD or XML Schema, if one is. XML File in Another XML File. CATALOGS allow you to use local version of this DTD during processing. Each XML developer can have own.
XML Parser for Java Overview. Oracle provides XML parsers for Java, C, C++, and PL/SQL. This chapter discusses the parser for Java only. Each of these parsers is a standalone XML component that parses an XML document (and possibly also a standalone document type definition (DTD) or XML Schema) so that they can be processed by your application. In this chapter, the application examples presented are written in Java. The process of checking the syntax of XML documents against a DTD or XML Schema is called validation.
Without it there is no way for the parser to know what to validate against. Including the reference is the XML standard way of specifying an external DTD. Otherwise you need to embed the DTD in your XML Document. The DOM or SAX parser interface parses the XML document. The parsed XML is then transferred to the application for further processing.
We present a query language for XML. XML Tutorial The Document Type Definition – aka DTD Author.
Using the XSLT Processor, you can transform XML documents from XML to XML, XML to HTML, or to virtually any other text- based format. These are sent together with the parsed XML to the XSLT Processor where the selected stylesheet is applied and the transformed (new) XML document is then output. Figure 3- 1 shows a simplified view of the XML Parser for Java. An XML processor does its work on behalf of another module, your application. This parsing process is illustrated in Figure 3- 2.
Namespaces are a mechanism to resolve or avoid name collisions between element types (tags) or attributes in XML documents. Such tags are qualified by uniform resource identifiers (URIs), such as. EMP xmlns: oracle=.
Walkthrough: Word 2007 XML Format. Word 2003 embeds all custom XML data directly into the WordprocessingML that describes the document. If you add a custom XML data from another file. Guide to the W3C XML Specification ('XMLspec') DTD, Version 2.1. The DTD file is available at http:// This markup will allow them to reflect the differences directly in the XML form.
This enables an application to more easily identify elements and attributes it is designed to process. Otherwise, you need to use the set. Base. URL(url) functions to set the base URL to resolve the relative address of the DTD if the input is coming from Input.
Stream. The solution is to set. Base. URL() on DOMParser() to give the parser the URL hint information to be able to derive the rest when it goes to get the DTD.
Parsed data is made up of characters, some of which form character data, and some of which form markup. XML provides a mechanism to impose constraints on the storage layout and logical structure. Table 3- 1 XML Parser for Java Validation Modes Name of Mode. Mode Value in Java. Non- Validating Mode. NONVALIDATINGThe parser verifies that the XML is well- formed and parses the data into a tree of objects that can be manipulated by the DOM API.
If one is not present, the mode is set to Non- Validating Mode. With this mode, the schema validator locates and builds schemas and validates the whole or a part of the instance document based on the schema.
Location and no. Namespace. Schema. Location attributes. See code example. XSDSample. java in directory /xdk/demo/java/schema. It does not raise an error if it cannot find the definition. This is shown in the sample XSDLax. If neither is available, it is set to NONVALIDATING mode value, which is the default.
See code example XSDSet. Schema. java. By using the set. XMLSchema() method, the validation mode is automatically set to SCHEMA. You can also change the validation mode to SCHEMA. It contains the sections. Enabling DTD Caching.
DTD caching is optional and is not enabled automatically. After you set the DTD using this function, XMLParser will cache this DTD for further parsing. Here is an example.
Test using Input. Source. parser = new DOMParser().
Error. Stream(System. Warnings(true). File. Reader r = new File.
Reader(args. Use this technique to read a DTD out of your product's JAR file. So setting the DTD in the document does not help validate the DOM tree that is constructed.
The only way to validate an XML file is to parse the XML document using the DOM parser or the SAX parser. Here is some sample code to do this.
DOMParser domparser = new DOMParser(). Validation. Mode(DTD. When you run in non- validation mode only well- formedness counts. However < test> < /Test> signals an error even in non- validation mode. The only way to get a DTD object is to parse the DTD file or the XML file using the DOM parser, and then use the get. Doc. Type() method. It creates an XMLNode object with the type set to DOCUMENT.
The Class. Cast. Exception is raised because append. Child expects a DTD object (based on the type). It provides classes and methods for an application to navigate and process the tree.
For example, for the immediately preceding XML document, the DOM creates an in- memory tree structure as shown in. Figure 3- 3. Your Java application deals with these events through customized event handlers. Events include the start and end of elements and characters. Therefore, in general, SAX is useful for applications that do not need to manipulate the XML tree, such as search operations, among others.
The preceding XML document becomes a series of linear events as shown in Figure 3- 3. SAX does not support it. DOM consumes more memory. Make sure to select the COUNT(*) of an indexed column (the more selective the index the better). This way the optimizer can satisfy the count query with a few inputs and outputs of the index blocks instead of a full- table scan. Multiple handler registrations per SAX parsing: oracle. V2. XMLMulti. Handler.
The compression is based on tokenizing the XML tags. The assumption is that any XML document has a repeated number of tags and so tokenizing these tags gives a considerable amount of compression.
Therefore the compression achieved depends on the type of input document; the larger the tags and the lesser the text content, then the better the compression. The compressed stream contains all the . The compressed stream can also be generated from the SAX events.
Using the compression feature, an in- memory DOM tree or the SAX events generated from an XML document are compressed to generate a binary compressed output. The compressed stream generated from DOM and SAX are compatible, that is, the compressed stream generated from SAX can be used to generate the DOM tree and vice versa. When a large XML document is parsed and a DOM tree is created in memory corresponding to it, it may be difficult to satisfy memory requirements and this can affect performance. The XML document is compressed into a byte stream and stored in an in- memory DOM tree. This can be expanded at a later time into a DOM tree without performing validation on the XML data stored in the compressed stream.
This serialized stream regenerates the DOM tree when read back. SAX events generated by the SAX parser are handled by the SAX compression utility, which handles the SAX events to generate a compressed binary stream. When the binary stream is read back, the SAX events are generated.
Decompression reduces performance. If you are transferring files between client and server, then HTTP compression can be easier.
The following are the sample Java files in its subdirectories (common, comp, dom, jaxp, sax, xslt). Table 3- 2 XML Parser for Java Sample Programs Sample Program. XSLSample. A sample application using XSL APIs. DOMSample. A sample application using DOM APIs. DOMNamespace. A sample application using Namespace extensions to DOM APIs. DOM2. Namespace. A sample application using DOM Level 2.
APIs. DOMRange. Sample. A sample application using DOM Range APIs. Event. Sample. A sample application using DOM Event APIs.
Node. Iterator. Sample. A sample application using DOM Iterator APIs. Tree. Walker. Sample. A sample application using DOM Tree. Walker APIs. SAXSample. A sample application using SAX APIs.
SAXNamespace. A sample application using Namespace extensions to SAX APIs. SAX2. Namespace. A sample application using SAX 2. A sample application using XMLToken interface APIs. DOMCompression. A sample application to compress a DOM tree. DOMDe. Compression. A sample to read back a DOM from a compressed stream.
SAXCompression. A sample application to compress the SAX output from a SAX Parser. SAXDe. Compression.
A sample application to regenerate the SAX events from the compressed stream. JAXPExamples. Samples using the JAXP 1.
API. The Tokenizer application implements XMLToken interface, which you must register using the set. Token. Handler() method. A request for the XML tokens is registered using the set.
Token() method. During tokenizing, the parser does not validate the document and does not include or read internal or external utilities. The Content Handler is inside the Java file ora. Content. Handler. In this case, a DTD is not required. Some of the methods to use with this object are.
Validate. Mode()set. Preserve. White. Space()set.
Doctype()set. Base. URL()show. Warnings()The results of DOMParser() are passed to XMLParser. XML input. The XML input can be a file, a string buffer, or URL. The methods to apply to this object are. Validate. Mode()set. Preserve. White. Space()set.
Doc. Type()set. Base. URL()show. Warnings()The results of DOMParser() are passed to XMLParser. DTD() method along with the DTD input. The example uses. Error. Stream(System.
Validation. Mode(DTD. The following example illustrates how to use the DOMNamespace class.
XML Parser for Java Example 2: Parsing a URL — DOMNamespace. See the comments in this source code for a guide to the use of methods. The program begins with these comments. This file demonstates a simple use of the parser and Namespace.
DOM APIs. Here is another excerpt from later in this program. Attributes(). if (nnm != null). XMLReader is the interface that an XML parser's SAX2 driver must implement. This interface enables an application to set and query features and properties in the parser, to register event handlers for document processing, and to initiate a document parse. The XMLReader interface contains two important enhancements over the old parser interface. It adds a standard way to query and set features and properties.
Table 3- 3 lists all the available methods. Meanwhile the process waits for an event- handler callback to return before reporting the next event. Interfaces used are. Document. Handler. Entity. Resolver. DTDHandler. Error.
Guide to the W3. C XML Specification (XMLspec) DTD, Version. Following is information on the sources of analysis input, the. DTD form, and outstanding. The following information gives background on implementation. This DTD was previously given a formal public identifier in the. W3. C//DTD XML Specification: :yyyymmdd//EN. For easier identification, the DTD now uses a formal public.
W3. C//DTD XML Specification Version n. EN. The current version is identified as. W3. C//DTD Specification Version 2. EN. The policy, beginning with Version 2. Minor revisions (revising. V2. 0. to V2. 1 or from V2. V2. 2) can add to the markup model, but.
For example, a. new kind of list element could be added, but it would not be. Thus, any document. Major revisions (revising. V2. 1 to V3. 0) can both add to the markup model and make. Ideally these will be accompanied. XSLT transformation specifications that help legacy documents to.
Always review the change history in any new version of the DTD. Currently, DTD changes are at the discretion of the maintainer. DTD within the W3. C. A more formal. This DTD does not yet have an official schema. If you want to. refer to the XMLspec vocabulary for namespace management purposes.
URI to identify it. XML/1. 99. 8/0. 6/xmlspec- v.
Note that this identifying URI may change in the future. The element names from the original DTD on which XMLspec was. Hyphens are typically avoided, except in the . To indicate their different roles, unique suffixes are.
The name, declared value, and default value specifications for a. Some descriptions may have a sub- suffix, such as - req, which means that the.
A set of related elements that are typically available as. These entities are referenced from within descrip. If you add a new standalone or phrase- level element, make sure. If you create a new class, incorporate references to. A set of elements that are available to writers in certain. These entities. are referenced from within content models. A set of #PCDATA and elements that are.
These entities are referenced from within. The presence of #PCDATA. The keyword indicating the entity type. DTD is read. Because DTDs and namespaces don't mix well, the xlink namespace prefix has been hardwired. As support for the XPointer construct.
When the XLink. specification reaches Recommendation status and if such. DTD will be published that will require changes to.
The DTD is beginning to be used more widely by W3. C contributors. (as well as by authors of non- W3. C specifications). While this DTD. was designed with the needs of XML technical reports firmly in.
W3. C. Therefore, the DTD. Modification of certain content models that are likely to be. Working Group preference.
Addition of new elements at the . You may want to indicate the derivation. ID//DTD XML Specification Version n.
Based your- descrip- and- version//lang. Following is the change history for the DTD.
Note that you can.