什么是xml processing instruction(PI)？

from:

http://zhidao.baidu.com/question/67891842.html?si=1

 

下面的一行就是在第二本书的定义之前的：

<?page render multiple authors ?>

虽然它看上去很像XML序言，但实际上是一种称为处理指令（processing instruction）的不同类型的语法。处理指令（以下简称PI）的目的是为了给处理页面的程序（例如XML解析器）提供额外的信息。PI通常情况下是没有固定格式的，唯一的要求是紧随第一个问号必须至少有一个字母。在此之后，PI可以包含除了小于号和大于号之外的任何字符串序列。

最常见的PI是用来指定XML文件的样式表：

这个PI一般会直接放在XML序言之后，通常由Web浏览器使用，来将XML数据以特殊的样式显示出来。

 

 

 

 

from:

http://e-learning.zjgsu.edu.cn/jdk5doc_zh_CN/org/w3c/dom/ProcessingInstruction.html

org.w3c.dom
接口 ProcessingInstruction

public interface ProcessingInstruction
extends Node

ProcessingInstruction 接口表示“处理指令”，该指令作为一种在文档的文本中保持特定于处理器的信息的方法在 XML 中使用。

不对处理指令的内容进行任何词汇检查，因此在该内容中可能有字符序列 "?>"，按照 [XML 1.0] 的 2.6 节，该序列是非法的。出现此字符序列一定会在序列化期间生成严重错误。

 

 

 

 

 

from:

http://www.javacommerce.com/displaypage.jsp?name=pi.sql&id=18238

 

Processing Instructions

Processing Instructions are information for the application. PI's allow documents to contain instructions for applications. They are not really of interest to the XML parser. Instead, the instructions are passed to the application using the parser, because the purpose of processing instructions is to represent special instructions for the application.

Like comments, they are not textually part of the XML document.

All processing instructions, including the XML declaration, begin with <? and end with ?>. Following the initial <?, you will find the name of the processing instruction. The PI begins with the PITarget  used to identify the application to which the instruction is directed.

<?name pidata?>

<?xml version="1.0"? encoding="UTF-8" standalone="yes"?>

Version Declaration is a form of PI.

 

A particular document may have processing instructions for several different applications, so the processing instruction target (PITarget), right after the opening <?, identifies the target application for this processing instruction.

 

 

from:

http://xmlshippingtest.dhl-usa.com/toolkit/FAQ.htm

 

What is XML-PI?. 1

What is it?. 1

What is it for?. 1

What services are offered?. 1

How does this process work?. 2

Who can use it?. 2

Can I ship Internationally as well as Domestically?. 3

Is the interface Universal?. 3

How do I get started?. 3

What do I need to have or know to incorporate XML-PI into my own application?. 4

How long does the process take?. 4

 

What is XML-PI?

XML-PI stands for ‘XML Public Interface’.

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What is it?

XML-PI is a publicly available interface that uses a Java platform and XML messaging to provide access to DHL services.

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What is it for?

Customers of DHL have expressed an interest in having the ability to incorporate a link to DHL into their own client-side applications so that they can prepare and request shipping and other services offered by DHL for themselves and their customers.  They can do this from within their own applications whether they are shipping, tracking or procuring applications.

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What services are offered?

XML-PI provides access to the following shipping services:

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Shipment Processing

Allows customers to create a DHL compliant waybill from their own user interface for the following shipment types:

o       Domestic Express

o       Domestic Express Letter

o       USA 2ND Day

o       USA 2ND Day Letter

o       DHL Ground

o       International Document

o       International Express Document

o       Worldwide Priority Express

o       European community Express

o       Start Day Express

o       Mid day Express

                       

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Waybill Tracking

Allows the customer to track any valid DHL waybill number from their internal application without having to contact DHL.

 

Package Rating

Allows the customer to query DHL for the cost of a prospective shipment as well as providing cost information of actual packages shipped.

 

Pickup Scheduling

Allows the customer to request a DHL courier to visit the shipper’s location and pickup up packages that are required to be shipped.

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How does this process work?

DHL has defined four request message types (one for each service – shipping, tracking, rating and pickup).  The client application will populate an XML message of the appropriate type for the service required.  The application will then place an https call to the appropriate DHL URL, submitting the XML Request message to DHL.

 

The XML-PI application will invoke the appropriate back-end services and formulate a response message with the results of the request.  This message will be returned asynchronously to the requesting application.

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Who can use it?

Any DHL customer who has a systematic requirement for shipping services and who would benefit from this particular approach.  This would encompass users who typically do 20-200 shipments per day.

While other approaches are available for shipping with DHL, this approach enables a customer’s own application to interface directly with DHL with a minimum amount of development effort on the customer’s part.

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Can I ship Internationally as well as Domestically?

Yes.  XML-PI allows shipments to be made FROM anywhere in the world TO anywhere in the world.  (This is of course limited to those countries accessed by DHL, and those countries allowed by Federal Regulations).

DHL supports three specific regional processing centers:
- United States
- Europe/Middle East/Africa,
- Asia/Pacific. 

Each of these three regions has its own back-end service applications (due to the differing regional requirements of international processing).  The same URL is used to access the generic service (which is located in the USA), and XML-PI will determine from the consignee (shipper’s) country which back-end service is required, and will invoke it accordingly.

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Is the interface Universal?

For each of the services to be requested, there is an interface for each region.  This arises from the differing processing needs of each country (language, currency, local regulations etc).  Within XML-PI interfaces the differences are minor.  However, a client who wishes to deploy the same application world-wide would need to recognize those differences in each regional deployment.

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How do I get started?

Contact a DHL Customer Service Representative and they will be able to walk you through the process.  In summary the steps are these:

Send an email request to the request message email address:
In the USA this is [e-mail]).
Complete the resulting forms that ask about the nature of your business, the volume of expected shipping, and such things as the level of experience you have with B2B systems.  This is in order to determine if this solution is the right one for you.  If so, you will:

Receive from DHL a test-level site id and password, a URL for the Customer Toolkit, and the URL for the DHL test site that you will use in testing your application.

Submit to DHL some sample test results that demonstrate that you are able to create shipping materials (Airwaybills) from the system that will be successfully read and processed by DHL systems

Receive from DHL a production-level site id and password, and the URL for the DHL production site that you will use in the future.

Start shipping!

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What do I need to have or know to incorporate XML-PI into my own application?

DHL will provide you the URL to a download-able suite of technical documents called the “Customer Toolkit” that provides the means by which you can develop and test your application in conjunction with XML-PI.  Owing to differences of regional shipping requirements there is a separate toolkit defined for each region.

The toolkit contains definitions of all the services offered, the request message formats and validation criteria, the response message formats and data values, and templates that you will need to download to your system in order to generate the airwaybill which will be affixed to your shipment.

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How long does the process take?

XML-PI is a readily available service.  Since the bulk of the development effort resides with the customer who is building or modifying the client application, the duration of the process will depend upon the needs of the client.

Experience has shown that with a nimble client that can be as little as two weeks.  With new application development, a typical development cycle may be two months.