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OK why should I use XML

 
tumbleweed
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Look I'm an old IBM mainframe programmer and I just cant understand this fuzz about XML.
Heck if you want someone to read your data you give him your record layout. If someone wants to read your XML you still have to pass him your DTD. Or am I wrong.
Convince me guys why should I take the time to learn XML ??
 
Sheriff
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Why should you program in Java?? You can as well give your VisualBasic( or a VC++ ) runtime files along with your .exe
Well... there lies your answer. If you haven't heard this famous quote already - XML is to data what Java is to code. ie., XML is portable data and Java is portable code.
If each vendor has its own proprietary data format, as you said it has to exchange the format along with the data with its clients. Not just that, it also has to make sure to send the "updated" format everytime the data format is changed. This may not seem like a big problem, but think about twenty vendors exchanging data with each other. Each sender is also a recipient and hence should be able to understand and maintain 19 different data formats. Then there is this issue of compatibility. Newer vendor applications should be able to support both old and new formats for backward compatibility and/or vendors should publish compatibility matrix and give their clients tools that convert the data from the old format to the new one. Naturally this is a lot of work, a lot of expensive work to be precise. Since there are so many dominant variables in the equation, there will be as many points of failure in the entire system. Here we are not talking about only your application(s), but how well each vendor application can collaborate with other application(s) to facilitate complete data exchanges - aka typical B2B scenario.
Use of XML alleviates this problem by not only providing a highly portable data format, but also a set of tools( parsers, XSLT engines etc ) that can be used to construe and manipulate the data. Remember, it is all about data and standardizing a format for universal data representation. Why do you think HTML is so popular and ubiquitous even today? Not because of its capabilities, but because of standardization. If you write a standard HTML code, you can be assured any standard browser will be able to open it.
Just like a merchant who accepts VISA and MASTERCARDs as valid forms of payment, if your application supports XML format for standard data exchange, you will immediately open up your system to a huge number of potential clients. You can still keep all your system implementation in whatever language they are written in, and just provide "adapters" which can take the incoming XML document and convert it to any "legacy" format your application supports, and vice-versa.
I think I have campaigned enough about XML. Checkout the dozens of free web resources which are out there. I feel the XML hype is less of an hype ( when compared to Java hype ) and shouldn't just be disposed off as yet another noise.
Good luck,
------------------
Ajith Kallambella M.
Sun Certified Programmer for the Java�2 Platform.
IBM Certified Developer - XML and Related Technologies, V1.
 
Greenhorn
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Even IBM is on-board...they have a new set of classes for IMS 7.0 called IMS Java for accessing IMS via DLI or Applications....these packages include a some trace classes which generate XML in their output. It is my understanding that IBM Websphere and possibly the HTTP server are also configured using XML. No more Babel of proprietary scripting and binary languages for configuring various similar products such as web servers, application servers, etc. With a single set of agreed upon tags...the world becomes much easier even on the Big Iron...
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Ranch Hand
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Hi Johannes,
I started playing with XML when I became involved in a project here on the Ranch and I have to say, the more I look into XML and XSLT the more excited I get! The possibilities are amazing!
For example, in my environment at work we generate numerous reports from various sources (DB2, Notes, server logs, telephony systems, etc, etc). There's always duplication and what's worse, managers want what is basically the same information in different forms .. some want text, others want graphics, some info is stored on one site, some on another. What if we could feed all that source into one spot, using one format and provide a single web-based front-end? What if generating a new report layout or delivery system was just a matter of manipulating one file? With XML and XSLT that looks possible!
Yes, I know it can be done in other ways but having to interface with a number of legacy systems can be a headache; sources have different versions of DB2 installed and we run into binding problems; some tools are written in C and are OS/2 based and can't be used on NT, tons of REXX files have been created over the years; users have various Operating Systems at different revision levels.
XML and Java provide an opportunity to gradually bring everything together in a format that will run everywhere, for everyone with the flexibility to meet new management requirements as they occur.
OK, it may not be the next best thing to sliced bread .. but hey ... it's well worth looking into
Just my 2-cents ...
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Jane Griscti
Sun Certified Programmer for the Java� 2 Platform
 
Ranch Hand
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chk out the bunch of articles on java world
regds.
- satya
 
Ranch Hand
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XML has following advantages :
1. XML can allow two different systems with different data format to talk to each other.
2. The data access is faster. You don't have to pick up your data from database all the time. You can maintain a data island.
3. XML allows presentation to be seperated from data elements. Thus depending on the user various customised presentaions can be provided for the same web page.
 
Greenhorn
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I am not sure whether this is one of the goals of XML; I doubt it is. However, XML turns out to be extremely useful for data that are hierarchical in nature. The data do not have to be trees, as long as they are hierarchical. These data are not as easy to store as tables. And when they are stored as tables in a relational database, the access and manipulation of them are not as easy as it takes a bit of time to reconstrct the hierarchical nature of the data from the tables.
Secondly, XML documents are easy to extend. When you design a relational database, it is not easy to migrate to a different data schema. So, you tend to think much more about the data before you commit the design. In XML, if the data is hierarchical, adding a new element somewhere is not a big problem.
Remember, the fact that the data you see is in XML does not mean that it cannot be processed and stored in a different paradigm entirely. For instance, the last time I looked at eXchelon XML database, they used an OODBMS as the actual database but with XML and XSLT as the front end.
Of course, there are aspects of XML that have been totally overblown. For instance, many people say XML is good because the element names are in English. That is of course assuming that yu can read English. And when somebody from Japan is designing a DTD, he/she can easily assign the element names in Japanese, as XML names can be in Unicode. So, the fact that an XML can be readable to somebody does not mean that it will be readable to you, unless you happen to know the language used in the document. Also, sloppy designers can always chose completely inappropriate names as well.
But there is really no alternative if you want a (almost) univerally acceptable data format that is powerful enough to handle almost all structured data.

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Khun Yee Fung
Author of XSLT: Working with XML and HTML
 
Johannes de Jong
tumbleweed
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If I understand correctly XML changes nothing about the way the data in represented internally. XML is only a way external systems can "communicate" with the owner of the data. As such XML one can see XML as a sort of Esperanto for computer systems. I know this is a very simplified view, but heck I'm a very simple soul
Once I know Java well enough I'll tackle XML in a Java-XML project and then hopefully "really" understand the benefits.
Till then thank you all for the replies, especially the author and Jane
[This message has been edited by Johannes de Jong (edited March 14, 2001).]
 
Ranch Hand
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I am just starting to learn XML and already see many advantages. Thank you for this discussion. Many good points were made that helped me understand XML better. I am involved in a project to integrate a legacy system with ours where the legacy system is sending data in flat files (they won't use XML), but we are mapping the data to XML so our web based app can use it. We hope the XML will be a standard for future legacy integrations.
 
Jane Griscti
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Hi Tony,
I think XML may become the standard; I know SIEBEL will produce XML files as output for data exchange and it has become a very popular system ..
Jane
 
Greenhorn
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And what about the security?
Is XML data is secure as other database like oracle, mySQL?
 
Sheriff
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I think you may be missing the point with that last question. XML is not a database. It's not any sort of executable software, it's just a specification of a "grammar" for a set of data formats.
Security is up to the applications which use it. Data represented in XML can be encrypted for transmission or storage; it can be password-protected or locked in a safe or whatever, just like any other data.
 
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