So I'm starting to learn XML. It seems like a simple flat file data system of which you can view output by using a server side language of your choice and some parsing. I don't really see the benefit to using XML over storing values in a database and doing the same kind of parsing. I mean it would seem that databases would be faster.
So what can you really do with XML that you can't/shouldn't do with a database? Is XML really that useful?
So what can you really do with XML that you can't/shouldn't do with a database? Is XML really that useful?
XML is an interchange format first and foremost. It allows you to transport structured data between programs, servers, or people, and retain a common parser and schema system.
XML of course can be horribly misused or overused.
This question is to broad (i.e. there are too many aspects in which they differ), yet main reason for XML is not even about data storage. It was designed as ultimate common platform for data exchange with defined rules how data is organised. Thus you can read/write valid XML on almost every platfrom and language.
XML is designed to be more human readable. XML can be opened easily in a text editor and read. Some XML readers can support folding, which also helps with getting a hierarchical organization to your data.
If you're processing files that's a different story. I think databases often have the option of exporting to XML.
You can carry your datas from one type database to another (example from MS-SQL to MySQL) by using XML.
Or sending datas from an application to another, which is used on many web applications.
I think it can be very useful for this.
I think it is comparison of apples to oranges...
There are a lot of usages of XML but it is not primarily used for storing data. It is very loosely coupled data structure when compared to databases.
One of the many usages of XML, which I encounter with very frequently is exchanging data from one program to another. Because it is very simple format one can create an XML file in Java program and other can parse(read) the xml file in VB/C#/Python/Cocoa or any other language.
One such use of XML is Webservices where client programs can call(Execute) code residing on servers, where requests and response both are in XML.
So one can say that strong feature of XML is interoperability.
On the other had databases are mainly used for storing and retrieving data, databases are extremely powerful to do fast retrieval/insertion of values in tables where XML will immensely fail because most of the time XMLs have to be read serially as oppose to tables residing in databases.
XML can contain highly complex tree data structures that cannot be easily represented in relational databases.
XML is also useful for representing documents (Word docs for example or HTML).
The thing that's so appealing about XML is that it is quite simple to create.
Python is a great language for converting text files into XML for example.
XML vs databases is a false dichotomy, because you can store XML in databases. Though it's true that a simple XML document can sometimes be used for an application that would otherwise have needed a database.
If you're dealing with documents (like articles in technical journals) then your only real choice is between XML and some proprietary equivalent. This of course is the problem that XML was originally invented to solve.
XML is also used extensively for data messaging. It supplanted EDI and ASN.1 in this role because it can handle all the complex data that EDI and ASN.1 can handle, but is itself much simpler. More recently we've seen JSON taking over some of this role, especially for "private" (as distinct from standardised) protocols, because JSON is simpler still, and works better with general-purpose programming languages.
XML, like any successful technology, has also been used extensively for problems where it isn't really needed. That's not a misuse, any more than it is a misuse of this forum to send a plain text message in a field that is capable of holding richly formatted text, or to ride my bicycle on a road that's engineered to take 40ton lorries: once the technology is in place, you might as well use it.
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I have an XML file, with a schema defined in it.
The scheme has several nested elements (e.g., Family (root) -> Family Members (list of sub-nodes) ).
What would be the easiest way to break this down to a mysql database with multiple tables? Preferably an automated tool/GUI to handle this process. I am trying to avoid writing dedicated code to parse the file and extract the data, an approach that was common in other related questions.
I am using a mac, so windows tools are not relevant.
mysql has load xml as a command which is quite nice if your data can be formatted to match this specification. It's hard to tell if that would work for your dataset without seeing more.
The first thing you would have to do is create a mysql schema based on the XML schema. There are some projects to do this, but it's worth noting that not everything that can be described in XSD can be implemented in SQL.
You could use XSLT or regexp or an editor to get what you want, then do an import. If you have to use a DOM parser to convert your XML to CSVs to load to mysql, it's not too tough at all.
You're essentially asking how to automate the process of (relational) normalization, and that's very difficult if you're only starting from an instance. For example, if your instance has
<book>
<author>Kay</author>
</book>
there's no way of knowing whether a book can have multiple authors, which would affect the SQL table structure.
If you've got a schema then you can do better, but it's still not ideal because inferring the non-hierarchic relationships from an XSD is going to be pretty difficult. Apart from anything else, there are usually cross-document relationships which XSD can't describe - it's unusual to put all your data in one giant XML document.
To do this job properly, you really need to reverse-engineer the object model, and that requires a semantic understanding of the data, not just syntactic manipulation.
I have implemented RDFa on a shopping website.
Now, how to create triple store using those structured data?
There are thousands of products in the website. So, manually visiting each and every page and extracting RDF is not a good solution. Is there any automatic tools for this?
The answer depends on how you "implemented RDFa". It is unlikely that the majority of your content is expressed as static information, so it is also unlikely that the majority of your content requires scraping.
There are tools, such as D2R Server, that give you facilities for exposing your underlying datastore as a read-only SPARQL endpoint. The only trick will be if you do have static content and wish to expose that as automatically generated RDF as well. That would require some finessing.
The data which is in RDFa format on your website probably comes from a database, where it is in relational form, since you probably didn't add the RDF triples to the HTML manually. So the easiest way to get the data into the triple store would not be from the HTML, but by some kind of transformation of the original data in the database. In the end, RDF triples can be seen as a ternary relation that can well be stored in any relational database.
GRDDL (Gleaning Resource Descriptions from Dialects of Languages) is a way of using XSLT to extract the RDF triples from the HTML, in case you do not have access to a relational database that stores the data. Hope this helps.
I need help from you experts about practices regarding database development. I have a few questions regarding MySQL databases:
Is there a way for MySQL that a database and its structure is developed in an XML language and then converted to a fully functional MySQL database?
Is it possible to generate the XML source file from question 1 (see above) based on an existing database in MySQL ?
As far as I know, XML is not suitable for developing database structures. However can we say that XML is a language to demonstrate hierarchical structures and a MySQL database also shows a hierarchical structure, so in fact it is suitable for database development?
Thank you very much!
You can certainly store XML data in MySQL. You can also use any number of approaches to converted hierachical XML data into individual relational database field representations.
I would however say that if you just want to work with intact XML documents, you might look to go the NoSQL route, which is really better suited for this type of data storage. You also might consider JSON as the format for storage as it is more concise (saves space and transmissions badnwidth) and is more aligned with the popular NoSQL data stores out there.
1) yeah there is a way, but you should check out mongodb if you want a dynamic database structure, it was developed with that in mind. also, unless you need the rss features of xml or something similar, you might want to consider using json as a format for you documents.
2) json and mongodb work very well together to quickly and easily get documents in and out of the db. you can technically do it in mysql as well, but you might spend more time scripting in php or ruby to get the desired format you want.
3) you could use xml to demonstrate your db structure because of it's loose structure, but i'm not sure it would be intuitively clear to others. hard to say, really depends on how you implement it and how complicated your db structure is going to be.
I am developing a web application right now, where the user interacts with desktop software that exports files as XML.
I was curious if there was a way to take the data from the XML file and insert that data into a mySQL database using ColdFusion?
Of course you can, ColdFusion provides powerful tools for handling XML.
Typically you'll need to parse XML file into the XML document object with XmlParse and search through it using XPath language with XmlSearch. Fetched data you can easily use for inserting into the database or any other manipulations.
Please note that there are more useful XML functions present, for example you may be interested in validation XML before parsing it.
If you'll need help for specific situations -- please extend your question or ask another one.
If you are working with XML documents that fit into memory when parsed, #Sergii's answer is the right way to go. On the other hand, XML being verbose as it is, and ColdFusion's using a DOM XML parser, can easily lead to Out of Memory errors.
In that situation, given MySQL and ColdFusion, I see two alternative paths. One is exporting the data from the desktop application as CSV, if possible. Then use MySQL's LOAD DATA INFILE, which you can call from ColdFusion to import the data. This is probably the fastest performance.
If you cannot change the desktop application's export format, consider using a Java StAX parser instead. See my answer from another question for an example of how to do this with ColdFusion. This has the advantage of only pulling in part of the XML document into memory at any given time, but is somewhat more difficult to work with than a DOM parser. As such you will not get OOM errors.
Note, there is a third type of parser available as well from Java - SAX - that has the same quality as a StAX parser of not loading the whole document into memory. However, it's a more difficult approach IMO to work with, thus the StAX recommendation.
I am interested in XML. I know it from Google's CSE.
It is often a pain for me to manipulate 3000-rows XML files.
This raises a question.
Why does Google use XML, not MySQL, such that I need to manipulate large XML -files?
XML has at least these advantages over SQL for data interchange purposes:
It's self-describing, you don't need to have any additional information to parse it.
It's a true standard, universally interoperable.
You aren't limited to tabular-oriented data: you can also use it to model hierarchies, for instance.
Probably the best you can do with SQL is ship tables in source code form, ie, as CREATE TABLE statements followed by a lot of INSERT statements. This is fine if you have a compatible database, but since SQL never really crystallized as a standard, interoperability at this level is very poor, and Google would have to offer multiple dialects (perhaps even for incompatible versions of the same DBMS).
XML is mostly human readable and cross platform. How would google send you data from just MYSql? Would you expect them to send you a binary blob that assumes you have the proper database to insert it into? How would you use that blob if MYSql wasn't installed, or a different version of MYSql was installed on your machine than on google?
XML is often uses as a transport format between systems. In CSE I would guess that google is transferring a lot of data from them to you in a format that many systems can use. If they used MySQL it would be no use to me as I don't know anything about it. However, pretty much most modern software frameworks can work with XML.
ADDITIONAL
Also, CSE (Customised Search Engine) probably expects that you don't need to do a lot of manipulation to the XML, just transform if for rendering to a web page. You can very easily perform an XSLT (Extensible Stylesheet Language Transformation) to an XML file to transform it in to an HTML fragment to use on your website.
MySQL is a specific SQL database engine. One not very suitable for providing the backend for the very very large dataset and special special needs that a search engine like google have.
I'm sure you can dig up info on how google's infrastructore, e.g. starting here
Relying on and exposing something specific like MySQL is not something you want to do when exchanging data over the internet.
XML on the other hand, being a general and textual markup language is ideal when you need
to interface and exchange data between systems. Thus it provides an ideal way to interface services such as Google CSE. You don't need to care about the specific implementation google have to provide the data, and Google don't need to care about the specific technology you use to manipulate the data
In addition to #Jared, there are XML databases. If the data is stored in XML, then it can be queried, transformed into html on the fly, or used in applications without the need for wrapping the data.
Why does Google use XML, not MySQL, such that I need to manipulate large XML -files?
access time, because there is no security check routine in DOM level on the accesed/open port /-: