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Storing all data of a website on Apache Jena as RDF?

I am trying to build a web site build on semantic technologies. It is a CMS, to make it simple lets say it's a blog. I need to be able to do simple CRUD operations. All data will be saved on Jena like blog posts, user informations, blog categories etc.
I have a php system. Here is the path what i am planing to follow:
Use Apache Jena as RDF Store
Use Apache Jena for storing and retrieving the data.
Write a web service on java
Communicate through web service with PHP in JSON format to view, control the data.
My main focus is to build a web site on semantic technologies.
Is there anything wrong with my approach?
If not the main question is when a user made a blog post how will i create a relation with the blog post and user.
With mysql it was just a froeign key. How can i make a relations on Jena between new blog post and existing user?

I can't see anything wrong with your approach. Maybe I would suggest to use JSON-LD as an interchange format, because Jena can read it and write it directly instead of having to create your own converters to RDF (see https://jena.apache.org/documentation/io/).
Regarding the modeling question, I strongly recommend to have a look at the SIOC vocabulary (http://rdfs.org/sioc/spec/), which aims to represent exactly what you are looking for, and more.

Another hardcore solution would be to create the pages of the website in RDF (serialized in RDF/XML), and use XSL to generate the HTML version on demand for each page. It really depends on the size of your website.

knowing ontology concepts from owl files

I have downloaded a load of owl files. I want to know what are the concepts defined in these files and then want to annotate other text based off these concepts. How would this be done? Code in Java would be good. I am a beginner. Thanks in advance

You need to use either OWL API, mainly for parsing OWL, or Apache Jena, mainly for RDF. Depending on what you want to do, they have great tutorials with sample code. If you have any specific question after you have read these, post a detailed question with the error message.

Jena, RDF and Jade implementation

I have an OWL ontology and I want to store data as RDF . When I search in the Google I saw Jena library is used for this purpose. But I could not understand how can I represent data as RDF in Jade.. Plz can somebody help me ???

Jade and Jena are more-or-less independent libraries, so using them both in a project is not hard. Indeed, they have been used in various projects - try a Google search for AgentOWL,for example.
Your agents will need one or more Jena Model objects to hold the RDF information they are going to reason with. These models can be loaded into memory in each agent instance, or you can use a persistent store, such as TDB.
When agents need to send inter-agent messages via Jade, as I recall the default mechanism that Jade uses is Java object serialization (this may have changed, it has been a while since I looked at Jade). Serialization won't work for Jena objects, you'll need to construct a model that contains just the RDF triples you want to send, and then toString() that into the content for an ACL message. I'd suggest using Turtle as the serialization format; it's more compact and easier to read.

Getting data using OAI-PMH from an insitutional repository

I'm developing an application where I've requested data from an external institution's website. They have informed me that the data will be provided by OAI-PMH.
Could someone show me some sample code in Java how data is extracted from a OAI-PMH ?
I wonder how different it is from reading and parsing XML data.
Thank you.
Warmest wishes,
Shoubhik

For a Java implementation, for example, you could use some already existent library, like XOAI with an easy to use API. There are some provided samples.
To extract metadata from each Record you could use a XML Parser or a XML bind approach (JAXB). For other languages, like PHP and Perl there are also other alternatives.

CRUD Operation in OWL

I have created an ontology. Now I want to create an application but how can I perform CRUD operations in owl file. I came across different apis like Dotnetrdf, jena etc all support RDF/RDFS but there is not support for owl file
http://www.semanticoverflow.com/questions/2704/using-jena-to-query-owl-files
Problem of reading OWL/XML
Also, most of apis are available in Java and I dont know how to write simple hello world program in java. I am confused with servlet, jsp and .java and lots of configuration is required. So I prefer php.
So is there any api or any alternative way to query owl file in php ?
Regards,
anas anjaria

The only libraries I know that support SW standards in PHP are rdfapi [1] and redland php binding [2], but the level is RDF (i.e. the building block of RDFS and OWL) you will need to add CRUD operations at the triple level (i.e. simple axioms like foaf:knows )
[1] http://www4.wiwiss.fu-berlin.de/bizer/rdfapi/
[2] http://librdf.org/docs/php.html

So, it looks like you're talking about the Web Ontology Language, an XML/RDF dialect.
A few moments in Google shows pretty much zero interest in this in the world of PHP.
But, being XML, you can use one of the PHP XML extensions so read and work with the XML directly without a problem. How well this will actually work for you, I can't say. OWL looks freakishly complex, and working with it at the DOM node level will very likely stretch your sanity far worse than working with mature, established libraries in Java.

i made my final project at the university by using Jena. The Research Group where i work develop ontology generator tool which is capable of all crud operations. They also developed the Eclipse plug-in of this project.
You just create your OWL Data Model in the editor and right click the data model create everything, i creates owl files, Crud class and it's test codes for you.
Let's check it out
Download
Name of Plug-in is "SEAGENT Ontology Generator Plugin (Beta)"
I hope it will be beneficial for you like me