Posts Tagged ‘language’

Json + JqueryThere is no direct way to iterate over a Java List with jQuery, see the following case study : Spring controller @RequestMapping(value = “/”, method = RequestMethod.GET) public ModelAndView getPages() { List list = new ArrayList(); list.add(“List A”); list.add(“List B”); list.add(“List C”); list.add(“List D”); list.add(“List E”); ModelAndView model = new ModelAndView(“somepage”); model.addObject(“list”, list); return model; } JSP page, you can…

 

Gouldamadine

One of the most handy (and cool) tricks a web developer could learn to use is collapsible DIVs. This allows you to make a page that will only show the user what they want to see. If they’re interested in some part of content, such as a “mail to friend” or an expanded definition, they could click a link or image and make the page dynamically grow in size to show that added bit of content.

This was inspired by some comments in a post on Aaron’s SEO Buzz Box, and while I think he might be looking for a slightly more advanced solution, it gave me the idea to type up this post.

There’s a few different bits of code we’ll use in this. First we’ll create a div we want to expand or contract. For example:

mydiv” style=”display:none”>

This is a test!
Can you see me?

Notice our tagging the div with a unique id. This allows our Javascript to be able to find it when we alter it’s visibility. We also added a style property, setting it’s display attribute to “none”, which makes that DIV hidden when the page loads originally.

Next we’ll create a link with some inline Javascript to hide or show our div. It’s quite a bit to take in at once, but don’t worry I’ll explain it in depth in a second. Here it is:
mydiv').style.display == 'none'){ document.getElementById('mydiv').style.display = 'block'; }else{ document.getElementById('mydiv').style.display = 'none'; }">Toggle Div Visibility Whew! It’s so complicated because it’s done with inline Javascript. I’ll show an alternate method that’s much cleaner a bit later. But first, let’s tackle this. It’s a simple anchor tag, but you’ll notice the href is “javascript:;”. The purpose of this is to basically do nothing. You don’t want to direct to any other page, and if you put everything in the onmousedown property in the href property, it would work the exact same, but the user would see a mess of javascript in his status bar when he moused over the link, so this keeps it cleaner. Another common do-nothing insert to use for the href property is a pound sign (#), and while that will work, it’ll also move the user’s scroll bar to the very top of your website, which can get quite annoying.

Note, the following explanation is very detailed and assumes virtually no knowledge of Javascript… so if this seems basic to you, feel free to skip it.

Now, we have the href property clean so there’s nothing ugly in the status bar on mouseover, but we still need to actually do the hiding or showing of the div. We call this through the onmousedown property of the anchor tag. We can find the DIV we created earlier by document.getElementById(‘mydiv’), so we decide to first check if it’s already visible or hidden by running a simple if-statement of if(document.getElementById(‘mydiv’).style.display == ‘none’){. If this returns true, meaning the display property is set to none (hidden), we continue past the first bracket and change it’s display property to “block”, which means visible. This will also create a line break before and after our div, so if you want it to appear in the middle of your text or other content, without line breaks, change “block” to “inline”. Following that setting statement, we have our else block, which it run if the first clause isn’t met (the display is NOT set to ‘none’). If it’s not set to none, we assume the div is visible, so we toggle it and hide the div, setting it’s display property to “none” (hidden) again.

An alternative which is a bit cleaner than that inline anchor tag (above) is creating a javascript function for toggling the DIV’s visibility. For this method, use the following anchor tag:
mydiv');">Toggle Div VisibilityThis anchor tag behaves like the above inline javascript, except instead of executing the change in the anchor tag itself (inline), it instead calls the toggleDiv function, passing the div name as a parameter.

This anchor tag above calls the following function. Simply insert this text (the function) somewhere in your document above the link in the body tag, or in the HEAD tag of the HTML itself:
<script language="javascript">
function toggleDiv(divid){
if(document.getElementById(divid).style.display == 'none'){
document.getElementById(divid).style.display = 'block';
}else{
document.getElementById(divid).style.display = 'none';
}
}
</script>
This function does exactly what the above inline javascript does, only it’s a bit cleaner. When it’s called by the anchor tag, it checks the div with the name passed to see if it’s currently not visible (display set to “none”), and if so, it shows it by changing the display to “block”. If the original if statement fails (display is not set to “none”), then it assumes the DIV is visible and hides it again (sets the display property to “none”).

Finally, here’s an example of it in action:

Toggle Div Visibility

Also note, search engines WILL read and index the content in these DIVs, so don’t worry about using collapsible DIVs hurting your SEO.

Web Services – Web Services Tutorials

Posted: January 12, 2012 in Random Posts
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In this section of the Web Services tutorial you will be familiarized with the Web Services.

Introduction

The next generation of distributed computing has arrived. A Web service is a unit of managed code that can be remotely invoked using HTTP, that is, it can be activated using HTTP requests.

Historically speaking, remote access to binary units required platform-specific and sometimes language-specific protocols. For example, DCOM clients access remote COM types using tightly coupled RPC calls. CORBA requires the use of tightly coupled protocol referred to as Internet Inter-ORB Protocol (IIOP), to activate remote types. Enterprise JavaBeans (EJBs) requires a Remote Method Invocation (RMI) Protocol and by and large a specific language (Java). Thus each of these remote invocation architectures needs proprietary protocols, which typically require a tight connection to the remote source.

One can access Web services using nothing but HTTP. Of all the protocols in existence today, HTTP is the one specific wire protocol that all platforms tend to agree on. Thus , using Web services, a Web service developer can use any language he wish and a Web service consumer can use standard HTTP to invoke methods a Web service provides. The bottom line is that we have true language and platform integration . Simple Object Access Protocol (SOAP) and XML are also two key pieces of the Web services architecture.

What is a Web Service

Web services constitute a distributed computer architecture made up of many different computers trying to communicate over the network to form one system. They consist of a set of standards that allow developers to implement distributed applications – using radically different tools provided by many different vendors – to create applications that use a combination of software modules called from systems in disparate departments or from other companies.

A Web service contains some number of classes, interfaces, enumerations and structures that provide black box functionality to remote clients. Web services typically define business objects that execute a unit of work (e.g., perform a calculation, read a data source, etc.) for the consumer and wait for the next request. Web service consumer does not necessarily need to be a browser-based client. Console-baed and Windows Forms-based clients can consume a Web service. In each case, the client indirectly interacts with the Web service through an intervening proxy. The proxy looks and feels like the real remote type and exposes the same set of methods. Under the hood, the proxy code really forwards the request to the Web service using standard HTTP or optionally SOAP messages.

Web Service Standards

Web services are registered and announced using the following services and protocols. Many of these and other standards are being worked out by the UDDI project, a group of industry leaders that is spearheading the early creation and design efforts.

Universal Description, Discovery, and Integration (UDDI) is a protocol for describing available Web services components. This standard allows businesses to register with an Internet directory that will help them advertise their services, so companies can find one another and conduct transactions over the Web. This registration and lookup task is done using XML and HTTP(S)-based mechanisms.

Simple Object Access Protocol (SOAP) is a protocol for initiating conversations with a UDDI Service. SOAP makes object access simple by allowing applications to invoke object methods or functions, residing on remote servers. A SOAP application creates a request block in XML, supplying the data needed by the remote method as well as the location of the remote object itself.

Web Service Description Language (WSDL), the proposed standard for how a Web service is described, is an XML-based service IDL (Interface Definitition Language) that defines the service interface and its implementation characteristics. WSDL is referenced by UDDI entries and describes the SOAP messages that define a particular Web service.

ebXML (e-business XML) defines core components, business processes, registry and repository, messaging services, trading partner agreements, and security.

Implementing Web Services

Here comes a brief step-by-step on how a Web service is implemented.

  • A service provider creates a Web service
  • The service provider uses WSDL to describe the service to a UDDI registry
  • The service provider registers the service in a UDDI registry and/or ebXML registry/repository.
  • Another service or consumer locates and requests the registered service by querying UDDI and/or ebXML registries.
  • The requesting service or user writes an application to bind the registered service using SOAP in the case of UDDI and/or ebXML
  • Data and messages are exchanged as XML over HTTP

Web Service Infrastructure

Even though Web services are being built using existing infrastructure, there exists a strong necessity for a number of innovative infrastructures. The core architectural foundation of Web services are XML, XML namespaces, and XML schema. UDDI, SOAP, WSDL, ebXML and security standards are being developed in parallel by different vendors

Web Services Technologies and Tools

There are a number of mechanisms for constructing Web services. Microsoft has come out with a new object-oriented language C# as the development language for Web services and .NET framework. Microsoft has an exciting tool called Visual Studio .NET in this regard. The back end database can be Microsoft SQL Server 2000 in Windows 2000 Professional.

Sun Microsystems has its own set of technologies and tools for facilitating Web services development. Java Servlets, Java Server Pages (JSPs), Enterprise JavaBeans (EJB) architecture and other Java 2 Enterprise Edition (J2EE) technologies play a very critical role in developing Web services.

There are a number of tools for developing Web services. They are Forte Java IDE, Oracle JDeveloper, and WebGain Studio.

Sun Microsystems has taken an initiative called Sun ONE (Open Network Environment) and is planning to push Java forward as a platform for Web services. It is developing Java APIs for XML-based remote procedure calls and for looking up services in XML registries – two more JAX family APIs: JAX/RPC (Java API for XML Remote Procedure Calls) and JAXR (Java API for XML Registries). These will wrap up implementations of Web services standards, such as SOAP and UDDI.

IBM also for its part has already developed a suite of early-access tools for Web services development. They are Web Services Toolkit (WSTK), WSDL Toolkit, and Web Services Development Environment (WSDE).

Apache Axis is an implementation of the SOAP (“Simple Object Access Protocol”) submission to W3C.

From the draft W3C specification:

SOAP is a lightweight protocol for exchanging structured information in a decentralized, distributed environment. It is an XML based protocol that consists of three parts: an envelope that defines a framework for describing what is in a message and how to process it, a set of encoding rules for expressing instances of application-defined datatypes, and a convention for representing remote procedure calls and responses.

Apache Axis is an Open Source SOAP server and client. SOAP is a mechanism for inter-application communication between systems written in arbitrary languages, across the Internet. SOAP usually exchanges messages over HTTP: the client POSTs a SOAP request, and receives either an HTTP success code and a SOAP response or an HTTP error code. Open Source means that you get the source, but that there is no formal support organization to help you when things go wrong.

Conclusion

For the last few years, XML has enabled heterogeneous computing environments to share information over the Web. It now offers a simplified means by which to share process as well. From a technical perspective, the advent of Web services is not a revolution in distributed computing. It is instead a natural evolution of XML application from structured representation of information to structured representation of inter-application messaging.

Prior to the advent of Web services, enterprise application integration (EAI) was very difficult due to differences in programming languages and middleware used within organizations. This led to the situation where interoperability was cumbersome and painful. With the arrival of Web services, any application can be integrated as long as it is Internet-enabled.

It is difficult to avoid the popularity and hype that is surrounding Web services. Each software vendor has some initiative concerning Web services and there is always great speculation about the future of the market for them. Whichever way it turns out, Web service architectures provide a very different way of thinking about software development. From client-server to n-tier systems, to distributed computing, Web service applications represent the culmination of each of these architectures in combination with the Internet.