I'm learning about web services and most of the resources I've been reading talk about registering your web service once it's ready for use by others. Is registering a web service required to use the service?
For example, let's say I have a web application on a company intranet and I create another web service app that retrieves some sort of useful information to be displayed on this private intranet site. Would this new web service require being registered just so my web app can use it or can the web app simply interface directly to the new web service (following the WSDL file) without the need of some sort of UDDI registry?
You can certainly use the service without the UDDI registry.
I have created several Web Services and have immediately used them without registering them. Registration gives others confidence that your Web Service is legitimate and descriptions of how to interact with those services.
Imagine doing development where you have to register any Web Service before using it. Yikes!
No, not at all.
You are probably talking about API directories you may register your WS at. Like UDDI or what it’s named. Entirely optional.
Nobody uses UDDI anymore. It's an idea whose time has come and gone.
It was thought that there would be public registries of web services that everyone would use to find a web service to meet their needs. That never happened.
How could either the service or the app know whether or not the service was registered?
Furthermore, why would they care?
If you're trying to use service orientation the right way, your web services should be registered within a service registry. The registry should contain the published contract of the services and any meta-data that helps the discovery process.
A different questions is: does a service consumer program need to look up a registry and dynamically bind the service it needs to call? NO, NOT AT ALL.
But then, what discovery process am I talking about?
I'm referring to a human (developer, architect, etc.) who is designing/developing a program that needs to call a service. This person should have means to search what services are available in his/her organization. If not, the benefit of reusing services is compromised.
Discovery is also about humans finding out there's a service somewhere in the IT organization that offers the functionality they want.
In this case, the registry can be as simple as an html report that is created and updated manually or generated by parsing (xslt comes handy) the wsdl files.
Related
I have searched a lot upon internet but still i didn't get the clear difference between web services and web APIs? Somewhere I read that all web services are API's but all API' are not web services. How?
What all I know is both allow to utilize the functionality of other applications.Can someone describe me clear difference?
I have been on the same journey to learn the differnce between Web API (not JUST API) vs Web Services.
First, we know for a fact that both use the Web as the communication tool as stated by #Kris.
While looking at these 2 videos, both serve as the "middleman" (the waiter in the restaurant) for a client to ask a Web Server to process and deliver a response.
Web Service (From 0:35)
API (In general) (From 1:12)
When I was looking for an actual differnce between the two, usually most articles and videos go on an unrelated comparison between "Web Services vs API" as they exclude the "Web" out of "Web API".
See this article, for example, which contains the title "Web API Vs Web Service...." yet, contain sub-titles like:
"Differences of API vs Web Service"
"Pros and Cons of Web Services vs API Service"
"Web Service vs API: Fueling Both With Scraping Robot’s API"
The only difference I could find is if we were to discuss this in .NET context.
Here's a question post related to this.
To sum it up, Web Services are used in the SOAP protocal while Web API is usually created in the RESTful way. The more detailed answers are in the post but ultimatelly do not answer the main question that is asked.
Conclusion: The question raised in the public domanin has no clear definition to what is difference between the two, thus the 2 terms are ,for the most part,
interchangeable
All web services are APIs. An API is an Application Programming Interface. But there are offline APIs, which are not web services. There are APIs for all things from Office to Websites. The API is just a defined interface to be able to control/communicate with some software. Web Services just provide that means of connecting over the web.
There is more to discuss when you are talking about APIs which are communication protocols and data formats, but you get the basic idea.
An API (Application Program Interface) is the interface through which another program can communicate with a program.
A web service in this context is one of those programs with an API. 'Web' means that it is accessible via the web, mostly via HTTP. A service usually has a well defined purpose.
For instance a date web service's purpose could be to provide the current date. The API of my service would have a single 'endpoint': get the date. The service then implements this API. It somehow retrieves the date and sends it back.
I am not sure if I am comparing onion with a cabbage. But I am really confused with the portlet and a web service. I know that web service is making your software components in your application as a service to other applications but to me it is similar to a portlet responding to requests. I know that my understanding is making you(Portlet & SAAS developers) really upset. But I need some clarity on this.
Why cannot I use the request-response to portlet work similar to a web service?
If yes, what is the benefit I get in using a web service than a portlet?
If not, then what are portlets lacking to act as a web service?
I am a newbie in portlet development. Please dont curse me for this question.
Please suggest.
EDIT:
Most of the answer say that the portlet is a UI component. My customer has requested me to create a webservice in liferay. So is it to make a portlet as a web service? If yes, can you please provide a pointer or some code snippet?
Addressing your 'edit' specifically with regards to Liferay...
Liferay plugin projects can expose web services without too much work.
The Liferay Service Builder actually has facilities so you can create SOAP web services or JSON web services backed by tables in the Liferay database (and that make queries on existing database tables). In the case of JSON web services, the URL scheme generated is not RESTful (unfortunately), but it is well defined. With a bit of work on your part you can impose Liferay's permission system on web service calls as well.
Here's a reasonable starting point in the Liferay Developer's Guide:
See the links on that page to SOAP and JSON services.
Note that a 'portlet' is only one type of Liferay plugin. The web service facility is part of the service layer - which can be used by many plugin types. So there isn't necessarily a portlet involved in creating a web service in Liferay, you can make a web service that has no visual component associated with it.
Portlets are areas you create to add and display content. Portlets can be added to the left and right of the center body area and can contain myriad content ranging from news, events, calendars, RSS feeds, collections, plain text, and more. Also, you can set properties and policies for showing the portlets.
you want to use portlet when
You have content you want to have special focus, like news.
You need to specify the configuration data for an item. - i.e. number of entries to show.
You want to give the content editors a choice about when and where to display content.
You'd like to show it only to some groups or users.
On the other hand, web services:
Enables applications to expose their services
“progammatically”, i.e. the services can be invoked by programs
Enables software running on other computers (could be a desktop, mobile phone, PDA, etc.) to invoke operations exposed by Web applications
if you are trying to identify the main difference portal historically, the portlets have three layers architechture (client, middle tier, backend) this cause two weakness:
Different portal groups have no well established way of sharing services
Different technologies(Java, Perl, CORBA, EJB) in middle tier.
Different protocols(GRAM, IIOP,...)
Consequently, lots of redundancy, reinvention
Example: batch script generation
so Web services address the service sharing problem and reduces the redundancy.
source1 source2 source3
Portlets are meant to be a user interface component in a portal solution.
Web Services provide functionality to remotely interact with a system commonly using SOAP, REST, JMS or other related
They provide completely separate functions. The closest you get is the serveResource method in portlets. This functionality is used to serve various types of content from a portlet (such as a PDF document or an AJAX response) without the need to perform a full page request.
I am using Axis2 (1.5.3 currently) and Tomcat (6.0.26 currently) and am running a web service. I would like to also host HTML pages for configuring the web service.
What is the best way to go about this? I assume keeping the same context is key, but perhaps it is not.
My current distribution is located under a folder structure similar to this:
Tomcat/webapps/mycompany
With the actual service code here:
Tomcat/webapps/mycompany/WEB-INF/services/myService
In a browser, I can hit my web service by going to here:
/mycompany/services/myService
I note that I can drop actual HTML files in this path and Tomcat will, indeed serve them up.
For instance, if I put "index.html" under Tomcat/webapps/mycompany, I can navigate to /mycompany/index.html and see my html.
What I want to do is have this HTML be attached to JAR/class files that can interact with the already-existing service class files in the same context as the service. Therefore, I can have the browser configure the web service directly.
Is this possible, and is there a tutorial or something out there that will help me with this? Note that I have been working with Tomcat and Axis2 for a while now for this particular web service, but I have never actually deployed a web application/html using Tomcat before.
Thanks.
First of all what do you mean by a configuring a service. Normally in SOA world services are analogous to interfaces. IMHO you can just change a service, since their are other users that rely on the services you are exposing.
If i want to change a service i would rather introduce a new version of the service after deprecating the existing one.
Are you talking about applying QoS to existing serviecs. Then that makes sense.
Anyway, If you want to have a web-app alongside with axis2 service engine, it is possible. If you look inside the axis2 war file you'll find the web.xml entry to Axis2Servlet. It is this servlet that serves the web services requests.
So, what you need is the Axis2Servlet mapping in your web-app along with your usual servlet-mappings. Number of possible ways to configure your services using web-app files. One options is to use web-services call itself to (with authentication) to configure it.
By "configure a service", take this example:
The service has a set of datasets.
Each dataset exists in a separate database.
The service can manage 0..n datasets.
The service must be configured to know about each dataset.
This is what I'm configuring. I'm not trying to configure Axis itself or redefine the service.
I would like to host the HTML using the same instance of Tomcat that I'm hosting the web service with. It needs to manage sessions, have login capability, an whatnot, and has to be able to configure the web service live.
From what I'm reading, it's probably best to make an interface to the web service that the web application module can call into from a different context.
Is there a better way?
I am new to developing web services using java. I have an academic project where I need to do dynamic service composition. For that I can't directly create a service-client for a particular service because if I do so then that client will call that particular service only. Client need to search various web services and then out of those services select any one at run time and also call that service at run time.
I was able to develop the web service(JAX-WS) using Eclipse(indigo), I also created the client for that web service and every thing is working fine. Now my problem is that while creating the client I am hard coding the client to call that particular web service only(since I am creating the client using the WSDL file of the service). However I actually need to call any one of the searched service, but for that I need to publish the service some where then discover it and then call it.
I tried publishing the service to juddiv3. But on juddiv3 I could only publish the sample service supplied with the juddiv3. When I try to publish service created by me then it is not getting displayed in the group of published services.
Is there any other UDDI server which I could install on my local machine and then publish and discover the service from that. Also I was not able to figure out how to create a client that will modify itself at run time to call any one service out of various searched services.
Kindly provide the necessary steps and code.
Thanks
You can use jUDDI (http://juddi.apache.org/ ).
juddi is based on UDDI v2.0, v 3.0 .
Here, you can publish as well as discover your web service.
For integration, you have to make some application which integrates with jUDDI.
But I think for your academic project, and for your purpose, jUDDI is best suitable! ( :) )
jUDDI has a boat load of examples in the source code trunk. You may want to check them out. It's difficult to guess what the problem is from the little information you've provided. Consider contacting the jUDDI team for further assistance. http://svn.apache.org/repos/asf/juddi/trunk/juddi-examples/. There's also additional document for working with UDDI in the jUDDI user's guide, which is at the jUDDI web site
You cannot directly publish on jUDDI. You need to create publisher entities in jUDDI server also. You'll find Rename4Sales and Rename4Marketing examples in 'Classes' folder in the standalone server's juddi application. Use these XMLs as your basis and create your own entity. You also need to configure the server's login credentials.
I suggest you follow the tutorials on jUDDI blog.
This will sound naive (but then I am a junior programmer), but if I write a web service say in Python (standard WSDL web service), I then need to host it so it is reachable from an end point.
This will give a URI for the service and then from another language, say Java or VB.NET (any), I can add a web service (this one) and then call the web service's object model, correct?
Thanks
if I write a web service say in Python (standard WSDL web service), I then need to host it so it is reachable from an end point.
By definition, a web service need to be exposed through HTTP i.e. "hosted" (by the way, WSDL is a language to describe a web service).
then from another language, say Java or VB.NET (any), I can add a web service (this one) and then call the web service's object model, correct?
Without entering in the details, web services are basically web APIs accessed via HTTP. So yes, you will be able to call a web service from any language than can make HTTP requests (not sure what you mean by "add a web service" though).
If you are expecting a more precise answer, feel free to ask a more precise question :)