I got a query while developing rest service.
As per the REST design, GET is to read , PUT or POST are to create or update based on scenario , DELETE is to delete the resources.
But technically, Can't we perform a create or delete operation in GET call.
i.e. It is up to client way of calling by using specified URL pattern and required response type to hit the exact method in the service class of REST application. But why can't we perform a delete or create of some data in the GET service.
so my question is the DELETE or CREATE technically not possible in GET service or is it a rule to adhere to REST principles.
so my question is the DELETE or CREATE technically not possible in GET service or is it a rule to adhere to REST principles.
The latter. It is only a convention to use the DELETE HTTP method for delete operations. However using the GET HTTP method for delete operations is a bad idea. Below is a quote from "RESTful Java with JAX-RS 2.0, 2nd Edition" that explains why:
It is crucial that we do not assign
functionality to an HTTP method that supersedes the specification-defined boundaries
of that method. For example, an HTTP GET on a particular resource should be readonly.
It should not change the state of the resource it is invoking on. Intermediate services
like a proxy-cache, a CDN (Akamai), or your browser rely on you to follow the semantics
of HTTP strictly so that they can perform built-in tasks like caching effectively. If you
do not follow the definition of each HTTP method strictly, clients and administration
tools cannot make assumptions about your services, and your system becomes more
complex
so my question is the DELETE or CREATE technically not possible in GET
service or is it a rule to adhere to REST principles?
REST uses standards aka. uniform interface constraint. One of these standards is the HTTP standards which defines the HTTP methods. According to the HTTP standard the GET is a safe method:
In particular, the convention has been established that the GET and
HEAD methods SHOULD NOT have the significance of taking an action
other than retrieval. These methods ought to be considered "safe".
This allows user agents to represent other methods, such as POST, PUT
and DELETE, in a special way, so that the user is made aware of the
fact that a possibly unsafe action is being requested.
According to the RFC 2119:
SHOULD NOT - This phrase, or the phrase "NOT RECOMMENDED" mean that there may exist valid reasons in particular circumstances when the particular behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label.
For example write can be a side effect by GET, if you want to increase the visitor count by each request.
How the server software (API) is constructed and what 'rules' are applied is somewhat 'arbitrary'. Developers and their product managers could enforce 'rules' such as 'thou shalt not code or support DELETE operations through the GET operation', but in practice, that is not necessarily the main reason POST is chosen over GET. As others have mentioned, there may be assumptions based on the HTTP protocol that other vendors may rely on, but that is a rather complex and not necessarily relevant reasoning. For instance, your application may be built to connect directly to a server application, and another vendor's rules may not apply.
In a simpler example, on the world wide web and due to compliance and other factors, query string has a limited byte length. Because of this, operations that require a lot of data, such as a few very long encrypted data strings that might be needed for a DELETE operation in a database, GET may not be able to pass enough data, so POST may be the only viable option.
Custom built applications using a CuRL library might extend to include other RESTful operations with their intended functionality, but that would be for the benefit of the server API. Coding more operations on the client-side doesn't necessarily make things 'easier', 'faster', or necessarily 'more secure' from the client perspective, but doing so could help manage resources (a bit) on the server side and help maintain compatibility with third party software and appliances.
I am developing a service to get data from Echo System using their Scheduling API.
Echo System Scheduling API requires each request to be signed by OAuth(2-legged).
I have generated the request URL but I am getting "I/O Exception: Name in certificate" Error.
Echo System uses https, so i am thinking it might be the cause but i am not sure.
Any comments
Make sure you are doing the signature correctly. Signatures can be real tricky. You'll need to make encoding is being done to the different RFC spec requirements that it needs (for example, Twitter uses the RFC 3986 spec) and really there's no language that will do this outright (including ColdFusion), you'll need to create a function to do it. Also, make sure you are using the right type of encryption (oAuth specifies many different type of encryption possibilities, but different services use whatever they want: all of them, or only one of them, etc. etc.). Make sure the elements of your unencoded signature are in lexicographical order (generally, this means fields in ABC order).
Read the documentation very carefully. Anything dealing with oAuth gets very specific. Also, don't be afraid to do a lot of trial-and-error kinds of things. Sometimes, you'll just find the right combination that makes it all work. Good luck!
Related:
Why would one use REST instead of Web services?
When deciding whether to implement a web service using SOAP or REST (by which I mean HTTP/XML in a RESTful manner) what should I be aware of and what should I be thinking of? I presume that this isn't a one size fits all thing so how do I choose which to use.
The two protocols have very different uses in the real world.
SOAP(using WSDL) is a heavy-weight XML standard that is centered around document passing. The advantage with this is that your requests and responses can be very well structured, and can even use a DTD. The downside is it is XML, and is very verbose. However, this is good if two parties need to have a strict contract(say for inter-bank communication). SOAP also lets you layer things like WS-Security on your documents. SOAP is generally transport-agnostic, meaning you don't necessarily need to use HTTP.
REST is very lightweight, and relies upon the HTTP standard to do it's work. It is great to get a useful web service up and running quickly. If you don't need a strict
API definition, this is the way to go. Most web services fall into this category. You can version your API so that updates to the API do not break it for people using old versions(as long as they specify a version). REST essentially requires HTTP, and is format-agnostic(meaning you can use XML, JSON, HTML, whatever).
Generally I use REST, because I don't need fancy WS-* features. SOAP is good though if you want computers to understand your webservice using a WSDL. REST specifications are generally human-readable only.
The following links provide useful information about WSDL vs REST including Pros and Cons
A couple of key points are that
1) SOAP was designed for a distributed computing environment where as REST was designed for a point to point environment.
2) WADL can be used to define the interface for REST services.
http://www.ajaxonomy.com/2008/xml/web-services-part-1-soap-vs-rest
http://ajaxonomy.com/2008/xml/web-services-part-2-wsdl-and-wadl
Regarding WSDL (meaning "SOAP") as being "heavy-weight". Heavy matters how? If the toolset is doing all the "heavy lifting" for you, then why does it matter?
I have never yet needed to consume a complicated REST API. When I do, I expect I'll wish for a WSDL, which my tools will gladly convert into a set of proxy classes, so I can just call what appear to be methods. Instead, I suspect that in order to consume a non-trivial REST-based API, it will be necessary to write by hand a substantial amount of "light-weight" code.
Even when that's all done, you still will have translated human-readable documentation into code, with all the attendant risk that the humans read it wrong. Since WSDL is a machine-readable description of the service, it's much harder to "read it wrong".
Just a note: since this post, I have had the opportunity to work with a moderately complicated REST service. I did, indeed, wish for a WSDL or the equivalent, and I did, indeed, have to write a lot of code by hand. In fact, a substantial part of the development time was spent removing the code duplication of all the code that called different service operations "by hand".
This probably really belongs as comments in several of the above posts, but I don't yet have the rep to do that, so here goes.
I think it is interesting that a lot of the pros and cons often cited for SOAP and REST have (IMO) very little to do with the actual values or limits of the two technologies. Probably the most cited pro for REST is that it is "light-weight" or tends to be more "human readable". At one level this is certainly true, REST does have a lower barrier to entry - there is less required structure than SOAP (though I agree with those who have said that good tooling is largely the answer here - too bad much of the SOAP tooling is pretty dreadful).
Beyond that initial entry cost however, I think the REST impression comes from a combination of the form of the request URLs and the complexity of the data exchanged by most REST services. REST tends to encourage simpler, more human readable request URLs and the data tends to be more digestable as well. To what extent however are these inherent to REST and to what extent are they merely accidental. The simpler URL structure is a direct result of the architecture - but it could be equally well applied to SOAP based services. The more digestable data is more likely to be a result of the lack of any defined structure. This means you'd better keep your data formats simple or you are going to be in for a lot of work. So here SOAP's additional structure, which should be a benefit is actually enabling sloppy design and that sloppy design then gets used as a dig against the technology.
So for use in the exchange of structured data between computer systems I'm not sure that REST is inherently better than SOAP (or visa-versa), they are just different. I think the comparison above of REST vs SOAP to dynamic vs. static typing is a good one. Where dyanmic languages tend to run in to trouble is in long term maintenance and upkeep of a system (and by long term I'm not talking a year or 2, I'm talking 5 or 10). It will be interesting to see if REST runs into the same challenges over time. I tend to think it will so if I were building a distributed, information processing system I would gravitate to SOAP as the communication mechanism (also because of the tranmission and application protocol layering and flexibility that it affords as has been mentioned above).
In other places though REST seems more appropriate. AJAX between the client and its server (regardless of payload) is one major example. I don't have much care for the longevity of this type of connection and ease of use and flexibility are at a premimum. Similarly if I needed quick access to some external service and I didn't think I was going to care about the maintainability of the interaction over time (again I'm assuming this is where REST is going to end up costing me more, one way or another), then I might choose REST just so I could get in and out quickly.
Anyway, they are both viable technologies and depending on what tradeoffs you want to make for a given application they can serve you well (or poorly).
REST is not a protocol; It's an architectural style. Or a paradigm if you want. That means that it's a lot looser defined that SOAP is. For basic CRUD, you can lean on standard protocols such as Atompub, but for most services you'll have more commands than just that.
As a consumer, SOAP can be a blessing or a curse, depending on the language support. Since SOAP is very much modelled on a strictly typed system, it works best with statically typed languages. For a dynamic language it can easily become crufty and superfluous. In addition, the client-library support isn't that good outside the world of Java and .NET
To me we should be careful when we use the word web service. We should all the time specify if we are speaking of SOAP web service, REST web service or other kind of web services because we are speaking about different things here and people don't understand anymore if we named all of them web services.
Basically SOAP web services are very well established for years and they follow a strict specification that describe how to communicate with them based on the SOAP specification.
Now REST web services are a bit newer and basically looks like simpler because they are not using any communication protocol. Basically what you send and receive when you use a REST web service is plain XML. People like it because they can parse the xml the way they want without having to deal with a more sophisticated communication protocol like SOAP.
To me REST services are almost like if you would create a servlet instead of a SOAP web service. The servlet get data in and return data out. The format of the data are xml based. We can also imagine to use something else than xml if we want. For instance tags could be used instead of xml and that would be not REST anymore but something else (Could be even lighter in term of weight because xml is not light by nature). Would we call that still a web service? Yes we could but that will not follow any current standard and this is the main issue here if we start to call everything web services but we can do it the way we want then we are loosing on the interoperability side of the things. That means that the format of the data that is exchanged with the web service is not standardized anymore. That requires then that server and client agree on the format of the data whereas with SOAP this is all predefined already and server and client can interoperate without to know each other because they follow the same standard.
What people don't like with SOAP is that they have hard time to understand it and they cannot generate the queries manually. Computers can do that very well however so this is where we need to be clear: are web services queries and response supposed to be used directly by the end users or do we agree that web services are underneath API called by computer systems based on some normalized standards?
SOAP: It can be transported via SMTP also, means we can invoke the service using Email simple text format also
It needs additional framework/engine should be in web service consumer machine to convert SOAP message to respective objects structure in various languages.
REST: Now WSDL2.0 supports to describe REST web service also
We can use when you want to make your service as lightweight, example calling from mobile devices like cell phone, pda etc...
for enterprise systems in which your system is confined within your corporations, its easier and proper to use soap because you are almost in control of clients. it's easier since there a variety of tools which creates classes (proxies) and looks like you are doing your regular OOP which matches your java or .net environment (in which most corporates use).
I would use REST for internet facing applications for exposing interfaces (like twitter api) since clients can be using javascripts or html or others in which typing is not strict. REST being more liberal makes more sense.
Also for internet facing clients (world wide web), its easier to parse json or xml coming out of a rest interface rather than a purely xml coming from a soap interface. it's hard to use proxies on javascript and javascript does not naturally support objects. If you are using REST with javascript, you would just usually parse the json string and you're off. internet facing interfaces are usually very simple (so most of the time its simple parsing) and does not usually demand consistency that is why REST is adequate enough.
For enterprise applications I don't think REST is adequate because transactions, security, strict typing, schemas play a very important in enterprise applications development that is why SOAP is more suited for them.
My conclusion is that SOAP is for Enterprise systems, REST is for the Internet or WWW.
You can use it interchangeably but you may find yourself having a difficult time eventually not using the correct tool for the job.
sorry for my bad english.
In defence of REST it closely follows the principles of HTTP and addressability e.g. read operations use GET, update operations use POST etc. I find this to be a far cleaner approach. The Oreilly book RESTful Web Services explains this far better than I can, if you read it I think you would prefer the REST approach
The toolset on the client side would be one. And the familiarity with SOAP services the other. More and more services are going the RESTful route these days, and testing such services can be done with simple cURL examples.
Although, it's not all that difficult to implement both methods and allow for the widest utilization from clients.
If you need to pick one, I'd suggest REST, it's easier.
The previous answers contain a lot of information, but I think there is a philosophical difference that hasn't been pointed out. SOAP was the answer to "how to we create a modern, object-oriented, platform and protocol independent successor to RPC?". REST developed from the question, "how to we take the insights that made HTTP so successful for the web, and use them for distributed computing?"
SOAP is a about giving you tools to make distributed programming look like ... programming. REST tries to impose a style to simplify distributed interfaces, so that distributed resources can refer to each other like distributed html pages can refer to each other. One way it does that is attempt to (mostly) restrict operations to "CRUD" on resources (create, read, update, delete).
REST is still young -- although it is oriented towards "human readable" services, it doesn't rule out introspection services, etc. or automatic creation of proxies. However, these have not been standardized (as I write). SOAP gives you these things, but (IMHO) gives you "only" these things, whereas the style imposed by REST is already encouraging the spread of web services because of its simplicity. I would myself encourage newbie service providers to choose REST unless there are specific SOAP-provided features they need to use.
In my opinion, then, if you are implementing a "greenfield" API, and don't know that much about possible clients, I would choose REST as the style it encourages tends to help make interfaces comprehensible, and easy to develop to. If you know a lot about client and server, and there are specific SOAP tools that will make life easy for both, then I wouldn't be religious about REST, though.
You can easily transition your WSDL-spewing WCF web components to other uses just by changing your configuration settings. You can go across HTTP and then also named pipes, tcp, custom protocols, etc without having to change your code. I believe WCF components may also be easier to set up for stuff like security, two-way calling, transactions, concurrency, etc.
REST pretty much limits you to HTTP (which is fine in many cases).
I know that this discussion is an old one, but after reading all the answers and commented, I believe that everyone missed the most important point about the difference between the 2 systems: SOAP uses complex types to not only give you the data, but validate it and keep it in the strict type designation it was defined for. A WSDL tells you what the data format is, what the data type is, allows you to add reg-ex pattern-style rules, and defines how many times a piece of data must be, and may be, allowed in a request/response.
Rest on the other-hand has none of these mechanisms.
SOAP is complex and heavy because it allows you to send complex heavy hierarchical data. REST is plain text, with the origin and endpoint sorting out the rules.
SOAP is business independent, because it has all the data rules embedded in the document.
The difference between SOAP and REST is that SOAP is a self-contained business oriented schema. REST is a text document.
Our whole system is being designed around REST and are now considering how processes which are quite clearly RPC in intent can be mapped to RESTful resources without using verbs in the URL. Our remote procedure call is used to rebuild our search index when a content listing has been modified elsewhere.
What we are thinking about doing is this:
POST /index_updates
<indexUpdate><contentId>123</contentId></indexUpdate>
Nothing wrong with that in itself, but the smell is this resource which has been created does not return the URL of the newly created resource e.g. /index_updates/1234 which we can then access with a GET.
The indexing engine we are using does have a log mechanism, so in theory we could return a URL to a index_update resource so as to allow a GET to retrieve the resource, but to be honest we're not interested in the resource as this is nothing more than an RPC in disguise.
So my question is whether RESTfulness is expressed in structure or intent. I feel the structure of what I have outlined is restful, but the intent is not.
Does anyone have an comments or advice?
Thanks,
Chris
Use the right tool for the job. In this case, it definitely seems like the right tool is a pure remote procedure call, and there's no reason to pretend it's REST.
One reason you might return a new resource identifier from your POST /index_updates call is to monitor the status of the operation.
POST /index_updates
<contentId>123</contentId>
201 Created
Location: /index_updates/a9283b734e
GET /index_jobs/a9283b734e
<index_update><percent_complete>89</percent_complete></index_update>
This is obviously a subjective field, but GET PUT POST DELETE is a rich enough vocabulary to describe anything. And when I go to non-English-speaking Asian countries I just point and they know what I mean since I don't speak the language... but it's hard to really get into a nice conversation with someone...
It's not a bad idea to disguise RPC as REST, since that's the whole exercise. Personally, I think SOAP has been bashed and hated while in fact it has many strengths (and with HTTP compression, HTTP/SSL, and cookies, many more strengths)... and your app is really exposing methods for the client to call. Why would you want to translate that to REST? I've never been convinced. SOAP lets you use a language that we know and love, that of the programming interface.
But to answer your question, is it a bad idea to disguise RPC as REST? No. Disguising RPC as REST and translating to the four basic operations is what the thing is about. Whether you think that's cool or not is a different story.
I have a website (ASP.NET) and some winforms(.Net 2.0) for a project (written in C#). I use the webservice (IIS6) for task that both require like sending email inside the business.
I think Webservice is nice but I would like from your experience what should and what should not be in a webservice?
In My Opinion:
Web services should be reserved for code that
You either can't or don't want to distribute; or,
code that needs to seriously scale up.
One example is custom business logic that multiple applications need access to.
Code you don't want to put into web services include:
code that is performance based;
code that applies only to the application in question.
Well it sounds like you have a limited Service Oriented Architecture (at least, that's what I think you're getting at), which according to Gartner means you'll be rich soon. :)
I find that the benefit of SOA for me really comes down to the heterogeneity of the systems involved (sounds like yours doesn't qualify there because it's all .NET), and the negative of SOA is primarily because of the verbose nature of XML. True, you don't need XML for SOA, but it's the current majority, IMHO.
But if you're not concerned about the bandwidth/parsing penalties, who cares? Maybe you're not piping through 10,000 service calls a minute. With this style of implementation, you're following DRY, just with a WS instead of a sub, and you're adhering to a standard that is by nature compatible with multiple systems.
There's worse approaches.
It seems like the new trend for web services/SOA is to more or less expose a light-weight middle tier that your host application can use. Instead of having individual method calls exposed through a service (as in your example), SOA-oriented applications have extensive Data/Operation contracts that act as the "traditional" middle tier assembly.
As little as possible, while still being useful.
By default, DON'T put every field of the return objects in the return data, and DON'T expose every method of an existing class.
read this too...