# OSLC/Lyo Questions **URL:** \ **Category:** Lyo\ **Created:** [July 19, 2022, 2:54pm UTC](https://forum.open-services.net/t/oslc-lyo-questions/642 "2022-07-19T14:54:42Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![jad](https://forum.open-services.net/user_avatar/forum.open-services.net/jad/32/42_2.png) [@jad](https://forum.open-services.net/u/jad)\ **Post date:** [July 19, 2022, 5:17pm UTC](https://forum.open-services.net/t/oslc-lyo-questions/642/2 "2022-07-19T17:17:05Z")
Hi @fritter, What is producing the 404 exception to a sparql request? Now I try to answer your questions **1.** yes, Lyo is still based on OSLC 2.0, and 3.0 should be backward compatible with 2.0. And yes, in both specs ServiceProvider and a ServiceProviderCatalog are not mandatory (most things in the OSLC specs are not mandatory. But your implementation should implement them if you find the features necessary). Note that ServiceProvider and a ServiceProviderCatalog are defined as Containers in 3.0. **2.** WebService & Service are the terms LyoDesigner uses in its interface. Only the latter - Service - is defined in the specs. Service corresponds to that you see in the specs (See for example the figure [OSLC Core Version 3.0. Part 2: Discovery](https://docs.oasis-open-projects.org/oslc-op/core/v3.0/os/discovery.html#discoveryModel)), which then contains references to QueryCapability, CreationFactory, etc. The Service itself is contained within a ServiceProvider. I believe your point 6 below relates to this question too, Now, WebService defines the C.R.U.D. methods on resources to handle a specific resource with a given URL. Note that these C.R.U.D. methods are not part of the OSLC Service (See the figure I just referenced). and that’s why LyoDesigner lets you model them separately. When you model a Service, you need to define the query/creation capabilities and they have a property that specify the URL of that service. (queryBase, or creation) For a particular resource, you already know the URL of that resource, so you can then simply call GET/PUT/DELETE on it. This older thread might be of some help too > [@Why Doesn't OSLC Fully Comply with Roy Fielding's HTTP Semantics?](https://forum.open-services.net/t/why-doesnt-oslc-fully-comply-with-roy-fieldings-http-semantics/371/3): > > Hi Mario, My confusion is not really on the methods and how they are implemented in OSLC, but rather how they are implemented with respect to a particular path. Given /foo/{id}, per Fielding: GET on /foo returns all foo objects. A set of query string parameters can be used to filter the underlying data set. GET on /foo/{id} returns the foo with the given id. DELETE on /foo/{id} deletes the foo with the given id POST on /foo updates a foo, the underlying semantics (create a new one? update i… **3.** I did indeed use some java code to translate from the EMF meta-model of Sysml to define the OSLC shapes (and hence the resulting code). I have not made this code public. I am not sure what I will do with this code. Is the resulting classes insufficient? **4.** The current Sysml implementation does not make use of oslc.properties. I believe the Lyo SDK does support it, but I have not had much use of it recently. so I can’t think of examples. Hope someone else can give better tips. **5.** Both Bugzilla and Sysml support ServiceProviders. Sysml has one for each commit. For Bugzilla, you should have one for each Project. Here’s for example a link to the Sysml ServiceProviderCatalog [http://sysml2-oslc-dev.intercax.com:8080/sysml\_oslc\_server/oslc/catalog/singleton](http://sysml2-oslc-dev.intercax.com:8080/sysml_oslc_server/oslc/catalog/singleton). As you can see, the link on that page is that for its - only - ServiceProvider. Do a GET on that to get more info about the ServiceProvider. **6.** Was figure 1 of any help? I view a ServiceProvider as the context for your Services. If you take Bugzilla (or Jira) as an example, you cannot simply create an Issue/changeRequest on a global level. You create an Issue/ChangeRequest/Bug **in the context** of a specific Project. Each Project hence correspond to an OSLC ServiceProvider. And for each ServiceProvider/Project, you will then get a specific URL to create an Issue/ChangeRequest/Bug within it. That’s the value of the oslc:creation value of the CreationFactory object in fgure 1. Simlarly, if you want to search **within the context of** a project/ServiceProvider, you use the URL defined in hte oslc:queryBase of a QueryCapability. A Service is nothing but a container of all the capabilites of a ServiceProvider/Project. Hope this helps to get you started, and hope you find OSLC of value to your project. --- _[View the full topic](https://forum.open-services.net/t/oslc-lyo-questions/642)._