Ian Blackburn from bbits.co.uk gives the Silverlight UK User Group a talk on the new .NET RIA Services and its implementation within Silverlight applications. This presentation was given on 29th September 2009 at the EMC Consulting offices in London.

1. .Net Ria Services for Silverlight Ian Blackburn Download RIA Services and documentation from http://www.microsoft.com/downloads/details.aspx?FamilyID=76bb3a07-3846-4564-b0c3-27972bcaabce&displaylang=en This presentation is a summary of the ~200 page document from there (plus some examples ;-)

2. Overview www.bbits.co.uk

3. Where do RIA Services Exist? www.bbits.co.uk

4. Presentation Technologies and DALs The current preview illustrates the pattern primarily through the end-to-end experience with Silverlight and EF or Linq to Sql but RIA Services are designed to work other Presentation and DALS as well www.bbits.co.uk

5. Getting Started www.bbits.co.uk

6. The DomainService Class This is the main class for authoring operations Such as CRUD behaviours It can be generated code in the first instance. You add your custom application logic to this class The [EnableClientAccess] attribute causes the tools to generate the corresponding client-tier classes when the project is built www.bbits.co.uk

7. The DomainContext Class A client side DomainContext class is generated for each DomainService This provides basic services such as invocation of operations, accumulation of results, object identity and change tracking www.bbits.co.uk

8. Sharing Code Between Client and Server Code that is written in the server side can be reused in the client side. To do this create a new class in the server side with a .shared.cs or .shared.vb suffix Mark the class and methods you want to share with the [Shared] attribute After you build the solution, Visual Studio will copy this file to the Silverlight client application: www.bbits.co.uk

9. Creating Query Methods in the Service Define Query Methods in your Domain Service These must: return a single instance T, or an IEnumerable<T> or IQueryable<T> where T is a valid Entity type takes 0 or more parameters Optionally be adorned with the QueryAttribute

10. Using Generated Query Methods in Silverlight When a query method is defined in the domain service, the code generator automatically creates A query factory method named [NameOfQueryMethod]Query The entity Type of the query method You use it by: createinganEntityQuery instance Applying LINQ query operators to it as needed Passing the query instance into DomainContext.Load

11. Example Note that the “orderby” is still happening on the server, and the Load is asynchronous

12. Support Query Operators in Silverlight EntityQuery exposes only a subset of LINQ query operators. These are: Where OrderBy / ThenBy Skip / Take

13. Metadata classes To add some validation rules that are applied on both tiers, you create a metadata class for the Domain Service affectionately called the “buddy class” This can be generated when you create the domain service by checking the box shown Or you can just add the MetadataType attribute manually to an entity class www.bbits.co.uk

14. Using Include on MetaData You need to mark the Suppliers metadata with an equivalent Include attribute so the correct code is generated on the client

15. Adding Validation rules to the Metadata class www.bbits.co.uk This is achieved through attributes on the properties of the class on the server This causes the generated entity class in the client to have the same validation applied

16. Modifying Data If you use the DomainService class wizard to generate DomainService class, then the generated service class has Create/Read/Update/Delete (CRUD) operations already

17. EntityContainer, EntityList and Change Tracking Entities loaded into a DomainContext are stored and change tracked by its EntityContainer This is the Entities collection on the context object An EntityContainer manages a set of EntityLists there is a 1:1 mapping between EntityLists and the entity Types exposed by your service You can get a list of entities for a particular type using GetEntityList<T> You can inspect the Entity.EntityState of an entity to determine the state of the entity Unmodified, Modified, New, Deleted

18. Change Sets (Unit of Work) A change set is a set of one or more entity operations to be processed as a single unit of work and can contain Entity Insert/Update/Delete operations Custom domain operations When SubmitChanges is called on the context the changes are all sent to the service all together You can get the current ChangeSet using the GetChanges method of the EntityContainer You can discard all pending changes, by calling RejectChanges on the context.

19. Server Side Change Set Processing

20. Error Handling You can throw validation exceptions in the Domain Service and then handle them in the client SubmitOperation completed event

21. Other Supported Features Concurrency Handling Concurrency errors are reported from the DomainService to the client You can handle them in the SubmitOperation completed event You can also create a Resolve method on your service to deal with resolution Transactions Support No built in support from the client, but you can of course wrap your domain methods in transactions Identity Management The Key attribute on entities is used to keep track of local entities Whenever an entity is loaded if there is a cached instance locally with the same identity or key value(s) the local instance will be retained, and the newly read instance is discarded You can change this behaviour with the MergeOption in the context Load method

22. Custom Methods and Service Operations Using Custom Methods You can create custom server methods in addition to basic create/update/delete operations These also support tracking on entities and deferred execution (e.g. When SubmitChanges is called) Mark them with the [Custom] attribute Call from the context or the entity itself in the client Service Operations More closely related to traditional web service Use the [ServiceOperation] attribute Don’t support tracking of deferred execution

23. Other features Silverlight DomainDataSource Use declarative code to define the interactions between your UI and the data Supports filtering, sorting, grouping, editing... Restrict Access to DomainService Operations You can authenticate using the membership system in asp.net Then configure access against operations roles and users Code Generated Hook Points Partial methods are supported in the generated code to give extensibility points E.g. OnCreated, OnPropertyNameChanged

24. Other Features .NET RIA Services Class Libraries permits packaging business logic into N-tier class library components rather than the Silverlight client and Web Site Ado.Net Data Services Stated goal is to align the two technologies such that Microsoft .NET RIA Services uses the same protocol as ADO.NET Data Services Business Applications Templates VS templates that builds on the Silverlight Navigation Application and using .NET RIA Services and provides support for Authentication and User Registration

25. Questions?

26. Concurrency Error

27. Naming Conventions Insert “Insert”, “Add”, “Create” prefixes Method signature : void InsertX(T entity), where T is an entity Type Update “Update”, “Change”, “Modify” prefixes Method signature : void UpdateX(T current), where T is an entity Type Delete “Delete”, “Remove” prefixes Method signature : void DeleteX(T entity), where T is an entity Type Query Method signature returning a singleton, IEnumerable<T> , IQueryable<T> where T is an entity Type, and taking zero or more parameters Resolve “Resolve” prefix Method signature : boolResolveX(T curr, T original, T store, boolisDelete) where T is an entity type