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ASP.NET Web PDF Document Viewer/Editor Control LibraryNow that you have seen how to obtain details regarding the current caller, the next logical step is to understand how to constrain what the current caller may do based on her identity. The .NET role-based security model enables to you restrict access to type allocation and type member invocation using one or two approaches: Imperative RBS: Use RBS types directly in your code, making run-time demands and decisions where needed. Declarative RBS: Use .NET attributes to require demands. When you use declarative RBS, you are able to apply numerous attributes that inform the .NET runtime to ensure the current caller is within a specified role before creating a given type or invoking a given member. This approach results in hard-coded assembly metadata, and, therefore, you have fewer ways to customize the process of handling run-time exceptions. For example, assume you have authored a class method that should never be successfully invoked by any user who is not within the built-in NT Administrators role. Using a declarative approach, you would apply the PrincipalPermission attribute to the method as so: [PrincipalPermission(SecurityAction.Demand, Role = @"BUILTIN\Administrators")] private void SomeMethod() { // If we got this far, the user is in the correct role. DoAdminStuff(); } If you would rather take an imperative approach, you gain the capability to monitor access violations gracefully in code via try/catch constructs or simply deny a given course of action. Ponder the following related code example: private void SomeMethod() { // Set the default principal for threads in this appdomain. AppDomain myDomain = AppDomain.CurrentDomain; myDomain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal); barcode font excel, create barcodes in excel 2010, microsoft excel 2007 barcode add in, barcode add in for word and excel 11.10 free download, create barcode in excel, barcode generator excel 2010 freeware, barcode inventory excel program, excel barcode add-in, barcode plugin excel free, barcode add-in for word and excel 2010,( $* ) ( * ) ( * ) ( * ) ( .* ) ( .* ) ( + ) ( + ) This is because we only needed to compile the package body of procedure p1. As long as the package specification does not change (and hence is not recompiled), only the objects depending on the package body get invalidated. In this case, package pkg2 is dependent on the package specification of pkg1. Similarly, pkg3 is dependent on the package specification of pkg2. Hence, they are both still valid. This exercise demonstrates how packages help break the dependency chain and avoid spending precious Oracle resources on unnecessary compilations. Next, we will look at some PL/SQL techniques that can help you write high-performance PL/SQL code. In a previous chapter, you learned about collections. You saw in that chapter why using nested table and varrays as columns in a table is not a good idea in general. However, collections can be very useful when implementing array operations in PL/SQL. This section covers some of these techniques. : 'a * Matrix<'a> -> Matrix<'a> : RowVector<'a> * Matrix<'a> -> RowVector<'a> : Matrix<'a> * Vector<'a> -> Vector<'a> : Matrix<'a> * Matrix<'a> -> Matrix<'a> : Vector<'a> * Vector<'a> -> Vector<'a> : Matrix<'a> * Matrix<'a> -> Matrix<'a> : Vector<'a> * Vector<'a> -> Vector<'a> : Matrix<'a> * Matrix<'a> -> Matrix<'a> // Get the current principal. WindowsPrincipal wp = (WindowsPrincipal)Thread.CurrentPrincipal; // Do 'admin stuff' if caller is in role. if(wp.IsInRole(WindowsBuiltInRole.Administrator)) DoAdminStuff(); } Now, be very aware that ASP .NET web applications also provide an RBS implementation, which is similar (but not identical to) the RBS model you just examined. The bulk collect clause allows you to fetch more than one row of a table into a collection variable in a single statement. Using bulk collect, you reduce the number of server roundtrips because you are fetching more data per round-trip. You will run these examples in Oracle9i, since Oracle 10g automatically bulk fetches 100 rows at a time when you use an implicit for loop cursor (code that looks like for x in ( select * from emp )). Let s look at an example. In the following code snippet, we first create a nested table of varchar2(30): benchmark@ORA92I> create or replace type object_name_list as table of varchar2(30); 2 / Type created. Next, we select ten object names from all_objects into the collection using the bulk collect clause (highlighted in bold) and print them out: benchmark@ORA92I> declare 2 l_object_name_list object_name_list; 3 begin 4 select object_name Scalar-matrix multiplication Vector-matrix multiplication Matrix-vector multiplication Matrix multiplication Pointwise multiplication Pointwise multiplication Pointwise addition Pointwise addition
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