free 2d barcode generator asp.net Dealing with Common Information in vb

Printing qrcode in vb Dealing with Common Information

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Services that communicate over HTTP must reside on a Web server in order for their endpoints to be accessible. However, services that communicate over TCP

WHERE Id=@id AND LastChanged=@lastChanged IF @@ROWCOUNT = 0 RAISERROR('Row has been edited by another user', 16, 1) SELECT @newLastChanged = LastChanged FROM Projects WHERE Id=@id RETURN Again, this procedure only updates the record in the Projects table; the related records in the Assignments table are updated separately. Notice the @lastChanged parameter required by the procedure. This represents the last known timestamp value for the row. In 8, you ll see how this value is maintained by the business object. When the object attempts to update the row, it provides the last known value for the LastChanged column. If that value hasn t changed in the database, then no other user has updated the row since the object read its data. But if the value has changed in the database, then some other user did change the data in the row since the object read the data. First-write-wins optimistic concurrency specifies that this second update can t be allowed, because it could overwrite changes made by that other user. The UPDATE statement itself uses this parameter in the WHERE clause to ensure that the row is only updated if the value matches. The procedure then checks to see if the row was actually updated. If no rows were updated, it raises an error, which shows up as a database exception in the data access code of the business object. On the other hand, if the update goes through and the row is changed, then a SELECT statement is executed to return the new value of the LastChanged column as an output parameter, so that the object can maintain the new value to allow possible future updates.

The structure of the Model explains why you need the two for loops to render the whole model. First, you cycle through the ModelMeshes of the Model. Each ModelMesh contains one or more ModelMeshParts, which can all have a different effect. So, you would expect the second for loop to scroll through all ModelMeshParts of the current ModelMesh, setting the parameters of their own effect. However, if multiple ModelMeshParts were to use the same effect, this would cause the same effect to be set twice, which is clearly a waste of time. To avoid this, the ModelMesh keeps track of all unique effects used by its ModelMeshParts. It is this list that is being scrolled through in the second for loop. Finally, after all effects used by a ModelMesh have been configured, you call the Draw method on the ModelMesh object, which causes all ModelMeshParts of the ModelMesh objects to be drawn using their specified effect.

The final object used by Project, ProjectResources, ProjectResource, and Assignment is the RoleList collection. This is a name/value list based on the Roles table from 6. The name (key) values are of type Integer, while the values are the String names of each role. The CSLA .NET framework includes the NameValueListBase class to help simplify the creation of name/value list objects. Such objects are so common in business applications that it is worth having a base class to support this one specialized scenario. 7 includes a template for name/value list classes, and RoleList will follow that template. It includes the Business Methods, Factory Methods, and Data Access regions. The class is declared like this:

You should always explicitly terminate your transactions with a COMMIT or ROLLBACK; otherwise, the tool or environment you re using will pick one or the other for you. If you exit your SQL*Plus session normally, without committing or rolling back, SQL*Plus assumes you wish to commit your work and it does so. If you just exit from a Pro*C program, on the other hand, an implicit rollback takes place. Never rely on implicit behavior, as it could change in the future. Always explicitly COMMIT or ROLLBACK your transactions.

The Three-State workflow is interesting because it is a good example of codifying a generic process but still providing a workflow that can be easily applied to multiple situations. It places only one significant requirement upon the list to which is applied the need for a Choice field with at least three values. While we haven t gotten to workflow forms yet (that s not until 7), this workflow is also a great example of a pretty complex workflow form delivered via ASP.NET. Next up, we ll take a more detailed look at one of the out-of-the-box MOSS workflows.