Meaning of diffgram in ASP.Net

Question

What is meant by diffgram in ASP.Net

Satyapriya Nayak · Answer

Hi Monika A DiffGram is an XML format that is used to identify current and original versions of data elements. The DataSet uses the DiffGram format to load and persist its contents and to serialize its contents for transport across a network connection. When a DataSet is written as a DiffGram it populates the DiffGram with all the necessary information to accurately recreate the contents though not the schema of the DataSet including column values from both the Original and Current row versions row error information and row order. When sending and retrieving a DataSet from an XML Web service the DiffGram format is implicitly used. Additionally when loading the contents of a DataSet from XML using the ReadXml method or when writing the contents of a DataSet in XML using the WriteXml method you can select that the contents be read or written as a DiffGram. The DiffGram format is divided into three sections: the current data the original (or before) data and an errors section as shown in the following example. xmlns:msdata=urn:schemas-microsoft-com:xml-msdata xmlns:diffgr=urn:schemas-microsoft-com:xml-diffgram-v1 xmlns:xsd= http://www.w3.org/2001/XMLSchema > The DiffGram format consists of the following blocks of data: The name of this element DataInstance is used for explanation purposes in this documentation. A DataInstance element represents a DataSet or a row of a DataTable. Instead of DataInstance the element would contain the name of the DataSet or DataTable. This block of the DiffGram format contains the current data whether it has been modified or not. An element or row that has been modified is identified with the diffgr:hasChanges annotation. This block of the DiffGram format contains the original version of a row. Elements in this block are matched to elements in the DataInstance block using the diffgr:id annotation. This block of the DiffGram format contains error information for a particular row in the DataInstance block. Elements in this block are matched to elements in the DataInstance block using the diffgr:id annotation. Thanks

Hemant Kumar · Answer

DiffGram: The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service. ADO.NET introduced the DataSet class to support the disconnected distributed data-access scenarios. With DataSet the data retrieved from the database is cached in-memory in addition to the constraints and relationships among the tables. When the ADO.NET DataSet is serialized as XML (for example when returning a DataSet from an ASP.NET XML Web service method) the XML format used for DataSet serialization is known as DiffGram. Like Updategrams DiffGrams also contains the tags that specify the original and new state of data. SQLXML and .NET Managed classes can be used to execute DiffGrams to perform the database updates however there are many things that are supported by Updategrams and not by DiffGrams (ability to pass parameters being one example).