Benefits of Using the SharePoint List Object Model and Client Object Model
The following are the benefits of using the SharePoint List and client object models.
· Simple and familiar object model. The SharePoint List object model (SPList class) is simple to work with and is familiar to SharePoint developers.
· Availability. The BDC object model is available on a client only with Office Professional Plus 2010 installed. However, the SharePoint object model is available on both the server and the client.
· Runs in partial trust environment. The SharePoint object model can run in a partially trusted environment. BDC object models cannot.
Limitations of Using the SharePoint List Object Model and Client Object Model
The following are the limitations of using the SharePoint List and Client object models.
· Requires external lists. The SharePoint List and Client object models perform CRUD operations on an external list from the server. Therefore, they require the creation of an external list on the server. The BDC object model does not have this requirement as it performs CRUD operations directly through an external content type.
· Only works for supported simple types. The SharePoint List and Client object models work only if the external list has simple fields. By design, external lists are flat, row-based representations of data. Complex types and simple types that are not supported by the SharePoint List type system are omitted. In particular, you cannot have fields of the following types:
1. Complex types For example, a "CustomerAddress" field as part of the "Customer" structure, which in turn has child elements defining "Street", "City", "State", and "PostalCode".
2. Custom types Example, a "Resume field as part of the "Applicant" structure, which might not have child elements but cannot be represented by using one of the supported SharePoint List field types.
3. Unsupported .NET types The following .NET Framework types are not supported by external lists: System.GUID, System.Object, System.URI, System.UInt64, and System.Int64. Therefore, if one of the fields of the external list are of the .NET Framework types listed here, these fields are omitted.
The BDC object model does not have this requirement and can work with all types of complex fields mentioned here.
· No support for advanced features of BDC. The SharePoint List and Client object models do not have support for the following advanced features supported by the BDC:
1. Paging External lists do not provide paging or chunking of data.
2. Bulk operations External lists cannot perform bulk operations, for example, reading 25 instances simultaneously.
3. Streaming There is no support for streaming data such as binary large objects (BLOBs) from external systems.
4. Complex associations External lists do not support associations.
Things to know when using the List Object Model with External Lists
· BdcIdentity is a field of the SharePoint List object that represents the identity of a specific list item. This is the only deterministic way to uniquely identify a particular list item. You can get it by using the Fields collection of the SPList object. See Code Snippets: Using the SharePoint List Object Model with External Lists on the Server and Code Snippets: Using the SharePoint Client Object Model with External Lists for some examples.
· The ItemID for external list items is always zero. You should use BdcIdentity instead.
· When you use the SharePoint client object model with external lists, you need to remember a few additional things. See Code Snippet: Get Item Data from an External List on the Client for more information.
The following are the benefits of using the SharePoint List and client object models.
· Simple and familiar object model. The SharePoint List object model (SPList class) is simple to work with and is familiar to SharePoint developers.
· Availability. The BDC object model is available on a client only with Office Professional Plus 2010 installed. However, the SharePoint object model is available on both the server and the client.
· Runs in partial trust environment. The SharePoint object model can run in a partially trusted environment. BDC object models cannot.
Limitations of Using the SharePoint List Object Model and Client Object Model
The following are the limitations of using the SharePoint List and Client object models.
· Requires external lists. The SharePoint List and Client object models perform CRUD operations on an external list from the server. Therefore, they require the creation of an external list on the server. The BDC object model does not have this requirement as it performs CRUD operations directly through an external content type.
· Only works for supported simple types. The SharePoint List and Client object models work only if the external list has simple fields. By design, external lists are flat, row-based representations of data. Complex types and simple types that are not supported by the SharePoint List type system are omitted. In particular, you cannot have fields of the following types:
1. Complex types For example, a "CustomerAddress" field as part of the "Customer" structure, which in turn has child elements defining "Street", "City", "State", and "PostalCode".
2. Custom types Example, a "Resume field as part of the "Applicant" structure, which might not have child elements but cannot be represented by using one of the supported SharePoint List field types.
3. Unsupported .NET types The following .NET Framework types are not supported by external lists: System.GUID, System.Object, System.URI, System.UInt64, and System.Int64. Therefore, if one of the fields of the external list are of the .NET Framework types listed here, these fields are omitted.
The BDC object model does not have this requirement and can work with all types of complex fields mentioned here.
· No support for advanced features of BDC. The SharePoint List and Client object models do not have support for the following advanced features supported by the BDC:
1. Paging External lists do not provide paging or chunking of data.
2. Bulk operations External lists cannot perform bulk operations, for example, reading 25 instances simultaneously.
3. Streaming There is no support for streaming data such as binary large objects (BLOBs) from external systems.
4. Complex associations External lists do not support associations.
Things to know when using the List Object Model with External Lists
· BdcIdentity is a field of the SharePoint List object that represents the identity of a specific list item. This is the only deterministic way to uniquely identify a particular list item. You can get it by using the Fields collection of the SPList object. See Code Snippets: Using the SharePoint List Object Model with External Lists on the Server and Code Snippets: Using the SharePoint Client Object Model with External Lists for some examples.
· The ItemID for external list items is always zero. You should use BdcIdentity instead.
· When you use the SharePoint client object model with external lists, you need to remember a few additional things. See Code Snippet: Get Item Data from an External List on the Client for more information.
