About the Type of Document Storage

For a publishable document type, you can set the storage type to determine how Integration Server and the messaging provider store instances of this document. The storage type also determines how quickly the document moves through the webMethods system. You can select one of the following storage types:

Volatile storage specifies that instances of the publishable document type are stored in memory. Volatile documents move through the webMethods system more quickly than guaranteed documents because resources do not return acknowledgements for volatile documents. (An acknowledgement indicates that the receiving resource successfully stored or processed the document and instructs the sending resource to remove its copy of the document from storage.) However, if a volatile document is located on a resource that shuts down, the volatile document is not recovered when the resource restarts.

Integration Server provides at-most-once processing for volatile documents. That is, document delivery and processing are attempted but not guaranteed for volatile documents. Integration Server might process multiple instances of a volatile document, but only if the document was published more than once. Specify volatile storage for documents that have a short life or are not critical.

Guaranteed storage specifies that instances of the publishable document type are stored on disk. Resources return acknowledgements after storing or processing guaranteed documents. Because guaranteed documents are saved to disk and acknowledged, guaranteed documents move through the webMethods system more slowly than volatile documents. However, if a guaranteed document is located on a resource that shuts down, the resource recovers the guaranteed document upon restart.

webMethods components provide guaranteed document delivery and guaranteed processing (either at-least-once processing or exactly-once processing) for guaranteed documents. Guaranteed processing ensures that once a trigger receives the document, it is processed. Use guaranteed storage for documents that you cannot afford to lose.

Note:
Some Broker document types have a storage type of Persistent. The Persistent storage type automatically maps to the guaranteed storage type in the Integration Server.