18. A system comprising: a computer readable medium including a program product; and one or more processors configured to execute the program product to perform: receiving, concurrently with parsing a structured document, a request from a client to access data in the structured document while the parsing by a computing device is performed serially from a beginning to an end of the structured document, the parsing and producing a data object in a memory which is tree-structured and changes as the parsing progresses; in response to the request, and while the structured document is being parsed, determining that the data is not yet available in a portion of the data object by ascertaining a state of the parsing; and when the data becomes available in the data object, and before the parsing has completed, performing the requested access on the portion of the data object, returning any requested data to the client, and deleting the portion of the data object as parsing progresses.
18. A system comprising: a computer readable medium including a program product; and one or more processors configured to execute the program product to perform: receiving, concurrently with parsing a structured document, a request from a client to access data in the structured document while the parsing by a computing device is performed serially from a beginning to an end of the structured document, the parsing and producing a data object in a memory which is tree-structured and changes as the parsing progresses; in response to the request, and while the structured document is being parsed, determining that the data is not yet available in a portion of the data object by ascertaining a state of the parsing; and when the data becomes available in the data object, and before the parsing has completed, performing the requested access on the portion of the data object, returning any requested data to the client, and deleting the portion of the data object as parsing progresses. 22. The system of claim 18 where the access is one of read access or write access.