1. A computer program product encoded on a tangible, non-transitory, machine-readable storage device for, providing message-based services using a service-oriented methodology, the medium comprising: program code for implementing a project management deployment unit including: a project request business object is used to simulate several alternative project setups; a project business object is characterized by a unique set of conditions and structured by phases and tasks; a project snapshot business object is a copy of the whole project at a certain point in time; a project simulation business object is used to find out about the effect of changes on an operational project; a project purchase request business object is used to monitor procurement documents; and a project template business object is used for standardizing a new project execution; wherein the project management deployment unit further includes instructions for executing service operations including: a change project based on purchase request confirmation operation operable to send a confirmation to a requester of the extent to which a requisition has been fulfilled; a change project based on purchase order operation operable to notify the project about the creation of a purchase order for an external resource; a change project based on employee time calendar operation operable to send a confirmation of working time for a project task; a check task availability for accounting operation operable to notify of task availability; a request service operation operable to request a buyer to procure external resources or services; a notify of project operation operable to inform accounting about a creation or change of project elements; a request project cost estimate operation operable to inform accounting about a creation or change of project elements that are costing relevant; a request project cost estimate simulation operation operable to request to perform a synchronous project costing simulation; and a query project cost estimate operation operable to query costing for the last costing result for project elements; program code for implementing a financial accounting deployment unit including an overhead cost sheet object including a set of rules for the calculation of overhead charges, a time based accrual business object including the specification for accrual methods, an overhead cost assessment rule business object used for the assessment of overhead cost to the proper originators, an accounting view on project business object representing the project structure in financials, a general ledger account distribution run business object including an automatic periodically-executed rule-based posting assistant, an overhead cost ledger account overhead cost calculation run business object including an automatic calculation run to calculate and post the overhead costs at period end, an overhead cost assessment run business object including an automatic rule-based calculation of collected amounts and quantities in overhead cost ledger accounts based on key figures or keys, an accounts receivable payable ledger account foreign currency re-measurement run business object including an automatic period-end re-measurement of foreign currency amounts, a work in process clearing run business object including an automatic clearing of work in process at period end, a sales ledger account business object including a view of sales activities defined for financial accounting purposes, a production ledger account overhead cost calculation run business object including an automatic calculation run to calculate and post the overhead costs at period end, a sales ledger account overhead cost calculation run business object including an automatic calculation run to calculate and post the overhead costs at period end, a fixed asset depreciation run business object including an automatic depreciation of asset values for a set of fixed assets, a balance carry forward run business object including an automatic carry forward of year end balances for all general ledger accounts and fixed assets to the following fiscal year, an inventory price change run business object including a change to the inventory price, an accounts receivable payable ledger account regrouping run business object including an automatic transfer posting of valuated receivables and payables for a set of accounts receivable payable ledger accounts, an accounting entry business object used to directly enter business transactions in financial accounting, an accounting document business object representing a business transaction in financial accounting, a goods receipt invoice receipt clearing run business object including an automatic calculation of price variances between the valuated goods received and the related invoice received at period end, an overhead cost distribution run business object including an automatic periodically-executed rule-based posting assistant, a general ledger account assessment run business object including an automatic rule-based calculation of collected amounts and quantities in general ledger accounts, an other direct cost ledger account including a record of debit and credit entries showing an effect of business transactions on costs as a result of a particular job or activity, an accounting notification business object including a common input channel for all kinds of operational business transactions into financial accounting, a sales ledger account accruals run business object including an automatic valuation of sales transactions for a set of sales ledger accounts at period end, an accounting adjustment run business object including an automatic valuation of a set of ledger accounts, an accounts receivable payable ledger account discounting run business object including an automatic discounting of valuated payables and receivables, a cash ledger account foreign currency re-measurement run business object including an automatic re-measurement of foreign currency amounts, a purchase ledger account business object including a view of purchasing activities defined for financial accounting purposes, a cash ledger account business object including a record of the valuated liquid assets of a company, a material ledger account business object including a record of materials assets in a company that are relevant to valuation, a production ledger account business object including a view of production related business transactions defined for financial accounting purposes, a chart of accounts business object used to chart account status, a general ledger account business object including a view of the value of assets, liabilities, equity, revenues and expenses for financial accounting purposes, an overhead cost ledger account business object including a record of the costs incurred by the provision of resources, a fixed asset business object including a view of one or more objects, rights, or other items owned by the enterprise that is intended for long-term use, a tax ledger account business object including a summary of tax liabilities defined for financial accounting purposes, an accounts receivable payable ledger account business object including a record of valuated payables and receivables of a company for a specific business partner, a project cost estimate business object including a listing of the elements of a project that incur costs, a service product valuation data business object representing internal prices for valuation of business transactions related to a service product or a service product group and for cost estimation, a material valuation data business object representing internal prices for the valuation of business transactions related to a material or a material group, for material inventory valuation and for cost estimation, a resource valuation data business object representing internal prices for the valuation of business transactions related to a material or a material group, for material inventory valuation and for cost estimation, an overhead cost scheme business object representing a set of rules for the calculation of overhead charges, a financial accounting view of project business object representing a financial accounting project and its structure, an overhead cost assessment rule business object specifying costs to be allocated and the assessment base to calculate charges, a general ledger account balance distribution run business object specifying balances accrued on profit and loss and balance sheet accounts to be distributed, a time based accrual business object representing an assignment of revenues or expenses relating to services provided over a period to the correct periods in terms of accepted accounting practice, and a material cost estimate business object including a listing of the elements involved in the procurement or production of a material that incur costs, wherein the financial accounting deployment unit further includes instructions for executing service operations including: a create accounting entry operation operable to receive an accounting document from another instance of accounting; a maintain subledger account operation operable to receive a project accounting notification from project processing; a create accounting document operation operable to receive an expense accounting notification from expense and reimbursement processing; a synchronous valuate product and resource operation operable to synchronize access to price information for products; a maintain project cost estimate operation operable to inform costing document processing about the creation or change of project elements that are costing relevant; a cancel accounting document operation operable to receive an expense accounting notification from expense and reimbursement processing; and a simulate project cost estimate operation operable to request performance of a synchronous project costing simulation and response; wherein each of the said project management and financial accounting deployment units are deployable and executable.