Schema data type

Schemas are a newer development on the XML landscape. Like a DTD, a schema supplies the rules for building a document and indicates what tags may be used, what their attributes are, and how they relate to one another. Unlike a DTD, however, a schema has an additional level of specificity in that it can define data types. For example, a DTD might have a tag designated as , the content of which might be either numerical or a character string. A schema, by contrast, could ensure that the value entered was a number. This is clearly an appealing feature for the pharmaceutical industry, especially in the case of information exchange between databases or other applications making use of rigidly defined data types.

The first step of the wrapper development process is to understand the given COM interface of a tool to be wrapped on the syntactical level. Therefore, its type hbrary is parsed and transformed, into a language-independent graph model, according to the schema in Fig. 5.60. Language independence is achieved, for example, by mapping specific COM data types to general ones. 

Schema evolution primitives in the SQL language and in commercial DBMS are atomic in nature. Unless there is a proprietary extension to the language, each statement describes a simple change to a schema. For instance, individual tables may be added or dropped, individual columns may be added or dropped from a table, and individual constraints may be added or dropped. Additionally, individual properties of a single object may be changed so, one can rename a column, table, or constraint one can change individual properties of columns, such as their maximum length or precision and one can change the data type of a column under the condition that the conversion of data from the old type to the new type can be done implicitly.

It is not possible to propose a schema with tables that can accommodate experimental results of any type. It is important to consider the needs of each project and assay so that appropriate tables can be created with the necessary data types and constraints. One common feature of any table of experimental data is a column containing a reference to a chemical compound or compounds involved in the experimental measurement. While the examples so far have considered only one compound for each test result row, it is important to consider how results will be handled when multiple compounds are involved in each experimental measurement, or when multiple measurements are made for the same compound with samples prepared at different time or perhaps in different ways. A common way to handle these situations is to use the concept of a sample. 

Besides these, most DBMSs provide interfacing mechanisms with which developers can implement applications in a general-purpose language (referred to in this context as a host language) and use the latter to invoke whatever operations are supported over the stored data (because they are part of the behavior of either the data types made available by the data model or the application types declared in the application schema). 

For exampie, a singie document may use namespaces to take eiement definitions from more than one schema, with each eiement being vaiidated against the appropriate schema. Schemas aiso ailow eiement content to be restricted to specified data types (string, booiean, decim number, etc.). Ai-though the Worid Wide Web Consortium has issued a specification for XML schemas, other schema ianguages are aiso used. 

To illustrate how we model the data types of generic components, we show below the model for the ADDER component of the quadratic solver. It is a straightforward translation of the Ada code to Z. The DATA PACKET TYPE is a record (schema) that includes the parameter and the components of the Ada record. The predicate (invariant) of the schema defines the range restriction in the declaration of the type. 

More interesting is the model of the OUTPUT MANAGER, which embodies the structures that allow the data configuration. This model, except in its dependency on the definitions of the DATA-PACKET-TYPE schemas for each of the generic components, is the same for all deployments. This is the most complex part of the model, but since the output manager is a generic component, what we have is a DATA-PACKET-TYPE record. 

The data types used in the reference schema definition have to be mapped onto FORTRAN capabilities. For example, the representation of STRUCTURE, LIST, IDENTIFIER, REFERENCE, and the others must be defined in terms of INTEGER, REAL, ARRAY etc.. 

A library of operations to manipulate the data modeled by the schema. This library includes operations on standard mathematical data types (e.g. matrix multiplication)... 

Figure 5 Sample database schema. A database schema shows the types and nature of links between different types of data. Each box represents a table within the database. The rows within that box correspond to the fields of the table. The lines connecting the boxes identify the required relationships amongst the different types of data stored in the different tables.

Fig. 3. Property of gene delivery with BLs and US exposure (a) Schema of transfection mechanism by BLs and US. The mechanical effect based on the disruption of BLs by US exposure, which results in generation of some pores on plasma membrane, is associated with direct delivery of extracellular plasmid DNA into cytosol, (b) Luciferase expression in COS-7 cells transfected by BLs and US. COS-7 cells (1x10 cells/500 pLAube) were mixed wifh pCMV-Luc (5 pg) and BLs (60 pg). The cell mixture was exposed with US (Frequency 2 MHz, Duty 50%, Burst rate 2 Hz, Intensity 2.5 W/ cm. Time 10 s). The cells were washed and cultured for 2 days. Affer fhaf, luciferase acfivify was measured, (c) Effecf of US condition on transfection efficiency with BLs. COS-7 cells were exposed with US (Frequency 2 MHz, Duty 50%, Burst rate 2 Hz, Intensity 2.5 W/cm Time 0,1, 5,10 s) in the presence of pCMV-Luc (0.25 pg) and BLs (60 pg). Luciferase activity was measured as above, (d) Effect of serum on transfection efficiency of BLs. COS-7 cells in the medium containing EBS (0,10, 30, 50% (v/v)) were treated with US (Erequency 2 MHz, Duty 50%, Burst rate 2 Hz, Intensity 2.5 W/cm, Time 10 s), pCMV-Luc (0.25 pg) and BLs (60 pg) or transfected with lipoplex of pCMV-Luc (0.25 pg) and lipofectin (1.25 pg). (e) In vitro gene delivery to various types of cell using BLs and US. The method of gene delivery was same as above. S-180 mouse sarcoma cells, Colon26 mouse colon adenocarcinoma cells, B16BL6 mouse melanoma cells, Jurkat human T cell line, HUVEC human umbilical endothelial cells. Luciferase activity was measured as above. <10 RLU/mg protein, <10 RLU/mg protein Each data represents the mean S.D. n=3). L PEG-liposomes, LF Lipotectin...

An object model-based query interface to ArrayExpress is being developed. The Web interfaces for predefined types of queries will be provided on top of the general query mechanism. For the database to be used for efficient data mining and interactive visualization, extensive optimization may be required, e.g., by tuning of table indexing or producing a denormalized database schema for some parts of the database. 

In general, each class corresponds to a type in an XML schema with an element and a key. Attributes correspond to nested elements, while associations map to key references. The refactoring operation above therefore results in removing the nested element from the Employee type, creating a new type and element with a key for Department, and a key reference between the two types. An XSLT stylesheet is also generated to migrate data to ensure Department data is not lost. 

These works represent the type of focus on schema merging present in the more recent view integration literature. After this point, more of the database research in schema merging came from data integration (Sect. 4) and generic schema management (Sect. 6). 

In Proceedings BTW Conf., Aachen, pp 449 164 Lenzerini M (2002) Data integration A theoretical perspective. In PODS. ACM, NY, pp 233-246 Lemer BS (2000) A model for compound type changes encountered in schema evolution. TPCTC 25(1) 83-127... 

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