Web Services Workflows—Composition, Co-Ordination, and Transactions in Service-Oriented Computing

Web services can be seen as a newly emerging research area for Service-oriented Computing and their implementation in Service-oriented Architectures. Web services are self-contained, self-describing modular applications or components providing services. Web services may be dynamically aggregated, composed, and enacted as Web services Workflows. This requires frameworks and interaction protocols for their co-ordination and transaction support. In a Service-oriented Computing setting, transactions are more complex, involve multiple parties (roles), span many organizations, and may be long-running, consisting of a highly decentralized service partner and performed by autonomous entities. A Service-oriented Transaction Model has to provide comprehensive support for long-running propositions including negotiations, conversations, commitments, contracts, tracking, payments, and exception handling. Current transaction models and mechanisms including their protocols and primitives do not sufficiently cater for quality-aware and long running transactions comprising loosely-coupled (federated) service partners and resources. Web services transactions require co-ordination behavior provided by a traditional transaction mechanism to control the operations and outcome of an application. Furthermore, Web services transactions require the capability to handle the co-ordination of processing outcomes or results from multiple services in a more flexible manner. This requires more relaxed forms of transactions—those that do not strictly have to abide by the ACID properties—such as loosely-coupled collaboration and workflows. Furthermore, there is a need to group Web services into applications that require some form of correlation, but do not necessarily require transactional behavior. The purpose of this paper is to provide a state-of-the-art review and overview of some proposed standards surrounding Web services composition, co-ordination, and transaction. In particular the Business Process Execution Language for Web services (BPEL4WS), its co-ordination, and transaction frameworks (WS-Co-ordination and WS-Transaction) are discussed.

Theoretical studies of the C60 and alkali metal-containing complexes C60 M

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Comparison of the shape parameters of DNA-cationic lipid complexes and model polyelectrolyte-lipid complexes

In this study, we used a rheological method to study the shape of DNA-cationic lipid complexes and model polyelectrolyte-lipid complexes. We introduced two kinds of anionic polyelectrolytes, sodium polygalacturonate (PGU) and sodium dextran sulfate (DSS), of varying size, as models for DNA. The prepared complexes were incubated under laminar flow conditions. The results show the same quantitative relation between the shape parameter of lipoplexes and the length of anionic polyelectrolytes, including DNA. The rheological behavior of PGU and DSS were similar to that of DNA. (C) 2004 Elsevier Inc. All rights reserved.

Synthesis, Reactivity, and Characterization of Sodium and Rare-Earth Metal Complexes Bearing a Dianionic N-Aryloxo-Functionalized -Ketoiminate Ligand

The synthesis and reactivity of a series of sodium and rare-earth metal complexes stabilized by a dianionic N-aryloxo-functionalized beta-ketoiminate ligand were presented. The reaction of acetylacetone with 1 equiv of 2-amino-4-methylphenol in absolute ethanol gave the compound 4-(2-hydroxy-5-methylphenyl)imino-2-pentanone (LH2, 1) in high yield.

Syntheses, crystal structures and near-infrared luminescent properties of holmium (Ho) and praseodymium (Pr) ternary complexes

A series of near-infrared (NIR) luminescent complexes Ho(dbm)(3)L and Pr(dbm)(3)L [where dbm = dibenzoylmethane; L = 1,10-phenanthroline (phen), 2,2'-bipyridine (bipy), or triphenyl phosphate oxide (TPPO)] were synthesized. Their elemental analyses, crystal structures, fluorescence spectra and luminescent lifetimes were successfully investigated.

Synthesis and characterization of titanium complexes bearing two beta-enaminoketonato ligands with electron-withdrawing groups and their behavior in ethylene polymerization

A series of new titanium complexes with two asymmetric bidentate beta-enaminoketonato (N,O) ligands (4b-t), [RN=CCF3)CHC(t-BU)O](2)TiCl2 (4b, R = -C6H4F(o); 4c, R = -C6H4F(m);4d, R = -C6H4F(p); 4e, R = - C6H3F2(2,3); 4f, R = -C6H3F2(2,4); 4g, R = -C6H3F2(2,5); 4h, R = -C6H3F2(2,6); 4i, R = -C6H3F2(3,4); 4j, R = -C6H3F2(3,5); 4k, R = -C6H2F3(2,3,4); 4l, R = -C6H2F3(3,4,5); 4m, R = -C6H4CF3(o); 4n, R =-C6H4CF3(m); 4o, R = -C6H4CF3(p); 4p, R = -C6H4Cl(p); 4q, R = -C6H4I(p); 4r, R = -C6H4NO2(P); 4s, R = -CH2C6H5; 4t, R = -C6H11), have been synthesized and characterized.

The nanocomposite scaffold of poly(lactide-co-glycolide) and hydroxyapatite surface-grafted with L-lactic acid oligomer for bone repair

Nanohydroxyapatite (op-HA) surface-modified with L-lactic acid oligomer (LAc oligomer) was prepared by LAc oligomer grafted onto the hydroxyapatite (HA) surface. The nanocomposite of op-HA/PLGA with different op-HA contents of 5, 10, 20 and 40 wt.% in the composite was fabricated into three-dimensional scaffolds by the melt-molding and particulate leaching methods. PLGA and the nanocomposite of HA/PLGA with 10 wt.% of ungrafted hydroxyapatite were used as the controls. The scaffolds were highly porous with evenly distributed and interconnected pore structures, and the porosity was around 90%. Besides the macropores of 100-300 mu m created by the leaching of NaCl particles, the micropores (1-50 mu m) in the pore walls increased with increasing content of op-HA in the composites of op-HA/PLGA. The op-HA particles could disperse more uniformly than those of pure HA in PLGA matrix. The 20 wt.% op-HA/PLGA sample exhibited the maximum mechanical strength, including bending strength (4.14 MPa) and compressive strength (2.31 MPa). The cell viability and the areas of the attached osteoblasts on the films of 10 wt.% op-HA/PLGA and 20 wt.% op-HA/PLGA were evidently higher than those on the other composites.

In vivo mineralization and osteogenesis of nanocomposite scaffold of poly (lactide-co-glycolide) and hydroxyapatite surface-grafted with poly(L-lactide)

Nanocomposite of hydroxyapatite (HAP) surface-grafted with poly(L-lactide) (PLLA) (g-HAP) shows a wide application for bone fixation materials due to its improved interface compatibility, mechanical property and biocompatibility in our previous study. In this paper, a 3-D porous scaffold of g-HAP/poly (lactide-co-glycolide) (PLGA) was fabricated using the solvent casting/particulate leaching method to investigate its applications in bone replacement and tissue engineering. The composite of un-grafted HAP/PLGA and neat PLGA were used as controls. Their in vivo mineralization and osteogenesis were investigated by intramuscular implantation and replacement for repairing radius defects of rabbits. After surface modification, more uniform distribution of g-HAP particles but a lower calcium exposure on the surface of g-HAP/PLGA was observed. Intramuscular implantation study showed that the scaffold of g-HAP/PLGA was more stable than that of PLGA, and exhibited similar mineralization and biodegradability to HAP/PLGA at the 12-20 weeks post-surgery.