The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with constrained nodes and constrained (e.g., low-power, lossy) networks. The nodes often have 8-bit microcontrollers with small amounts of ROM and RAM, while constrained networks such as IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs) often have high packet error rates and a typical throughput of 10s of kbit/s. The protocol is designed for machineto-machine (M2M) applications such as smart energy and building automation.

The Constrained Application Protocol (CoAP) is a RESTful application protocol for constrained nodes and networks. The state of a resource on a CoAP server can change over time. This document specifies a simple protocol extension for CoAP that enables CoAP clients to "observe" resources, i.e., to retrieve a representation of a resource and keep this representation updated by the server over a period of time. The protocol follows a best-effort approach for sending new representations to clients and provides eventual consistency between the state observed by each client and the actual resource state at the server.

The reaction of malononitrile or malononitrile dimer (1,1,3-tricyano-2-aminopropene-l) with phenylhydrazine and methylhydrazine is shown to give 1-phenyl-and l-methyl-3-cyanomethyl-4-cyano-5-aminopyrazole (I and XVIII), respectively. The structure of I is established by degradation to l-phenyl-3-methyi-5-aminopyrazole (XIV), and the structure of XVIII is established by degradation to 1,3-dimethyl-4-nitroso-5-pyrazolone (XXIX). These readily available pyrazoles are versatile intermediates for the synthesis of condensed pyrazole heterocycles, including a number of derivatives of 1phenyl-and l-methyl-4-aminopyrazolo [3,4-d]pyrimidine.

Durch Reduktion von Schwefelkohlenstoff mit Kalium in Dimethylformamid und anschlieRende Alkylierung erhalt man die Isotrithione 2, die sich mit Quecksilber(I1)-acetat zu den 1,3-Dithiol-2onen 3 entschwefeln lassen. 2a ist auch iiber mehrere Stufen aus (Methy1thio)dithioessigsauremethylester (6) zuganglich. Die photochemische Decarbonylierung von 4,5-Bis(methylthio)-I ,3dithiol-2-on (3a) liefert Dimethyl-tetrathiooxalat (Ila), das in Losung mit seinem [4 + 2l-Dimeren 13 im Gleichgewicht steht. Cyclische Tetrathiooxalester sind bei Raumtemp. vermutlich instabil. Thiono and Dithio Esters, XXIV') Synthesis of TetrathiooxalatesReduction of carbon disulfide with potassium in dimethylformamide and subsequent alkylation yields the isotrithiones 2, which have been desulfurised with mercury acetate to give the 1,3dithiol-2-ones 3. 2a is also available by a stepwise synthesis starting with methyl (methy1thio)dithioacetate (6). The photochemical decarbonylation of 4,5-bis(methylthio)-1,3-dithiol-2-one (3 a) leads to the formation of dimethyl tetrathiooxalate (lla). In solution I l a is in equilibrium with its [4+ 21 dimer 13. Cyclic tetrathiooxalates are probably unstable at room temperature.Nach der erfolgreichen Darstellung der Dithionoxalester2) ist uns kiirzlich auch die Synthese der bislang unbekannten Tetrathiooxalester auf photochemischem Wege gelungen3). Die hierzu notwendigen Einzelschritte wurden inzwischen so weit optimiert und erganzt, daR Tetrathiooxalester jetzt leicht zuganglich sind.

The Constrained Application Protocol (CoAP), although inspired by HTTP, was designed to use UDP instead of TCP. The message layer of CoAP over UDP includes support for reliable delivery, simple congestion control, and flow control.