Matching in thin labour markets: panel data evidence from Finland, 1991-2002

The matching function that postulates a relationship between the flow of new matches and stock of job seekers and vacancies has attracted considerable attention, both theoretical and empirical during the last decade. In this paper the properties of a matching function are examined by using a large panel data set from Finland. The data has a high frequency and it is highly disaggregated, comprising monthly data on 174 work-to-travel areas from a 12-year period between January 1991 and August 2002. We test for density effects, i.e. the importance of the size of markets on matching efficiency. The robustness and importance of our empirical findings are guaranteed by the quality of data. First the data allows us to model matching functions for two different measures of endogenous variables, namely total matches and total outflow from unemployment. Second, we can measure job seekers by their origin, i.e. whether they are unemployed, employed or outside of the labour force. We can thus construct matching models where the measure of job matches and the pool of job searchers are consistent with each other. Third, the data includes information on the composition of the registered job seekers, including age, sex and the share of short- and long-term unemployment. These controls provide interesting information on possible differences in matching rates by these groups.

Regional Matching Frictions and Aggregate Unemployment

The study shows that a stochastic frontier approach applied to regional level data offers a convenient and interesting method to examine how regional differences in matching efficiency and structural factors contribute to aggregate unemployment. The study finds notable and time-wise stable differences in the matching efficiency across travel-to-work areas in Finland. If all areas were as efficient as the most efficient one, the number of hires would increase about 40 per cent. This would decrease the aggregate unemployment rate from the current 8.5 percent level to 6.0 per cent. If all the areas shared the same structural characteristics as the most favourable area, the aggregate unemployment rate would drop to 7.1 per cent.

An XML Messaging Service for Mobile Devices

In recent years, XML has been accepted as the format of messages for several applications. Prominent examples include SOAP for Web services, XMPP for instant messaging, and RSS and Atom for content syndication. This XML usage is understandable, as the format itself is a well-accepted standard for structured data, and it has excellent support for many popular programming languages, so inventing an application-specific format no longer seems worth the effort. Simultaneously with this XML's rise to prominence there has been an upsurge in the number and capabilities of various mobile devices. These devices are connected through various wireless technologies to larger networks, and a goal of current research is to integrate them seamlessly into these networks. These two developments seem to be at odds with each other. XML as a fully text-based format takes up more processing power and network bandwidth than binary formats would, whereas the battery-powered nature of mobile devices dictates that energy, both in processing and transmitting, be utilized efficiently. This thesis presents the work we have performed to reconcile these two worlds. We present a message transfer service that we have developed to address what we have identified as the three key issues: XML processing at the application level, a more efficient XML serialization format, and the protocol used to transfer messages. Our presentation includes both a high-level architectural view of the whole message transfer service, as well as detailed descriptions of the three new components. These components consist of an API, and an associated data model, for XML processing designed for messaging applications, a binary serialization format for the data model of the API, and a message transfer protocol providing two-way messaging capability with support for client mobility. We also present relevant performance measurements for the service and its components. As a result of this work, we do not consider XML to be inherently incompatible with mobile devices. As the fixed networking world moves toward XML for interoperable data representation, so should the wireless world also do to provide a better-integrated networking infrastructure. However, the problems that XML adoption has touch all of the higher layers of application programming, so instead of concentrating simply on the serialization format we conclude that improvements need to be made in an integrated fashion in all of these layers

XML Messaging for Mobile Devices

In recent years, XML has been widely adopted as a universal format for structured data. A variety of XML-based systems have emerged, most prominently SOAP for Web services, XMPP for instant messaging, and RSS and Atom for content syndication. This popularity is helped by the excellent support for XML processing in many programming languages and by the variety of XML-based technologies for more complex needs of applications. Concurrently with this rise of XML, there has also been a qualitative expansion of the Internet's scope. Namely, mobile devices are becoming capable enough to be full-fledged members of various distributed systems. Such devices are battery-powered, their network connections are based on wireless technologies, and their processing capabilities are typically much lower than those of stationary computers. This dissertation presents work performed to try to reconcile these two developments. XML as a highly redundant text-based format is not obviously suitable for mobile devices that need to avoid extraneous processing and communication. Furthermore, the protocols and systems commonly used in XML messaging are often designed for fixed networks and may make assumptions that do not hold in wireless environments. This work identifies four areas of improvement in XML messaging systems: the programming interfaces to the system itself and to XML processing, the serialization format used for the messages, and the protocol used to transmit the messages. We show a complete system that improves the overall performance of XML messaging through consideration of these areas. The work is centered on actually implementing the proposals in a form usable on real mobile devices. The experimentation is performed on actual devices and real networks using the messaging system implemented as a part of this work. The experimentation is extensive and, due to using several different devices, also provides a glimpse of what the performance of these systems may look like in the future.Matkapuhelimien ja muiden mobiililaitteiden määrä on kasvanut erittäin nopeasti viime vuosina. Laitteiden pieni koko, niiden tarjoamat ohjelmointimahdollisuudet ja langattomat verkkoyhteydet mahdollistavat Internet- ja muiden verkkosovellusten käytön kaikkialla. Akusta johtuva rajallinen käyttöaika, heikko suoritusteho ja verkkokäytön vaatima virta ja aika toimivat kuitenkin selkeinä rajoitteina mobiililaitteiden mahdollisuuksille, ja jotta mobiilimaailma ei joutuisi kokonaan tulevaisuuden Internetin ulkopuolelle, järjestelmien ja sovellusten suunnittelussa on otettava sen erityispiirteet huomioon. Tulevaisuuden verkkosovelluksissa suoran päätelaitteiden välisen viestinnän odotetaan olevan keskeinen osa sovelluksen toimintaa. Nyky-Internetissä tällaisessa viestinnässä käytetään yhä useammin XML-kieltä, joka laajennettavuutensa ja helppokäyttöisyytensä ansiosta vähentää sovelluskehittäjän taakkaa. XML-kielen ongelmina ovat kuitenkin sen vaatimat suuret tiedonsiirto- ja käsittelyajat, jotka ovat olleet esteenä XML:n laajalle käytölle mobiiliympäristöissä. Väitöskirja tutkii XML-pohjaisen laitteiden välisen viestinnän perusedellytyksiä mobiililaitteilla langattomissa verkoissa. Keskeiset tutkimuskohteet ovat tiivis ja tehokkaasti käsiteltävä XML-esitysmuoto, XML:n käsittelyyn paremmin sopivat ohjelmointirajapinnat ja mobiiliympäristön viestiprotokollat. Työn tuloksena on syntynyt mobiililaitteille suunniteltu XML-pohjainen viestintäjärjestelmä, joka on sellaisenaan käytettävissä verkkosovellusten perustana. Järjestelmälle on suoritettu kattavat mittaukset, jotka osoittavat järjestelmän sopivuuden käyttötarkoitukseensa. Tulosten analyysissa otetaan myös huomioon, miten järjestelmän eri ominaisuudet sopivat kuhunkin mobiililaitteiden tukemaan ympäristöön, sekä tarkastellaan, miltä tulevaisuuden mobiililaitteiden suorituskyky saattaisi näyttää

Mobility And Completeness In Publish/subscribe Topologies

The event paradigm and publish/subscribe systems allow clients to asynchronously receive information that matches their interests. The requirements of mobile computing present new challenges pertaining to event delivery that need to be solved. In this paper, we formally examine several state transfer protocols for different pub/sub topologies. The new results of this paper are the cost functions for both subscriber and publisher mobility, and investigation and formulation of completeness of subscriptions and advertisements. The results show that rendezvous points are good for pub/sub mobility, handovers in incomplete topologies are more costly than in complete, and the brokers involved with mobility have no way of detecting completeness based on local information alone

A Sequence-Based Type-Aware Interface for XML Processing

XML has recently made inroads into the data-oriented world of machine-to-machine interaction, most prominently in the form of SOAP and Web services. In this paper we present a new programming interface that views XML documents as sequences of events, and into which awareness of data typing is built in. These two features are intended to make the interface attractive for data-oriented applications that do not use XML internally. Our experience in using this interface in a mobile middleware system indicates that this sequentiality combined with type awareness and properly-layered higher-level interfaces provides a very natural way of handling XML for the data-oriented world

Employment-output link in Finland : evidence from regional data

This study examines the relation between employment and output using panel data on 452 Finnish municipalities regrouped into 85 areas, representing regions at the so called NUTS4 level in the EU. The results imply that: (i) the contemporaneous relation between changes in employment and output growth disappeared in the early 1990s; (ii) there is evidence of a recovery of this relation in the mid 1990s; (iii) there are differences in the employment-output relation between different regions; and (iv) the existing differences can be partly explained by differences in industrial specialisation.

Comparing SOAP Performance for Various Encodings, Protocols, and Connections

SOAP is rapidly gaining popularity as the Web service protocol

Xebu: A binary format with schema-based optimizations for XML data

Abstract. XML is currently being used as the message syntax for Web services. To enable small mobile devices to use Web services, this XML use must not be too resource-consuming. Due to several measurements indicating otherwise, alternate serialization formats for XML data have been proposed. We present here a format for XML data designed from the ground up for the mobile environment. The format is simple, yet gives acceptable document sizes and is efficiently processable. An automaton-based approach gives further improvements when full or partial schema information is available. We provide performance measurements verifying these claims and also consider some issues arising from the use of an alternate XML serialization format