M.-S. Chen et al. (Eds.): MDM 2003, LNCS 2574, pp. 212-229, 2003.
Springer-Verlag Berlin Heidelberg 2003
Policy-Driven Binding to Information Resources in
Mobility-Enabled Scenarios
Paolo Bellavista 1, Antonio Corradi 1, Rebecca Montanari 1, Cesare Stefanelli 2
1
Dipartimento di Elettronica, Informatica e Sistemistica
Università di Bologna
Viale Risorgimento, 2 - 40136 Bologna - Italy {pbellavista, acorradi, rmontanari}@deis.unibo.it
2Dipartimento di Ingegneria
Università di Ferrara
Via Saragat, 1 - 44100 Ferrara - Italy cstefanelli@ing.unife.it Abstract. The widespread diffusion of mobile computing and of portable devices with wireless connectivity identifies new challenging scenarios for the Internet provisioning of information services. The possible mobility of users,terminals, and even middleware/service components requires solutions to handle properly the links to information resources in response to the mobile entity migration. Binding decisions may depend on dynamic deployment conditions, e.g., local availability of resources, user preferences, and terminal hardware/software characteristics, and should be determined at service provision time. There is the need for novel middlewares capable of supporting mobility-enabled resource binding and of cleanly separating the application logic from binding strategies. The paper presents a middleware, called SCaLaDE, that supports the accessibility of mobile users/terminals to information services. SCaLaDE provides mobile clients with mobile agent-based proxies that can follow the user/terminal roaming and have their resource references transparently accommodated by the middleware depending on policy-driven binding strategies expressed in a high-level specification language and separated from the application logic. This separation of concerns is crucial to reduce the complexity and leverage the development of mobility-enabled information services.
1. Introduction
The ubiquitous availability of Internet points of attachment and the growing market of mobile devices with wireless connectivity present new challenging scenarios for service provisioning in contexts of mobility. Mobility-enabled services require to re-think and to re-design traditional middleware solutions to accommodate effectively the increased dynamicity stemming from the possible mobility, the temporary disconnection and the wide heterogeneity of client users/terminals [1, 2].
On the one hand, mobility encourages the development and deployment of new classes of information services that can take into account the relative position of users,
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 213 service components and available resources. For instance, a city guide assistance service should dynamically retrieve maps, audio descriptions, and detailed textual information about the buildings and restaurants close to the current physical position of the user. In the following, we will call location-dependent the information services that provide results also determined by the physical position of the user/device point of attachment to the network and by the consequent direct accessibility to the locally available set of information resources.
On the other hand, the enlarging market of portable devices is stressing the asymmetry between the resource availability (in terms of memory, computing power, network bandwidth, ...) at the client side and at the server side. Service provisioning to portable devices should consider the strict limitations on their hardware/software characteristics and their wide heterogeneity. For instance, a tourist equipped with a portable device would like to access information about the nearby artworks; already available Web services can provide very detailed multimedia tourist information that should be downscaled to fit the bandwidth and visualization capabilities of the portable device.
All the above requirements call for novel middlewares with increased dynamicity, capable of activating hosts in the Internet infrastructure to support mobility-enabled service provisioning [3, 4]. Few solutions are starting to explore active middleware components that can be deployed at service provision time to act over the fixed network on behalf of users/devices. The middleware components can perform both application-independent operations, e.g., dynamic installation and disconnection support, and application-specific ones, e.g., service configuration and tailoring. Recent research activities are recognizing the relevance of implementing middleware components as mobile entities that follow the client movements to offer the needed support only where and when needed [2, 5]. Mobile middleware components can operate autonomously to carry on service requests even in case of temporary device disconnection, can support location-dependent service provisioning, and can adapt service results to fit specific device characteristics.
It is also crucial to provide middleware solutions to handle properly the links to information resources in response to the migration of mobile users, terminals, or middleware/service components. Anytime a mobile entity changes its location, it is necessary to adopt a suitable strategy to update its references to the needed information resources: a mobile entity could take the needed resources (or their copies) with itself; or it could transform its references to resources in the origin locality into remote resource references when re-connected at the destination locality; or it could re-qualify its old resource bindings to new suitable resources in the new hosting locality. The choice of the most proper re-binding strategy requires the visibility of the location of mobile users/terminals and information resources; in addition, it may depend on dynamic deployment conditions and, therefore, should be decided only at service provision time.
The paper claims the need for novel location-aware middlewares capable of supporting the flexible binding of mobility-enabled services to information resources and of cleanly separating the application logic of information services from the binding strategies. This separation of concerns is crucial to reduce the complexity and leverage the development of mobility-enabled information services in different, statically unknown, usage scenarios. To this purpose, the paper proposes to separately
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specify binding strategies via high-level policies, which can be modified, deployed and activated dynamically with no impact on the implementation of service components.
We have designed and implemented a middleware, called SCaLaDE (Services with Context awareness and Location awareness for Data Environments), that supports the accessibility of mobile users/terminals to information services. SCaLaDE provides mobile clients with location-aware proxies, implemented as Mobile Agents (MAs), that can follow the user/terminal roaming and have their resource bindings accommodated after migration depending on location-dependent policies expressed via a declarative policy language. The paper specifically focuses on how different resource binding strategies are supported in SCaLaDE as the result of the dynamic enforcement of different policies.
The rest of the paper is structured as follows. Section 2 presents several usage scenarios that show the need for different re-binding strategies depending on dynamic deployment conditions. Section 3 gives a general SCaLaDE overview, by concentrating on the middleware components for the MA binding management and the policy enforcement. Section 4 shows how SCaLaDE can support the usage scenarios sketched in Section 2 via the enforcement of declarative resource binding policies, by showing the improved flexibility, dynamicity and re-usability deriving from a policy-based approach. Related work, lessons learned and directions of on-going work end the paper.
2.Possible Usage Scenarios for Mobility-Enabled Information
Services
Both in the case that a mobile user/terminal accesses resources directly and in the case it exploits the mediation of a mobile proxy hosted in the fixed network infrastructure, mobility-enabled services impose to face the issues of managing the bindings of mobile entities to the needed information resources. In the following, for the sake of simplicity, we will always refer to service architectures where mobile terminals directly access information resources. The same discussion on resource binding applies, with very slight modifications, to novel service architectures where mobile proxies access the resources and roam in the distributed system in response to the movement of the mobile users/terminals they are working for [6].
A mobile terminal MT can refer information resources through various types of binding, each type describing how the MT mobility impacts on its bounded resources. It is possible to identify four possible binding strategies [7]:
?resource movement strategy. In this case, when MT moves, its bounded information resources are moved along with it. Obviously, this type of binding is possible only if the resource transfer is technically/semantically possible, and requires to handle properly the modifications of other possible client bindings to the moved resources;
?copy movement strategy. When MT changes its point of attachment, copies of its bounded resources are instantiated and transferred along with it. This type of binding is permitted only if the resource copy is technically/semantically possible,
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 215 and may require to merge the updates and to resolve conflicts in case of concurrent modifications on multiple resource copies;
?remote reference strategy. This strategy requires to modify MT resource bindings after its migration to refer remotely the resources, which are not moved from the source location. Any MT operation on bounded resources requires a network communication with the remote execution environments hosting the information resources;
?rebinding strategy. In this case, the MT movement has to trigger a re-establishment of bindings to equivalent resources available in the new locality of attachment. This strategy can apply not only in case of by-type bindings [8] but also anytime MT is interested in accessing already existing disseminated instances of information resources, whose content possibly depends on the instance location.
The above classification for resource binding types is well recognized in the mobile objects/agents domain where different research activities have proposed similar classifications, with minor differences and variations of the names associated to binding types [8-10].
Let us start to examine the specific issues related to information resource binding in contexts of mobility by presenting some different usage scenarios that point out how the most suitable binding strategy often depends on dynamic deployment conditions.
https://www.doczj.com/doc/d415764832.html,age Scenario 1: On-Board Resources
Suppose that MT is a fully-equipped laptop with no strict constraints on locally available resources, from free space on the file system to memory resources and computing capabilities. MT can decide to move/copy a data resource DR (or a part of it) on-board and work in a completely local way (resource/copy movement). This enables MT to operate on DR also when MT is disconnected from the network. In particular, in case of multiple clients working with write permissions on their local DR copies, a copy/movement strategy requires to merge the updates and to resolve possible conflicts when DR copies are concurrently modified by multiple clients.
The resource/copy movement strategies can be suitable if the information service has to support disconnected operations or if the costs associated to the network traffic of DR migration are less than the ones due to the sequence of service requests/replies between MT and DR in its original location. However, depending on dynamic deployment conditions, moving/copying DR can be either unsuitable or not absolutely feasible. For instance, if MT is going to move close to the DR position, it can be unsuitable to move/copy DR on-board. Or, if MT is a limited portable device with no storage resources (or MT currently has insufficient free space on its file system) it is not possible to enforce the resource/copy movement strategies.
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https://www.doczj.com/doc/d415764832.html,age Scenario 2: Moving Resources Locally to the Client
If MT is a wireless personal digital assistant or a smart phone with strict limitations on local computing resources and connectivity bandwidth, it should move/copy DR close to its current point of attachment to the network and access DR by maintaining a remote reference to it. By presuming co-location of MT and DR, MT can perform operations on data also in case of network partitioning between the current MT locality and the original DR position; however, this imposes MT to maintain a continuous connection to the network.
Similarly to the previous scenario, the suitability of a remote reference strategy in conjunction with the resource/copy movement towards the current MT locality in place may depend on dynamic deployment conditions. For instance, it is influenced by network-specific deployment conditions such as the possible high heterogeneity in the average network bandwidth available for MT local connections vs. MT remote connections: if MT remote connections are significantly more expensive than local ones and MT is expected to interact several times with DR for a long interval, then moving/copying DR can be preferred. In addition, the binding type decision should take into consideration application-specific expected client behavior, possibly determined by the past history of the user interaction with the service. If one client exhibits a high ratio of writing/reading operations, then the access to DR via a remote reference can be convenient to avoid the overhead needed to resolve possible conflicts among concurrent modifications.
https://www.doczj.com/doc/d415764832.html,age Scenario 3: Location-Dependent Information Services
Novel location-aware information services should provide mobile clients with results that depend on client position. For instance, a location-aware movie-info service should provide data (title, director, main actors, theatre, starting hour, trailer, place availability, ...) about the movies shown in the theatres in the area where MT is currently located. In this scenario, information services can deploy different instances of the same type of information resources in the different localities, each instance of resource with the specific data related to its locality. The resources can be considered different and type-equivalent local instances (they usually have the same format, or are expressed according to well-know common rules). In this case, the expected binding strategy is to reconnect MT to the locally equivalent information resources anytime MT changes its locality.
This requires not only to sense the MT disconnection/reconnection to the network as in the two previous scenarios, but also to organize the network topology in disjoint localities in order to track inter-locality MT movements. In addition, the rebinding strategy can significantly benefit from naming solutions, such as discovery-based naming services, that are capable of maintaining information (address and simple configuration data) about resource availability with a local visibility scope and by imposing minimal client-side knowledge about the current hosting environment.
Let us observe that the rebinding strategy can also require to choose among different local instances of information resources, available in the MT locality and all compatible with the MT rebinding needs. In fact, the local resource to rebind can be
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 217 identified not only on the basis of simple description attributes, e.g., its type identifier, but also depending on even complex application-specific information and terminal profile of characteristics. For instance, a location-aware information service can provide different resource instances, each one with a different version of data. Any copy represents a differently downscaled version suitable for the access of a specific category of device. In the movie-info service example, there could be different versions for any local database instance, one that includes full movie information, one that does not include multimedia trailers, and one with only textual information; in addition, there could be different versions of the same content expressed in different languages. The middleware should rebind MT to the most suitable resource instance depending on MT hardware/software capabilities and on the preferred language specified by the currently logged user. Such a scenario for the rebinding strategy calls for interoperable formats to describe information resources, terminal profiles and user preferences, and requires to evaluate all these metadata to perform the most suitable rebinding at any MT change of locality.
The above scenarios point out that the decision of the most suitable strategy for the MT binding to information resources requires to evaluate different (and possibly complex) system conditions during service provisioning and anytime MT changes its point of attachment in the distributed system. Putting these evaluations within the service application code forces service developers to have a deep knowledge of even low-level characteristics of the deployment environment and can make the development of mobility-enabled information services extremely complex, long and error-prone.
3.SCaLaDE
SCaLaDE is a novel middleware that supports the provisioning of both traditional Web services and new location-dependent ones to wireless portable devices. The design of SCaLaDE is centered on the distributed deployment of active middleware proxies over the fixed network to support mobility-enabled service scenarios. These proxies dynamically extend the Internet infrastructure, where and when needed, to adapt services to user preferences and system conditions and to perform the needed service configuration/management operations suited to a wide variety of highly heterogeneous client devices. In particular, SCaLaDE provides any portable device with a shadow proxy that is designed to discover service components, to possibly negotiate service tailoring to fit device characteristics, to act on behalf of the device in case of disconnection, and to possibly follow the device movements among network localities by maintaining the session state. The adoption of shadow proxies emphasizes our choice of handling location-awareness at the middleware level to simplify the management of location visibility and of location-dependent service adaptation. Exporting location-awareness management up to the application-level could impose a significant extra-burden to service developers.
We have designed and implemented SCaLaDE middleware proxies in terms of Mobile Agents (MAs) to achieve the crucial properties of mobility, asynchronicity and
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autonomy. MAs can act as autonomous entities with a large capacity of coordination, able to dynamically move, together with their code and reached execution state, where the needed resources are located, and able to operate asynchronously to their launching users/devices [2]. In addition, the MA programming paradigm is typically location-aware and MAs have visibility of their execution environment to adapt their actions, primarily their migration, to the position of needed resources.
As a distinguishing feature, SCaLaDE supports the dynamic programmability of binding strategies for shadow proxies. This means that binding strategies can be defined and changed even at run time without any impact on proxy implementation. Toward this goal SCaLaDE adopts a policy-based model: choices in the type of binding between proxies and needed resources are expressed through declarative policies, separated from the middleware proxy code. In particular, binding policies define the circumstances that trigger a binding change for an MA-based proxy, e.g., from the remote reference strategy to the resource movement one, the new type of binding to exploit, and the dynamic conditions that must hold in the deployment environment for resource binding adaptation to take place.
3.1.Resource Binding in SCaLaDE
The proposed middleware for portable devices is implemented on top of the Secure and Open Mobile Agent (SOMA) framework that provides a wide range of support facilities for MA applications, from basic facilities, such as agent naming, communication, migration, to advanced facilities to achieve proper levels of agent security and interoperability. In particular, SOMA execution environments for MAs are called places and several places are grouped into domains that usually correspond to a network locality [11].
SCaLaDE shadow proxies are implemented by SOMA agents. With a finer degree of details, a shadow proxy is implemented by one SOMA agent running on a place in the SOMA domain where the portable device is currently located. Several shadow proxies for different devices can execute concurrently on the same place without interference because the SOMA platform provides isolated execution environments with separated security domains for the different agents.
SCaLaDE complements the SOMA environment with the facilities required to support adaptive binding to resources, whereas it exploits the SOMA support facilities for the execution and migration of SCaLaDE middleware proxies. In particular, the new facilities integrated on top of SOMA include a Binder facility responsible for managing the bindings between incoming MA-based proxies and resources, and a set of policy-enforcement facilities enabling Binder to perform data space management operations accordingly to desired binding strategies (see Section 3.2).
The Binder facility mediates proxy access to resources and dynamically adapts the set of proxy bindings accordingly to the desired strategies. In particular, at start up, SCaLaDE proxies can refer only to the Binder facility without any direct access to resources. At the first resource request, proxies receive from Binder a resource descriptor, i.e., an object that has the same methods and constructor interface of the needed resource. Afterwards, SCaLaDE proxies can operate on resources directly via the obtained resource descriptors.
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 219
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Figure 1. The internal structure of proxy bindings to resources in SCaLaDE.
Currently, SCaLaDE supports policy-driven resource binding only for application-level resources, e.g., database objects, whereas it adopts a default binding strategy for system resources, e.g., files and I/O devices. At proxy migration toward a new node, the proxy bindings to system resources are voided and re-established a the arrival at the new execution environment. In particular, SCaLaDE proxies re-bind to the locally available system resources using Java local references. Our future work will extend the applicability of the policy-driven binding model also to system resources.
Figure 1 depicts the internal structure of proxy bindings to resources. When one SCaLaDE shadow proxy is first instantiated, SCaLaDE creates a resource table to record the list of proxy resource descriptors. In a more detailed view, each table entry associates a resource name RN to the corresponding resource descriptor RD along with a binding and a reference object. The binding object encapsulates the resource binding strategy to apply upon proxy resource usage on the basis of the policies currently enabled for the shadow proxy. SCaLaDE supports all the binding strategies described in Section 2, as detailed in the following. The reference object implements binding mechanisms accordingly to the required resource binding strategy. In particular, the reference object uses Java Remote Method Invocation to refer resources in the case of remote reference or rebinding strategies. For resource movement and copy movement binding strategies, the reference object exploits Java serialization mechanisms to keep valid resource bindings upon proxy migration toward a new place: either the resource object or its copy, respectively, are transmitted as a sequence of bytes to the new execution environment and rebuilt through the deserialization process upon arrival [12].
Let us note that Binder plays a crucial role in the dynamic re-adjustment of resource references upon proxy migration. When a proxy arrives at a new place, the Binder facility of the new execution environment updates, transparently to programmers, the proxy binding object to reflect possibly changes in binding
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strategies on the basis of proxy-specific binding policies. In addition, when the new incoming proxy tries to access any resource at the new place, Binder updates the proxy reference object so to modify resource binding implementation accordingly to the possibly new binding strategy. For instance, when a rebinding strategy is set, Binder exploits JINI discovery solutions to obtain information about resource availability and location without any static knowledge of the new hosting environments [13]. If several instances of the same resource type are available, it is the Binder that selects the local resource instance to bind, depending on retrieved user/terminal profiles as detailed in Section 4.
It is worth observing that in the current SCaLaDE implementation the binding decision is evaluated only at the proxy arrival at a new execution environment. This choice represents a trade-off between flexibility and efficiency in binding management. In our opinion, the assumption that proxy-specific bindings do not change while the proxy executes on the same place is reasonable and makes possible an effective implementation.
3.2.The SCaLaDE Policy Middleware
The key feature of SCaLaDE is the distinction between computational and binding aspects of mobility-enabled services. Doing so is an instance of the well-known design principle of separation of concerns. Separation of concerns in SCaLaDE is obtained via the adoption of a policy-based approach. Policies are rules governing choices in the behavior of a system separated from the components in charge of their interpretation [14]. SCaLaDE policies permit to define dynamically the most appropriate binding strategies to apply in order to adapt proxy-resource interactions to the current environment state.
As a consequence of separation of concerns, developers of SCaLaDE proxies do not have to specify at design time the type of binding to apply when the proxy uses resources. The code of MA middleware proxies contains only the directives to retrieve resource descriptors and resource invocation methods when needed. Binding strategies are all defined as policy rules externally to the proxy code; policies can be specified even at run-time with no intervention on the proxy code and are evaluated on the basis of dynamic operating conditions.
SCaLaDE expresses the binding strategies in the Ponder language, which permits the specification of several types of management policies for distributed systems and networks [15]. For instance, Ponder includes authorization policies for access control, obligation policies for proactive management, and organizational policies used to structure responsibility based on organizational models, e.g., role policies. In particular, SCaLaDE uses a subset of Ponder policies, i.e., obligation policies, to specify binding decisions. Obligation policies are declarative event-action-condition rules that define the actions that policy subjects (entities having the authority to initiate a management decision) must perform on target entities when specific events occur if specific pre-conditions hold at event occurrence. The syntax of an obligation policy is shown in Figure 2A.
When applied to binding decisions, the event clause captures a change relevant to binding management operations and the action clause specifies the method that allows
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 221 to set the type of binding strategy to activate at event occurrence. Events are related to generic changes in the system and can model any variation in the environment state. For instance, changes in binding strategies can be triggered by variations in the user/device location, by resource method invocations, or by proxy migration.
Figure 2B shows a simple example of a Ponder obligation policy for binding management. Bind1 states that when the policy subject (the MA-based ProxyID shadow proxy) arrives at a new node it should command Binder to set the proxy binding type to the “resource movement” value if the new hosting node has sufficient free space on disk (as observed by the underlying SOMA monitoring facility [16]).
Figure 2. Ponder policy syntax (A) and an example of Ponder-based binding policy (B). The SCaLaDE policy-driven binding model makes necessary the design and development of a policy middleware to support automated binding management accordingly to high-level policy specifications and transparently to proxy developers. SCaLaDE provides a set of middleware services to support the binding policy dynamic specification, modification, check for correctness, installation and enforcement. Policy enforcement consists in detecting changes in the operating environment relevant for binding management, in notifying proxies about event occurrence and in interpreting policy specifications so as to activate low-level binding management actions accordingly to desired binding strategies.
Several tools are available in SCaLaDE to assist users and administrators in the editing of Ponder well-written policies; the same tools can compile Ponder policy specifications and automatically generate lower-level policies in terms of Java objects [17]. Both Ponder policy specifications and correspondent Java objects are published in a distributed LDAP-compliant directory. It is worth noticing that conflicts between policy specifications could arise due to omissions, errors or conflicting requirements of the specifying users. Currently, SCaLaDE faces the problem of conflicts between policy specifications by relying on the solutions provided by the Ponder framework [18].
To support the policy enforcement, SCaLaDE provides the following main services:
?the Monitoring Service (MS) detects modifications in the environment state. MS can observe the state of system/application resources, from the percentage of CPU usage on one place to the allocated heap memory and the network bandwidth consumed by SOMA agent threads. MS exploits the Java Virtual Machine Profiler Interface to enable the observation of the JVM state at the
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application level, and platform-dependent monitoring modules via the Java
Native Interface to obtain visibility of resource state at the kernel level [16];?the Event Service (ES) manages and communicates the monitored variations in the whole distributed system. ES typically receives state information from MS,
possibly aggregates monitored data in higher level event objects, and notifies
events to any entity subscribed for them. Events can be viewed as high-level
objects that encapsulate information related to the changes they represent and that
can be organized in extensible hierarchies to accommodate application
requirements and environment characteristics. As a key feature, ES is designed to
take into account MA mobility and to notify events to interested entities, e.g.,
SCaLaDE proxies, even in case of agent migration;
?the Policy Manager Service (PMS) installs Java-based Ponder policies into policy subjects and enforces them at event occurrence. The PMS component consists of two modules, the Obligation Coordinator (OC) and the Obligation Enforcer (OE).
The OC module retrieves new specified policies from the distributed directory
and parses them to retrieve relevant information: object events, subjects, targets
and actions. Then, it registers the significant events to ES on behalf of policy
subjects. At event occurrence, the events are dispatched to all interested policy
subjects that trigger binding management actions. It is the OE module that
concretely enforces policies on behalf of the policy subjects. In particular, it
retrieves the proxy-specific policies, interprets policy specifications, checks
policy constraints in the system and if the verification process succeeds, extracts
the policy actions and activates their enforcement.
4.SCaLaDE at Work in Different Usage Scenarios
To illustrate how SCaLaDE supports and facilitates the development of mobility-
enabled information services, let us re-consider the different usage scenarios sketched
in Section 2. In particular, the scenarios will show how it is possible to modify the
resource binding strategy of SCaLaDE-based services, depending on requirements
specified at service provision time and on dynamic deployment conditions, without
any intervention on the code of service components.
As a case study, we have designed and implemented a Mobile News Service
(MNS) that permits the reading and browsing of news, automatically retrieved from
network servers at regular time intervals. When a user with her mobile terminal MT
requests to open an MNS session, a dedicated shadow proxy ProxyID is instantiated.
ProxyID runs on MT if MT can host a full Java Virtual Machine and a SOMA place
on top of it. Otherwise, ProxyID executes on a host on the fixed network in the same
locality where MT is currently attached. In this case, ProxyID automatically follows
the MT changes of points of attachment to maintain co-locality with its client [6].
Figure 3A shows an excerpt from the simple, reusable and binding-transparent
code of the MNSProxy class. Any shadow proxy executes the init() method at its first
instantiation. init() initializes in ProxyID a reference to an information resource called
“newspaper”. DataResource.get() produces an invocation of Binder that adds a new
line in the ProxyID ResourceTable and returns a resourceID reference to access the
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 223 resource. Up to now, we have implemented the DataResource class in SCaLaDE to support HTTP-based access to XML files written according the News Industry Text Format DTD [19]. We work on extending DataResource with other types of data sources, e.g., databases with a JDBC interface. Apart from this initialization, ProxyID repeats a user-specified query on resourceID if the state variable isConnected is set, to visualize freshly obtained results. Other ProxyID threads, not shown in the code excerpt, serve in the user browsing of the results and the insertion of new queries.
Figure 3. A code excerpt from MNSProxy (A) and Default triggered by the ProxyInit-Completed event (B).
The end of the execution of the ProxyID init() method is monitored by SCaLaDE MS to ascertain the notification of a ProxyInitCompleted event. This event triggers the enforcement of a first Default policy, shown in Figure 3B. Default specifies which is the default binding type for information resources: OE, on behalf of ProxyID, makes Binder invoke the setAgentBindingType() method to set to "remoteReference" the binding type for all resources in the ProxyID ResourceTable.
https://www.doczj.com/doc/d415764832.html,age Scenario 1: Disconnected Operations
Without any modification of the MNSProxy class, it is possible to deploy MNS to support disconnected operations, by specifying the Pol1 policy, shown in Figure 4A, at service deployment time. In any moment, the user can click a button on the MNS GUI to communicate willingness to operate disconnected from the current point of attachment. This generates a disconnectRequest event that ES notifies to ProxyID by triggering the Pol1 enforcement. ProxyID pops up a message window to ask user to wait before disconnecting MT until the resource management process is completed (the current MNS prototype implementation does not handle the physical disconnection of MT before the completion of the resource movement phase). Then, OE forces the isConnected variable to false, to set the binding type to "resourceMove" for any referenced resource in the ProxyID ResourceTable and to possibly update the corresponding reference objects. All the actions specified in Pol1 are performed only if the dynamic condition about the free space available on the MT disk is verified.
updateReferenceObjects()checks the binding type for any reference in the ProxyID ResourceTable and updates accordingly the reference objects. In particular, in case of resource movement of a resource DR, the MT-local Binder coordinates with Binder in the DR locality and requests for the DR serialization and transmission. After DR
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reception, the MT-local Binder de-serializes it and puts the (now local) DR reference in ResourceTable. In the current SCaLaDE implementation, the serializing Binder first checks whether DR is already referred by other MNSProxy objects. Only if there are no active references to DR, DR is serialized and moved; otherwise, the binding type is reset to the default "remoteReference" and DR is not accessible while disconnected. https://www.doczj.com/doc/d415764832.html,age Scenario 2: Copy Movement to the Client Locality
When MNS is deployed for mobile terminals with very limited local space on disk and in a scenario where their communications with the current locality are extremely cheaper than remote ones, the main goal is the maximization of local interaction with resource copies without disconnected operation support. To enable this, SCaLaDE service providers can simply substitute the Pol2 policy instead of Pol1 (see Figure 4B), without modifying any detail in the MNS implementation. In fact, anytime MT connects to a new point of attachment, MS senses the reconnection and delivers the corresponding connection event to ES. ES processes the reconnection events and, in particular, notifies a domainArrival event only if MT has reconnected to one SCaLaDE domain different from its previous one. The domainArrival event triggers Pol2: OE forces Binder to set the binding type to "copyMove" for any resource in the ProxyID ResourceTable and to set the isConnected variable to true.
Let us stress that Pol2 does not include any Binder action to update the reference objects in the ProxyID ResourceTable. In fact, as already stated in Section 3, Binder automatically performs the update at the first use of one ProxyID resource reference in a new locality, in order not to waste time for re-qualifying resource links not used during the ProxyID execution in one locality. Only at first resource utilization, Binder checks the corresponding resource binding type and, in case of copy movement, coordinate with the remote Binder that is local to the to-copy resource, as described in the previous scenario. In the current SCaLaDE implementation, Binder moves a copy also if the resource is already referred by other MNSProxy instances; this cannot generate inconsistencies in MNS because users can perform only read operations on data resources. To support more general mobility-enabled information services, you need to provide Binder with update merging and conflict solving functions, in order to allow concurrent modifications of distributed copies. We are currently implementing an extended Binder version that supports the consistency restoration schema proposed in [20].
https://www.doczj.com/doc/d415764832.html,age Scenario 3: Location-Dependent Information Services
A crucial added value for service provisioning in mobile scenarios is the possibility to develop and deploy services that take into account the client position and adapt their results to this location information, e.g., a location-dependent MNS version that offers local news about the current MT locality. To achieve this goal, service developers should usually re-design the service as a location-aware one that directly handles the client changes of location and dynamically discovers the locally available resources. On the contrary, SCaLaDE permits to deploy a location-dependent MNS version
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 225 simply by specifying a suitable Pol3 policy, shown in Figure 4C, without changing the MNS code.
Figure 4. Pol1 (A), Pol2 (B), and Pol3 (C) for enabling different MNS provisioning scenarios, i.e., respectively, disconnected operations, local copy movement, and location-dependent news.
The event-related mechanisms are the same as described for Pol2. In this scenario the domainArrival event triggers Pol3 and OE forces Binder to set the binding type to "rebind" for any resource in the ProxyID ResourceTable and to set isConnected. In the example shown in the figure, the actions specified in Pol3 are performed if and only if, at the moment the policy is triggered, there is a discovery server running in the new MT locality.
At the first request for resource usage by ProxyID, due to the binding type set to "re-bind", Binder performs a series of operations very different from the previous usage scenarios. In particular, in this case Binder also considers the access terminal properties (and the user preferences) to rebind MT with the most suitable DR instances in the new locality. This is crucial to permit wide heterogeneity in the hardware/software characteristics of portable devices as they roam between statically unknown hosting environments [6]. First of all, Binder retrieves the terminal/user profiles from the globally available SOMA profile directory [2]. Profiles are expressed in an interoperable XML-based format compliant with the W3C Composite Capabilities/Preferences Profile (CC/PP) specification [21]. Then, for any ResourceTable entry to rebind, Binder interrogates the local discovery service and obtains a list of locally available resources with compatible interfaces. SCaLaDE exploits the JINI discovery protocol to register/de-register resources with the visibility scope of one SCaLaDE domain [13].
If the list of locally available resources includes more items, Binder exploits the profile metadata to choose the resource to rebind. The current SCaLaDE implementation requires the discoverable resources to provide their own CC/PP profile by implementing a getProfile() method. Binder collects resource profiles and compare them with the involved terminal/user profiles; it performs simple parsing and processing operations on the attribute-value pairs contained in the profiles, and increments a score counter anytime a user/terminal profile attribute is compatible with
226 Paolo Bellavista et al.
the corresponding resource one, e.g., "Hardware/DisplayHoriz-Resolution > 320" in the terminal profile and "Hardware/DisplayHorizResolution = 400" in the resource profile. After these comparisons, Binder chooses the resource with the maximum score and updates the corresponding reference object in ResourceTable with the dynamically downloaded Jini-based client stub to the chosen information resource.
Let us finally observe that in this usage scenario the location awareness of the SCaLaDE middleware (and of its Binder component) permits to develop SCaLaDE-based distributed applications that are location-dependent from the point of view of service results but completely location-transparent in their application logic and code. This dramatically simplifies the design and implementation of location-dependent services and can significantly increase the reusability and modularity of service components.
5.Related Work
The effective design and deployment of mobility-enabled services in dynamic environments should consider novel paradigms to provide flexible binding management and its provision-time reconfiguration. While traditional services could be conceived, designed and implemented in quite fixed scenarios of environment conditions, which vary only under exceptional circumstances, novel mobile scenarios clash with static assumptions on available resources and network connections. Network topology can dynamically change, with nodes that are discontinuously connected and users that change location frequently. The conventional approach of hard-coding binding strategies into the service-specific code lacks flexibility and dynamicity. As a consequence, any mobility-enabled service should adapt its execution to all possible operating conditions where it may be deployed.
This section does not provide a general survey on the state-of-the-art solutions for achieving dynamic adaptability of services in contexts of mobility, but focuses on the few proposals that, to the best of our knowledge, explicitly deal with dynamic binding management in mobility-enabled services built with mobile-code technologies. All solutions have in common the principle of separation between binding and computational concerns: this separation is considered as the key design requirement. However, the proposals differ on how to achieve the needed separation of concerns. The approach described in [10] uses reflection for defining customizable application-level binding strategies. In particular, binding strategies are implemented as basic reusable metaobjects that can be attached to any mobile application component. Neither the developers of application components nor the designers of resources are aware of the binding strategies to apply upon component migration. Binding strategies are not embedded within the component or resource code, but implemented by metaobjects. However, the linking between application components and binding strategies is performed at the beginning of the execution, and cannot change at service provisioning time unless an execution re-start. Another interesting approach is proposed by the FarGo system that allows to program various binding relationships between FarGo entities as a separate part of the application [9]. However, similarly to [10], the binding strategies to apply can be associated to entities only at application
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 227 launching time. Our proposal has several points in common with the FarGo binding model; the main difference is in the possibility to specify binding strategies at a higher level of abstraction, to modify them even during the application execution, thus enabling dynamic changes in binding management at deployment time, transparently to service developers.
6.Conclusions and On-Going Work
The complexity of service provisioning in mobile scenarios makes more and more relevant the separation of concerns between resource binding strategies and application logic, in order to achieve a high level of dynamicity, flexibility and reusability of middleware/service components. At the state-of-the-art policy-driven middlewares represent a viable and effective solution to realize this separation. In addition, it is crucial that middleware solutions have visibility of location information to take location-dependent support decisions by freeing service developers and application-level service components from all the involved implementation issues.
First experiences in the use of SCaLaDE have shown that our middleware can significantly simplify the design and implementation of services in a wide variety of different mobile usage scenarios. These encouraging results are stimulating further research along different guidelines to improve the current prototype and to develop more complex services on top of it. In particular, we are working on extending SCaLaDE to support flexible binding management even in the case of mobile resources. In the current implementation resource consumers can autonomously migrate across the network, whereas needed resources can be copied/moved only as a result of consumer movements. This implies that service providers cannot relocate resources while shadow proxies are using them.
Another issue that we are investigating is the possibility for SCaLaDE service providers to specify policies with different priorities. When multiple binding policies are simultaneously eligible for enforcement, but only one should be activated in the system, policy priorities may help in choosing the most appropriate binding strategy. For instance, suppose that two policies apply for a resource-limited MT both commanding the MT to move two different resources on-board upon its arrival at a new locality. In the case that only one resource can be moved on-board due to limited disk space,. the choice on which resource to transfer could be driven by policy priorities. The support for precedence between policies requires to extend SCaLaDE to allow both the priority specification and the evaluation of policy precedence at run-time before activation.
In addition, we are interested in a more in depth investigation about the policy conflicts that could arise at run-time when a specific system state results in a conflict. This is still an open and challenging research area with very few solutions. Run-time conflicts are hard to detect in advance because it is extremely difficult to predict all the system possible states.
228 Paolo Bellavista et al.
Acknowledgements
This investigation is supported by the University of Bologna (Funds for Selected Research Topics: "An integrated Infrastructure to Support Secure Services"), by CNR (Funds for Young Researchers: “An Integrated Security Infrastructure for Multimedia Services”) and by MIUR within the framework of the Project “MUSIQUE: Multimedia Ubiquitous Service Infrastructure in a QoS Universal Environment". References
1.L. Capra , G. Blair, C. Mascolo, W. Emmerich, P. Grace, “Exploiting Reflection in Mobile
Computing Middleware”, to appear in ACM SIGMOBILE Mobile Computing and Communications Review.
2.P. Bellavista, A. Corradi, C. Stefanelli, "Mobile Agent Middleware for Mobile
Computing", IEEE Computer, Vol. 34, No. 3, March 2001.
3.H. Chen, A. Joshi, T. Finin. "Dynamic Service Discovery for Mobile Computing:
Intelligent Agents Meet Jini in the Aether", Baltzer Science Journal on Cluster Computing, Vol. 4, No. 4, March 2001.
4. A. Baggio, G. Ballintijn, M. van Steen, A.S. Tanenbaum, "Efficient Tracking of Mobile
Objects in Globe", The Computer Journal, Vol. 44, No. 5, 2001.
5.IKV++ Technologies AG, enago Open Service Platform, http://www.ikv.de.
6.P. Bellavista, A. Corradi, C. Stefanelli, "The Ubiquitous Provisioning of Internet Services
to Portable Devices", IEEE Pervasive Computing, Vol. 1, No. 3, Sept-Oct. 2002.
7.L. Cardelli, "Mobile Computation", in J. Vitek and C. Tschudin (eds.), Mobile Object
Systems: Towards the Programmable Internet, LNCS 1222, Springer-Verlag, 1997.
8. A. Fuggetta, G. P. Picco, G. Vigna, "Understanding Code Mobility", IEEE Trans. on
Software Engineering, Vol. 24, No. 5, May 1998.
9.O. Holder, I. Ben-Shaul, H. Gazit, "Dynamic Layout of Distributed Applications in
FarGo", 21st Int. Conf. On Software Engineering (ICSE'99), ACM Press, USA, 1999. 10. E. Tanter, J. Piquer, "Managing References upon Object Migration: Applying Separation
of Concerns", Int. Conf. Chilean Computer Science Society (SCCC'01), IEEE Press, Punta Arenas Chile, November 2001.
11.P. Bellavista, A. Corradi, C. Stefanelli, "Protection and Interoperability for Mobile
Agents: A Secure and Open Programming Environment", IEICE Transactions on Communications, Vol. E83-B, No. 5, , 2000.
12.W. Grosso, R. Eckstein (eds.), Java RMI, O'Reilly, 2001.
13.K. Arnold et al., Jini Specification, Addison Wesley Longman, 1999.
14.M. Sloman, “Policy Driven Management For Distributed Systems”, Journal of Network
and Systems Management, Vol. 2, No. 4, Plenum Press, 1994.
15.N. Damianou, et al., “The Ponder Policy Specification Language”, Proc. 2nd
International Workshop on Policies for Distributed Systems and Networks (Policy 2001), LNCS 1995, Springer Verlag, Bristol, UK, 2001.
16.P. Bellavista, A. Corradi, C. Stefanelli How to Monitor and Control Resource Usage in
Mobile Agent Systems Proc. 3rd International Symposium on Distributed Objects & Applications (DOA'01), IEEE Press, Rome, Italy, 2001.
17.R. Montanari et al., "A Policy-based Infrastructure for the Dynamic Control of Agent
Mobility", Proc. Third International Workshop on Policies for Distributed Systems and Networks (Policy 2002), IEEE Press, Monterey, CA (USA), 2002.
Policy-Driven Binding to Information Resources in Mobility-Enabled Scenarios 229 18. E. Lupu, M. Sloman , “Conflicts in Policy-Based Distributed Systems Management”,
IEEE Transactions on Software Engineering, Vol. 25, No. 6, Nov./Dec. 1999.
19.International Press Telecommunications Council, News Industry Text Format,
https://www.doczj.com/doc/d415764832.html,/
20. E. Pitoura, B. Bhargava, “Data Consistency in Intermittently Connected Distributed
Systems”, IEEE Trans. on Knowledge and Data Engineering, Vol. 11, No. 6, 1999.
21.World Wide Web Consortium, Composite Capabilities/Preferences Profile,
https://www.doczj.com/doc/d415764832.html,/Mobile/CCPP/
茶成分与健康 ----王岳飞 茶成分与健康，可以从三个方面来诠释：第一，就是茶叶中的化学成分和特征成分是什么；第二，中国茶为什么分为六大茶类；第三，环境因子对茶的品质有什么影响。 好，我们首先来看一下，整个茶叶的化学成分的总表。第一层意思，现在已经经过分离鉴定的化合物有七百多种在茶叶里面。也就是说在茶叶里的化学成分多如牛毛。 第二，我们看到有人在采茶叶或者是炒茶叶，你就可能会问他，几斤鲜叶可以做一斤茶。其实都是，四斤做一斤。为什么呢？因为水分占鲜叶的四分之三，干物质则仅占四分之一。也就是说水和干物质的比例是3:1左右。所以四斤鲜叶做一斤干茶的化学原理，就是水分的含量在75%-78%，干物质在22%--25%。这是很重要的一个成分。做到干茶以后，像龙井茶的水含量，是3%--5%.这个要求是比较高的，一般6%-7%就可以了。5%--6%，就可以达到名优绿茶的规格了。 第三，茶叶里这七百多种成分里面，含量最多的有十几类，就是课件上这些，大家看一下蛋白质的含量是多少？20%-30%。糖类中主要是纤维素，有20%-25%.第三类含量较多的是多酚类，即是茶多酚，18%-36%.脂类含量是8%。生物碱是3%-5%。氨基酸是1%-4%.在此比较重要的是，茶多酚类，生物碱和氨基酸的含量。 在此，我们可以吧这七百多种成分，十几类，分为四个层面去理解。 第一个层面叫产量成分，产量成分就是每亩地有多少茶叶产量，产量里面到底是什么成分。就是含量最高的这四种，即蛋白质，糖类，茶多酚类和脂类。这四类加起来达90%以上。1980s以前，我们出口茶叶，对一亩地的考核就是考核的茶叶产量。那时候没有名优绿茶，最重视的就是产量。1990s至今，我们的名优绿茶发展的很好，名优绿茶不讲产量，12年西湖龙井的市场价最贵三万元一斤，出口的珠茶五六块钱一斤。那么三万块钱的茶叶利润有多少？我觉得应该有25000.但是珠茶如果也卖到三万块钱一斤，它的利润可能只有250.这就是品质比产量要重要的一个实证。我们讲的这四个成分要是提高了，茶叶的产量也就提高了。可是品质主要依赖于哪个成分呢？ 品质啊，取决于，各个成分的比例关系，就好像人的五官，你像成龙的鼻子过大了，就不帅了。所以品质，一定要讲究比例协调。我们学到评茶里颜色香气味道，它的内质，是由不同的化学成分决定的。 第三个层面，是营养成分。很多人爱问，喝茶是不是营养成分很多啊？我们也都告诉别人确有很多营养成分。但是这个回答应该是对错参半的。为什么呢？什么叫营养成分呢？营养成分就是用来维持生命的，你想一下，我们不吃饭，只喝茶水能不能活？绝对不能。我们不吃饭，只喝白开水能活七天。如果喝茶水，也和白开水差不了多少。从这个层面可以感觉到，茶叶里好像营养成分确实不多啊。但是如果你把茶渣吃了，那你可能可以活下来。不过也不会活得太好。所以他的绝对量和营养成分也并不是太多。但是我为什么说对错参半呢？因为茶叶里的营养成分种类繁多。大家看一下，六大食品营养素，五类四十四种人体所必须的营养素，可见喝茶虽然维持生命是不行的，但是拿它来补充营养是可以的。 我们喝茶是为了什么呢？这就是第四个层面，功效成分。我们喝茶最主要的
Deems Taylor: The Monster 怪才他身材矮小，头却很大，与他的身材很不相称——是个满脸病容的矮子。他神经兮兮，有皮肤病，贴身穿比丝绸粗糙一点的任何衣服都会使他痛苦不堪。而且他还是个夸大妄想狂。他是个极其自负的怪人。除非事情与自己有关，否则他从来不屑对世界或世人瞧上一眼。对他来说，他不仅是世界上最重要的人物，而且在他眼里，他是惟一活在世界上的人。他认为自己是世界上最伟大的戏剧家之一、最伟大的思想家之一、最伟大的作曲家之一。听听他的谈话，仿佛他就是集莎士比亚、贝多芬、柏拉图三人于一身。想要听到他的高论十分容易，他是世上最能使人筋疲力竭的健谈者之一。同他度过一个夜晚，就是听他一个人滔滔不绝地说上一晚。有时，他才华横溢；有时，他又令人极其厌烦。但无论是妙趣横生还是枯燥无味，他的谈话只有一个主题：他自己，他自己的所思所为。他狂妄地认为自己总是正确的。任何人在最无足轻重的问题上露出丝毫的异议，都会激得他的强烈谴责。他可能会一连好几个小时滔滔不绝，千方百计地证明自己如何如何正确。有了这种使人耗尽心力的雄辩本事，听者最后都被他弄得头昏脑涨，耳朵发聋，为了图个清静，只好同意他的说法。他从来不会觉得，对于跟他接触的人来说，他和他的所作所为并不是使人产生强烈兴趣而为之倾倒的事情。他几乎对世间的任何领域都有自己的理
论，包括素食主义、戏剧、政治以及音乐。为了证实这些理论，他写小册子、写信、写书……文字成千上万，连篇累牍。他不仅写了，还出版了这些东西——所需费用通常由别人支付——而他会坐下来大声读给朋友和家人听，一读就是好几个小时。他写歌剧，但往往是刚有个故事梗概，他就邀请——或者更确切说是召集——一群朋友到家里，高声念给大家听。不是为了获得批评，而是为了获得称赞。整部剧的歌词写好后，朋友们还得再去听他高声朗读全剧。然后他就拿去发表，有时几年后才为歌词谱曲。他也像作曲家一样弹钢琴，但要多糟有多糟。然而，他却要坐在钢琴前，面对包括他那个时代最杰出的钢琴家在内的聚会人群，一小时接一小时地给他们演奏，不用说，都是他自己的作品。他有一副作曲家的嗓子，但他会把著名的歌唱家请到自己家里，为他们演唱自己的作品，还要扮演剧中所有的角色。他的情绪犹如六岁儿童，极易波动。心情不好时，他要么用力跺脚，口出狂言，要么陷入极度的忧郁，阴沉地说要去东方当和尚，了此残生。十分钟后，假如有什么事情使他高兴了，他就会冲出门去，绕着花园跑个不停，或者在沙发上跳上跳下或拿大顶。他会因爱犬死了而极度悲痛，也会残忍无情到使罗马皇帝也不寒而栗。他几乎没有丝毫责任感。他似乎不仅没有养活自己的能力，也从没想到过有这个义务。他深信这个世界应该给他一条活路。为了支持这一信念，他
必修一阅读鉴赏第一单元1.*沁园春?长沙……………………………………毛泽东3 2.诗两首雨巷…………………………………………戴望舒6 再别康桥………………………………………徐志摩8 3.大堰河--我的保姆………………………………艾青10 第二单元4.烛之武退秦师………………………………….《左传》16 5.荆轲刺秦王………………………………….《战国策》18 6.*鸿门宴……………………………………..司马迁22 第三单元7.记念刘和珍君……………………………………鲁迅27 8.小狗包弟……………………………………….巴金32 9.*记梁任公先生的一次演讲…………………………梁实秋36 第四单元10.短新闻两篇别了，“不列颠尼亚”…………………………周婷杨兴39 奥斯维辛没有什么新闻…………………………罗森塔尔41 11.包身工………………………………………..夏衍44 12.*飞向太空的航程……………………….贾永曹智白瑞雪52 必修二阅读鉴赏第一单元1.荷塘月色…………………………………..朱自清2.故都的秋…………………………………..郁达夫3.*囚绿记…………………………………..陆蠡第二单元4.《诗经》两首氓采薇5.离骚………………………………………屈原6.*《孔雀东南飞》(并序) 7.*诗三首涉江采芙蓉《古诗十九首》短歌行……………………………………曹操归园田居(其一)…………………………..陶渊明第三单元8.兰亭集序……………………………………王羲之9.赤壁赋……………………………………..苏轼10.*游褒禅山记………………………………王安石第四单元11.就任北京大学校长之演说……………………..蔡元培12.我有一个梦想………………………………马丁?路德?金1 3.*在马克思墓前的讲话…………………………恩格斯第三册阅读鉴赏第一单元1.林黛玉进贾府………………………………….曹雪芹2.祝福………………………………………..鲁迅3. *老人与海…………………………………….海明威第二单元4.蜀道难……………………………………….李白5.杜甫诗三首秋兴八首(其一) 咏怀古迹(其三) 登高6.琵琶行(并序)………………………………..白居易7.*李商隐诗两首锦瑟马嵬(其二) 第三单元8.寡人之于国也…………………………………《孟子》9.劝学……………………………………….《荀子》10.*过秦论…………………………………….贾谊11.*师说………………………………………韩愈第四单元12.动物游戏之谜………………………………..周立明13.宇宙的边疆………………………………….卡尔?萨根14.*凤蝶外传……………………………………董纯才15.*一名物理学家的教育历程……………………….加来道雄第四册阅读鉴赏第一单元1.窦娥冤………………………………………..关汉卿2.雷雨………………………………………….曹禹3.*哈姆莱特……………………………………莎士比亚第二单元4.柳永词两首望海潮(东南形胜) 雨霖铃(寒蝉凄切) 5.苏轼词两首念奴娇?赤壁怀古定风波(莫听穿林打叶声) 6.辛弃疾词两首水龙吟?登建康赏心亭永遇乐?京口北固亭怀古7.*李清照词两首醉花阴(薄雾浓云愁永昼) 声声慢(寻寻觅觅) 第三单元8.拿来主义……………………………………….鲁迅9.父母与孩子之间的爱……………………………..弗罗姆10.*短文三篇热爱生
教育资料 《短歌行》 《短歌行》赏析(林庚) 曹操这一首《短歌行》是建安时代杰出的名作，它代表着人生的两面，一方面是人生的忧患，一方面是人生的欢乐。而所谓两面也就是人生的全面。整个的人生中自然含有一个生活的态度，这就具体地表现在成为《楚辞》与《诗经》传统的产儿。它一方面不失为《楚辞》中永恒的追求，一方面不失为一个平实的生活表现，因而也就为建安诗坛铺平了道路。 这首诗从“对酒当歌，人生几何”到“但为君故，沉吟至今”，充分表现着《楚辞》里的哀怨。一方面是人生的无常，一方面是永恒的渴望。而“呦呦鹿鸣”以下四句却是尽情的欢乐。你不晓得何以由哀怨这一端忽然会走到欢乐那一端去，转折得天衣无缝，仿佛本来就该是这么一回事似的。这才是真正的人生的感受。这一段如是，下一段也如是。“明明如月，何时可掇?忧从中来，不可断绝。越陌度阡，枉用相存。契阔谈宴，心念旧恩。月明星稀，乌鹊南飞。绕树三匝，何枝可依。”缠绵的情调，把你又带回更深的哀怨中去。但“山不厌高，海不厌深”，终于走入“周公吐哺，天下归心”的结论。上下两段是一个章法，但是你并不觉得重复，你只觉得卷在悲哀与欢乐的旋涡中，不知道什么时候悲哀没有了，变成欢乐，也不知道什么时候欢乐没有了，又变成悲哀，这岂不是一个整个的人生吗?把整个的人生表现在一个刹那的感觉上，又都归于一个最实在的生活上。“我有嘉宾，鼓瑟吹笙”，不正是当时的情景吗?“周公吐哺，天下归心”，不正是当时的信心吗? “青青子衿”到“鼓瑟吹笙”两段连贯之妙，古今无二。《诗经》中现成的句法一变而有了《楚辞》的精神，全在“沉吟至今”的点窜，那是“青青子衿”的更深的解释，《诗经》与《楚辞》因此才有了更深的默契，从《楚辞》又回到《诗经》，这样与《鹿鸣》之诗乃打成一片，这是一个完满的行程，也便是人生旅程的意义。“月明星稀”何以会变成“山不厌高，海不厌深”?几乎更不可解。莫非由于“明月出天山”，“海上生明月”吗?古辞说：“枯桑知天风，海水知天寒”，枯桑何以知天风，因为它高；海水何以知天寒，因为它深。唐人诗“一叶落知天下秋”，我们对于宇宙万有正应该有一个“知”字。然则既然是山，岂可不高?既然是海，岂可不深呢?“并刀如水，吴盐胜雪”，既是刀，就应该雪亮；既是盐，就应该雪白，那么就不必问山与海了。 山海之情，成为漫漫旅程的归宿，这不但是乌鹊南飞，且成为人生的思慕。山既尽其高，海既尽其深。人在其中乃有一颗赤子的心。孟子主尽性，因此养成他浩然之气。天下所以归心，我们乃不觉得是一个夸张。 .
曹操《短歌行【对酒当歌】》原文、翻译、赏析译文 原文 面对美酒应该高歌，人生短促日月如梭。对酒当歌，人生几何？ 好比晨露转瞬即逝，失去的时日实在太多！譬如朝露，去日苦多。 席上歌声激昂慷慨，忧郁长久填满心窝。慨当以慷，忧思难忘。 靠什么来排解忧闷？唯有狂饮方可解脱。何以解忧？唯有杜康。 那穿着青领（周代学士的服装）的学子哟，你们令我朝夕思慕。青青子衿，悠悠我心。 正是因为你们的缘故，我一直低唱着《子衿》歌。但为君故，沉吟至今。 阳光下鹿群呦呦欢鸣，悠然自得啃食在绿坡。呦呦鹿鸣，食野之苹。 一旦四方贤才光临舍下，我将奏瑟吹笙宴请宾客。我有嘉宾，鼓瑟吹笙。 当空悬挂的皓月哟，你运转着，永不停止；明明如月，何时可掇？ 我久蓄于怀的忧愤哟，突然喷涌而出汇成长河。忧从中来，不可断绝。 远方宾客踏着田间小路，一个个屈驾前来探望我。越陌度阡，枉用相存。 彼此久别重逢谈心宴饮，争着将往日的情谊诉说。契阔谈讌，心念旧恩。 明月升起，星星闪烁，一群寻巢乌鹊向南飞去。月明星稀，乌鹊南飞。 绕树飞了三周却没敛绕树三匝，何枝
翅，哪里才有它们栖身之 所？ 可依？ 高山不辞土石才见巍 峨，大海不弃涓流才见壮阔。（比喻用人要“唯才是举”，多多益善。）山不厌高，水不厌深。 只有像周公那样礼待贤 才（周公见到贤才，吐出口 中正在咀嚼的食物，马上接 待。《史记》载周公自谓： “一沐三握发，一饭三吐哺， 犹恐失天下之贤。”），才 能使天下人心都归向我。 周公吐哺，天 赏析 曹操是汉末杰出的政治家、军事家和文学家，他雅好诗章，好作乐府歌辞，今存诗22首，全是乐府诗。曹操的乐府诗多描写他本人的政治主张和统一天下的雄心壮志。如他的《短歌行》，充分表达了诗人求贤若渴以及统一天下的壮志。 《短歌行》是政治性很强的诗作，主要是为曹操当时所实行的政治路线和政策策略服务的，但是作者将政治内容和意义完全熔铸在浓郁的抒情意境之中，全诗充分发挥了诗歌创作的特长，准确而巧妙地运用了比兴手法，寓理于情，以情感人。诗歌无论在思想内容还是在艺术上都取得了极高的成就，语言质朴，立意深远，气势充沛。这首带有建安时代"志深比长""梗概多气"的时代特色的《短歌行》，读后不觉思接千载，荡气回肠，受到强烈的感染。 对酒当歌，人生几何？ 譬如朝露，去日苦多。 慨当以慷，幽思难忘。 何以解忧，唯有杜康。 青青子衿，悠悠我心。 但为君故，沈吟至今。 呦呦鹿鸣，食野之苹。 我有嘉宾，鼓瑟吹笙。 明明如月，何时可掇？ 忧从中来，不可断绝。 越陌度阡，枉用相存。 契阔谈，心念旧恩。 月明星稀，乌鹊南飞， 绕树三匝，何枝可依？ 山不厌高，海不厌深， 周公吐哺，天下归心。 《短歌行》是汉乐府的旧题，属于《相和歌?平调曲》。这就是说它本来是一个乐曲的名称，这种乐曲怎么唱法，现在当然是不知道了。但乐府《相和歌?平调曲》中除了《短歌行》还有《长歌行》，唐代吴兢《乐府古题要解》引证古诗“长歌正激烈”，魏文帝曹丕《燕歌行》“短歌微吟不能长”和晋代傅玄《艳歌行》“咄来长歌续短歌”等句，认为“长歌”、“短
茶叶的主要成分 谈到饮茶的作用，要从茶叶中的主要成分说起，各种茶的主要成分是一样的，因为不管什么茶，从植物学角度来看，它们首先都是茶叶，之所以会有那么多的茶叶种类，例如楼主提到的“红茶、绿茶、茉莉花茶、铁观音、普洱”等等，一来是原料茶树所属的种略有差别，但主要还是加工方法和加工工艺的不同，一般来说，它们只会改变茶叶的口感和香气，不会改变茶叶中的成分。 茶叶中的主要成分及其作用： 1、有机酸 茶叶中有机酸种类较多，含量约为干物质的3%左右。 茶叶中的有机酸多为游离有机酸，如苹果酸、柠檬酸、琥珀酸、草酸等。在制茶过程中形成的有机酸，有棕榈酸、亚油酸、乙烯酸等。 茶叶中的有机酸是香气的主要成分之一，现已发现茶叶香气成分中有机酸的种类达25种，有些有机酸本身虽无香气，但经氧化后转化为香气成分，如亚油酸等；有些有机酸是香气成分的良好吸附剂，如棕榈酸等。 虽然茶叶中柠檬酸对人体无直接危害，但可以促进体内钙的排泄和沉积，如长期大量摄入，有可能导致低钙血症。 2、茶多酚： 茶多酚是茶叶中酚类物质及其衍生物的总称，并不是一种物质，因此常称为多酚类，约占干物质总量的20%～35%。过去茶多酚又称作茶鞣质、茶单宁。 茶多酚的功效主要有：能消除有害自由基、抗衰老、抗辐射、抑制癌细胞、抗菌杀菌、抑制艾滋病病毒。 可以与食物中的铁元素发生反应，生成难以溶解的新物质，时间一长引起人体缺铁，甚至诱发贫血症。 3、氨基酸： 分析表明，茶叶中至少含有25种氨基酸，人体必需的氨基酸是8种，茶叶中就含有6种。氨基酸是构建生物机体的众多生物活性大分子之一，是构建细胞、修复组织的基础材料。 4、蛋白质： 茶叶中的蛋白质含量占干物质量的20-30%，能溶于水直接被利用的蛋白质含量仅占1-2%，所以茶叶中蛋白质含量不是很高，这部分水溶性蛋白质是形成茶汤滋味的成分之一。 蛋白质是维持机体的生长、组成、更新和修补人体组织的重要材料,通过氧化作用为人体提供能量。 需要说明的是，蛋白质遇到茶多酚，会产生很难溶解的鞣酸蛋白，对人体不利。 5、生物碱： 茶叶中的生物碱包括咖啡碱、可可碱和条碱。其中以咖啡碱的含量最多，约占2%～5%；其他含量甚微，所以茶叶中的生物碱含量常以测定咖啡碱的含量为代表。咖啡碱易溶于水，是形成茶叶滋味的重要物质。 咖啡碱，具有兴奋大脑神经和促进心脏机能亢进的作用。过量饮（食）用，能扰乱胃液的正
Frankenstein's Monster Part 1 The story of Frankenstein Frankenstein is a young scientist/ from Geneva, in Switzerland. While studying at university, he discovers the secret of how to give life/ to lifeless matter. Using bones from dead bodies, he creates a creature/ that resembles a human being/ and gives it life. The creature, which is unusually large/ and strong, is extremely ugly, and terrifies all those/ who see it. However, the monster, who has learnt to speak, is intelligent/ and has human emotions. Lonely and unhappy, he begins to hate his creator, Frankenstein. When Frankenstein refuses to create a wife/ for him, the monster murders Frankenstein's brother, his best friend Clerval, and finally, Frankenstein's wife Elizabeth. The scientist chases the creature/ to the Arctic/ in order to destroy him, but he dies there. At the end of the story, the monster disappears into the ice/ and snow/ to end his own life. Part 2 Extract from Frankenstein It was on a cold November night/ that I saw my creation/ for the first time. Feeling very anxious, I prepared the equipment/ that would give life/ to the thing/ that lay at my feet. It was already one/ in the morning/ and the rain/ fell against the window. My candle was almost burnt out when, by its tiny light，I saw the yellow eye of the creature open. It breathed hard, and moved its arms and legs. How can I describe my emotions/ when I saw this happen? How can I describe the monster who I had worked/ so hard/ to create? I had tried to make him beautiful. Beautiful! He was the ugliest thing/ I had ever seen! You could see the veins/ beneath his yellow skin. His hair was black/ and his teeth were white. But these things contrasted horribly with his yellow eyes, his wrinkled yellow skin and black lips. I had worked/ for nearly two years/ with one aim only, to give life to a lifeless body. For this/ I had not slept, I had destroyed my health. I had wanted it more than anything/ in the world. But now/ I had finished, the beauty of the dream vanished, and horror and disgust/ filled my heart. Now/ my only thoughts were, "I wish I had not created this creature, I wish I was on the other side of the world, I wish I could disappear!” When he turned to look at me, I felt unable to stay in the same room as him. I rushed out, and /for a long time/ I walked up and down my bedroom. At last/ I threw myself on the bed/ in my clothes, trying to find a few moments of sleep. But although I slept, I had terrible dreams. I dreamt I saw my fiancée/ walking in the streets of our town. She looked well/ and happy/ but as I kissed her lips，they became pale, as if she were dead. Her face changed and I thought/ I held the body of my dead mother/ in my arms. I woke, shaking with fear. At that same moment，I saw the creature/ that I had created. He was standing/by my bed/ and watching me. His
人教版高中语文必修必背课文精编W O R D版 IBM system office room 【A0816H-A0912AAAHH-GX8Q8-GNTHHJ8】
必修1 沁园春·长沙（全文）毛泽东 独立寒秋， 湘江北去， 橘子洲头。 看万山红遍， 层林尽染， 漫江碧透， 百舸争流。 鹰击长空， 鱼翔浅底， 万类霜天竞自由。 怅寥廓， 问苍茫大地， 谁主沉浮。 携来百侣曾游， 忆往昔峥嵘岁月稠。
恰同学少年， 风华正茂， 书生意气， 挥斥方遒。 指点江山， 激扬文字， 粪土当年万户侯。 曾记否， 到中流击水， 浪遏飞舟。 雨巷（全文）戴望舒撑着油纸伞，独自 彷徨在悠长、悠长 又寂寥的雨巷， 我希望逢着 一个丁香一样地
结着愁怨的姑娘。 她是有 丁香一样的颜色， 丁香一样的芬芳， 丁香一样的忧愁， 在雨中哀怨， 哀怨又彷徨； 她彷徨在这寂寥的雨巷，撑着油纸伞 像我一样， 像我一样地 默默彳亍着 冷漠、凄清，又惆怅。她默默地走近， 走近，又投出 太息一般的眼光
她飘过 像梦一般地， 像梦一般地凄婉迷茫。像梦中飘过 一枝丁香地， 我身旁飘过这个女郎；她默默地远了，远了，到了颓圮的篱墙， 走尽这雨巷。 在雨的哀曲里， 消了她的颜色， 散了她的芬芳， 消散了，甚至她的 太息般的眼光 丁香般的惆怅。 撑着油纸伞，独自
彷徨在悠长、悠长 又寂寥的雨巷， 我希望飘过 一个丁香一样地 结着愁怨的姑娘。 再别康桥（全文）徐志摩 轻轻的我走了，正如我轻轻的来； 我轻轻的招手，作别西天的云彩。 那河畔的金柳，是夕阳中的新娘； 波光里的艳影，在我的心头荡漾。 软泥上的青荇，油油的在水底招摇； 在康河的柔波里，我甘心做一条水草！ 那榆荫下的一潭，不是清泉， 是天上虹揉碎在浮藻间，沉淀着彩虹似的梦。寻梦？撑一支长篙，向青草更青处漫溯， 满载一船星辉，在星辉斑斓里放歌。
曹操《短歌行》其二翻译及赏析 引导语：曹操(155—220)，字孟德，小名阿瞒，《短歌行 二首》 是曹操以乐府古题创作的两首诗， 第一首诗表达了作者求贤若渴的心 态，第二首诗主要是曹操向内外臣僚及天下表明心迹。 短歌行 其二 曹操 周西伯昌，怀此圣德。 三分天下，而有其二。 修奉贡献，臣节不隆。 崇侯谗之，是以拘系。 后见赦原，赐之斧钺，得使征伐。 为仲尼所称，达及德行， 犹奉事殷，论叙其美。 齐桓之功，为霸之首。 九合诸侯，一匡天下。 一匡天下，不以兵车。 正而不谲，其德传称。 孔子所叹，并称夷吾，民受其恩。 赐与庙胙，命无下拜。 小白不敢尔，天威在颜咫尺。 晋文亦霸，躬奉天王。 受赐圭瓒，钜鬯彤弓， 卢弓矢千，虎贲三百人。 威服诸侯，师之所尊。 八方闻之，名亚齐桓。 翻译 姬昌受封为西伯，具有神智和美德。殷朝土地为三份，他有其中两分。 整治贡品来进奉，不失臣子的职责。只因为崇侯进谗言，而受冤拘禁。 后因为送礼而赦免， 受赐斧钺征伐的权利。 他被孔丘称赞， 品德高尚地位显。 始终臣服殷朝帝王，美名后世流传遍。齐桓公拥周建立功业，存亡继绝为霸 首。
聚合诸侯捍卫中原，匡正天下功业千秋。号令诸侯以匡周室，主要靠的不是 武力。 行为磊落不欺诈，美德流传于身后。孔子赞美齐桓公，也称赞管仲。 百姓深受恩惠，天子赐肉与桓公，命其无拜来接受。桓公称小白不敢，天子 威严就在咫尺前。 晋文公继承来称霸，亲身尊奉周天王。周天子赏赐丰厚，仪式隆重。 接受玉器和美酒，弓矢武士三百名。晋文公声望镇诸侯，从其风者受尊重。 威名八方全传遍，名声仅次于齐桓公。佯称周王巡狩，招其天子到河阳，因 此大众议论纷纷。 赏析 《短歌行》 (“周西伯昌”)主要是曹操向内外臣僚及天下表明心 迹，当他翦灭群凶之际，功高震主之时，正所谓“君子终日乾乾，夕惕若 厉”者，但东吴孙权却瞅准时机竟上表大说天命而称臣，意在促曹操代汉 而使其失去“挟天子以令诸侯”之号召， 故曹操机敏地认识到“ 是儿欲据吾著炉上郁!”故曹操运筹谋略而赋此《短歌行 ·周西伯 昌》。 西伯姬昌在纣朝三分天下有其二的大好形势下， 犹能奉事殷纣， 故孔子盛称 “周之德， 其可谓至德也已矣。 ”但纣王亲信崇侯虎仍不免在纣王前 还要谗毁文王，并拘系于羑里。曹操举此史实，意在表明自己正在克心效法先圣 西伯姬昌，并肯定他的所作所为，谨慎惕惧，向来无愧于献帝之所赏。 并大谈西伯姬昌、齐桓公、晋文公皆曾受命“专使征伐”。而当 今天下时势与当年的西伯、齐桓、晋文之际颇相类似，天子如命他“专使 征伐”以讨不臣，乃英明之举。但他亦效西伯之德，重齐桓之功，戒晋文 之诈。然故作谦恭之辞耳，又谁知岂无更讨封赏之意乎 ?不然建安十八年(公元 213 年)五月献帝下诏曰《册魏公九锡文》，其文曰“朕闻先王并建明德， 胙之以土，分之以民，崇其宠章，备其礼物，所以藩卫王室、左右厥世也。其在 周成，管、蔡不静，惩难念功，乃使邵康公赐齐太公履，东至于海，西至于河， 南至于穆陵，北至于无棣，五侯九伯，实得征之。 世祚太师，以表东海。爰及襄王，亦有楚人不供王职，又命晋文登为侯伯， 锡以二辂、虎贲、斧钺、禾巨 鬯、弓矢，大启南阳，世作盟主。故周室之不坏， 系二国是赖。”又“今以冀州之河东、河内、魏郡、赵国、中山、常 山，巨鹿、安平、甘陵、平原凡十郡，封君为魏公。锡君玄土，苴以白茅，爰契 尔龟。”又“加君九锡，其敬听朕命。” 观汉献帝下诏《册魏公九锡文》全篇，尽叙其功，以为其功高于伊、周，而 其奖却低于齐、晋，故赐爵赐土，又加九锡，奖励空前。但曹操被奖愈高，心内 愈忧。故曹操在曾早在五十六岁写的《让县自明本志令》中谓“或者人见 孤强盛， 又性不信天命之事， 恐私心相评， 言有不逊之志， 妄相忖度， 每用耿耿。
茶的主要成分检测 一，水分 占比：茶鲜叶含水量75%~78%，干茶4%~6% 性质：含水量越高，茶叶越易变质，含量超过12%时，茶叶内部各种化学反应还在继续进行，且茶还能被氧气氧化变质。 检测方法：GBT8304-2002 二，灰分 概念：茶叶经过高温灼烧后残留下的无机物质的统称。 占比：4%~7%。灰分含量过高，茶品质越差，灰度中可溶性部分含量越高，茶的品质越好。 检测方法：
三，茶多酚 概念：茶叶中30多种酚类物质的总称。 占比：占鲜叶干物质的33% 组成： 1，儿茶素：含量最高，占多酚类物质的70%~80%，具有收敛性，苦涩味较重。 2，黄酮类物质：又叫花黄素 3，花青素：又叫花色素，具有明显的苦味，在干旱高温季节容易形成并积累，因此夏茶具有明显的苦涩味。 4，酚酸：含量较小，味苦涩。 检测方法： GB/T 8313-2002 茶叶中多酚类物质能与亚铁离子形成紫褐色络合物，用分光光度法测定其含量。四，蛋白质和氨基酸
蛋白质： 1，组成：谷蛋白（含量最大），白蛋白（溶于水，对茶汤滋味起到积极作用），球蛋白，精蛋白组成。 2，性质：在鲜叶加工中，部分蛋白质可以分解为氨基酸，具有花香和鲜味。 氨基酸 1，性质：溶于水，具有鲜爽味，决定着茶汤的品质的鲜爽度。 2，组成：茶氨酸（占比50%以上，嫩芽嫩茎中占比最大）天门冬氨酸，谷氨酸，精氨酸，丝氨酸 检测方法： 凯氏定氨法测定茶叶中蛋白质 试剂及主要仪器 1、浓硫酸(AR) 2、硫酸钾(AR) 3、硫酸铜(AR) 4、3.0%NaOH溶液 5、2%硼酸溶液 6、0.05mol/L的标准HCL溶液 7、0.1%混合指示剂：0.1%甲基红酒精溶液和0.1%甲基蓝酒精溶液，按1:1混合。上海创赛提供甲基红指示剂盒，商品编号：C015217-5ml*2，价格20元。 8、微量凯氏定氨仪 处理样品 准确称取样品2g，小心移入烧瓶中，再CuSO4 1g,K2SO4 10g和浓H2S04 50mL.用电炉加热消化至液体变成蓝绿透明后，冷却，定容至100mL。上海创赛提供2-溴
Unit 7 The Monster Deems Taylor 1He was an undersized little man, with a head too big for his body ― a sickly little man. His nerves were bad. He had skin trouble. It was agony for him to wear anything next to his skin coarser than silk. And he had delusions of grandeur. 2He was a monster of conceit. Never for one minute did he look at the world or at people, except in relation to himself. He believed himself to be one of the greatest dramatists in the world, one of the greatest thinkers, and one of the greatest composers. To hear him talk, he was Shakespeare, and Beethoven, and Plato, rolled into one. He was one of the most exhausting conversationalists that ever lived. Sometimes he was brilliant; sometimes he was maddeningly tiresome. But whether he was being brilliant or dull, he had one sole topic of conversation: himself. What he thought and what he did. 3He had a mania for being in the right. The slightest hint of disagreement, from anyone, on the most trivial point, was enough to set him off on a harangue that might last for hours, in which he proved himself right in so many ways, and with such exhausting volubility, that in the end his hearer, stunned and deafened, would agree with him, for the sake of peace. 4It never occurred to him that he and his doing were not of the most intense and fascinating interest to anyone with whom he came in contact. He had theories about almost any subject under the sun, including vegetarianism, the drama, politics, and music; and in support of these theories he wrote pamphlets, letters, books ... thousands upon thousands of words, hundreds and hundreds of pages. He not only wrote these things, and published them ― usually at somebody else’s expense ― but he would sit and read them aloud, for hours, to his friends, and his family. 5He had the emotional stability of a six-year-old child. When he felt out of sorts, he would rave and stamp, or sink into suicidal gloom and talk darkly of going to the East to end his days as a Buddhist monk. Ten minutes later, when something pleased him he would rush out of doors and run around the garden, or jump up and down off the sofa, or stand on his head. He could be grief-stricken over the death of a pet dog, and could be callous and heartless to a degree that would have made a Roman emperor shudder. 6He was almost innocent of any sense of responsibility. He was convinced that
高中语文必修一背诵篇目 1、《沁园春长沙》毛泽东 独立寒秋，湘江北去，橘子洲头。 看万山红遍，层林尽染；漫江碧透，百舸争流。 鹰击长空，鱼翔浅底，万类霜天竞自由。 怅寥廓，问苍茫大地，谁主沉浮？ 携来百侣曾游，忆往昔峥嵘岁月稠。 恰同学少年，风华正茂；书生意气，挥斥方遒。 指点江山，激扬文字，粪土当年万户侯。 曾记否，到中流击水，浪遏飞舟？ 2、《诗两首》 （1）、《雨巷》戴望舒 撑着油纸伞，独自 /彷徨在悠长、悠长/又寂寥的雨巷， 我希望逢着 /一个丁香一样的 /结着愁怨的姑娘。 她是有 /丁香一样的颜色，/丁香一样的芬芳， /丁香一样的忧愁， 在雨中哀怨， /哀怨又彷徨； /她彷徨在这寂寥的雨巷， 撑着油纸伞 /像我一样， /像我一样地 /默默彳亍着 冷漠、凄清，又惆怅。 /她静默地走近/走近，又投出 太息一般的眼光，/她飘过 /像梦一般地， /像梦一般地凄婉迷茫。 像梦中飘过 /一枝丁香的， /我身旁飘过这女郎； 她静默地远了，远了，/到了颓圮的篱墙， /走尽这雨巷。 在雨的哀曲里， /消了她的颜色， /散了她的芬芳， /消散了，甚至她的 太息般的眼光， /丁香般的惆怅/撑着油纸伞，独自 /彷徨在悠长，悠长 又寂寥的雨巷， /我希望飘过 /一个丁香一样的 /结着愁怨的姑娘。 （2）、《再别康桥》徐志摩 轻轻的我走了， /正如我轻轻的来； /我轻轻的招手， /作别西天的云彩。 那河畔的金柳， /是夕阳中的新娘； /波光里的艳影， /在我的心头荡漾。 软泥上的青荇， /油油的在水底招摇； /在康河的柔波里， /我甘心做一条水草！那榆阴下的一潭， /不是清泉，是天上虹 /揉碎在浮藻间， /沉淀着彩虹似的梦。寻梦？撑一支长篙， /向青草更青处漫溯， /满载一船星辉， /在星辉斑斓里放歌。但我不能放歌， /悄悄是别离的笙箫； /夏虫也为我沉默， / 沉默是今晚的康桥！悄悄的我走了， /正如我悄悄的来；/我挥一挥衣袖， /不带走一片云彩。 4、《荆轲刺秦王》 太子及宾客知其事者，皆白衣冠以送之。至易水上，既祖，取道。高渐离击筑，荆轲和而歌，为变徵之声，士皆垂泪涕泣。又前而为歌曰：“风萧萧兮易水寒，壮士一去兮不复还！”复为慷慨羽声，士皆瞋目，发尽上指冠。于是荆轲遂就车而去，终已不顾。 5、《记念刘和珍君》鲁迅 （1）、真的猛士，敢于直面惨淡的人生，敢于正视淋漓的鲜血。这是怎样的哀痛者和幸福者？然而造化又常常为庸人设计，以时间的流驶，来洗涤旧迹，仅使留下淡红的血色和微漠的悲哀。在这淡红的血色和微漠的悲哀中，又给人暂得偷生，维持着这似人非人的世界。我不知道这样的世界何时是一个尽头！
必修1 沁园春·长沙（全文）毛泽东 独立寒秋， 湘江北去， 橘子洲头。 看万山红遍， 层林尽染， 漫江碧透， 百舸争流。 鹰击长空， 鱼翔浅底， 万类霜天竞自由。 怅寥廓， 问苍茫大地， 谁主沉浮。 携来百侣曾游， 忆往昔峥嵘岁月稠。 恰同学少年， 风华正茂， 书生意气， 挥斥方遒。 指点江山， 激扬文字， 粪土当年万户侯。 曾记否， 到中流击水， 浪遏飞舟。 雨巷（全文）戴望舒 撑着油纸伞，独自 彷徨在悠长、悠长 又寂寥的雨巷， 我希望逢着 一个丁香一样地 结着愁怨的姑娘。 她是有 丁香一样的颜色， 丁香一样的芬芳， 丁香一样的忧愁， 在雨中哀怨， 哀怨又彷徨；
她彷徨在这寂寥的雨巷， 撑着油纸伞 像我一样， 像我一样地 默默彳亍着 冷漠、凄清，又惆怅。 她默默地走近， 走近，又投出 太息一般的眼光 她飘过 像梦一般地， 像梦一般地凄婉迷茫。 像梦中飘过 一枝丁香地， 我身旁飘过这个女郎； 她默默地远了，远了， 到了颓圮的篱墙， 走尽这雨巷。 在雨的哀曲里， 消了她的颜色， 散了她的芬芳， 消散了，甚至她的 太息般的眼光 丁香般的惆怅。 撑着油纸伞，独自 彷徨在悠长、悠长 又寂寥的雨巷， 我希望飘过 一个丁香一样地 结着愁怨的姑娘。 再别康桥（全文）徐志摩 轻轻的我走了，正如我轻轻的来；我轻轻的招手，作别西天的云彩。 那河畔的金柳，是夕阳中的新娘；波光里的艳影，在我的心头荡漾。 软泥上的青荇，油油的在水底招摇；
在康河的柔波里，我甘心做一条水草！ 那榆荫下的一潭，不是清泉， 是天上虹揉碎在浮藻间，沉淀着彩虹似的梦。 寻梦？撑一支长篙，向青草更青处漫溯， 满载一船星辉，在星辉斑斓里放歌。 但我不能放歌，悄悄是别离的笙箫； 夏虫也为我沉默，沉默是今晚的康桥。 悄悄的我走了，正如我悄悄的来； 我挥一挥衣袖，不带走一片云彩。 记念刘和珍君（二、四节）鲁迅 二 真的猛士，敢于直面惨淡的人生，敢于正视淋漓的鲜血。这是怎样的哀痛者和幸福者？然而造化又常常为庸人设计，以时间的流驶，来洗涤旧迹，仅使留下淡红的血色和微漠的悲哀。在这淡红的血色和微漠的悲哀中，又给人暂得偷生，维持着这似人非人的世界。我不知道这样的世界何时是一个尽头！ 我们还在这样的世上活着；我也早觉得有写一点东西的必要了。离三月十八日也已有两星期，忘却的救主快要降临了罢，我正有写一点东西的必要了。 四 我在十八日早晨，才知道上午有群众向执政府请愿的事；下午便得到噩耗，说卫队居然开枪，死伤至数百人，而刘和珍君即在遇害者之列。但我对于这些传说，竟至于颇为怀疑。我向来是不惮以最坏的恶意，来推测中国人的，然而我还不料，也不信竟会下劣凶残到这地步。况且始终微笑着的和蔼的刘和珍君，更何至于无端在府门前喋血呢？ 然而即日证明是事实了，作证的便是她自己的尸骸。还有一具，是杨德群君的。而且又证明着这不但是杀害，简直是虐杀，因为身体上还有棍棒的伤痕。 但段政府就有令，说她们是“暴徒”！ 但接着就有流言，说她们是受人利用的。 惨象，已使我目不忍视了；流言，尤使我耳不忍闻。我还有什么话可说呢？我懂得衰亡民族之所以默无声息的缘由了。沉默啊，沉默啊！不在沉默中爆发，就在沉默中灭亡。