CN104636213A - Degradation service replacing technology enhancing SOA survivability - Google Patents

Abstract

The invention discloses a survivability system to solve the problems that all software will break down inescapably. Within the emergency repairing time from malfunction starting to normal work recovering of a system, an available candidate service needs to be found for successful implementation of service replacing. The service is provided with an exchanging protocol and has a flow form. A grey box strategy is adopted, and a message exchanging behavior of the service is described by describing a receiving/sending message sequence allowed by the exchanging service. Exchanging behaviors allowed by member services are described by describing a contract of a service system. Service compatibility is defined as the executable completion attribute of a combined system. An attached map describes degradation replacing of BPEL flow form services.

Description

A kind of degraded service replacement technology strengthening SOA biological treatability

Technical field:

The invention belongs to degraded service technology, wherein relate to SOA framework technology and degraded service algorithm etc.

Background technology:

, all can inevitably there are some faults in any software systems.SOA service system is no exception.System is recovered in this emergency repair time of normal work from breaking down to, it is find rapidly available candidate service that the ultimate challenge faced is replaced in successful implementation service.Especially, be difficult to find rapidly and be replaced the candidate service of serving equivalent.

But for a critical system, in fault correction time, desired is not that whole system does not thoroughly work, but a system with biological treatability.That is, system need not be operated in normal condition, but still can continue the service providing limited function, especially provides kernel service.In emergency circumstances this, allowing degraded service to replace is one of main emergency measure.

In this biological treatability environment, the problem that degraded service is replaced is, implementing the system after replacing still can keep Service Compatible to take what fallback relationship theory to ensure.

Be suitable for scene:

The present invention be directed to the degradation replacement judgement with interaction protocol, Process flow service, i.e. WS-BPEL flow services.For replacement service and candidate service, and the context environmental of Services Composition and replacement, the Message Opcode on its service interface, interface and message interaction protocol are known.

Summary of the invention:

The present invention be directed to any software all unavoidably to break down, system is recovered in the emergency repair time of normal work from breaking down to, successful implementation service is replaced and needed to find available candidate service, reaches a kind of system of biological treatability.It is the service with interaction protocol, Process flow.Adopting grey box strategy, by describing reception/transmission message sequence that interactive service allows, portraying the interacting message behavior of service.By describing the contract of service system, portray admissible interbehavior between member service.What Service Compatible was defined as combined system can complete attribute.

1, after mark enforcement replacement, the degraded service of influential system compatibility is not replaced;

Can the system after 2, mark implements replacement meet user's requirement

Accompanying drawing illustrates:

The degradation that accompanying drawing 1 is served for BPEL Process flow is replaced;

Accompanying drawing 2 is contract of service operational semantics rule;

Embodiment:

The first, formalized description WS-BPEL serves

Adopt π to calculate description WS-BPEL flow services (i.e. contract of service) C, concrete syntax is as follows:

C：|O|π.C|C+C|C|C|new x C|rec x.x|c\x

Here, x represents an interface of flow services.X (m) represents transmission Message Opcode, namely initiates a message along interface x; represent receipt message operation, namely along interface x receipt message; τ represents the built-in function not having interacting message.

The operational semantics of contract of service refers to accompanying drawing 1.Wherein, c ' is evolved into after representing contract of service executable operations λ.C x represent hide operation, mean in Message Opcode x become τ.That is, when multiple Services Composition becomes a service system, some service only may provide part of interface, and some interface and message-related operations thereof to become inside not observable.

The second, the degraded service of compatibility is kept to replace

One group of WS-BPEL flow services combination, is designated as system.System has met compatible attribute, is designated as if one of following condition is set up:

(1) if self-contained system, for any p ¹consequently

(2) if open system, for any ω consequently exist ω ' so that

In WS-BPEL flow services interactive environment, distinguish the decision point of three class contracts of service:

1, the decision point sending Message Opcode is only had;

2, the decision point accepting Message Opcode is only had;

3, comprise the decision point sending Message Opcode and accept Message Opcode simultaneously.

Wherein, the 3rd class flow process decision point refers to the transmission Message Opcode of same service interface and accepts Message Opcode.

A WS-BPEL flow services contract C ₂another contract of service C ₁sub-contract, be designated as, if following condition set up:

1. if C ₁a decision point (namely top layer operation is a selection), so C ₂also be one and C ₁there is the decision point of identical type;

2. for each receipt message operation x (m) so that exist consequently;

3. for each transmission Message Opcode consequently exist consequently.

In above-mentioned condition, there is both condition (1) requires the decision point of identical type; Condition (2) requires that sub-contract can not provide the ability of less receipt message; Condition (3) requires that sub-contract can not have less decisive selection of transmission message.Recursive condition describes the requirement to order of operation in interaction protocol.

If, WS-BPEL flow services contract C ₂c ₁sub-contract, so, for identical running environment, C ₂replace C ₁after do not change that system is original completes attribute, that is:

If C ₂| C, so, after the sub-contract of use implements replacement, a system still can the original compatibility of keeping system.

But, because the replacement using sub-contract to implement is that non-equivalence is replaced, so some service behavior of system may be affected.This impact is divided into two aspects:

If the first, sub-contract provides more message receipt capability, and has identical transmission message nonlinearity selection, and so, this replaces the operation of not influential system, and system will have more service ability.

If the second, sub-contract provides more message receipt capability, but the nonlinearity sending message is selected to reduce, and namely sends less message, and so, replacement can produce the impact of two aspects on the global behavior of system, that is:

1. less message set;

2. less completed calculating path.

The degraded service of three, meeting consumers' demand is replaced

Here, describe degraded service with the contract of service (preserved contract) retained and replace the systemic-function that rear user expects reservation, be designated as prsv (p).Wherein, be WS-BPEL flow services system.According to the requirement that correct service is replaced, service implementation must meet after replacing

Order wherein, C _iwS-BPEL flow services contract, and $P\⇒0,\mathrm{prsv}\left(p\right)\⇒0.$ For arbitrarily, $\mathrm{prsv}\left(P\right[\frac{C_i^{\′}}{C_i}\left]\right)\⇒0$ If following condition is set up:

(1)；C′ _i|C _i

(2) for each message transmit operation consequently, at C ' _iin also exist

Claims (3)

1. one kind strengthens the feature of the degraded service replacement of SOA biological treatability:

(1) degradation of BPEL Process flow service is replaced;

(2) flow process of the degradation replacement of BPEL Process flow service.

2. the degradation that the BPEL Process flow required according to right 1 is served is replaced.

3. the flow process that the degradation that the BPEL Process flow required according to right 1 is served is replaced.